SDA crossover upgrades

[Mr. Bubbles]

This post is not really for you "hardcore " guys out there with unlimited budgets but more for the guys on a budget considering crossover upgrades.

This upgrade was done on a pair of SDA SRS's. I am sure there are better components than what I used but i was on a tight budget and felt that most any decent quality components must be an improvement over 25 year old stock components.

I searched many sites and brands and settled on the Dayton 1% metalized poly caps for all caps directly in the signal path and standard Dayton metalized poly's for all shunt capacitors. The only exception was that for the 4.4 micro farad i used a 4micro farad 1% metalized poly paralleled with (2) 2.2 microfarad film and foil Daytons to get as close to the 4.4 as possible. I debated heavily over the resistors as price was somewhat closer on these but finally decided on the Daytons as well due to total overall cost with resistors included. however budget did allow enough that i doubled all resistors to a parallel pair for the correct resistance, ie, 15ohm resistor was created with two 30ohm's in parallel. I did this to increase the increase the wattage limits so as to keep heat in the resistors (and therefore distortion) down after periods of higher volume levels.

I first replaced the resistors in the right cabinet. I then listened to the speakers in both cabinets in stereo and mono. I could hear a very slight improvement in the right cabinet. I would like to repeat, VERY SLIGHT. Resistors by themselves; definitely worth the money, but maybe not the time and effort. I then replaced the caps in the right cabinet and listened again. MUCH more detail and clarity. bass extension seems more prominent. let me not confuse anyone however, I use the word more as a description of my impression but it was not really that there was more of anything that was/ wasn't there before but LESS of the characteristics that masked these things, Almost like a haze was removed. Even my wife could hear the difference. The balance seemed to now shift towards the right cabinet slightly. I then upgraded all the same components in the left cabinet. DEFINITELY worth the time and money with the parts I used. As mentioned before i know that there are better parts out there but I am unfamiliar with how much better they may have sounded with those parts. I plan on trying more esoteric components in my 2A's as well as components such as these in the 2A's as well for comparison purposes.

Now let me tell you what i did NOT do. I changed no inductors. I did not change the 92uf cap in the shunt circuit for the tweets, and i did not change the pair of 130uf caps in the dimensional circuit. I realize that the mid range/mid-bass sound will be greatly effected by the 130's and now that I have changed the shunt caps in the stereo and dimensional circuits I realize the shunt cap in the tweet section would make a significant difference too. the reason i did not change these is that i am going to experiment with changing this crossover to match that of the 1.2's. it is actually MUCH cheaper to convert this to a 1.2 crossover than it is to update all the large caps mentioned here. Note here that my cost is further reduced as i have a good many quality inductors form my car stereo years, and happen to have the 2 1.25mH that I need to make this change. For that reason i am going to be trying this in the near future (in fact i ordered all of the necessary additional components to do this when i ordered the parts for this upgrade). if I like it then I have a better system and saved money. if i don't like it i can then order the parts and upgrade those circuits as well. The designs between these 2 models is virtually the same with only a few minor changes and the dimensional circuits are almost identical in crossover values except for the high pass circuit used in the SRS and it's absence in the 1.2. i will update on this when i try it. Before then, I would like to get some listening time in with the current upgrade so I can be sure of what i hear between the 2 crossover designs.

For now i have noticed a nice improvement in sound and hope to continue to do so as these components break in.

For those of you on a budget and having the ability to do your own work, this is a worthwhile investment. I only spent $120 including the parts for the future experimentation/ upgrade. Thought the more esoteric components may sound better (I am not sure) you need not spend $400-$500 to perform this upgrade and get good results. so if money is tight don't worry that you can not afford those high priced parts. use a GOOD affordable part and you will have a worthwhile improvement without breaking the bank.

[heiney9]

Mills makes the exact values for the resistors you needed that are 12W and more than enough and @ only $4.25 those are awesome sounding resistors. You don't mention cost or type of resistor used? Mills are non-negotiable whenever I do upgrades beause they make quite a difference over stock or cheap resistors. If I was going to go all out I'd look at Dueland. Otherwise, nice write up and I'm sure an equally nice job, but we need photos or it didn't happen :razz::mrgreen:

An SRS is still not a 1.2 even if you could mess with the x-over.

H9

[Joe08867]

15ohm resistor was created with two 30ohm's in parallel. I did this to increase the increase the wattage limits so as to keep heat in the resistors (and therefore distortion) down after periods of higher volume levels.

I have seen a few people do this. It was more prevelant in car audio than home audio but i look forward to you findings.

Give those caps and such about 300hrs to break in before you make any real judgements. I do hope the Dayton's aren't as harsh as when I did them on my SDA2's. Cost me more in the long run as I redid the crossovers again with Sonicaps.

[Mr. Bubbles]

You don't mention cost or type of resistor used?

Sorry, I mentioned they are Daytons but am unsure if Dayton makes different ones. They came from parts Express and are the only Dayton resistors they had. They are 10W 2% values. If this is fairly accurate they are much tighter than the original 10%. Stock was 5W and now with my set up they are effectively 20W at each resistor location. this should keep heat way down. Cost was .98 each. This was part of my decision to use the multiples in parallel; even at 2 (a couple had 3) at each location total cost was still a good bit below using the Mills (as far as my budget was concerned).


but we need photos or it didn't happen

Will get some pictures and detailed parts list. I was just excited about it this morning and wanted to share with those that may have some of the same enthusiasm I do (unlike my wife).


An SRS is still not a 1.2 even if you could mess with the x-over.

Agreed.... somewhat. But neither is a 1.2 a 1.2TL, just as it was not produced that way from the factory. We have been through this before, and we will just have to agree that we both see this issue differently. As a note though, I am not looking for a label here so much as i am the best sound I can get from these speakers.


Give those caps and such about 300hrs to break in before you make any real judgements. I do hope the Dayton's aren't as harsh as when I did them on my SDA2's. Cost me more in the long run as I redid the crossovers again with Sonicaps.

They're not what I would describe as harsh currently but could be after break-in. Also I have no reference of comparison to the Sonicaps at this point. I realize i may desire to change these again later but I wanted to do something to help them out as I was fairly disappointed in them as compared to my 2A's. I am not sure i will ever prefer these to the 2A's as just like preamps, amps etc, the simpler more basic, circuits usually sound better to my ears. I am anxious to hear how these change with time/ break-in.

[Joe08867]

What are you driving these SRS's with? I ask just because you still seem to like your SDA2's more. I am a huge fan of SDA2's but driven correctly and in the right room SRS's, 1.2's or 1.2TL's are really hard to beat.

I agree with H9 on the SRS's will not be 1.2's but hope you enjoy the trip you are taking nonetheless.

[heiney9]

I have to say at some point give the Mills a listen, wire wound non-inductive do sound better than a typical .75c - $1.25 resistor. Again, not diminishing what you've done so far. I understand being on a budget and what not.

H9

[Mr. Bubbles]

What are you driving these SRS's with? I ask just because you still seem to like your SDA2's more. I am a huge fan of SDA2's but driven correctly and in the right room SRS's, 1.2's or 1.2TL's are really hard to beat.

I agree with H9 on the SRS's will not be 1.2's but hope you enjoy the trip you are taking nonetheless.

Currently using an Adcom setup with GFA555ll amplifier. Don't get me wrong, I am liking the SRS's much better as I have now done a lot to them, Re-sealed cabinets, re-wired internally with 12awg on all mid-woofer circuits, binding posts for interconnect, Dynamatted baskets, new gaskets, T-nuts, and epoxied magnets to baskets. Now the crossover upgrades. I am enjoying them, but if I had to choose one pair it would still be the 2's. I just think they have a less colored sound.

I agree that the SRS's will not be 1.2's no matter what you do to them. I am not looking to have a speaker with any particular badge, just the best sound i can get with what I have. A modded SRS is still a modded SRS even if it has a 1.2 crossover in it. If it didn't come from the factory that way it is still what the factory made it, just a modded version. But a 1.2 crossover is a 1.2 crossover even if it is inside a pair of Realistic cabinets.

[DarqueKnight]

Now let me tell you what i did NOT do. I changed no inductors.


Note here that my cost is further reduced as i have a good many quality inductors form my car stereo years, and happen to have the 2 1.25mH that I need to make this change.

When changing inductors, the inductance value as well as the DC resistance (DCR) value must be considered. With the exception of the large inductor in the SDA circuit, Polk does not recomment changing inductors. If you do change the smaller inductors, you must take care to choose inductors with the same DCR values as the originals. Polk does recommend a lower DCR inductor in the SDA circuit. See this thread for additional information:

Improvements-To-Modified-SDA-SRS-1.2TL-Crossover (http://www.polkaudio.com/forums/showthread.php?109611-Improvements-To-Modified-SDA-SRS-1.2TL-Crossover)


The designs between these 2 models is virtually the same with only a few minor changes and the dimensional circuits are almost identical in crossover values except for the high pass circuit used in the SRS and it's absence in the 1.2.

No. The SRS and 1.2 are entirely different designs.


the reason i did not change these is that i am going to experiment with changing this crossover to match that of the 1.2's. it is actually MUCH cheaper to convert this to a 1.2 crossover than it is to update all the large caps mentioned here.

The 1.2 crossover was designed for the drivers and cabinet used in the 1.2. The SRS uses different drivers and a different cabinet. The cabinets have very different acoustic characteristics. All the parts of a speaker system (cabinet, crossover, drivers) are designed to work together. Simply replacing the SRS crossover with a 1.2 crossover is not recommended and could possibly damage the drivers. The only SDA models with interchangeable crossovers are the 1987 versions of the SDA 2B and SDA CRS+ and the 1989 versions of the SDA 2B and SDA CRS+.



Agreed.... somewhat. But neither is a 1.2 a 1.2TL, just as it was not produced that way from the factory. We have been through this before, and we will just have to agree that we both see this issue differently.

An SRS can be significantly improved, but it cannot be converted to a 1.2 or 1.2TL. The original SRS is an entirely different speaker, even down to the cabinet design. See these threads for additional information:

Improvements-to-the-SDA-SRS (http://www.polkaudio.com/forums/showthread.php?19053-Improvements-to-the-SDA-SRS)

Further-Improvements-to-the-SDA-SRS-Custom-PCB-and-SDA-Inductor&p=1488234 (http://www.polkaudio.com/forums/showthread.php?111239-Further-Improvements-to-the-SDA-SRS-Custom-PCB-and-SDA-Inductor&p=1488234)

A 1.2 can be converted to a 1.2TL. Polk used to sell a conversion kit.

[Mr. Bubbles]

wire wound non-inductive do sound better than a typical .75c - $1.25 resistor

The Daytons I got are labeled as non-inductive but I don't know much else about their makeup.

[heiney9]

The Daytons I got are labeled as non-inductive but I don't know much else about their makeup.

In my listening experience the Daytons have a fairly noticeable upward slope at the higher frequencies and had a tad bit of grain compared to the Mills, which is smoother and more flat at the upper frequencies. Of course we all hear differently and listen for different things.

H9

[Mr. Bubbles]

DK thanks for the link.


No. The SRS and 1.2 are entirely different designs.


The 1.2 crossover was designed for the drivers and cabinet used in the 1.2. The SRS uses different drivers and a different cabinet. The cabinets have very different acoustic characteristics. All the parts of a speaker system (cabinet, crossover, drivers) are designed to work together. Simply replacing the SRS crossover with a 1.2 crossover is not recommended and could possibly damage the drivers. The only SDA models with interchangeable crossovers are the 1987 versions of the SDA 2B and SDA CRS+ and the 1989 versions of the SDA 2B and SDA CRS+.

yes they are different models but not entirely. Cabinet volume is the same even though the different drivers are used, but internally the cabinet is different with the bracing structure. The dimensional crossover is virtually identical with the exception of the high-pass circuit in the SRS and its absence in the 1.2. the dimensional circuit is switched from a direct positive signal connection (which is electrically inverted) in the SRS to the dimensional drivers being connected through each other (electrically inverted) in the 1.2. the other components have all the same values. Yes the caps and inductors re different values individually but a 1.25mh inductor in series with another 1.25mH inductor (as connected from one cabinet to the other) is equivalent to a 2.5mH inductor, and a 40uf cap in series with a 40uf cap is equivalent to a 20uf cap. So, even though the drivers are different and I am sure have somewhat different sound characteristics, Polk found that they should use the same effective crossover components, and therefore theoretically even the drivers would be interchangeable. This is easily converted from one style to the other with the correct parts. the tweeter circuits are also very, very similar. even in the TL version that simply has varied values to accommodate the different electrical properties of the tweets, making it very simple to adapt the 198's into even the SRS's if desired. I am sure this will stir some controversy But technically speaking all three of these models are very similar with only minor upgrades in each (electrically and mechanically speaking of course).


An SRS can be significantly improved, but it cannot be converted to a 1.2 or 1.2TL. The original SRS is an entirely different speaker, even down to the cabinet design. See these threads for additional information:


Again I'm not trying to make a 1.2 or TL out of my SRS's just trying to get the best sound from these speakers and i am not comfortable being limited to what others done in the past. many times i can not do any better but sometimes I can. However, these are NOT, Entirely different, but quite the contrary.


A 1.2 can be converted to a 1.2TL. Polk used to sell a conversion kit.

Still just a converted 1.2 using the logic outlined here, and not a real 1.2TL. However i somewhat disagree with this logic. I believe that if it looks like a car and rides like a car it is a car no matter if it is made from tractor parts.

[Mr. Bubbles]

In my listening experience the Daytons have a fairly noticeable upward slope at the higher frequencies and had a tad bit of grain compared to the Mills, which is smoother and more flat at the upper frequencies. Of course we all hear differently and listen for different things.

thanks for the description, that may help me in my listening tto these if i seem to notice some detail like that. i have no experience as of yet with the Mills, but maybe in the future.

[nooshinjohn]

I believe that if it looks like a car and rides like a car it is a car no matter if it is made from tractor parts.

Enzo Ferrari would say that you described a Lamborghini perfectly!:cheesygrin:

[Toolfan66]

The 1.2 and 1.2tl cabinets are the same except a couple added braces along the back wall, the crossover boards are the same as well along with the drivers. the only difference is the tweeters and a couple different values in the xovers. converting a 1.2 to a 1.2tl is a 1.2tl speaker..

[heiney9]

Oliver, why would you use a x-over that is designed for different drivers than what is currently in your SDA's? I don't get that. You say you want them to be the best they can be, how do you know the changes you make based on the 1.2 x-over will work with the drivers in the SRS's? Don't you think using different drivers and a different x-over in the 1.2's were done for a reason. You'd be better off changing the caps you didn't change and leaving it stock. That will make SRS's the best they can be.

Again, just trying to have a discussion about what you're thinking, etc. Not being critical or negative.

[Joe08867]

You make a good point H9. I would be cautious about using a 1.2 or 1.2tl crossover on SRS's without also changing out the drivers that do not match.

I do applaud your efforts, though I wonder if it will not be what you are hoping for.

[heiney9]

I believe that if it looks like a car and rides like a car it is a car no matter if it is made from tractor parts.

That's simply ridiculous, that means to you a Hyundai and Ferrari are the exact same thing. They aren't and that logic is just a little bit silly, IMO.

[Mr. Bubbles]

Oliver, why would you use a x-over that is designed for different drivers than what is currently in your SDA's? I don't get that. You say you want them to be the best they can be, how do you know the changes you make based on the 1.2 x-over will work with the drivers in the SRS's? Don't you think using different drivers and a different x-over in the 1.2's were done for a reason. You'd be better off changing the caps you didn't change and leaving it stock. That will make SRS's the best they can be.

Again, just trying to have a discussion about what you're thinking, etc. Not being critical or negative.

It is only a different crossover in the sense that it is an updated version. by that logic why did Polk make the changes to the tweeter section of the crossover when they used the same tweeters as before? Because it was an improvement that they hadn't recognized earlier when the SRS's were developed. Since the tweeters in mine are the same as the 1.2's and the cabinet has nothing to do with the tweeter section other than the mounting locations which are the same as well, then why not improve the tweeter section as Polk evidently saw fit to do. That part has nothing to do with the dimensional driver that many of you keep pointing out are different. between the 2 models. So if i stop there then why should i not improve the tweeter section just as Polk did? Someone please explain that to me since it is the same principal when one goes from the 1.2 to the 1.2TL. it is just doing the same thing Polk did just not at the factory.

The next part would be the mid-woofer portion. The drivers here are the same. The crossover is updated slightly changing the 2.75mH coil to a 2.5mH coil. Very slight change of crossover, again to the same driver. So apparently this driver will work with either of these crossovers. At least according to Polk.

Now to the dimensional circuit. the drivers did indeed change here between the SRS and the 1.2. however the crossover component values are identical between these and the Mid-woofers when you take the wiring of the dimensional circuit into account. Both cabinets are wired together in the 1.2 from the negative terminals of he dimensional drivers which places the crossover components from each cabinet in series with the components from the other cabinet. Doing the math, the crossover components for the dimensional drivers are exactly the same as the mid-woofers except the large inductor which is the same in all 3 models.

Now, since we can use the 6503 in either circuit of the SRS or the 1.2 and the 6511 uses the same circuit as the 6503 in the 1.2 then the 6503 can then use the same circuit as the 6511 (which it already does in the 1.2). So the crossover matches both drivers, even though they may have slightly different characteristics, surely I am not the only one outside of Polk that has figured that out.

Since Polk saw fit to improve/ update the crossover in both the tweeter section as well as the mid-woofer/ dimensional sections, why would I not want to start where they did in a quest for improved sound. It sounds like many of you have done the same by modding to the TL version.

Is the dimensional effect the same in later models, is it better, is it worse? I don't know as I don't have all versions to compare. DK may be able to answer this as I think he has both the SRS and the 1.2TL from posts I've read here.
from an electrical standpoint I doubt there is much if any difference in the dimensional effect. i would assume a slight difference in the bass response but can not be sure how significant.


The 1.2 and 1.2tl cabinets are the same except a couple added braces along the back wall, the crossover boards are the same as well along with the drivers. the only difference is the tweeters and a couple different values in the xovers. converting a 1.2 to a 1.2tl is a 1.2tl speaker..

This makes the cabinets as well as the crossovers different. But again the SL2000 is used with either the SRS and or the 1.2 tweeter section crossovers so these two crossovers are interchangeable with the drivers, we just assume there were improvements made to the sound due to the upgrades in the 1.2. The difference between the cabinets of the SRS and the 1.2 is the bracing just as you describe here. That makes it the same as the 1.2TL except for the bracing.


You say you want them to be the best they can be, how do you know the changes you make based on the 1.2 x-over will work with the drivers in the SRS's?

Being the best they can be doesn't mean that I will end up with any of the SRS crossover designs in the end. i want them to be the best they can be, not necessarily the best Polk design they can be. I do not know which sounds better, see above. I will always be able to change them back if I don't like it, but as far as working with the drivers, see above again.

as H9 mentioned, I am only having a discussion here and hope not to offend anyone. Discussions such as this challenge my thought process and help me to learn more in the long run.

[heiney9]

But the tweeters were the same, they didn't change (until the TL's) even though the circuit did a little bit. The drivers in the SRS aren't the same as the drivers in the 1.2's, that was my point. I'm not saying it won't work, I'm just wondering if you've considered that and what you expect to be "better" about it?

So then if the x-over components in the 1.2 are identical for the SDA circuit, then it must be the drivers that make the improvement. You don't have those drivers so what kind of improvement do you expect?

H9

[Mr. Bubbles]

That's simply ridiculous, that means to you a Hyundai and Ferrari are the exact same thing. They aren't and that logic is just a little bit silly, IMO.

from a transportation standpoint they are the same, in fact6 the Hyundai may be better since it can hold more passengers. Yes the ferrari is a better car and my comment was silly but is all in how we look at things and I think that I am looking at this situation as Apples to Apples (just maybe a golden delicious vs a granny smith vs a Rome, when many of you look at these models as apples, oranges and lemons.

[Mr. Bubbles]

But the tweeters were the same, they didn't change (until the TL's) even though the circuit did a little bit. The drivers in the SRS aren't the same as the drivers in the 1.2's, that was my point. I'm not saying it won't work, I'm just wondering if you've considered that and what you expect to be "better" about it?

H9

I have considered the fact that the drivers are different and will have a different sound than the 1.2's. better or worse i don't know until I try. But it is pretty plain that either driver will work with either crossover (well to me it is anyway), just as my 2A's have different drivers than called for even though they appear in every way to have been that way from the factory.

[audiocr381ve]

I have considered the fact that the drivers are different and will have a different sound than the 1.2's. better or worse i don't know until I try. But it is pretty plain that either driver will work with either crossover (well to me it is anyway), just as my 2A's have different drivers than called for even though they appear in every way to have been that way from the factory.

Keep up the great work, I'm interested in hearing about what you think of the final result.

[Mr. Bubbles]

One pint I failed to touch on earlier is the high pass filter (130uf caps) in the SRS dimensional circuit. This appears to me to be there solely to make the dimensional effect work with the amplifier since in those models (without the filter) the positive signal lead of one channel would be connected directly to the negative of the other channel. this obviously would damage the amp and not work at all. For this reason the high pass filter is necessary simply for function only and not to affect the sound. This is why it would not be necessary in the later models as the positive signal lead is not used directly in the dimensional circuit, but is fed through each channels crossover components and drivers. that is why I would expect little to no difference in the effect and sound.

[heiney9]

I am interested in your findings too, just playing a bit of devils advocate at times. Good luck

H9

[audiocr381ve]

I am interested in your findings too, just playing a bit of devils advocate at times. Good luck

H9

No this is great stuff guys. I love hearing the back and forth on this type of thing. Hopefully it leads to new discoveries!

[DarqueKnight]

But technically speaking all three of these models are very similar with only minor upgrades in each (electrically and mechanically speaking of course).


This is easily converted from one style to the other with the correct parts.

If that were true, Polk would not have implemented an entire redesign from the SRS to the 1.2. Here is something else to consider: NOT ALL 1.2's CAN BE CONVERTED TO 1.2TL's![b][/u] I have attached the instructions from the 1.2 to 1.2TL conversion kit. Notice this warning from Matthew Polk:

[b][i]"IMPORTANT: THE SRS 1.2TL Conversion kit can only be used with SRS 1.2 speakers whose serial numbers are 5001 or greater.

If conversion from one SRS model to another is as easy as you think it is, one has to wonder about the need for the warning. Why can only a specific run of 1.2's be converted to 1.2TL's? Isn't that odd? Aren't all 1.2's alike? What would happen if Matthew Polk's warning is cheerfully ignored and the owner of 1.2's with serial numbers 4999 and 5000 installed the 1.2TL upgrade kit? Would there only be a mild deterioration in sound quality or would amps and speakers blow up?


I am sure this will stir some controversy

Not controversy, more like amusement. You are not the first person who thought he had more knowledge and insight into modifying Polk speakers than Matthew Polk and Polk's engineering department.

Why don't you submit an inquiry to Polk's engineering department about your modification plans? That is what I did prior to doing my first SDA modification in 1990. Polk engineers were very helpful in pointing out certain pitfalls to avoid. Electrical circuit modification is not just a simple matter of reading a schematic and substituting parts. Schematics don't, and can't, tell the whole story about the speaker designer's performance goals. If you submit an inquiry, it will have to be forwarded through Polk's customer service department (contact Kim Jasper). The engineering department no longer communicates directly with the public.


Again I'm not trying to make a 1.2 or TL out of my SRS's just trying to get the best sound from these speakers and i am not comfortable being limited to what others done in the past.

What others have done in the past (and I'm speaking of legitimate modifications) have been done under the advisement of Polk's engineering department. Do what you want with your speakers, but if you are interested in performance improvement, it would seem prudent to seek advisement from the people who designed and built them.


Being the best they can be doesn't mean that I will end up with any of the SRS crossover designs in the end. i want them to be the best they can be, not necessarily the best Polk design they can be.

My modification goals are based on enhancing performance and getting as close as possible to the designer's ideal. If I wanted to stray from the original Polk design, I would just buy another speaker.

I choose loudspeakers based on their sonic performance attributes. Any modifications I do would be toward improving and enhancing those performance attributes. With any loudspeaker design, there is a limit to the amount of modification you can do and still maintain the performance attributes that attracted you to the speaker in the first place. This is similar in concept to the fact that there is a limited amount of cosmetic surgery one can undergo and still look like a human being.


I believe that if it looks like a car and rides like a car it is a car no matter if it is made from tractor parts.

You are entitled to believe whatever you want, but the fact is, if you replace an automobile engine and suspension parts with corresponding tractor parts, the car will still get you from point A to point B, but comfort and safety will be compromised.

However, I understand your premise: You think that if you put different (or what you consider "improved") circuitry in an SRS cabinet and keep the same drivers and tweeters, you will still have an SRS, just an improved version. No, you will not have an improved SRS. You will have a pair of "Frankenpolks". There are design rules and which must be respected during the course of a modification.


It is only a different crossover in the sense that it is an updated version.

You are confusing redesign with updating. The SRS, 1.2 and 1.2TL use entirely different crossover designs intended to achieve different performance goals. An update substitutes better parts than those originally used, but the circuit design remains the same. I replaced most of the parts in my 1.2TL crossovers, even down to the printed circuit boards, with higher quality, better performing parts. However, I did not deviate from the original circuit design. I did not achieve a "different" sound. I achieved a huge enhancement to the sound.


by that logic why did Polk make the changes to the tweeter section of the crossover when they used the same tweeters as before? Because it was an improvement that they hadn't recognized earlier when the SRS's were developed.

No.

Your question does not make sense when you consider that 17 models of SDA's used the SL2000 tweeter. Tweeters have to be sonically blended with drivers. Reusing the same tweeters with different driver and cabinet combinations usually requires some adjustment to the crossover circuit.


Since the tweeters in mine are the same as the 1.2's and the cabinet has nothing to do with the tweeter section other than the mounting locations which are the same as well, then why not improve the tweeter section as Polk evidently saw fit to do.

Tweeters have to blend in with the drivers and passive radiator and the drivers and passive radiator have to be acoustically complimentary with the cabinet. Loudspeakers should be modified with due regard to the totality of their design in order to maintain coherency of sound.


Now, since we can use the 6503 in either circuit of the SRS or the 1.2 and the 6511 uses the same circuit as the 6503 in the 1.2 then the 6503 can then use the same circuit as the 6511 (which it already does in the 1.2). So the crossover matches both drivers, even though they may have slightly different characteristics, surely I am not the only one outside of Polk that has figured that out.

Where did you get this misinformation from?

The SRS uses 6503's in the stereo and dimensional circuits. The 1.2 and the 1.2TL use 6503's in the stereo circuit and 6511's in the dimensional circuit. Therefore, there is no rational basis for thinking that the SRS crossover "matches" both the 6503 and 6511 drivers. Also, the 6503 and 6511 have very different electrical and mechanical characteristics. For example, the DC resistance of the 6503 is 6.15 ohms compared to 2.7 ohms for the 6511. The maximum impedance of the 6503 is 39.78 ohms compared to 21.28 ohms for the 6511.


Since Polk saw fit to improve/ update the crossover in both the tweeter section as well as the mid-woofer/ dimensional sections, why would I not want to start where they did in a quest for improved sound. It sounds like many of you have done the same by modding to the TL version.

The only TL mods I recall being done by members of this forum were 1.2==>1.2TL mods, CRS+==>CRS+ TL and SDA 2B==>SDA 2B TL mods. These were all Polk recommended mods.


Is the dimensional effect the same in later models, is it better, is it worse? I don't know as I don't have all versions to compare. DK may be able to answer this as I think he has both the SRS and the 1.2TL from posts I've read here. from an electrical standpoint I doubt there is much if any difference in the dimensional effect. i would assume a slight difference in the bass response but can not be sure how significant.

I addressed this in post #29 of my "Improvements to the SDA SRS" thread:



Modified SRS compared to the modified SRS 1.2TL

The midrange reproduction between the two speakers was close, with the SRS 1.2TL providing a little more detail, presence, and image solidity. Whereas the soundstage of the SRS is fully three-dimensional, the soundstage of the 1.2TL was more holographic. The SRS 1.2TL gives more of a sense of space between the individual instruments in the soundstage. The SRS 1.2TL was far better in reproducing upper treble and lower bass frequencies.

With the SRS 1.2TL, tenor and alto saxophone notes have a more "reedy" and "airy" quality. Rim shots on the drum kit have more impact and transient attack. The high-hat has more metallic shimmer and overtones. The bass notes are stronger, more articulate and more defined. In summary, the SRS 1.2TL presents a more "real" aural illusion.


The difference between the cabinets of the SRS and the 1.2 is the bracing just as you describe here. That makes it the same as the 1.2TL except for the bracing.

The SRS and 1.2 cabinets are different with regard to bracing, panel construction and in the way the panels are joined together. They are completely different cabinets. I understand that you find this difficult to believe. Again, Polk's engineering department will be able to provide additional insight. I hope you consider them to be a credible source of information about SDA's.

[inspiredsports]

. . . the only SDA models with interchangeable crossovers are the 1987 versions of the SDA 2B and SDA CRS+ and the 1989 versions of the SDA 2B and SDA CRS+ . . .

Qualifying as "almost" the same, 1986 SDA 1B's and SDA SRS II's had identical drivers and identical crossover boards (cabinet size and passive radiators were different). The only difference in the crossovers was the first resistor after the black wire on the binding post; 1 ohm on the 1B and 3.5 ohm on the SRS II.

[Toolfan66]

Thanks for that info DK!!! That answers a lot as the 1.2's the tweeters are wired out of phase and that's why they sent you a new wiring harness for the tl upgrade. The only other odd thing is the passives on the tl version has weights on them and the 1.2's do not, the SRS passives are or look a lot different from the back side then the 1.2/1.2tl's.

Not sure why they would send the extra bracing and not a weight for the passives. I added three extra braces in my cabinets. The only reason I kept the 1.2 cabs over the 1.2tl cabs is the 1.2's were in much better shape..

[DarqueKnight]

Thanks for that info DK!!! That answers a lot as the 1.2's the tweeters are wired out of phase and that's why they sent you a new wiring harness for the tl upgrade. The only other odd thing is the passives on the tl version has weights on them and the 1.2's do not, the SRS passives are or look a lot different from the back side then the 1.2/1.2tl's.

Not sure why they would send the extra bracing and not a weight for the passives. I added three extra braces in my cabinets. The only reason I kept the 1.2 cabs over the 1.2tl cabs is the 1.2's were in much better shape..

My 1.2TL's were born as 1.2TL's. The 1.2TL instructions are not from a conversion kit I purchased, they are just part of the information I've collected over the years.

As seen in the picture below, my 1.2TL passives are weighted. The passive radiator for the SRS, 1.2 and 1.2TL all have the model number SW150, but as you noted, all three look different. Maybe lighter weight materials were used in later model SW150's used in the 1.2TL's and this required the use of the weight. I expect that all three models of SW150 had the same mechanical properties. Therefore, a 1.2 owner would not need a weight.

[Toolfan66]

I still own all the parts for my 1.2's and of course I am running all my parts from my 1.2tl's both passives look identical except for the weight. We have a nice digital scale at work I should weigh them and see if there is a difference..

[Toolfan66]

I wonder if they sold many conversion kits.

[Mr. Bubbles]

Only for the sake of innocents reading this...

Not controversy, more like amusement. You are not the first person who thought he had more knowledge and insight into modifying Polk speakers than Matthew Polk and Polk's engineering department.

Dude, relax; don't be so arrogant. I respect all your opinions and realize that you are very knowledgeable about Polks, SDAs , and I would think about many other things. I can tell that you are very thorough in your research, upgrades and tests of your equipment before and after upgrades/ mods that you do. I have read many of your posts and gleaned a lot of information from them. One thing that jumps out to me is that I have not found a post where you came up with a new idea or concept on your own; it appears to have all come from someone else making a suggestion. I am not knocking you for that, it may very well be a much safer road to follow than the roads I take, but that is not the way that I am.

I in no way think I know more about these speakers than the guys that designed these speakers. But i also will bet just about anything that these guys know more now about speaker design than they did when they designed these speakers. That is obvious by the changes and improvements that they made to each successive model. They were learning, even back then.


If that were true, Polk would not have implemented an entire redesign from the SRS to the 1.2. Here is something else to consider: [b][i]NOT ALL 1.2's CAN BE CONVERTED TO 1.2TL's![b][/u] I have attached the instructions from the 1.2 to 1.2TL conversion kit. Notice this warning from Matthew Polk:

"IMPORTANT: THE SRS 1.2TL Conversion kit can only be used with SRS 1.2 speakers whose serial numbers are 5001 or greater.

If conversion from one SRS model to another is as easy as you think it is, one has to wonder about the need for the warning. Why can only a specific run of 1.2's be converted to 1.2TL's? Isn't that odd? Aren't all 1.2's alike? What would happen if Matthew Polk's warning is cheerfully ignored and the owner of 1.2's with serial numbers 4999 and 5000 installed the 1.2TL upgrade kit? Would there only be a mild deterioration in sound quality or would amps and speakers blow up?

We obviously see design changes as different in each of our minds. I see a design change as the difference between the 1.2, 2.3, and 3.1. Not simply an updated version of the same model. you evidently do not see it that way and that is one aspect of why we are all different.

First I've heard of the serial number issue but my first question is why? i am sure you have had that question but evidently haven't found the answer. If that information is true (and I presume it is) then there is a difference that was not made known. Was it because there was a crossover point from the finality of using up old parts as they had in other models? That information would lead one to believe that there are at least 2 different 1.2 versions.

finally to your last point in that quote; can you read a schematic (not a literal question as i am sure you can), can you trace a circuit board to see if it matches that schematic? I am sure the sound may be different with the different drivers from the SRS to 1.2 but can you say it would be negative? Not unless you try it and listen to it first. But if you connect a crossover similar to the 1.2's with an interconnect like the SRS you will absolutely damage an amp. was this part of the warning/ I don't know but it could have been if there was a transitional model there.


I choose loudspeakers based on their sonic performance attributes. Any modifications I do would be toward improving and enhancing those performance attributes. With any loudspeaker design, there is a limit to the amount of modification you can do and still maintain the performance attributes that attracted you to the speaker in the first place.

I do the same and agree with this 100%. Where we differ is that I see that Polk did the same thing and made changes that I see to be not as drastic as you see them.


My modification goals are based on enhancing performance and getting as close as possible to the designer's ideal. If I wanted to stray from the original Polk design, I would just buy another speaker.

Again I agree completely. i am not trying to stray from Polk design but using ideas that they used later in development of these models. That is not to say that I will not try my own ideas later but I feel I should use the designers ideas first and then progress from there.


You are entitled to believe whatever you want, but the fact is, if you replace an automobile engine and suspension parts with corresponding tractor parts, the car will still get you from point A to point B, but comfort and safety will be compromised.

This was just meant to make a point and as H9 said it was silly. But it is correct and absolutely what we have in the market. everything from Kia's to Ferrari's to Cadillac's, and many others.


You are confusing redesign with updating. The SRS, 1.2 and 1.2TL use entirely different crossover designs intended to achieve different performance goals. An update substitutes better parts than those originally used, but the circuit design remains the same. I replaced most of the parts in my 1.2TL crossovers, even down to the printed circuit boards, with higher quality, better performing parts. However, I did not deviate from the original circuit design. I did not achieve a "different" sound. I achieved a huge enhancement to the sound.

Actually the definition of updating to to modernize or bring up to date. that would be to make changes to make the product a modern equivalent to it's original self. That is what Polk did as the models progressed. many of the mods that you and i have done do not match that definition, even if they may have been the things that Polk wanted to do but didn't. ie, a 10awg 16mH inductor is NOT and updated version of the original inductor, but a different inductor altogether and therefore by your definition, a design change. I would also tend to bet that the changes you made absolutely made a difference in the sound of your speakers and that this difference was indeed an improvement.


Where did you get this misinformation from?

The SRS uses 6503's in the stereo and dimensional circuits. The 1.2 and the 1.2TL use 6503's in the stereo circuit and 6511's in the dimensional circuit. Therefore, there is no rational basis for thinking that the SRS crossover "matches" both the 6503 and 6511 drivers. Also, the 6503 and 6511 have very different electrical and mechanical characteristics. For example, the DC resistance of the 6503 is 6.15 ohms compared to 2.7 ohms for the 6511. The maximum impedance of the 6503 is 39.78 ohms compared to 21.28 ohms for the 6511.

Please read the entire post. I explain this in technical detail. I also point out that I realize that these driver have different characteristics. that doesn't mean they can't use the same crossover components. using the 1.2 solely as an example,( you may want to inquire of an engineer to verify this since you may not understand my explanation) the crossover circuit for the stereo drivers uses the exact same values as the circuit for the dimensional drivers (except for the 16mH inductor to keep all frequencies below roughly 150hz in phase) when you adjust for the series connection between the 2 cabinets. Therefore Polk found it effective that both of these different drivers use the same crossover.


The only TL mods I recall being done by members of this forum were 1.2==>1.2TL mods, CRS+==>CRS+ TL and SDA 2B==>SDA 2B TL mods. These were all Polk recommended mods.

Again this looks like the safer road. The safe road is filled with complacency and definitely does not lead to progress. It only takes you where you know you are going but never offers suspense or new ideas.


The SRS and 1.2 cabinets are different with regard to bracing, panel construction and in the way the panels are joined together. They are completely different cabinets.

Ummm, ok. A cabinet drawer with mortise and tenon joints and a brace underneath does not make it completely different from cabinet drawer with square joints and screws holding it together. the same size and strength drawers serve the exact same function. They are different , but not completely.


Again, Polk's engineering department will be able to provide additional insight. I hope you consider them to be a credible source of information about SDA's.

I am sure they can be a great help. thank you for pointing them out. If one can indeed make some form of contact with the engineers I am sure it would be beneficial. That is not the case with most companies; with others you can only get "Peggy" on the phone. Think credit card commercial for those of you who don't catch that right away.

DK thanks for you response. As I mentioned earlier i enjoy this type discussion as it almost always makes e check myself and either re-think or think of new things. Again I respect your opinions as I can tell from your posts that you are very intelligent and thorough I am just not the kind of person to look to you as the Polk "god" as many on these forums appear to do. To me you are a very intelligent man that has previously started a similar path that I myself have only recently begun. being that we are different people, we are likely to approach that path in different ways.

[Face]

I did not see any arrogance, just a no nonsense reply.

[Mr. Bubbles]

I did not see any arrogance, just a no nonsense reply.


To me it seemed arrogant. I could have misinterpreted, I have surely done so before.

[Joe08867]

I think the arrogance is in the reader and i don't mean you I mean anyone reading can misinterpret something. I have read into posts such as this and felt the same way. I believe not hearing the person and only reading what they say can change a phrase drastically.

In either case, I do have a question for you.

Did you compensate in your redesign of the crossover for the disparity in the drivers needed for each design? I have a feeling the 6511 to 6503 differences are going to be quite apparent in your work if you did not. I am seeing a future of weak Dimensional sound.

You are adding a lot of Ohms to the SDA side using the crossover for the 1.2 or 1.2tl. While it may make the dimensional side easier to drive for the amp you are also attenuating the SDA effect. Not a trade off I would vote for in the larger SDA's. You almost have to add more resistance to the stereo side to compensate or rewire the Dimensional side to drop the ohms back down.

[michael1947]

I have a pair of sds srs 1a's and they sound just fine. Do we rebuild/replace the crossovers because they wear out or because we think Mathew and the boys at Polk Audio got it wrong. Just curious.

[Mr. Bubbles]

Joe, you are absolutely right. I have sent and received many messages that have been taken wrong. If i have done so in this case, I apologize, but the comment about the innocent seemed to be kind of a smart ass comment.


Did you compensate in your redesign of the crossover for the disparity in the drivers needed for each design? I have a feeling the 6511 to 6503 differences are going to be quite apparent in your work if you did not. I am seeing a future of weak Dimensional sound.

I have done no other compensation, at this point, than what Polk did when they made their upgrade (redesign as others see it) to the 1.2. I truly have a hard time believing so many intelligent members don't see that Polk used the same crossover on both of these drivers. Once again, if someone does the math on the dimensional series circuit between the two cabinets of the 1.2 the stereo drivers have exactly the same value components as the dimensional drivers. That is ALL I mentioned doing to the dimensional circuit; exactly what Polk did but with a different driver. Albeit a different driver that Polk saw fit to use the same crossover on. Will it sound different? I am sure it will. Will it be better than the SRS sounded originally? maybe, maybe not. If it doesn't, it is easy enough to remove 4 parts and put 4 others back in and switch the interconnect cable back to the original layout. It is a simple mod, and just as simple to go back to original if it doesn't make an improvement. Maybe it should be considered more like research than a mod. I am willing to bet that the SDA effect will be almost no different than the 1.2's in their original form, though I am sure the tonality will be somewhat different due to the different driver characteristics.


You are adding a lot of Ohms to the SDA side using the crossover for the 1.2 or 1.2tl. While it may make the dimensional side easier to drive for the amp you are also attenuating the SDA effect. Not a trade off I would vote for in the larger SDA's. You almost have to add more resistance to the stereo side to compensate or rewire the Dimensional side to drop the ohms back down.

Actually I will be keeping the same impedance that I have already. It will be different than the actual 1.2 since , as DK points out above, the impedance of the two different drivers is different.

As many of you think this could very well be a waste of time, but as mentioned before it is too easy not to try and if it doesn't work to put it back like it was.

[Mr. Bubbles]

Another point to note that the SRS, 1.2 and 1.2TL are similar is the parts list posted in the sticky. All the crossovers have the same part # with a different version designation at the end. If they were completely redesigned it would stand to reason that they would have entirely different model #'s instead of designations to indicate different versions of the same.

[Joe08867]

I have a pair of sds srs 1a's and they sound just fine. Do we rebuild/replace the crossovers because they wear out or because we think Mathew and the boys at Polk Audio got it wrong. Just curious.

We usually redo crossovers to update/upgrade the parts from there 20+ year old crossovers as they do wear out over time, and honestly they make better parts for these now.

There are also those that mod them with ideas from Polk engineers as well. Like the 4.1TL mod for SDA2b's and the CRS+ so they can use the Tri-Laminate tweeter with these models.

What Oliver is doing is shooting for something I have not seen before on this forum. I applaud the effort but I think some key items are being overlooked.

[Joe08867]

Actually I will be keeping the same impedance that I have already. It will be different than the actual 1.2 since , as DK points out above, the impedance of the two different drivers is different.

As many of you think this could very well be a waste of time, but as mentioned before it is too easy not to try and if it doesn't work to put it back like it was.

Actually you won't be keeping the same impedance. The issue you are not seeing is that the two crossover designs and drivers are different. So you will be gaining impedance with the new crossover design. Lets look at the speaker in both forms. I do not have the figures in front of me but for arguments sake lets say Original SRS's have a dimensional impedance of 8 ohms and 1.2TL's have an impedance of 4ohms. By not changing drivers with to compensate you will be doubling the ohm's rating that the 1.2TL crossover will see. Do you see what I mean? In a way you will be attenuating the circuit. In what way I am not sure but the ohm sweep is different for each as well as there response curves. These all have to be taken into account before changing the crossover.

[heiney9]

I have a pair of sds srs 1a's and they sound just fine. Do we rebuild/replace the crossovers because they wear out or because we think Mathew and the boys at Polk Audio got it wrong. Just curious.

Caps, especially inexpensive eletrolytic caps, have a finite shelf life of anywhere from 10-15 years many time less. So we rebuild to replace old worn parts and while we are in there we change things up that have proved to be better in the span of when something was assembled like in the 80's until now. We replace inductors on the advice of "Matt and the Boys" because it's been roughly 20 years and components and technology change by either being something new and or cost is dramatically less now. We change resistors to something like Mills wire wound non-inductive because they sound better, etc.

H9

[Mr. Bubbles]

Actually you won't be keeping the same impedance. The issue you are not seeing is that the two crossover designs and drivers are different. So you will be gaining impedance with the new crossover design. Lets look at the speaker in both forms. I do not have the figures in front of me but for arguments sake lets say Original SRS's have a dimensional impedance of 8 ohms and 1.2TL's have an impedance of 4ohms. By not changing drivers with to compensate you will be doubling the ohm's rating that the 1.2TL crossover will see. Do you see what I mean? In a way you will be attenuating the circuit. In what way I am not sure but the ohm sweep is different for each as well as there response curves. These all have to be taken into account before changing the crossover.

I will be keeping the same impedance as i will be keeping the same drivers in the same wiring configuration. The crossover (effectively the 1.2 crossover) will see a different impedance than what it would normally see in the 1.2 since the driver impedance is different. What this will do is effect the response curve as the actual crossover frequency will be somewhat different. This can be easily compensated for with the inductor /capacitor values. the main concern I have is the differing output levels of the drivers due to impedance/ and efficiency. This too can be compensated for but does then get more in depth. But as I've said several times; if it doesn't work it can be changed back very easily.

[Mr. Bubbles]

The SRS uses 6503's in the stereo and dimensional circuits. The 1.2 and the 1.2TL use 6503's in the stereo circuit and 6511's in the dimensional circuit. Therefore, there is no rational basis for thinking that the SRS crossover "matches" both the 6503 and 6511 drivers. Also, the 6503 and 6511 have very different electrical and mechanical characteristics. For example, the DC resistance of the 6503 is 6.15 ohms compared to 2.7 ohms for the 6511. The maximum impedance of the 6503 is 39.78 ohms compared to 21.28 ohms for the 6511.

I am not sure what the nominal impedance is for either of these drivers. I would assume however that the 6503 is roughly double that of the 6511. this is somewhat (though not precisely) verified by the DCR specs given by DK. above. lets look at the dimensional circuits as a whole in both models.

The numbers i have here are simply numbers rounded from DK's specs above. they are IN NO WAY intended to represent the actual impedance of these drivers. say the SRS has 4 drivers of roughly 6 ohms each in a series/ parrallel configuration and the crossover is designed for this nominal 6 ohm total impedance and only sees these 4 drivers to get this impedance match.

now we look at the 1.2 drivers; say their are 4 of them in each cabinet, just as the SRS's each cabinet wired seies parallel with 3 ohm speakers. this gives us 3 ohms in each cabinet. but now this crossover not only sees these 4 drivers but also the 4 drivers in the other cabinet that these are in series with. This equates to 6 ohms total impedance, just as the SRS's. the only difference id that we now have all components in the dimensional circuit of both cabinets run in series with each other so not only do the driver electrically add together but so do the crossover components in this circuit.

Just like DK and others have built the same crossover for their speakers using different components, Polk did the same thing here between these 2 models. this describes the dimensional circuit only.

[DarqueKnight]

Joe, you are absolutely right. I have sent and received many messages that have been taken wrong. If i have done so in this case, I apologize, but the comment about the innocent seemed to be kind of a smart ass comment.


To me it seemed arrogant. I could have misinterpreted, I have surely done so before.

Perhaps it seemed arrogant to you because that is the world you live in. It is interesting that you accuse me of arrogance while your discourse is sprinkled with arrogant, passive-aggressive remarks. Even if I were the most arrogant jerk that ever lived, plus a serial killer, what difference would that make pertaining to the soundness of my ideas? Either my ideas make sense or they do not. I don't understand the relevance of any real or perceived character flaws to the soundness of my comments. I would not refuse a cure for cancer if it were invented by a serial killer.

I have continually and consistently pointed you toward the source of knowledge for modding SDA's:


Why don't you submit an inquiry to Polk's engineering department about your modification plans? That is what I did prior to doing my first SDA modification in 1990. Polk engineers were very helpful in pointing out certain pitfalls to avoid. Electrical circuit modification is not just a simple matter of reading a schematic and substituting parts. Schematics don't, and can't, tell the whole story about the speaker designer's performance goals. If you submit an inquiry, it will have to be forwarded through Polk's customer service department (contact Kim Jasper). The engineering department no longer communicates directly with the public.


What others have done in the past (and I'm speaking of legitimate modifications) have been done under the advisement of Polk's engineering department. Do what you want with your speakers, but if you are interested in performance improvement, it would seem prudent to seek advisement from the people who designed and built them.


The SRS and 1.2 cabinets are different with regard to bracing, panel construction and in the way the panels are joined together. They are completely different cabinets. I understand that you find this difficult to believe. Again, Polk's engineering department will be able to provide additional insight. I hope you consider them to be a credible source of information about SDA's.

This was not arrogance. This was showing concern about you and others getting into an unfortunate situation with your speakers.

In contrast, these type of comments could be construed as insights into your character:


...surely I am not the only one outside of Polk that has figured that out.


I truly have a hard time believing so many intelligent members don't see that Polk used the same crossover on both of these drivers. drivers is different.

Why do you feel the need to passively-aggressively question the intelligence of forum members? While I applaud your ability to look at schematics that some of us have been using for over two decades and "see" things that we overlooked, I wonder why you can't just show us the error of our ways without calling our intelligence into question?

Along those lines, I have a question. I have attached a copy of the forward statement from the 1989 Polk Audio In Field Technical Manual. Warranty Manager Helen Yarbor states, in all caps (which is the written equivalent of screaming):

"IT IS IMPORTANT TO REALIZE THAT WE MANUFACTURE A VARIETY OF 6 1/2" DRIVERS WHICH ARE OPTIMIZED FOR SPECIFIC MODELS. THEREFORE IT IS HIGHLY RECOMMENDED THAT ONE READS THE QC STICKER ON THE BACK OF EACH DRIVER AND MATCH THE PART NUMBER TO ITS PARENT MODEL USING THE CROSS REFERENCE SUPPLIED IN THIS MANUAL."

Ms. Yarbor's comment appears to indicate that drivers are not as interchangeable among SDA models as you purport. Am I interpreting this correctly, or am I overlooking something?


DK Again I respect your opinions as I can tell from your posts that you are very intelligent and thorough I am just not the kind of person to look to you as the Polk "god" as many on these forums appear to do.

That's kind of (passive-aggressively) over the top don't you think? I certainly don't consider myself to be a Polk "god" and it is insulting to the membership that you ascribe this to them. If I did consider myself a "Polk god", Would I have consistently referred you to Polk's engineering department? Since you are discussing model conversions, which is not a trivial undertaking, I suggested that you confer with Polk about that.

With regard to whether the change from the SRS to the 1.2 is a mere "upgrade" or a "redesign", I can only refer you to what Polk said. Their marketing literature said the 1.2 cabinet was a new "monocoque" design. They said the crossover was "redesigned" to enhance imaging and to present and easier load to an amplifier. Perhaps their use of the words "monocoque cabinet structure" and "crossover redesign" were just marketing hype. You probably won't have to go to Polk's engineering department for clarification on those points. Polk's customer service manager, Kim Jasper, should be able to provide such information.

As for me, since I own both the SRS and the 1.2TL, I can just look inside the cabinets and see that they are very different. This also applies to the crossover circuits. However, I don't doubt that you might look inside my speaker cabinets and not see much difference.


Being the best they can be doesn't mean that I will end up with any of the SRS crossover designs in the end. i want them to be the best they can be, not necessarily the best Polk design they can be.


As many of you think this could very well be a waste of time, but as mentioned before it is too easy not to try and if it doesn't work to put it back like it was.

Experimentation is not a waste of time, if it is appropriately conducted. However, as I and others have pointed out, you are overlooking many important design factors. You may not be able to "put it back like it was". In any event, enjoy your venture.


One thing that jumps out to me is that I have not found a post where you came up with a new idea or concept on your own; it appears to have all come from someone else making a suggestion.

Really Oliver...why would this jump out to you? You talk like it's a bad thing that I take a conservative approach to modifying expensive vintage loudspeakers that would be close to impossible to replace if I screwed something up.

***Guess what?*** I am not in audio to come up with new ideas and concepts. In fact, I have stated many times that I do not enjoy the work involved in researching and implementing modifications. I am in audio for the enjoyment of music. It just so happens that my musical enjoyment can be greatly enhanced by carefully executed modifications. I get enough electronics "play time" at work. When I come home I just want to listen to music.


I am not knocking you for that, it may very well be a much safer road to follow than the roads I take, but that is not the way that I am.

I realize that. However, you clearly stated that this thread was aimed at "guys on a budget", many of whom are inexperienced and unknowledgeable in this sort of thing:


This post is not really for you "hardcore " guys out there with unlimited budgets but more for the guys on a budget considering crossover upgrades.

Therefore, the "innocents" I referred to were those who might be induced to error and catastrophic misfortune by the abundant misinformation and wild speculation in your posts. We have seen "innocents" start out with your mindset and end up with the following:

1. Passive radiators replaced with active woofers.
2. Tweeters replaced with "upgrade" horn tweeters.
3. "Enhanced" SDA circuitry that makes all music sound like it was recorded in a garage.
4. Drivers replaced with "upgrades" that were totally inappropriate and in some cases electrically unsafe.
5. Brutally butchered, and sometimes burned, crossovers.

Examples of the hack jobs in items 1-5 above periodically show up on eBay, after which we have a great time marveling at the *genius* of the mind behind such "performance enhancements".

As I said before, do what you want to do with your speakers. You asked for discussion and I provided my thoughts.

[Joe08867]

Oliver, DK is right on all his counts as far as the cabinets are concerned. Different building methods and bracing do change the sound characteristics of a speaker. Go over to a DIY speaker forum and look at what they have done. 1/2 in mdf won't hold a candle to 1/2 inch birch ply and triple bracing a cabinet compared to double bracing is almost night and day.

This comment.

Ummm, ok. A cabinet drawer with mortise and tenon joints and a brace underneath does not make it completely different from cabinet drawer with square joints and screws holding it together. the same size and strength drawers serve the exact same function. They are different , but not completely.

Makes you sound very silly, almost as bad as the car is a car comment. There are differences in the cab, the crossovers and the drivers. This isn't something we say just cause we want hear ourselves, its to help people not make mistakes.

I love the fact that you are trying something new but your method of thinking has me worried you will blow something up before long.

And your last post explains what I mean about impedance to a T. You in fact state it for me.

now we look at the 1.2 drivers; say their are 4 of them in each cabinet, just as the SRS's each cabinet wired seies parallel with 3 ohm speakers. this gives us 3 ohms in each cabinet. but now this crossover not only sees these 4 drivers but also the 4 drivers in the other cabinet that these are in series with. This equates to 6 ohms total impedance, just as the SRS's. the only difference id that we now have all components in the dimensional circuit of both cabinets run in series with each other so not only do the driver electrically add together but so do the crossover components in this circuit.

So instead of 6ohms total impedance you are going to have somewhere in the neighborhood of 12-14ohms. Do you see what I mean now? That is more than double the impedance so you will be attenuating the circuit.

Just letting you know, I have read your ideas and although commendable, I don't think you thought it through.

[Face]

I foresee another pair of Frankenpolks on the used market some day.

[Mr. Bubbles]

Perhaps it seemed arrogant to you because that is the world you live in. It is interesting that you accuse me of arrogance while your discourse is sprinkled with arrogant, passive-aggressive remarks. Even if I were the most arrogant jerk that ever lived, plus a serial killer, what difference would that make pertaining to the soundness of my ideas? Either my ideas make sense or they do not. I don't understand the relevance of any real or perceived character flaws to the soundness of my comments. I would not refuse a cure for cancer if it were invented by a serial killer.

really? that's not arrogance. maybe just compensation. Dude I'm not passive about anything. I can be pretty damn aggressive though. seems a little hypocritical there talking about the world i live in and all. you are correct your attitude, arrogance or not has nothing to do with what works and what doesn't. i tried to apologize for any misconception i may have had but you seem to want to point the me not being wrong in the first place. Either way, prick or not I still respect your opinions.


I have continually and consistently pointed you toward the source of knowledge for modding SDA's:

Yes you have and i remember thanking you for that. maybe you missed that part.



In contrast, these type of comments could be construed as insights into your character:

I'm an *******, never claimed any different. But these comments must have been misunderstood by you and since that is the cae possibly others. What i meant by them was that I am not the smartest person in the world and others, probably you included are smart enough to know this already so someone else out there has seen this besides me. i apologize to all who may have taken offense to this.


I wonder why you can't just show us the error of our ways without calling our intelligence into question?

I don't recall trying to show anybody the error of their ways, dude, I have enough problems of my own. i'm just trying to learn things here, and if you recall this all started by me simply posting my plans, not asking for opinions.


Along those lines, I have a question. I have attached a copy of the forward statement from the 1989 Polk Audio In Field Technical Manual. Warranty Manager Helen Yarbor states, in all caps (which is the written equivalent of screaming):

"IT IS IMPORTANT TO REALIZE THAT WE MANUFACTURE A VARIETY OF 6 1/2" DRIVERS WHICH ARE OPTIMIZED FOR SPECIFIC MODELS. THEREFORE IT IS HIGHLY RECOMMENDED THAT ONE READS THE QC STICKER ON THE BACK OF EACH DRIVER AND MATCH THE PART NUMBER TO ITS PARENT MODEL USING THE CROSS REFERENCE SUPPLIED IN THIS MANUAL."

This is all well and good but doesn't apply to what I have been saying (exactly). different drivers have different characteristics and will therefore sound different if placed in similar circuits. this does NOT mean that they will not be a close substitution or possibly a better substitution. And yes they could always sound worse. I have not shied away from this fact and have acknowledged it several times. Polk did this in my 2A's to use up old parts, and they sound better than any other speaker i have.


That's kind of (passive-aggressively) over the top don't you think? I certainly don't consider myself to be a Polk "god" and it is insulting to the membership that you ascribe this to them. If I did consider myself a "Polk god", Would I have consistently referred you to Polk's engineering department? Since you are discussing model conversions, which is not a trivial undertaking, I suggested that you confer with Polk about that.

Dude, read what i write; I never said you thought you were a "god", just that others act like you are. man take what you can get, if you're like most of us your wife never treats you that way. I am sorry if I am wrong, i am just assuming you are straight.


Really Oliver...why would this jump out to you? You talk like it's a bad thing that I take a conservative approach to modifying expensive vintage loudspeakers that would be close to impossible to replace if I screwed something up.

***Guess what?*** I am not in audio to come up with new ideas and concepts. In fact, I have stated many times that I do not enjoy the work involved in researching and implementing modifications. I am in audio for the enjoyment of music. It just so happens that my musical enjoyment can be greatly enhanced by carefully executed modifications. I get enough electronics "play time" at work. When I come home I just want to listen to music.


Once again, read what I wrote, and this time what you even copied and pasted from my post. I did. say being that way was a bad thing at all, it is just not the way i am. I am extremely competitive and if i do the same thing the next guy does i will only be playing at the same level. not that i am trying to win anything here, just explaining my nature.


I realize that. However, you clearly stated that this thread was aimed at "guys on a budget", many of whom are inexperienced and unknowledgeable in this sort of thing:

exactly! and this mod will cost me less than $20. if it doesn't work I can put it back to the way it was and only be out less than $20.


Therefore, the "innocents" I referred to were those who might be induced to error and catastrophic misfortune by the abundant misinformation and wild speculation in your posts. We have seen "innocents" start out with your mindset and end up with the following:

1. Passive radiators replaced with active woofers.
2. Tweeters replaced with "upgrade" horn tweeters.
3. "Enhanced" SDA circuitry that makes all music sound like it was recorded in a garage.
4. Drivers replaced with "upgrades" that were totally inappropriate and in some cases electrically unsafe.
5. Brutally butchered, and sometimes burned, crossovers.

Examples of the hack jobs in items 1-5 above periodically show up on eBay, after which we have a great time marveling at the *genius* of the mind behind such "performance enhancements".

Once again I tried to apologize for the arrogant comment if I took the innocent thing differently than you meant it. but now you seem to be calling into question my intelligence with the wild speculation and misinformation thing. again, sounds a little hypocritical to me. Those things don't appear to be anywhere closely related to my mindset, but I see your point. Again you compare my mindset to that and then make the *genius* comment. This seems to be calling my intelligence into question. Check yourself man, hypocrisy is not a trait that most people think of as good for ourselves. But hey, if you're good with it I am too.

[Mr. Bubbles]

. Different building methods and bracing do change the sound characteristics of a speaker. Go over to a DIY speaker forum and look at what they have done. 1/2 in mdf won't hold a candle to 1/2 inch birch ply and triple bracing a cabinet compared to double bracing is almost night and day.

I realize this completely, i worked in car audio for 22+ years and designed and built the loudest car in the world on the IASCA circuit, 2 years in a row. We were one of the first to break 176db when others were several db below this. AND this was done WITHOUT a factory sponsor on a budget of less than $25000 when the closest competitor was factory sponsored by more than one manufacturer and on a rough budget of about 1/4 million. We didn't get to replace our drivers or amps every run since we were not factory sponsored. The system was made to work and to last.

What does that have to do with any Polk speaker, NOTHING. but I let you know to tell you i know how cabinets work. I know the use of different materials, but that is not what happened here. Polk removed braces to open up the cabinet, if I had to guess why, it would have been to allow some of the standing waves inside the cabinet to help move the passive better. Did they make the cabinet thicker, or out of different material? not to my knowledge. they cut grooves in the cabinet boards so as to break up any sympathetic vibrations. DK's "monocoque" is simply describing an exoskeleton because they removed the internal bracing. I've built more cabinets than i care to think about (for home and automobile) out of everything from fiberglass to 1/2" steel plate. I've canceled resonances, damped drivers and cabinets and baffles, and then went back and added resonances back in where beneficial. There is NO rocket science to building speaker cabinets, and these are no different. In fact these cabinets are pretty poor. if they weren't using 6.5" active drivers they would never hold up.


So instead of 6ohms total impedance you are going to have somewhere in the neighborhood of 12-14ohms. Do you see what I mean now? That is more than double the impedance so you will be attenuating the circuit.

how do you get that. 4 3ohm drivers per cabinet wired series parallel as they are in these speakers will equal (3 ohms per cabinet in series with 3ohms from the other cabinet) 6ohms. the same as 4 6ohm drivers in a single cabinet.

[Mr. Bubbles]

Attached Images

* File Type: pdf Yarbor-FWD-1989FLDMAN.pdf‎ (82.8 KB, 3 views)

This letter also states that a suitable replacement will be recommended. indicating that some drivers are indeed interchangeable.

[heiney9]

Knock yourself out Oliver, I look forward to a new generation of better SDA's.

The mere fact that you feel the oldest SDA's you own, the SDA 2A's sound the best out of the 1C's and SRS's leaves me a little suspect because I have spent time with all those models and the 2A's, IMO, don't compete on any level with the newer SDA's. The 1C's, IMO, are about the best SDA's going as they are sort of the "sweet spot" for SDA's as in they fit in a majority of rooms without too much difficulty, they are fairly easy to drive comparatively, they aren't huge, they have a generous and forgiving sweetspot comparatively so one can listen off-axis and out of the sweet spot w/o too much listening penalty. They are fairly laid back in their presentation, most models have the ability to be used with the AI-1 interpahse cable, plus they look nice.

Again, just IMO, but there aren't too many here who would feel the 2A's trumph both the 1C's and SRS's all things being equal.

H9

[Joe08867]

how do you get that. 4 3ohm drivers per cabinet wired series parallel as they are in these speakers will equal (3 ohms per cabinet in series with 3ohms from the other cabinet) 6ohms. the same as 4 6ohm drivers in a single cabinet.

Because they are double the impedance. How are you not seeing this? Double the impedance in each cab, now wire them as they should be in the 1.2tl crossover and you get???????? That's right 12+ ohm's. The crossover changes the wiring so that the impedance doubles across the two speakers. Combining 6+ ohms in each cabinet gets you 12+ ohms total across the circuit. I do not know how to explain it any better.

[Mr. Bubbles]

Because they are double the impedance. How are you not seeing this? Double the impedance in each cab, now wire them as they should be in the 1.2tl crossover and you get???????? That's right 12+ ohm's. The crossover changes the wiring so that the impedance doubles across the two speakers. Combining 6+ ohms in each cabinet gets you 12+ ohms total across the circuit. I do not know how to explain it any better.

I apologize Joe, I do see that and i now see where the confusion is coming in. I have been describing this in "effective" terms as compared to each other instead of actual terms as you are here. That is my fault and i am sorry to have confused you. i may have also confised you in my answer to your previous question. so let me rephrase my previous answer; yes I am making adjustments to compensate for this actual difference.

H9, I think a big reason i like the 2's so much better is their simplicity and to me it shows in the sound as being less colored to my ears.

[heiney9]

Actually I believe the single board 1C's are equally as simple w/the exception of the progressive point source tweeter array. But I certainly won't say you're not allowed to like the 2A's better. It's just more uncommon for those that have compared them to later models.

H9

[Mr. Bubbles]

I apologize Joe, I do see that and i now see where the confusion is coming in. I have been describing this in "effective" terms as compared to each other instead of actual terms as you are here. That is my fault and i am sorry to have confused you. i may have also confused you in my answer to your previous question. so let me rephrase my previous answer; yes I am making adjustments to compensate for this actual difference.

I would like to elaborate on this. I have the components to compensate for this impedance difference but plan on trying it first with the stock component values of the SRS and then the stock values of the 1.2 and then if necessary make any changes that are needed. I have not pre-adjusted anything. If an attenuation circuit is needed I will rewire all 4 dimensional drivers per cabinet in parallel (which will then be in series with the other cabinet wired the same way) and then place the attenuation circuit on the dimensional drivers so as not to have to attenuate the stereo drivers and the tweeters, but only one portion of the crossover circuit. This should give the same listening levels as I have now. As I mentioned before; the biggest concern I have is exactly what I think Joe is getting at; the difference in levels and the response curve of the dimensional circuits as compared to the other circuits in the system.

[Face]

How do you plan on attenuating a woofer circuit? Seems like a huge waste of power.

[DarqueKnight]

I am sorry if I am wrong, i am just assuming you are straight.

You assume correctly...Mr. Bubbles.


Dude I'm not passive about anything. I can be pretty damn aggressive though.

Me too.


Yes you have and i remember thanking you for that. maybe you missed that part.

Yeah, I saw that...you're very welcome.


I'm an *******, never claimed any different.

O.K.


i apologize to all who may have taken offense to this.

No offense taken on my part. As I clearly stated, I was...and still am...amused. From the comments I have read from others, I don't think anyone else took offense either.


DK's "monocoque" is simply describing an exoskeleton because they removed the internal bracing.

Why did you refer to the cabinet design as "DK's "monocoque"? The term "monocoque" was Polk's descriptive term, not mine.


There is NO rocket science to building speaker cabinets, and these are no different. In fact these cabinets are pretty poor. if they weren't using 6.5" active drivers they would never hold up.

What do you mean by "if they weren't using 6.5" active drivers they would never hold up"? It appears that you are saying that Polk needed to use small drivers because the allegedly "poor" cabinets could not withstand the pounding from larger drivers. Using a larger number of smaller drivers can be more sonically advantageous than a single larger driver.


This letter also states that a suitable replacement will be recommended. indicating that some drivers are indeed interchangeable.

Well, common sense should indicate that if Ms. Yarbor wanted her "suitable replacement" comment to include drivers, she would have said that. She had the "driver" comment in bold all-capital type and the "components" comment later in normal type. This letter was written sometime in 1988 for the 1989 Field Service Manual. I don't recall that there were issues with driver availability during the time this was written. There is nothing in the manual about substituting one driver with another. Sometimes there were issues with sourcing electronic components (polyswitches, capacitors, etc.) and connectors.

Long after SDA's were discontinued, there were supply problems with some drivers (the 6513 comes to mind). "Workable" substitutions were suggested, but it was plainly stated that such substitutions were not optimal.


I am extremely competitive and if i do the same thing the next guy does i will only be playing at the same level.


not that i am trying to win anything here, just explaining my nature.


...i worked in car audio for 22+ years and designed and built the loudest car in the world on the IASCA circuit, 2 years in a row. We were one of the first to break 176db when others were several db below this. AND this was done WITHOUT a factory sponsor on a budget of less than $25000 when the closest competitor was factory sponsored by more than one manufacturer and on a rough budget of about 1/4 million. We didn't get to replace our drivers or amps every run since we were not factory sponsored. The system was made to work and to last.

What does that have to do with any Polk speaker, NOTHING. but I let you know to tell you i know how cabinets work. I know the use of different materials, but that is not what happened here. Polk removed braces to open up the cabinet, if I had to guess why, it would have been to allow some of the standing waves inside the cabinet to help move the passive better. Did they make the cabinet thicker, or out of different material? not to my knowledge. they cut grooves in the cabinet boards so as to break up any sympathetic vibrations. DK's "monocoque" is simply describing an exoskeleton because they removed the internal bracing. I've built more cabinets than i care to think about (for home and automobile) out of everything from fiberglass to 1/2" steel plate. I've canceled resonances, damped drivers and cabinets and baffles, and then went back and added resonances back in where beneficial.

(In my best Irish accent...) Surrrre, surrre...Mr. Bubbles...whatever you say.


http://i148.photobucket.com/albums/s23/darqueknight88/Topper/Topper-3.jpg

http://i148.photobucket.com/albums/s23/darqueknight88/Topper/Topper-2.jpg

http://i148.photobucket.com/albums/s23/darqueknight88/Topper/Topper-1.jpg

http://i148.photobucket.com/albums/s23/darqueknight88/Topper/Topper-5.jpg

http://i148.photobucket.com/albums/s23/darqueknight88/Topper/Topper-6.jpg

[Toolfan66]

Hahahaha!!!

[Mr. Bubbles]

Mr. Bubbles

yeah i got that name for my bubbly fu@&!N personality. Fits pretty well doesn't it.


Why did you refer to the cabinet design as "DK's "monocoque"?

Just tryin to give the "god" some credit.


What do you mean by "if they weren't using 6.5" active drivers they would never hold up"? It appears that you are saying that Polk needed to use small drivers because the allegedly "poor" cabinets could not withstand the pounding from larger drivers. Using a larger number of smaller drivers can be more sonically advantageous than a single larger driver.

That is exactly what I meant. Smaller driver are definitely more advantageous for accuracy and sound quality. but they can not produce the pressures of large drivers. Sure the SRS's, 1.2's, and 1.2TL's have the cone area of an 18 but with very little excursion and even less motor strength. Don't get me wrong they sound awesome and the cabinets are adequate for the drivers installed in them but the build quality on the ones I have seen sucks.


Well, common sense should indicate that if Ms. Yarbor wanted her "suitable replacement" comment to include drivers, she would have said that. She had the "driver" comment in bold all-capital type and the "components" comment later in normal type. This letter was written sometime in 1988 for the 1989 Field Service Manual. I don't recall that there were issues with driver availability during the time this was written. There is nothing in the manual about substituting one driver with another. Sometimes there were issues with sourcing electronic components (polyswitches, capacitors, etc.) and connectors.

Long after SDA's were discontinued, there were supply problems with some drivers (the 6513 comes to mind). "Workable" substitutions were suggested, but it was plainly stated that such substitutions were not optimal.

You have some of that? You read it one way i read it another. same text. I'm sure you're right though.

laugh all you want with your Family cartoons, I have stated many times on these forums that I am the one trying to learn here, you are apparently the resident book of knowledge. My background is not in home audio and I am trying to gain what knowledge I can. I have made that plain so your cartoon doesn't seem to work here. But hey laugh all you want. If you ever come to South Carolina, look me up. Maybe we can have a beer and discuss things like real men.

I almost forgot, if you wish to respond to this again, fine. I am growing tired of the BS so I will let you have the last word as any "god" should be able to. I will not respond to you on this matter again.

[heiney9]

Again, Mr. Oliver Bubbles, I await your new and improved SDA's for the 22nd Century. Please right all the wrongs Polk did when offering these to the public. Please build a worthy cabinet.

H9

[Mr. Bubbles]

Man the guy i bought these from was right; there are some fu@$in idiots around this forum. There are also some decent people too. Joe and a few others appear to be some of the latter. The rest of you dumba$$es please treat me like you are treating Audio and ignore me.

[Toolfan66]

Man the guy i bought these from was right; I am a fu@$in idiot on this audio forum . The rest of you please treat me like a dumba$$es and ignore me.

Fixed!!!

[Toolfan66]

http://i110.photobucket.com/albums/n102/KMEADE27/BUBBLES.jpg

The audio KING!!!!

[DarqueKnight]

61343


Man the guy i bought these from was right; there are some fu@$in idiots around this forum. There are also some decent people too. Joe and a few others appear to be some of the latter. The rest of you dumba$$es please treat me like you are treating Audio and ignore me.

Really ...Mr. Bubbles, swearing and vulgar namecalling on a family forum such as ours? It's very unbecoming.


yeah i got that name for my bubbly fu@&!N personality. Fits pretty well doesn't it.

No. Not lately.


Don't get me wrong they sound awesome and the cabinets are adequate for the drivers installed in them but the build quality on the ones I have seen sucks.

Yeah, I've seen some messed up SDA's with messed up cabinets...due to owner abuse. The cabinets of my SRS's and 1.2TL's are very good. Of the SDA's I have owned, the only ones where I had some issue with the cabinets were my CRS+'s. That was due to the "crumbly" nature of the particle board when drilling them to install steel driver retaining rings.


But hey laugh all you want. If you ever come to South Carolina, look me up. Maybe we can have a beer and discuss things like real men.

Based on your conduct on this forum, I assume "discussing things like real men" includes lots of insults and cursing. Therefore, I will politely decline.


I almost forgot, if you wish to respond to this again, fine. I am growing tired of the BS so I will let you have the last word as any "god" should be able to. I will not respond to you on this matter again.

OK. Good night Mr. Bubbles. It was nice chatting with you.

[rromeo923]

First of all you guys are mad geniuses as I dont understand half of what you all are talking about.

Second of all you guys are all crazed for getting into this heated discussion.

Third I am crazier for reading this entire thread.


Keep it up!!:biggrin::biggrin:

[CNWDI]

I'm really sorry I was busy elsewhere and missed this...entertaining discussion today. Someone should have told me to get online and bring the popcorn. Backing up several hours:


I have attached a copy of the forward statement from the 1989 Polk Audio In Field Technical Manual. Warranty Manager Helen Yarbor states, in all caps (which is the written equivalent of screaming):

"IT IS IMPORTANT TO REALIZE THAT WE MANUFACTURE A VARIETY OF 6 1/2" DRIVERS WHICH ARE OPTIMIZED FOR SPECIFIC MODELS. THEREFORE IT IS HIGHLY RECOMMENDED THAT ONE READS THE QC STICKER ON THE BACK OF EACH DRIVER AND MATCH THE PART NUMBER TO ITS PARENT MODEL USING THE CROSS REFERENCE SUPPLIED IN THIS MANUAL."

The key point that I think DK has made several times is that if someone wants to make changes to vintage Polk speakers, Polk is remarkably supportive of inquiries. In fact, when I inquired about a month ago about RD0198-1 and MW65xx availability, the response came from...Ms. Yarbor. There are few companies that still have the same (quite knowledgeable) people dealing with issues 20+ years later...so regardless of any experience or degree I might have, I'd personally tend to ask Polk for at least a review of any significant modification plans (beyond replacing specific capacitors/resistors with updated high-quality components of the same impedance).
--CNWDI

[inspiredsports]

For Mr. Bubbles (before I put you on ignore), the following may help you determine why you can't arbitrarily switch crossovers:

Driver ........ Q ........ BL .... Compliance .... DC Res ........... Fs ...

MW6501 - 1.470 - 5.96 N - 3.250 E 3N/M - 7.750 Ohms - 31 Hertz
MW6502 - 1.970 - 5.16 N - 1.470 E 3N/M - 3.520 Ohms - 44 Hertz
MW6503 - 1.820 - 5.24 N - 3.550 E 3N/M - 6.540 Ohms - 29 Hertz
MW6509 - 2.100 - 4.57 N - 3.540 E 3N/M - 8.970 Ohms - 30 Hertz
MW6510 - 1.390 - 6.32 N - 3.410 E 3N/M - 6.570 Ohms - 31 Hertz
MW6511 - 1.405 - 4.34 N - 3.496 E 3N/M - 3.130 Ohms - 29 Hertz
MW6512 - 1.905 - 4.99 N - 1.588 E 3N/M - 3.466 Ohms - 40 Hertz

Cabinet design/bracing/volume and the exact version of the passive used also come into play.

[TECHNOKID]

oliverbubbles, I'd like to commend you on your OP and your effort to improve your speakers (however, it is very unfortunate that the thread turned out the way it is now. Who's guilty, I don't really care and will not comment).


There are design rules and which must be respected during the course of a modification.The above quote is key, there are so many variables (mechanical, electrical, physical) that will make a speaker and this is best left to the engineers and the manufacturer that created a specific product. I really feel it would be in your interest to trust and seek Polk advices on mods you want to achieve as they can provide you with some valuable insight.

I do not know you so not sure where you would put your self but;

There are hobbyists:
"An activity or interest pursued outside one's regular occupation and engaged in primarily for pleasure." IMHO, a hobbyist has some skills, abilities and knowledge however, is not a specialist per say.

There are technicians: 1. A person employed to look after technical equipment or do practical work in a laboratory.
2. An expert in the practical application of a science.

However, IMHO the technician while having some skills they are somewhat limited to repair, maintenance and proven upgrades that are provided and approved by higher technical expertise.

Technologist: A specialist in technology. IMHO this is the guy that would attempt to do the type of modifications you are trying to attempt however; he would work closely and under the guidance of the engineer responsible for the project.

Engineer: A person who designs, builds, or maintains... IMHO, he is the creator (the god as you like to point out) that one (hobbyist, technician, technologist) would go to for guidance for any changes in design (IMHO, even a serious engineer would often refer to the creator of the design if intending to modify existing design).

Now, I am in no way trying to pick on you but 1st just want to know where you locate your self in this ladder? Secondly, IMHO it seems you are missing/miss-understanding the critical aspect of playing with the original value of each components of a design.

Personally, I am and I stop at the technician level. I know my abilities, what I can perform and exactly where I should stop and seek advices from the manufacturer. No big deal in most cases playing with series/parallel as long as the original values remain the same. No biggy replacing parts with better quality/newer technology as long as the original design is respected. No problem repairing and so on however, when it comes to altering the original design I realize this is not my place and if I have an idea I think that can improve or believe it will not affect the end result, I will not take my assumption for granted and will dare ask for advices at the engineering level. IMHO, you are to be commended for your effort to improve your speakers but IMHO, you would greatly benefit from seeking the creator (Polk) of your speakers.

Again, I commend you for your post, what you achieved so far and what you are actually trying to accomplish. Please keep us posted on your progress as I am very interested to see where this is leading you (good or bad). Life is a learning curve and I can definitely see this is exactly what you are doing/achieving.

[Joe08867]

I apologize Joe, I do see that and i now see where the confusion is coming in. I have been describing this in "effective" terms as compared to each other instead of actual terms as you are here. That is my fault and i am sorry to have confused you. i may have also confised you in my answer to your previous question. so let me rephrase my previous answer; yes I am making adjustments to compensate for this actual difference.

H9, I think a big reason i like the 2's so much better is their simplicity and to me it shows in the sound as being less colored to my ears.

No problem at all, I just wanted you to look at the whole picture and not separate as you had been.

I apologize if I came off angry. I will admit I was getting perturbed but only because my explanation was being missed. Probably why I don't have children. :biggrin:

Your idea for a possible fix may in fact work so again I say good luck.

[Marty913]

Disclaimer: All my opinions, no real facts involved.

Mr. Bubbles,

In case you’re wondering why the “shields were raised” in this whole thread and it turned decidedly south around post #32, it may have more to do with the audience / forum chosen than anything remotely related to the technical points raised. It might be helpful if you considered the following:

The Polk Audio Vintage Speaker threads may appear to simply be a collection of people who enjoy sharing ideas about old Polk speakers (be that acquisition, design, modification, or the simple enjoyment thereof). It is in fact all that, but perhaps just a little bit more – particularly where SDA models are involved. In large part, this forum exists because there are many people here that view the Polk SDA series as one of the finest and most unique speakers ever made - a legacy to be protected in a world of background music, inferior products, and throwaway technology.

Not to get all religious on you but in some respects the few hundred members here are the “Knights Templar” of a product that they believe represents far more than just “technology to be redesigned”. Whether it can or should be is somewhat irrelevant. I personally believe the Sistine Chapel would look a lot better with some alternate paint choices but I’m having a hard time selling that over on the Vatican Forum. I guess there are just some lines that are best left uncrossed.

You have to look a lot deeper than technology to understand the family here. It does take a little time but its well worth the effort. I wish you personal success with your experiments and hope you share the results.

[tpl12blk]

Thanks so much for this! This is exactly what I was looking for

[falconcry72]

Thanks so much for this! This is exactly what I was looking for

reported.

[Mr. Bubbles]

Simply for the sake of anyone who may be interested; I updated the tweeter section of the crossover to match that of the 1.2 and IMO it made a significant IMPROVEMENT. The detail came out about 1/4- 1/3 as much again as upgrading the capacitors. Not a lot of listening on this yet and will see if this changes as the components break in. The tweeters now seem to be more closely in line with the mid-range, but still not quite there.

[Mr. Bubbles]

Ok, I started wondering if I wasn't just wanting to hear an improvement as I think many times we want our work to be validated so we make ourselves hear what we want. That being said I put the right channel back to origional and listened in mono to compare the treble in each cabinet. I then switched to stereo again and listened for any dimensional imbalance. I hadn't heard any effect on the dimensional sound with this mod but wanted to simply triple check myself. especially after all this BS. No effect on the dimensional sound, just as expected since the circuit is not tied to the dimensional drivers or circuit. The tweeters definitely sound better with the update. Cymbals sound more metallic. Tambourines sound more crisp. everything is less hazy or as I've read here before as a description; like a veil was removed.

[evhudsons]

"FrankenPolks", Hilarious!

I had a feeling that has been around for a while after reading DK's warnings. I googled it and read some really good stuff. Personally I would go mad changing out so many things that I couldn't just go back and quickly fix something to figure out what went wrong, especially if it was all wrong and you had to start over again from scratch.

But..great info. I had driver questions regarding the 6511 and 6503 and they were answered.

Note to Oliver: I think people are still interested in your outcome. I hope you have a fire extinguisher handy just in case you need a quick mod fix.

[inspiredsports]

. . . the key point that I think DK has made several times is that if someone wants to make changes to vintage Polk speakers, Polk is remarkably supportive of inquiries. In fact, when I inquired about a month ago about RD0198-1 and MW65xx availability, the response came from...Ms. Yarbor. There are few companies that still have the same (quite knowledgeable) people dealing with issues 20+ years later...so regardless of any experience or degree I might have, I'd personally tend to ask Polk for at least a review of any significant modification plans (beyond replacing specific capacitors/resistors with updated high-quality components of the same impedance). . .

Paired with that, you also need the discipline to work within accepted speaker/crossover building practices, and that takes a huge committment of time and money.

You need to obtain and master software programs like ARTA/TrueRTA/REW/etc. and the learning curves are steep.

You need to learn if nearfield, 1 W@1 Meter or listening position measurements are needed, and how to neutralize modes if you are measuring from the listening position.

You need at least one high quality (preferably calibrated) omnidirectional mic, and two if you want to gather an accurate picture of how the room interacts with the speaker. You need DIN cables and mic booms, a decent DAC to send signal to your speakers and a decent USB Interface or approved internal soundcard to interface the mics.

Did I mention plotting impedance curves?

Without the ability to measure with more than your ears, you are taking a shot in the dark at a black needle in a black haystack.

I'm a huge proponent of listening, but when modding speakers accurate data is a must.

[heiney9]

Simply for the sake of anyone who may be interested; I updated the tweeter section of the crossover to match that of the 1.2 and IMO it made a significant IMPROVEMENT. The detail came out about 1/4- 1/3 as much again as upgrading the capacitors. Not a lot of listening on this yet and will see if this changes as the components break in. The tweeters now seem to be more closely in line with the mid-range, but still not quite there.


Ok, I started wondering if I wasn't just wanting to hear an improvement as I think many times we want our work to be validated so we make ourselves hear what we want. That being said I put the right channel back to origional and listened in mono to compare the treble in each cabinet. I then switched to stereo again and listened for any dimensional imbalance. I hadn't heard any effect on the dimensional sound with this mod but wanted to simply triple check myself. especially after all this BS. No effect on the dimensional sound, just as expected since the circuit is not tied to the dimensional drivers or circuit. The tweeters definitely sound better with the update. Cymbals sound more metallic. Tambourines sound more crisp. everything is less hazy or as I've read here before as a description; like a veil was removed.

So I have to ask, are you using old caps or new caps? Because if you are using new caps for the 1.2TL tweeter circuit config and the original caps for the SRS tweeter circuit then the improvements you hear are more than likely from the new vs. old caps. I believe you stated you didn't do the tweeter section because you were waiting to change it over to a 1.2TL, and I assumed you meant with new caps. So if you are switching back and forth between original and 1.2TL that means you spent twice as much on new caps and resistors so you can compare both ways with fresh caps, not old caps vs. new caps. I ask because you didn't make that part of the experiment clear at all. You stated you were on a budget and this was a budget tweak, but to compare them properly you have to spend twice as much.

Also much of the improvements you hear with better integration are probably related to the new caps you used in the low pass. You see your experiment might be flawed because you really haven't isolated a control part of your upgrade, so while I don't discount you hear differences, I am nit inclined to attribute them solely to the 1.2TL tweeter circuit mod, because so far, based on how you explained it, there is no way to know for sure that's what's causing the improvement.

The way it should have been done is to leave everything else alone and use the exact same brand new caps and resistors for both the SRS and 1.2TL tweeter circuits, changing nothing else and after 300-500 hours break-in for both configurations then the sound should be analyzed. Same music, same source, same listening position, etc, etc, etc.

H9

[Mr. Bubbles]

So I have to ask, are you using old caps or new caps? Because if you are using new caps for the 1.2TL tweeter circuit config and the original caps for the SRS tweeter circuit then the improvements you hear are more than likely from the new vs. old caps. I believe you stated you didn't do the tweeter section because you were waiting to change it over to a 1.2TL, and I assumed you meant with new caps. So if you are switching back and forth between original and 1.2TL that means you spent twice as much on new caps and resistors so you can compare both ways with fresh caps, not old caps vs. new caps. I ask because you didn't make that part of the experiment clear at all. You stated you were on a budget and this was a budget tweak, but to compare them properly you have to spend twice as much.

Also much of the improvements you hear with better integration are probably related to the new caps you used in the low pass. You see your experiment might be flawed because you really haven't isolated a control part of your upgrade, so while I don't discount you hear differences, I am nit inclined to attribute them solely to the 1.2TL tweeter circuit mod, because so far, based on how you explained it, there is no way to know for sure that's what's causing the improvement.

The way it should have been done is to leave everything else alone and use the exact same brand new caps and resistors for both the SRS and 1.2TL tweeter circuits, changing nothing else and after 300-500 hours break-in for both configurations then the sound should be analyzed. Same music, same source, same listening position, etc, etc, etc.

H9

I had originally updated all of the tweeter crossover components except for the 97uf shunt cap. When that update was done it made a HUGE difference/ improvement. Just as expected. I also updated all stereo and dimensional caps and resistors except the high-pass circuit for the interconnect. 2nd mod was simply to update the tweeter circuit to the 1.2. NOT the 1.2TL. The second mod created an additional unveiling over changing the caps and resistors. I have no plans in the near future to go to the TL in these speakers. I just wanted to hear the difference in the tweeter section between a SRS and 1.2. I do not have 1.2's but have changed the components in my SRS's tweeter section to match that of the 1.2's. To me it sounds much better and I will be using them in this configuration. The tweets are no louder but the instruments sound more detailed and realistic.

[heiney9]

Ok, still doesn't answer my questions. I know you changed between the SRS and 1.2. A simple yes or no will suffice to my questions. Also I didn't mean 1.2TL, that was my error. I meant original SRS and SRS 1.2. Ignore the 1.2TL as it's a typo/brain fart.

H9

[inspiredsports]

This thread is becoming more and more mystifying . . .

The initial premise (in fact the first sentence) was, "This post is not really for you "hardcore" guys out there with unlimited budgets but more for the guys on a budget considering crossover upgrades."

Yet now it spans multiple upgrades to multiple crossovers, plans to TL which requires at least 8 new RDO drivers, and no deference to the already accumulated knowledge base that would actually make a cost-efficient, champagne-on-a-beer-budget, upgrade possible.

[Mr. Bubbles]

H9, I am not clear on what your question is. None of the caps used have had time to break in yet. About 10 hours listening since updating all caps and resistors. then switch to 1.2 circuit. I am not sure how a yes or no would suffice. Yes it sounds better to me, no I don't care if anyone else on here likes the idea or not.

Inspired, please stop acting like my wife and getting only the part that works for you, or put me on ignore like you said you were gonna.

[Toolfan66]

I have yet to understand why one would waste the time and energy to do this. Why not just buy a set of 1.2/1.2tl's ooohh thats right we are on a budget but i am going to waste my time and money on something that may or may not work.

IMO if these speakers do not give you what your looking for then sell them and try something else..

either way they are your speakers so good luck with them!!!

[inspiredsports]

H9, I am not clear on what your question is. None of the caps used have had time to break in yet. About 10 hours listening since updating all caps and resistors. then switch to 1.2 circuit. I am not sure how a yes or no would suffice. Yes it sounds better to me, no I don't care if anyone else on here likes the idea or not.

Inspired, please stop acting like my wife and getting only the part that works for you, or put me on ignore like you said you were gonna.

I changed my mind.

Are you anywhere near NE Ohio? I'd be glad to bring my calibrated Behringer's, Alesis io2 Express, boom tripods and analysis software laden laptop over to show you all of the massive hills and valleys you've created.

[Mr. Bubbles]

Without the ability to measure with more than your ears, you are taking a shot in the dark at a black needle in a black haystack.

Awwww, you make me feel special. I didn't realize that I was one of so few that has ears than when they hear something are tied to a brain that actually tells them if they like it or not. But I actually have that ability. I am sorry for you but don't worry, just because you can't ride the short bus anymore doesn't mean that you aren't special too. I am glad you have the hearing equipment you need.

[inspiredsports]

Awwww, you make me feel special. I didn't realize that I was one of so few that has ears than when they hear something are tied to a brain that actually tells them if they like it or not. But I actually have that ability. I am sorry for you but don't worry, just because you can't ride the short bus anymore doesn't mean that you aren't special too. I am glad you have the hearing equipment you need.

You've missed so much of what I've written.

I place a huge value upon listening and listen for the pure artistic enjoyment of it most of the time, but when you start making massive changes to the fundemental components of a speaker design you simply can't do it with ears alone.

If you would take the time to learn how Polk designed/designs speakers (or any speaker designer designs speakers), you'll realize you have no chance of doing it properly with your ears alone.

You may get an over-compensated bottom and top end (the classic "smiley" curve) that sounds appealing to some, but you are simply pissing on dozens of successful careers and hundreds of thousands of R&D dollars. Statistically, you don't have a chance of being "right".

But, I do respect your right to experiment and please yourself, even if others may not agree.

Next Polkfest (2013) at your place?

[evhudsons]

If someone offers to help even if that means showing you the obstacles that may lay ahead then that person is not an ass. I'm interested in the FrankenPolk thing and I have yet to see one long time Polk forum member respond as an ass. I think they would rather not respond at all if they were so inclined to be an ass. Just my .02 which sometimes doesn't get much on the karma exchange rate.

[Face]

Awwww, you make me feel special. I didn't realize that I was one of so few that has ears than when they hear something are tied to a brain that actually tells them if they like it or not. But I actually have that ability. I am sorry for you but don't worry, just because you can't ride the short bus anymore doesn't mean that you aren't special too. I am glad you have the hearing equipment you need.I'm sure Polk didn't use any measuring equipment while designing them either.

[inspiredsports]

I'm sure Polk didn't use any measuring equipment while designing them either.

:mrgreen:



I just found this smiley icon, the "Lone Ranger" :loneranger:. Maybe Oliver should use it when he posts.

[evhudsons]

What is in the water lately? There sure seems like a sudden surge in DB's on this forum. To a point it's entertaining, well, not really. Several lone rangers running amuck. I understand if it were a bunch of knowitall preteens but these are grown adults. Oh well it's a forum.