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Polk SDA-SRS 1.2tl Initial Impressions

When that poly switch does engage it shuts down all the tweeters for about 30 seconds or so or until the volume is decreased. The switches are said to increase their resistance each time they are made to work. Polk will send you the replacements for free so that might be a good start on your diagnosis. I wouldn't recommend replacing those safety switches with the .5 ohm resistor as those little poly switches do in fact do their job and can save you from a very costly and totally unnecessary tweeter replacement.
 
SDA SRS 1.2 said:
One other thing to watch for is that the semiconductor tweeter protection device tends to degrade with age and can kick in prematurely, which will make the speaker sound dull. Replacing this can restore the original sound.
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During my SDA SRS crossover rebuild last year I removed the poly-switches to keep the signal path as clean as possible. From my experience, the muddy sound was coming from the 20 year old low quality factory caps and resistors as placement was not an issue. The room is probably on the small side but I'm not listening at concert db levels. The improvement after the rebuild was like removing a heavy blanket over the front of the speakers.
The original owner had installed Polk new updated soft dome tweeters that sound fantastic.
 
Xoaphexox,

You are seriously underpowering the speakers, so any impression so far has little merit. So you know, they love high current amps. Removing the polyswitches and replacing them with .5 ohm resistors is highly recommended, but only if you have the proper amp to drive them with.

Despite what you may think, that short distance on the one side is a major problem.

Despite what someone else wrote, using the SDA's without the cable does not result in all the drivers working full range. With the cable removed the SDA drivers are only producing sound below 100Hz.

The tweeters are designed as a progressive point source. Therefore, one tweeter will sound louder than the other 3. So, what you are hearing is normal.

When I move the balance the whole way right I hear only slightly the surround effect in the left channel. With the same volume level on the amplifier and the balance now moved to the left, I hear the surround effect in the right speaker MUCH louder.
Click to expand...

With the balance all the way to the right, the left channel SDA drivers should produce very little sound and vice versa. From what you say above, I would say you have an issue with the right speaker. That is, it seems as though the stereo drivers are playing when they shouldn't be.

John in MA, they are the "BEST SPEAKER EVER MADE ON EARTH DAMNIT!", you just don't have the room. :)
 
Sorry to read your initial impressions are not good, however the Sansui you are driving them with isn't helping a bit. Many folks have posted advice with merit. Even F1nut.... and he and I agree on next to nothing. :D

Having owned 3.1tl's, 2 pair of 2.3tl's and now the 1.2tl's I picked up recently, I can not share your disappointment......I've been pleased with all of them.

For me, high power and high DF rating work. As I have said elsewhere I'm well pleased with a QSC PLX 3402. In stereo mode the 3402 is rated to a 2 ohm load, many high end amps cannot match that. Botrytis has my old pair of Denon POA 2200's, he's well pleased with them on his Polks, even though elsewhere these amps were not well received by the Polk "cognoscenti". Best advice I can give you is try anything you can.

Can you put your hands on a known common ground high power amp to try? Maybe someone you know near you may have a Adcom GFA555II? These are plentiful and common ground, and quite a few are happy with them on big Polks. :yes: That would be a good starting point if you can't be sure your PA7II is common ground. Also make double sure all the time that you maintain polarity.

Don't give up. :thmbsp:

Best,

Paul
 
Thanks for the extra guidance F1Nut (I have followed your posts over at Polk) and Beemer (likewise).

I am trying to arrange this weekend to either bring the polks to the basement or bring the BA-3000 (170wpc) or PA-A7II (225wpc) upstairs. It all depends on what makes the wife happiest.

I have also contacted Polk CS for new polyswitches and Sonicraft for brand new resistors and caps for the crossovers.

I am determined to get these things to shine. The Sansui I am powering them with was not my 1st choice really, it was simply the only amp I had in the room where I managed to drag these monsters :)

In the event the Nak is common ground, is the BA-3000 underpowered at 170wpc? Any idea what the cost outlay is to build a "juggernaut" or whatever that giant isolation transformer thing is called?

Thanks guys - I won't give up!
 
PS one of my binding posts in that left channel is a bit wonky, I think the plastic cap got stripped. Can you recommend a good replacement? I read these would work somewhere but I could not find any one that said they have actually used them successfully: http://www.soniccraft.com/products/connections/bindingpost/cardas_ccgr.htm

I see these are the "economy" difference. At 50% of the price, I think they will still be an improvement over stock. I am trying to save some cashish :) http://www.hndme.com/productcart/pc/viewPrd.asp?idproduct=436&idcategory=139
 
170wpc should be fine unless you really crank it. I've been running mine with a ~110WPC Bryston in a small room for six months and it's been fine. If you want loud or have a larger listening space to fill, they can soak up much more power, though. I'd use the Nak on general principals. It's by far the heftiest amp you have there.

F1nut said:
Despite what someone else wrote, using the SDA's without the cable does not result in all the drivers working full range. With the cable removed the SDA drivers are only producing sound below 100Hz.
Click to expand...

I said you won't lose anything, not that all the drivers would work full-range. The SDA drivers don't produce a straight signal over 100Hz (200?) anyway. By unplugging the cable you lose the full-range mirror image, but their low frequency behavior as part of the normal sound should be unchanged.
 
xoaphexox said:
PS one of my binding posts in that left channel is a bit wonky, I think the plastic cap got stripped. Can you recommend a good replacement? I read these would work somewhere but I could not find any one that said they have actually used them successfully: http://www.soniccraft.com/products/connections/bindingpost/cardas_ccgr.htm
Click to expand...

First off, I didn't realize you were posting duplicate posts on this and the Polk forum. That said, I see where you posted on CP that you made your own interconnect cable and that you connected the blade wires, not good. In doing so, it's possible you may have damaged at least one of the crossovers, which could also explain, at least in part, the issues you're having. I see that you are going to rebuild them, so we'll have to wait and see what happens then.

As for the binding posts, the Cardas CCGR's are excellent, are well worth the little extra money and are all that I use.



John in MA said:
I said you won't lose anything
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I'll have to disagree.
 
F1nut said:
...it's possible you may have damaged at least one of the crossovers...
Click to expand...

Good to know, I will get the binding posts then so I can get the xovers fixed in one fell swoop.

Out of curiosity, in what way can the crossovers be damaged by connecting the blades to both ends? Thanks!
 
Good question and one that I'm not 100% sure of other than I do know that the circuit should not be completed unless the AI-1 isolation transformer is used.
 
Fair enough, it will probably be a week or so until I have my parts from Sonicraft so I will post my findings once I get that all sorted out. Until then thanks for the remarks!
 
F1nut said:
I'll have to disagree.
Click to expand...

You'll lose the SDA imaging and some of the intended sound quality. All I'm saying is that the functioning of stuff that's part of the the positive phase circuit shouldn't be changed. It's not like you unplug the cable and half your active midrange drivers stop working. The midrange coming out of the SDA row is the mirror signal.
 
BTW I finished the crossovers and also relocated some of the polyfill in the right speakers and I think they are tip-top now! I have been enjoying them for a few days and really learned the limits of my neighbors patience!
 
Good for you:thmbsp: Glad to hear you stuck it out and resolved the issues. After the cap break in you may be in for even more of a treat. When I had my sda's recapped it took a few weeks of playing time for them to sound their best.
Is there be a high current amp on your horizon to sweeten things up a little more?
 
motorstereo said:
Is there be a high current amp on your horizon to sweeten things up a little more?
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The Nakamichi I have is 90A peak so I think that is high enough current but unfortunately I have no preamp to drive it with. I refuse to hook it directly up to the source because there is no level controls on it. I have the Nak CA-5 on my eBay watch list in hopes one comes along but I am also open to any other preamps that might work. Space is limited - my entertainment stand has two shelves. One with the Mitsus in my sig on them and one with the cable box and dvd player on it. They are both maxed out.

I have cats so as a rule I put everything in enclosures to keep hair and paws off!
 
If you're looking for something decent until you find your dream Nak preamp, check out NAD, Rotel, and Adcom. All good mid-level gear. An Adcom GFP-555 or 565 is a solid unit.
 
Not a bad idea, I only wanted the CA-5 because it was aesthetically matched to my PA-7 but I would rather have one that sounds better!

I know this is opening the floodgates but do you have any suggestions for a nice (affordable) tube preamp? This will be my first tube unit as well..
 
I'm not familiar with the vintage pres that most use on here.

My entry level pre was a Audio Experience Symphonies ($300 + $100 nos tubes). Line level, no phono. Good value for the $$. Currently my backup pre.

I like my CJ PV-10AL ($500 + $100 nos tubes) better. A little warmer sound and has a true tape loop for a eq or dbx. Line level, no phono. The PV-10A wth phono will run you more like $600-$700.

btw these are not for sale. I was just quoting the prices these usually sell for.
 
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