Canadian Newbie - Proud 1.2TL Owner

[MGS]

Hi.
I'm new to this Club but not new to SDA's. I was a partner in a small chain of stores up here in the early 80's, sold 3a (remember them?), ESS and JBL speakers (still have a few pairs), JVC, Marantz (still have a few separates and receivers...more than the wife is aware of), SoundCraftsman and Fisher back then. I was at CES in Chicago when the SDA's were first introduced and met Matt Polk, as well as Saul (sp?) Marantz and Bob Carver...all great guys btw. However, not being a Polk dealer, I never got the chance to own a pair of these beauties until recently. I bought a beautiful pair of 1.2TL's on Audiogon last month, drove straight from Toronto to Ft. Lauderdale to pick them up. They were still owned by the original owner and looked like new. When I got them home, I hooked up my Bryston 7B SST (600watt mono) amps to them and started a sound check to ensure all the drivers were working. Low and behold, the 2 bottom tweeters of each speaker were silent, and by the end of the night after "flexing" the system, only 3 survived. I will order 8 new RDO198-1's tomorrow from Polk, as this is a simple/effective upgrade according to what I have learned so far, unless I have outdated info.
What I am very interested in are the crossover upgrades...so my question is: Who can provide me the most detailed/step-by-step instructions to accomplish this? I have built speakers and crossovers in the past (remember Philips Deforest in the 70's?) and can handle a soldering iron, but am not in any way savvy with electrical jargon, so I want to be 100% sure I use the BEST components with the BEST instructions to do it right the first time.
I welcome your feedback and thank you in advance for your help.
...and yes, Canadian jokes accepted :)

[janmike]

Welcome to Polk and congrats of the speakers. Sorry I cannot help you with your requirements but there are many here who can.
PS - Yes, I am sure there will be many Canadian jokes so remember to fire them back as well. :)

[engtaz]

Welcome MGS. Great pickup. I thought someone did a detailed crossover upgrade but I can only remember the 3.1TL upgrade. Good luck

engtaz

[heiney9]

Congrats. Just be aware that you can not run the SDA's on mono bloc amps or other non-common ground amplifiers without the optional AI-1 interconnect available separately at the time. You risk damaging the speakers or amp or both.

The AI-1 interconnect has built in transformer; the regular interconnect does not.

Lots of great threads with info on the x-over upgrade and the RD0's will make a very substantial improvement.

Good luck and stick around

H9

[MGS]

Thanks for the heads up. I was not aware of mono blocs being "non-common ground" and dangerous to the amps and speakers. I had them cranked to their limits when I was flexing the system a few nights ago. Although a few tweeters didn't survive, as mentioned earlier, the amps never got hot and the speakers sounded great. Do you have additional information on this grounding issue and the ramifications of not using an AI-1 Interconnect cable with mono blocs?

[engtaz]

Check you mids drivers also. Non common ground amp issues and SDA's are not a pretty thing.

engtaz

[heiney9]

Thanks for the heads up. I was not aware of mono blocs being "non-common ground" and dangerous to the amps and speakers. I had them cranked to their limits when I was flexing the system a few nights ago. Although a few tweeters didn't survive, as mentioned earlier, the amps never got hot and the speakers sounded great. Do you have additional information on this grounding issue and the ramifications of not using an AI-1 Interconnect cable with mono blocs?

Sales brochure for you TL's-clearly states not to use non-common ground amps (which mono blocs are)

http://www.polksda.com/pdfs/SRSTLBrochure1990.pdf

Owners manual for the original (non-TL) SRS line which clearly states not to use non-common ground amps (the TL owners manual would state the same thing)

http://www.polksda.com/pdfs/SDASRS1-2.pdf

Do a search (it can be tricky as the search function is little temperamental) you'll see this has been discussed and excellent answers given many many times.

Instructions for the AI-1 cable

http://www.polksda.com/A1_Interconnect.pdf

Addendum to SRS and other SDA models.

http://www.polksda.com/pdfs/SRSAddendum.pdf

H9

[Lasareath]

MGS,

Congrats on getting the 1.2TL's!!!!!, I'm sure you will love them. The following is a list of parts that I bought to upgrade my 1.2tl crossovers. You can also see some pictures below of mine and the steps I took to redo them.

Joe (Hearingimpared) sent me this list:

Call to order, 501-620-4444, you will be speaking to Elliot.
Sonic Craft http://www.soniccraft.com

Sonic Craft Generation 1 http://www.soniccraft.com/sonicaps.htm

“Sonic Capacitors Generation 1”

Ask for Custom Matched & as close to 1% tolerance as possible:

Qty Rating
6 12uf (he was able to get the 1% tolerance for me)
2 0.25uf (he is going to have problems matching this and will probably get within % tolerance which is okay.
2 13.5uf (he could get 3% tolerance here for me)
2 27uf (2% tolerance for me on this one)


Mills Wirewound Resistors – non-inductive http://www.soniccraft.com/mills_resistors.htm

All should be rated 12 watt

Qty Rating
2 2.7 Ώ
2 7.5 Ώ
2 11.5 Ώ (you may have to settle for 11 ohms here)
2 15 Ώ
2 22.5 Ώ (if you can only get 22 ohms that is okay)


1 Spool of Cardas Silver Solder

To summarize, you will be ordering 12 capacitors, 10 resistors & 1 spool of Silver solder

It is going to cost you around $450 + Shipping


Sal

[MGS]

Thanks for the responsiveness and level of support guys!
I checked the mid drivers and, although the lower units sound different from the uppers (different x-over frequencies?) as well as the left columns vs. rights (SDA effect?), all 16 are working. Should I remove and check each one individually, or does it sound like they're OK?

[engtaz]

Great job H9.

engtaz

[hearingimpared]

Welcome to the Club MGS. I think everthing you need is covered above so I won't pontificate on anything. However, if you have any questions about upgrading the crossovers, tweeters, binding posts, internal wiring etc please don't hesitate to email me.


EDIT, I forgot, there are also pictures floating around this forum in a "How To" format.

[GV#27]

Hi MGS ,your excellent 7B SST's use a bridged output stage so they definately belong in the non common ground group, so as mentioned you would best use the A1 cable.Unless it is an early unit(low serial #) all of Bryston's SST series non common ground amps can be easily identified by the use of a blue binding post for the negative speaker output.The common ground units use a black binding post.

[MGS]

Yes, there are blue binding posts on the 7B SST's (and black on my 6B ST)...thanks GV#27...you solved the mystery of the blue bp's for me.
Regarding upgrade plans, here's my order of priority:
1) Build AI-1 Interconnect Cable
2) Install 8 new RDO198-1's
3) Enjoy them for a while (after all, I've been waiting >20 years for a pair)
4) Rebuild the crossovers and possibly binding posts (not sold on upgraded bp's yet)
Help on 4) would be greatly appreciated, as I stated above.

[BSUfbfan]

Mills Wirewound Resistors – non-inductive http://www.soniccraft.com/mills_resistors.htm

All should be rated 12 watt

Sal

Are you sure on this? I have heard from several Polkies (including Jesse) that the Mills MRA-5 will work just fine, and have less inductance. I just ordered a gaggle of them for my 2.3's, so I'll hope for the best.

[Lasareath]

Are you sure on this? I have heard from several Polkies (including Jesse) that the Mills MRA-5 will work just fine, and have less inductance. I just ordered a gaggle of them for my 2.3's, so I'll hope for the best.

When the price difference is only a couple bucks more per unit I usually go for the "Oh what the Hell Factor"

http://www.soniccraft.com/mills_resistors.htm

From Sonic Craft site:

The MRA-12 (12 watt power rating) possesses a big power handling for its size. It will handle overloads 10X its power rating (120 watts) for 5 seconds with operating voltages up to 1,000 VAC. The body measures 1.188" +/- 0.062" in length by 0.312" +/- 0.031" in diameter. The leads measure 1.500" in length minimum by 0.040" in diameter.

The MRA-5 (5 watt power rating) exhibits even lower inductance than the MRA-12 due to its very compact size. It will handle overloads 5X its power rating (25 watts) for 5 seconds with operating voltages up to 500 VAC. The body measures 0.562" +/- 0.062" in length by 0.167" +/- 0.031" in diameter. The leads measure 1.500" in length minimum by 0.032" in diameter.

I think I rather have a resistor that can handle 10X its power rating for 5 seconds rather than 5x, especially if they only cost a buck or two more per.

Sal

[Ricardo]

Welcome to the forum. I think your priority list is right on; start with the interconnect so that you don't fry any drivers.....

Here's a thread from my X-over upgrade; there are others out there....use the search function..

http://www.polkaudio.com/forums/showthread.php?t=37333&highlight=crossover

[MGS]

Joe, Sal, Ricardo,
This may be a loaded question, so I will apologize in advanceif it creates a lengthy debate...Did you guys do the exact same crossover upgrades? If not, what were the differences and why?

[Ricardo]

I think we all did basically the same, though there can be some variations:

-Components brands; I used Solen capacitors, I think Joe/Sal used Sonicaps. There is a difference and you'd be better paying for the more expensive caps.
-You can choose to eliminate the polyswitches. Not sure if Sal/Joe did this, but it can be done with little/no risk if you have good amplification. Your ears will blow before the tweeters.
-By pass capacitors: if you use good modern caps, there's no need to use the by pass cap for the tweeters.

There's probably other variations also, but it gives you an idea.

[heiney9]

+1 with what Ricardo posted. The SDA's deserve the better caps and most of us have used Sonic Caps. Eliminate the ploy switch if you are sure no one in your castle will have an opportunity to overdrive them. If you are using a lower power amp, etc. then you might consider replacing them with new. Eliminate the bypass caps because they are not necessary when using newer high quality caps.

Is there an echooooooooooo in here :D?

[MGS]

OK...thanks. Who has the best "step-by-step" (idiot proof) instructions for the xover upgrade????
I'm running Bryston (good Canadian product) 7B SST's rated at 600wpc at 8 ohms/900 wpc at 4, so I should be safe eliminating the ploy switch.
BTW GV#27, I checked with Bryston and I can't ground the amps together, so I'm destined to build the AI-1 interconnect.
RDO198's were ordered today...right out of canada, eh!

[Lasareath]

Ricardo is correct, I used Sonicaps & Mills Resistors. I removed the polyswitches and the bypass caps as well.

The only thing different on my crossovers is that when I bought my caps from Elliot at SonicCraft he was out of 0.25uf Sonicaps so I had to buy Mundorfs. The Sonicaps in that size were $7.80, the Mundorfs were $29 each!!!!!!

Eventually one day I would like to redo the crossovers with all Mundorfs.

Some people have changed the Chokes as well with very good results.

I do not think there is a step by step guide that will show you how to proceed.

Basically you want to do one crossover at a time, take some photos of them in their existing state and remove all the caps and resistors.

Draw on a piece of paper the layout of the crossover circuit board and where all the connections for each of the caps & resistors get soldered to. Clean up all the soldering points with a solder wick or suction device and then start putting the new pieces in place.

you can look at my pictures to see how I laid out the caps & resistors.

Joe also has many pictures as well, maybe he can post some here.

Sal

[MGS]

Thanks Sal

[avguytx]

Wait.....you drove from Toronto to Ft. Lauderdale and back? Wow....that has to be a record distance to go! Isn't that about 1500 miles one way????

Congrats on the speakers!