Finally upgraded my 2.3 crossovers

[motorstereo]

Yes finally after almost 3 years of owning them I got them done. Sonicaps and theta film bypass caps were used as well as new resistors and new tweeter protection breakers from Polk. I wanted the job done right so I had Carl's speaker repair do the work. Isn't any way I could've done the nice job he did. Sometimes you gotta realize your limitations and this upgrade wasn't something I felt comfortable doing
Listening impressions so far are excellent. I can't wait for the 100 hours or so it takes these new caps to fully break in. I used to have to boost my midrange just a smidge as the vocals weren't all that forward. No problem hearing the vocals now and that's with the mids being flat. The very subtle loudness contour switch also seems to be finding itself not used anymore. The polks weren't bass shy before by any means but I usually ran the loudness switch unless I was really cranking them up. Imaging wasn't a problem either but the soundstage seems wider and more realistic now for lack of a better term. At any rate it seems like a very worthwhile upgrade and I'm glad I did it.
Next tune up will be trying dynamat on the drivers. What little rubber foam that didn't fall off my passsives I easily peeled off before reinstalling.
I'd also like to add that Carl found the sda compendium that I'd brought along for him to check out very very helpful.

[F1nut]

What are those bypass caps doing on there? You don't need those when using film/foil caps as all they do is create nasty artifacts. IMO, you should get rid of them. Why didn't they use a film and foil cap for the 20uF and 40uF?

[motorstereo]

Here we go again; defending my way of doing things. I should've known. Didn't know there was an etched in stone way of recapping the 2.3s. If "nasty artifacts" result in realistic imaging, soundstage and excellent overall sound quality then count me in. I'll pass on destroying Carl's fine workmanship based on your opinion. But thanks anyway. Out of curiosity what exactly do you base that opinion on? Have you ever heard this particular set up?

[ben62670]

You should do a little more research. Not a very good choice of parts. Ditch the by passes, and you should replace those electrolytes with polys.
Ben

[george daniel]

motor--FWIW,, last week, we removed the bypass caps from my brothers x-overs,(2.3 tl's) we had rebuilt them about one year ago, and replaced everything, after talking with others here that have been there-done that, we removed the bypass caps,and upgraded all of the "solens" (replaced with sonicaps)in the high circuit.I can say that there is an improvement, better detail,very noticable.I'm sure that you put alot of time and effort into yours as well.If the opportunity arises,try it.I'm sure that your 2.3's sound very good following your work.Have fun and enjoy.:)

[NJPOLKER]

motorstereo
Don't take what the guys here are saying as an insult to you or anyone else. The suggestions are made in YOUR best interest not their own. Just my opinion and experience. Enjoy them and let us know how you make out.

[motorstereo]

Thanks njpolker; no offense taken. In fact I'm chuckling to myself right now.

[F1nut]

Out of curiosity what exactly do you base that opinion on?

Actual experience.

[F1nut]

For your reading pleasure......

Bypass capacitors. In addition to the Multicap RTX, I have tried either .1 µF or .01 µF bypasses from Sonicap (Gen I and the Teflon® Platinum cap), Hovland, AudioCap, and Wima. In every case the results were similar. Let me digress for a minute or so (depending on how fast you read) and talk about crossovers.

In the simple first order high-pass crossovers we are using for this capacitor comparison, the value of the single capacitor, together with the impedance of the loudspeaker driver, determines the crossover frequency. An 8 µF capacitor with the 4 ohm impedance of the Magnepan quasi-ribbon tweeter gives a crossover frequency of about 5000 Hz (1/2πRC). A smaller value capacitor (for example, 4 µF instead of 8 µF) will raise the crossover frequency. If we used only the very small value .1 µF capacitor without the 8 µF, we would hear nothing because the crossover frequency is now almost 400,000 Hz. Even a dog would not hear it!

So why use a bypass at all? There are actually components of very high frequencies in some audio waveforms. Some are high order harmonics. If you think of a square wave, the right angles at the top of the wave are extremely high in frequency. Sometimes there are high frequency components in very fast audio sounds, for example, the instantaneous tap of a drum stick on a cymbal. These are the sounds that should be "helped" by including a small-value bypass capacitor in a high pass crossover.

Well, I don't think so. If the 8 µF capacitor blocks frequencies below 5000 Hz and passes frequencies above 5000 Hz, why do we need what is actually another crossover for the same tweeter, but operating at frequencies already passed by the big cap? I am sure engineers have a very good reason, and a couple of them have tried to educate me on this subject. I respect the science and electrical theory on this subject, and my technical background helps me to understand it fairly well. But there is one small problem: the bypasses all sound bad! They add a quality that at first sounds like an increase in air and detail, but after a couple of hours becomes an intrusive harshness and discontinuity in the upper treble. Remove the bypass: all of the detail is present but without that grating and annoying sound. The high frequencies are cleaner, smoother, and much more enjoyable. It doesn't matter if the bypass cap is Teflon®, polystyrene, or common polypropylene, the results are very similar. And to be avoided.

[ben62670]

I have tried using cheap caps verses better caps. Electrolytic caps have no place in an SDA. Sorry about being blunt. This is a public forum and to be wishy washy would be a disservice to anyone looking to do an XO upgrade. You can get 20 and 40uf caps plenty cheap enough. I did the bypass thing to, and did not like it. You really should ditch the electrolytic, and the bypass caps.

[Face]

Even replacing relatively new electrolytic caps with film caps in Polk LSi speakers made an improvement. I wouldn't use them unless you needed a ridiculously large value such as 300uf, etc...

[NJPOLKER]

Thanks njpolker; no offense taken. In fact I'm chuckling to myself right now.

You will have many many chuckles around here given that you have the time to do some reading.

[motorstereo]

Ok I guess I've chuckled long enough. Actually I'm quite surprised that no one caught this. The film caps aren't bypassed. They're lower value caps added on to give the correct value. Bypass caps were only used on the NPE. I do believe it was the film caps we were talking about being bypassed?

[ben62670]

Bypass caps are not still in place near P1 and c to d? Using a tiny cap to parallel a large cap is not suggested. Mixing 20+20 or 30+10 to get 40 is fine.The little one will actually act somewhat like a bypass when done like that. Sonicap does custom values at the price of the next size up so I don't understand the little caps being added to make up the value. You would be better off with a 4.3 than a 4.3+1uf to = 4.4. Also why didn't you omit the Poly switch? It's not bad if you actually are in the habit of tripping it, but if you don't over or under power the speakers to the point of clipping it should be removed.

[motorstereo]

Sorry Ben I can't answer all your questions on where exactly the bypass caps are. All I know is they're not the tiny ones that the experts thought. This fellow earns his living rebuilding crossovers. That's why I wanted him do it as I know I'm not capable. I trust his judgement explicitly; not to mention hearing is believing. He also asked if I wanted to bypass the tweeter breakers. The old ones were getting weak and easily tripped. I'd rather play it safe than burn out a tweeter. If I have to suffer somewhat in fidelity then so be it as I am only running a pair of "$300 amps." To sum it up I think; actually I know he did a great job and I'm quite happy with the update. I'm sure we could debate forever on how this should've been done and that undone, better wires, better solder, better amps and interconnects; ahh the list goes on. I do know that I'm very happy even if it doesn't please the "experts".
Now I'm wondering what kind of flak I'll catch for using the wrong sized t nuts when I do the mortite dynamat upgrade. That's next once the new caps get fully broken in. Yessir I'm sure I'll screw something up.

[ben62670]

I am happy you are happy.
Enjoy.

[F1nut]

Sorry Ben I can't answer all your questions on where exactly the bypass caps are. All I know is they're not the tiny ones that the experts thought.

No, Ben is right. Adding a .1uF to a 4.3uF pretty much makes it act like a bypass cap. So, the experts were correct.

I'll go a step further and say that just because someone does something for a living doesn't always mean they know the best way to do it.

That said, I'm glad you are happy. I/we are simply trying to make you happier.

[motorstereo]

"Pretty much makes it a bypass cap"? Either it is or isn't. In this case it isn't. Experts fooled again. You're right about just because someone does something for a living doesn't mean they know the best way to do something. Everyone is entitled to their own opinion. His way of doing things gets the job done and is no more right or wrong than any other crossover rebuild. Still amuses me that no-one picked up on how it was done.Thanks f1 for the thought of trying to make me happy.
Now on to the next mod of t nuts, mortite and dynamat. Hopefully I can accomplish that in a most unique way to give some life to this forum.

[F1nut]

I'm was trying to be nice to you, but that doesn't seem to be working, so I'll stop trying. You really don't understand this stuff, so why do you keep acting like you do!?!

What was done with the high frequency circuit was not a good choice and yes, they are pretty much acting like bypass caps, which IS what I picked up on. What was done with the shunt circuit is a joke.

It's silly to add a .1uF cap to a 4.3uF cap when the original 4.4uF cap had a tolerance of +/- 10%. Therefore, anything from 4.84uF to 3.96uF would be within tolerance.

That said, I'm out.

[ben62670]

Did he fix your VCR while you were at it Sorry I should been straight forward. Yes it acts like a bypass cap. Electricity fallows the pathof least resistance. Take a guess where the juice is going to go through first. F1nut has been doing speaker mods for years, and I have studied speaker building a lot. Both of us and many others have tried different caps/resistors and were trying to help. Both of us like many others have sought "expert" help from the designers of the speakers themselves(Polk engineers), and from cap manufactures. Now you don't like the info we gave you and you are hung on every word that one guy that you really don't know if he knows what he is doing. One guy. Not many experts. Sorry I didn't tickle your ears. To say that the XO was done properly would be a major disservice to guys that want it done right. Fire away Chuckles.
Ben

[motorstereo]

You really miss the point; guys really. I posted the pics of the crossover work and got told it was all wrong. No problem; that's your opinion and you're entitiled to it. Just because you rebuild crossovers one particular way doesn't mean it's any more right than the way I've had mine done. Just like the way I've "braced" my speakers and the fact that I only use "$300 amps". I also caught flak for doing those my own way and didn't really think all that much about it. I'll always defend my way of thinking. I think it's funny that's like that it's somewhat like grade school children playing in the sandbox kicking sand at one another. As usual though I'm sorry I posted pics here and mentioned what I had done. Ohh by the way Ben I designed and built my first quality pair of speakers in the winter of 1977. 15" woofer, 4" mid, dome tweeter and 4 cubic ft. mdf box with a variable crossover. What might you have been doing back in 77? I do have the utmost respect for those monsters that you've built yourself. It's quite obvious that you also know your stuff. I also seem to remember you catching some crap for your uncoventional set up. Carry on; I've got to go grade a new road in the sandbox.:)

[geoff727]

..... that's your opinion and you're entitiled to it.

..... I'll always defend my way of thinking.

As is all things audio (and many things in life, really), there's only one opinion that counts. The proof is in YOUR ears, not theirs. If it gets you closer to the music, then I say mission accomplished! :)

BTW, my SDA's have bypasses on the tweeter caps too (Sshhh....don't tell anybody!).

[GV#27]

I've got to go grade a new road in the sandbox.:)

LOL thanks for the chuckle,enjoy your updated crossovers.

[inspiredsports]

Lots of experience here. I believe it's worth it to follow it.

I think many professionals do an excellent and workmanlike job following schematics, but if they are not members here, probably shouldn't be doing their workmanlike work on Polks. Just my opinion.

You will definitely hear improved sound quality with new caps. You will hear full potential sound quality if you implement what the group has learned over the past couple of decades.

[comfortablycurt]

I'd take the advice of these guys. The members on this board that have been giving you suggestions have been using and modding Polk speakers for a long time, and have all experimented with different setups and different brands of parts, and they all seem to be in agreement on what would be best. Obviously your ears are your ears...but these are the Polk experts. I'd take their advice.

I know when I get some vintage Polks and I'm looking to mod them, I'll be following their advice. They've been through all the trials and tribulations with all the different caps, and all of the different crossover designs. They do know what they're talking about.

As others have said, sure the guy you had mod them may know a lot about crossover design, but the crossovers in the SDA's are pretty complex when compared to a standard crossover. There's a lot more to it...he may know a lot about crossovers, but probably isn't to knowledgeable when it comes to SDA crossovers particularly.

[motorstereo]

As is all things audio (and many things in life, really), there's only one opinion that counts. The proof is in YOUR ears, not theirs. If it gets you closer to the music, then I say mission accomplished! :)

BTW, my SDA's have bypasses on the tweeter caps too (Sshhh....don't tell anybody!).

Thanks geoff; That's what I've been trying to convey all along. The proof is in the hearing isn't it. After going back and forth with several emails to my tech this was a very well thought out modification. The law of physics doesn't change just because it says "polk sda" on the grillcloth. The use of bypass caps could be debated endlessly here and anywhere else I'm sure. I won't get involved in it simply because the damn frost is slowing down the drainage work on my sandbox road. It's very time consuming this time of the year:D I do know that there isn't any way that my 2.3s could possibly sound any better in spite of what some fellows here think. I must say you have lots of fortitude to even suggest that you may have bypass caps installed anywhere in your sda circuit; oh the horrors ohh the "artifical artifacts" (whatever that might be) I bet they sound great don't they.

[george daniel]

with all the "incoming" back and forth,, I forgot to ask,,how do they sound now,as compared to before, any difference in soundstage,SDA effect,mids,,etc.

[motorstereo]

with all the "incoming" back and forth,, I forgot to ask,,how do they sound now,as compared to before, any difference in soundstage,SDA effect,mids,,etc.

Jeez I almost forgot the most important part as well. The sound. A vast and quite noticable improvement. Finally had some time to play around with them now that they're almost completely broken in. I have a 200 watt dual 12'' m+k subwoofer and the polks easily out do it. Without the loudness engaged either. This did not happen before the recap. I used the sub to add a bit of low end crossed over at 60 hz and lower. The polks now have that region covered quite well and don't any assistance. I used to have them boosted one click in the midrange as well and that's no longer needed either. They are quite happy running dead flat with no loudness circuit. Soundstage has widened up considerably and the highs are especially crisp and very pleasant to listen to. I'd have to say the sda effect is a little more pronounced as well.
Overall I consider it a very worthwhile upgrade and it made much more of a difference to me than replacing the stock silver dome tweeters which is the only other mod I've done. I couldn't be happier with the sound. Even if I could wave a magic wand and undo the upgrade and go with the traditional approach I wouldn't do it. I'm being completely honest when I say I don't believe there's any way these 2.3s could possibly sound any better.

[NJPOLKER]

motorstereo
Its a great thing you are really enjoying your speakers and modifications. Most of the folks around here have felt similar after various modifications. I believe what the folks here are trying to relay, in a nice way, the mods could and should be better. Thats what most people who follow forums like this try to achieve, maximum performance. Make no mistake, whats been said/advised is based on experience with Polk speakers/crossovers. The company you used is great and you have excellent speakers. Congratulations.
In ending my thoughts on this thread I do have a question for you.
How would you feel if you were given advice here or anywhere for that matter which was not 100% accurate and factual?
The Polkers want accurate info nothing less and employing by-pass caps in SDA cross overs is bad advice. Please don't come back and say the folks that did your x-overs have more experience modifying or listening to Sda's than the folks here!!
I am correct! At least in my mind :D
Drew

[DarqueKnight]

This fellow earns his living rebuilding crossovers. That's why I wanted him do it as I know I'm not capable. I trust his judgement explicitly; not to mention hearing is believing.

The first time I went to France, I engaged the services of a professional travel service. They were quite helpful in advising about places to visit, places to shop, places to eat, etc. However, I did not trust their judgement completely.

Prior to my visit, I brushed up on my French in order to be able to engage the locals in conversation. They were able to steer me toward the non-tourist trap places to eat, shop, sight-see, etc. I found that I did not need to be an expert in French because, when I would start speaking in French with my American accent, the locals would usually laugh and say "I speak English, monsieur".

Coming back on the plane, I overheard two women talking about what a horrible time they had in France and how rude the French people were and how the country and the people were nothing like the professional travel agency said. I, on the other hand, had the opposite experience and was shown every courtesy.

There was another fellow across the aisle who was bragging about the "good deals" he had received on his purchases. He was dismayed to learn what I paid for similar items and that he had gotten "bent over".

The differences in my experiences and those of my fellow travelers was that they were advised by people who were experts in travel planning whereas I received further instruction from people who were "hands on" experts (natives) in the country I was visiting.;)

He also asked if I wanted to bypass the tweeter breakers. The old ones were getting weak and easily tripped. I'd rather play it safe than burn out a tweeter.

If you do not want to bypass or remove the tweeter protection polyswitches, then you should replace them with new ones. Polk provides them free of charge. The resistance rises each time they are tripped. This causes a loss of high frequency detail, until they eventually open and you get no sound at all from the tweeters.

You may find this thread helpful: SDA Polyswitches Are Nasty

If I have to suffer somewhat in fidelity then so be it as I am only running a pair of "$300 amps." To sum it up I think; actually I know he did a great job and I'm quite happy with the update.

We all have to start somewhere. Just because your amps are "only" $300 does not mean you can't optimize performance. Some members assume, erroneously at times, that people posting here are interested in optimizing performance. Therefore, when we see someone going contrary to that ideal, we try to intervene. I concede that we probably should not care to the extent that we do. It is something I am working on.

I'm sure we could debate forever on how this should've been done and that undone, better wires, better solder, better amps and interconnects; ahh the list goes on. I do know that I'm very happy even if it doesn't please the "experts".

A lot of the so-called "experts" here have audio systems with performance levels that are at or near state of the art. I can state unequivocally that they couldn't possibly care less about being "pleased" by someone else's audio toys. Again, the goal was to assist in the optimization of performance rather than to criticize.

Now I'm wondering what kind of flak I'll catch for using the wrong sized t nuts when I do the mortite dynamat upgrade. That's next once the new caps get fully broken in. Yessir I'm sure I'll screw something up.

Most of the guys here hastily recede once they realize their advice is not well taken. So, I wouldn't worry about any future "flak".

The purpose of these comments was not to give flak. They were offered out of genuine concern for a member who did not get the best value for his money. Many of us are audio performance enthusiasts and we enjoy seeing other enthusiasts get the most out of their rigs. I will admit that we can be over zealous at times.

I think it's funny that's like that it's somewhat like grade school children playing in the sandbox kicking sand at one another.

Nope. No sand kicking at all. Just trying to offer some helpful advice to you and others who might be reading this and contemplating using the services of a "professional". There is nothing wrong with going to a professional modification service, provided they actually understand the subtleties, nuances and theory of what they are modifying.

Thanks geoff; That's what I've been trying to convey all along. The proof is in the hearing isn't it. After going back and forth with several emails to my tech this was a very well thought out modification. The law of physics doesn't change just because it says "polk sda" on the grillcloth.

The same laws of physics that apply to a Ford Taurus equally apply to a Lamborghini Murcielago. However, I wouldn't take a Taurus to a Lamborghini service center and I absolutely would not take a Lamborghini to a Ford service center.

SDA's are not conventional speakers. A lot of conventional speaker theory must be modified when applied to SDA's. For example, the use of fast bypass capacitors is perfectly acceptable in some speakers. They are not optimal in SDA's and were only used because of the relatively low quality of the mylar film caps used at that time. Higher quality film caps were not available in sufficient quantities at the time. Polk Audio was quite forthcoming in advising against the use of bypass caps if high quality film caps are used. The unique spatial properties of SDA's will magnify the sonic aberrations caused by fast bypass caps. Some may find this effect sonically pleasing...just as some like to season their food with an abundance of salt.

Even if I could wave a magic wand and undo the upgrade and go with the traditional approach I wouldn't do it. I'm being completely honest when I say I don't believe there's any way these 2.3s could possibly sound any better.

Well, there's always room for improvement...in anything. I have spent over $2,000 in upgrades to my SDA SRS 1.2TL's, yet, I realize that the sound could be further improved with better cabinet structure, better drivers, better crossover components, etc. I have been an owner and modifier of SDA loudspeakers for over 20 years and I am still learning new things about them and I am still uncovering new levels of musical detail.

In the end, with regard to your audio life, all that matters is that you are happy with what you are hearing.

My reason for posting this reply was not to be critical of your choice in modification service. Rather, it was posted for the benefit of others who might be contemplating a similar modification. They should be aware that modification services from practitioners who are not knowledgeable in SDA's will likely result in a sub-optimal result.