Just got my dream speakers!! - the SDA SRS.... but there's a problem... pls help.

Polkvibes

Hello all, new forum member here but long time Polk fan. I got my first pair of CRS in 1986 and have been a fan ever since... that pair is long gone. Flash forward many many years and I've gotten back into the HiFi hobby and purchased a beautiful pair of Oak veneer CRS (blade/blade) and SDA 2s a few years ago -- but I've been wanting to get a pair of the 'big boys' forever.

Long story short, lo and behold, I found a local pair of "1.2s" on sale a few days ago about one hour away for a decent price, and I jumped on it. Turns out these are not 1.2, but original blade/blade SDA-SRS. Oh well. Anyway, they sound amazing.. best speaker I've ever owned. Sounds huge and look huge in a 28x25' room. The bass response is off the charts, and sounds totally natural and not boomy.

But herein lies the problem... I think the Right Dimensional array is not working. The soundstage on the left speaker is all "SDA" but the right speaker soundstage is anemic and missing something. (Speakers are in same room position as my previous SDA and those always had the big SDA effect across the spectrum)

Troubleshooting already done:
1. As per Polk manual, panned music to the right and checked that the left speaker's Dimensional cones are firing off low end content. YES! I can hear and feel the bass from the dimensional array. Panned music to the left and checked right speaker dimensional array - hardly any movement or sound from that array. There's either no sound or very little, very faint. (With balance at center - both speakers give sound)
2.Reverse Left/Right speaker cable to see if it was out of phase. No difference. Both speakers act the same either way, AFAIK.
3. Push-test on 15 " passive radiator... all eight cones on the problem speaker move in and out, nothing frozen and no noise.
4. Cleaned all speaker and IC connections with deoxit. No dice.
5. Used different blade/blade IC... no dice.
6. Unscrewed round back panel with speaker and IC connections - checked for lose IC connection (none) and cleaned all connections with deoxit. (Also had my first look at the crossover at this point -- nothing amiss visually with the crossover.) Haven't yet removed the front panel to look at the crossover more closely.

Any ideas guys? Its driving me nuts trying to locate the problem. I read through many old posts but the reference links in them have gone bad... and all I have is the Polk SRS Manual. One guy with the same problem was measuring the OHMs with a multi-meter on the IC connections. The link he referenced is gone.

I plan to get the Crossovers done soon, maybe sending them to a forum member who is more knowledgeable than myself. But I'm not sure that redoing the crossovers will fix the problem with the Right Speaker Dimensional Array.

Thanks for reading through my (too) long post, by the way!!

Gardenstater

Well you can and will get better answers than mine, since I have no SDA experience, but I would definitely get out the DVOM and trace the circuitry, measuring continuities and resistances, with the schematic and wiring drawing as a reference. Do it on both speakers and take notes and compare readings. Enjoy those speakers!

PS: I would print out the schematic and wiring diagram and assign numbers to various nodes. Then tabulate the resistance measurements between those nodes, for the L and R circuits. You have already tried reversing speaker cables and apparently the problem remains with the particular speaker, so I have no doubt that you will find some sort of irregularity between the two circuits.

dkfreebird

Did you reverse left and right cables or positive and negative wire on speakers? Is there a center image? I picked a a pair of crs+ speakers where the black and red wire nuts were reversed.

Tony M

dkfreebird wrote: »

Did you reverse left and right cables or positive and negative wire on speakers? Is there a center image? I picked a a pair of crs+ speakers where the black and red wire nuts were reversed.

This happened to me too.

Polkvibes

Thanks for the replies! Dkfreebird - there is a good center image. I only reversed the speaker cables themselves - ie plugging the red banana plug into the black terminal etc. I didn't examine any wire on the drivers nor did I reverse any wires going from the speaker posts to the crossover. Would reversing these internal wires be different from simply swapping the R/L speaker cable? I simply swap the wires on their posts?

Like I said, there is a center image but the SDA effect from the right speaker is weaker/not apparent when compared to my CRS and SDA 2 sets.

Gardenstater.. good idea. I actually found a schematic for this, but I'm not versed in reading schematics, lol. I do have a Digital Multimeter and can try to take continunity readings, but it will be hit or miss. My experience is with wiring up guitars so that is my frame of reference.

One more thing - this speaker model has four posts per speaker and there are jumper wires from the bottom two posts to the top ones. If those jumpers are original, they are 35 years old! I didn't actually loosen the nuts to clean the jumper connections. Maybe one of the jumper wires went bad? I can make new jumpers in a few days when my spade lugs arrive. It would be great if it turned out to be such a simple fix!

Thanks guys, I'll keep troubleshooting. The speakers sound so great as is, but I can't let it go unless they're running perfect. I'm gonna pull the crossover tomorrow and inspect it there and look for any bad connections or obvious problems. I'll try to see if there are continunity problems from the speaker posts to the crossover. This is something I don't know how to do yet, I'll have to learn as I go.

Polkvibes

Also I try to take pics this week, maybe that will make it easier. Stay tuned!

pitdogg2

Wouldn't hurt to clean the jumpers. Those only affect the tweeters not the SDA side. Are all the drivers working on the affected side. Do any have any scratchiness when pushing evenly around the center of the cone in and letting out easily?
The culprit could also be the SDA interconnect socket. Does the plug fit well as in not loose in the socket? No broken plastic?

Gardenstater

I would most definitely remove and clean the jumpers and the binding posts. Check them for continuity. So, you haven't actually swapped the speaker cables, or to try to be perfectly clear, you haven't removed the speaker cable from the left speaker and put it on the right one, and vice versa? I'd certainly do that and see if the problem remains with the same speaker.

Also, it's a fairly easy thing to remove each of the dimensional drivers from the problematic speaker and check the DC resistance of each one and clean the connections and make sure the connections are solid and firm. This is of course assuming they used faston connectors and didn't solder the wires to the drivers.

Also, like the other guys said, make sure the polarity of the binding posts is correct, ie. Red is + and Black is -. Use the schematic as a guide if necessary and trace each post to make sure it goes to the proper part of the circuit.

pitdogg2

No soldered wires on the speakers there.

teekay0007

Did you hear the speakers prior to buying them? No issues? Could the seller be of any help?

Polkvibes

Hi great responses all. The best way I can describe the problem is: "The left speaker SDA effect sounds normal (if not particularly huge), but the right speaker sounds like a regular "Stereo" speaker.

Ok so the jumpers don't affect the SDA array, but I'll still pull them and clean the sockets. The SDA interconnect socket is physically ok, not broken and cable is not loose but I will try to check the socket with a multimeter. The two wires that go from the IC socket to the Xover board are physically secure. The SDA drivers on the affected speaker seem ok, they move and no noise. I didn't move the speaker cable from the right speaker to the left speaker. I only swapped the Red/Black cables for each speaker. Cool, I will try that today! I'll also remove the drivers to take ohm readings.

Thank you for the schematic, that is helpful. I suspect there is a continuity issue somewhere, whether on the board or 'upstream' from tsomewhere. Plus, what if the dimensional array caps on the Xover board are shot? I'm gonna have the boards redone soon.

I actually did hear the speakers before buying - everything sounded ok -- the SDA effect is sometimes tricky though. I didn't notice anything was wrong 'till I got it home and put the speakers where my other SDAs usually are. Getting help from the seller isn't really an option unfortunately.

Final question: I want to do some continuity tests on the SDA IC socket and perhaps other areas. Any advice on that? Do I just clip one jack of the multi meter to one IC jack pin and the other to a speaker input jack pin to get an OHM reading? That way I can check the IC socket in relation to the Red and Black speaker jacks.

So I have a 'theory' about continuity, but I don't have the necessary experience to actually troubleshoot this yet. (Never messed with speakers before). When I pull the Xover board, I'll post some pics!! Thanks y'all.

Gardenstater

When checking continuity it is generally best to start as *zoomed out* as possible and if there is a problem with continuity there, start focusing in on smaller areas, point to point, to determine exactly where the problem is. I prefer to use the alligator clip leads where possible for hands free(ness) and uniformity of contact pressure. So, you could go from the amplifer side positive of your speaker cable all the way to the other end of the IC cable extension of the A designated terminal in the schematic, for your first check.

Polkvibes

Great, thank you for the tips. I have alligator clips. I'll try to locate the mysterious problem. Can't pull the crossover until this weekend though. In the meantime, the speakers still sound awesome if a little unbalanced.

Gardenstater

I'm sure you'll figure it out. What I said above doesn't require removing anything. You can do it for both speakers. Another thing you can do fairly easily on both speakers (with IC cable disconnected) is to remove the white ground wires from the 2 bottom stereo speakers (in schematic) and measure the resistance from the positive low frequency binding post (red) to the negative one (black). That will give you the DCR of the Dimensional Speaker array, including a couple of inductors. You can compare the Left Speaker with the Right one's readings.

Polkvibes

That's a great tip, thanks. I'll do that soon. So if the DCR is off between the Left and Right speakers, and I ascertain the DCR for the problem speaker... what would be the next diagnostics step? And lets say I get NO DCR reading for the problem speaker? Does that mean the inductor is bad? (Sorry, I'm a total noob at this)

I'm looking at the docs you posted (the wiring diagram is easier for me to start with). I'll have to teach myself to read a schematic because someone else had a similar problem a while ago and he was able to find the 'bad' caps for the Dimensional Array on the board. There's a few of them. He also put a jumper between "L1 or L2" (IC / Right binding post connection on the diagram -- and it fixed the problem. I'll post a link to that whole thread at the bottom of this post.

Here is what he said:

Long story short - the direct circuit board connection between L1 and L2 blades was faulty- something w/ the blades or the board copper or both - I installed a copper jumper across the top of board on those pins, and voila, all resistances were "as desired". Weird thing is, SAME EXACT PROBLEM was found on the other speaker! ! So if your SDA SRS is not functioning, check out those reference resistances!

When I pull the crossover, perhaps it will be something obvious. Maybe a cold solder joint or loose wire.

I can tech myself how to do cap testing with the multimeter. Since I can't rebuild the whole crossover, I'm hoping to at least isolate the problem and fix the damn thing. IIf I'm lucky it will just be a few parts swapping and maybe resoldering a wire or two.
Thanks Gardenstater, I'll update progress this week, (if there is any!!)

Post where guy figured out my similar problem:

https://forum.polkaudio.com/discussion/173687/sda-srs-upgrade-story

Gardenstater

Here's the reference resistances given in the SDA manual. Pin #1 is the Large Blade and Pin #2 is the Small Blade and all your MidWoofer drivers should be MW6503's:

Polkvibes

Very cool Gartdenstater! I was looking for those and couldn't find them. That should be very helpful!

Weird thing is "I think" I fixed something!!!.... I pulled the crossover and sprayed deoxit on all the faston connectors that go from the IC socket to the board and some other connections. Played my 'reference test' track Thiller by Michael Jackson (don't laugh -- the beginning of the song with the wolf howls & creaking door are a great test for the SDA effect)

Anyway, all of a sudden, sure enough, I could hear that 'huge spread' coming from the right side where it was obviously absent before. The strange thing is that the Right speaker's 4 Dimensional array mid-cones are still not firing nearly as hard as the left speaker -- but the SDA effect is pretty much there now... puzzling.

So that table you sent me -- Lets take the first example "R1" -- I can simply take those readings by removing the speaker jack panel, correct? Then I attach one prong of the multi-meter to Pin 2 of the IC socket and the other to the Black/- speaker terminal. Am I on course here?

Also haven't taken measurements of the Midwoffers because I believe I have to lay down the speaker, take out the 15" woofer and/or take off the bottom panel of the speaker to get to them. That's a huge undertaking on a 185 lb, almost 6' high speaker!!

I'm attaching pics of the board. I couldn't measure any caps (my MM doesn't have the ability to measure caps that are in a circuit, I'd have to desolder them.) Visually the board and components look okay -- no explosions.





So I have to do some more listening but it **may** be okay now!

Thanks Gardenstater for all your help, I greatly appreciate it!!

Oh yeah, just throwing this out there. If anybody on this forum wants to help me refurb the crossovers -- let me know!! I can send 'em to you with the parts, and work $$ something out with you -- I don't really trust myself to do the job.

Gardenstater

Polkvibes wrote: »

Very cool Gartdenstater! I was looking for those and couldn't find them. That should be very helpful!

Weird thing is "I think" I fixed something!!!.... I pulled the crossover and sprayed deoxit on all the faston connectors that go from the IC socket to the board and some other connections. Played my 'reference test' track Thiller by Michael Jackson (don't laugh -- the beginning of the song with the wolf howls & creaking door are a great test for the SDA effect)

Anyway, all of a sudden, sure enough, I could hear that 'huge spread' coming from the right side where it was obviously absent before. The strange thing is that the Right speaker's 4 Dimensional array mid-cones are still not firing nearly as hard as the left speaker -- but the SDA effect is pretty much there now... puzzling.

So that table you sent me -- Lets take the first example "R1" -- I can simply take those readings by removing the speaker jack panel, correct? Then I attach one prong of the multi-meter to Pin 2 of the IC socket and the other to the Black/- speaker terminal. Am I on course here?

Also haven't taken measurements of the Midwoffers because I believe I have to lay down the speaker, take out the 15" woofer and/or take off the bottom panel of the speaker to get to them. That's a huge undertaking on a 185 lb, almost 6' high speaker!!

I'm attaching pics of the board. I couldn't measure any caps (my MM doesn't have the ability to measure caps that are in a circuit, I'd have to desolder them.) Visually the board and components look okay -- no explosions.


So I have to do some more listening but it **may** be okay now!

Thanks Gardenstater for all your help, I greatly appreciate it!!

Oh yeah, just throwing this out there. If anybody on this forum wants to help me refurb the crossovers -- let me know!! I can send 'em to you with the parts, and work $$ something out with you -- I don't really trust myself to do the job.

You're welcome! It helps me to learn more about these speakers which I ultimately would like to own someday. It sounds like you may have made progress but perhaps you still have an unidentified issue remaining.

That first reading....R1......you don't have to use the alligator clips and most meters also have pointed probes which you could insert into the binding post and the IC sockets. Another trick would be to use a spare banana plug or simply clip the alligator clip onto the binding post. The IC socket may be a bit trickier and if you don't have something that you can insert that is the same size as the IC connector, you may have to use the probe or you can disassemble. Another option which I stated before is to measure all the way through the IC cable and you could easily clip your test lead onto the other end of that. Any DC resistance of that IC cable could be easily deducted from your measurements but it should be quite low.

You should be able to remove the MW driver screws with the speaker in its usual vertical position, as long as you are careful but I'd take the measurements in the Table above first and if nothing is off, it may not be necessary. I would definitely want to examine all the drivers at some point though and make sure the polarities are all correct and that the drivers are the correct MW6503 and that nobody has swapped out any incorrect drivers.

PS: Don't forget this detail on the schematic:

Polkvibes

Thanks Gardenstater, your help has been invaluable! I'm going to read through this whole thread this weekend troubleshoot as much as possible, to make sure that everything's tip top. Also found someone to refurb the crossovers in January.

Glad that we could discuss the SDS SRS -- they really are fantastic speakers!! (They're huge though!!) I'd be interested to hear the 1.2 and 2.3 versions, but these are not lacking anything. Super punchy and tight bass in my room being pushed by an Adcom GFA-555!

Cheers

PolksTillIDie

Hey guys, I'm having the same problem with my SDA-1Cs. Great sound in general, but no SDA effect from right speaker. Can you check out my thread "SDA-1C Right Channel No SDA Effect" here in Troubleshooting?

Thanks.