Dull Speaker

gabasa

Hi,

I bought a pair of SDA-1 speakers yesterday for a great price. When I got home, I realized that one of the speakers doesn't work as well as it should. I told this to the seller, along with a request for a refund, and he accused me of damaging them and now is ignoring my emails.

I did not damage them ... I got scammed.

Anyhow, I was thinking of restoring them by making sure that all the drivers are working and replacing the bad ones, since I did get a really good deal. This makes me think of a few questions that I was hoping someone might be able to answer:

• Is there a current replacement available for the original MW 6501 drivers? If not, I'll hunt eBay for them because they do come up once in a while for not much money.
• Is there a wiring diagram available for the SDA-1 speakers, so that I can double-check the black, white and blue wire connections?
• What else could make the right speaker sound dull compared to the left speaker? The left one is big, rich and clear while the right one is dull and lacking in comparison. Any ideas?

I haven't used an interconnect cable with them because I don't have one. I was thinking of making one, but not until these are up and running properly. I've done many, many internet transactions in my time, and something like this hasn't happened to me in at least 10 or 12 years.

Thanks for your help!

pitdogg2

You could also use mw6600. Check for magnet shift on the drivers. That could be the cause of dullness. The dimensional driver will not work without the interconnect cable.

gabasa

Thanks. Which ones are the dimensional ones? I couldn't find this info anywhere.
How can I check for magnet shift? I've found some resources on how to repair them, but I don't really know how to check if they're bad or not.

gabasa

Ok, found more info....

If I very carefully and gently tap on the speaker cones, some of them make a clicking noise from behind, as if the voice coils are hitting against the magnets. Is it a reasonable assumption then that the magnets have shifted?

If this is the case, I think that I can fix them with some Loctite.

Thanks for the help.

F1nut

Dull usually means the tweeter isn't playing. Swap a good one into the right speaker.

You don't tap on the driver, you gently push it in with your fingers spread evenly around the cone.

pitdogg2

Carefully push speakers in trying to keep centered. Feel for resistance and scratchy. On the right speaker dimensional is to top right woofer. On the left speaker dimensional top left speaker. They will still move when playing music because it is a sealed cabinet and sympathetic to the other drivers moving. To test for sealed cabinet push passive in fast to stop watch all other woofers. They should not just drop back. You should get about 3seconds. My sda1 signatures came with all mw6600 drivers except the SDA dimensional driver which was mw6501. The mw6600 drivers had a different felt like dust cap which the mw6501 was more open linen like. My mw6600 drivers will stay out a little longer than all mw6501 drivers. Magnet shift is very real on the older drivers.

By the way welcome to club Polk. We are a tight knit family here stick around and get to know folks. We can be very blunt at times but a ton of very knowledgeable folks from all walks of life.

Just to be sure your SDA1 has two side by side top tweeters not stacked on top of each other in the middle the cabinet.

gabasa

Thanks for all the help, I'm glad I joined this group! I have a pair of RT10 speakers I've been using for about 20 years, and in a way I'm glad I got these SDA-1 speakers and joined this group. I've always been a Polk fan!

Yes, these have two side-by-side tweeters. So I take it that the outer, top speaker is the dimensional one.

Are either of the tweeters dimensional? Is there a good method to test the tweeters?

There's some great advice here, I feel like there's a chance I can get these up and running! Thanks.

F1nut

Correct, outside tweeter. Most find the SDA speakers with SDA tweeters sound better with them disconnected.

Like I said, swap the good tweeter from left speaker to the right. That will tell you if the problem is the tweeter or something else.

gabasa

Thanks for the advice. So, if I'm not using an interconnect cable right now, I should swap the left tweeter on the right speaker with the right tweeter of the left speaker to see if the problem remains or switches speakers.

Correct?

txcoastal1

Correct
but even with the SDA interconnect, many leave the dimensional tweeter disconnected

gabasa

Ok, thanks. I just swapped tweeters and the same speaker (the right one) still sounds dull. This tells me that the tweeters are good and there's another issue elsewhere.

I was playing some music and whenever I covered the tweeter on the left speaker with my palm, it would muffle the sound. If I'd cover the tweeter on the right speaker, it wouldn't make much of a difference at all.

Can this be a repairable crossover issue? Perhaps (hopefully) a capacitor somewhere?

pitdogg2

The dimensional tweeters will not function without the interconnect cable. Left speaker left tweeter will not work. Right speaker right tweeter will not work.

Do you have fuses on the back? If yours have big square crossover panel where binding post are you have fuses for both tweeters. Clean fuse holders real well and take fuses out and check fuses for continuity. Fuses should be 1amp fast blow.

gabasa

Rats, no fuses in this one. Yeah, the only tweeters I checked were the active ones, not the dimensional ones.

I removed the large woofers and was surprised to see that passive literally means passive and unconnected to any power source!

I did this to take a better look at the crossovers from the front to see if there's anything obviously wrong with them and found nothing.

Would my logical next step be to remove all the foam from inside and follow the tweeter wires to the crossovers to see what they connect to? That way I might be able to localize the issue. Am I barking up the right tree here?

gabasa

The seller just offered me a chunk of my money back, so in the end I paid the equivalent of $138 USD for this problematic pair. If I can't get them to work eventually, it won't be too much of a loss.

pitdogg2

That was a nice gesture.

F1nut

If you have the SDA 1A, then you have a polyswitch on the crossover, which acts like a fuse. They go bad over time from being tripped too often. Cut the leads, twist the stubs together and check for sound.

Dabutcher

Do you have another pair of speakers to inject into your system to see if it is the new speakers or some other part of your system? Good luck and welcome to club Polk. Peace. D

gabasa

Yes, that was a nice gesture. I think that perhaps I should have given him the benefit of the doubt earlier.

I'll check the polyswitch. If that's the issue, should I replace it with a current part?
Maybe I'll try to check them all for continuity with my multimeter to see if any are open.

I did try other speakers, as well as other receivers and cables just to be certain where the problem lies. There's definitely issues with this speaker.

This forum is awesome, thanks for all the help!

pitdogg2

Polyswitches are a pain in the posterior. We get rid of them when we recap. For now twist the legs together IF possible. We put a .5ohm resistor in its place.

gabasa

It's been a while because I've been busy with work, but I finally got around to working on these speakers. Thanks again for everyone's help.

I clipped out both polyswitches on both speakers and soldered in some wire in their place. Right away, they both started to play well and the tweeters are all working.

There seems to be some magnet shift on the drivers, but it is only audible when hooked up to high powered amps. With my Harman HK930 or my Marantz 1070, they work just fine.

I don't have an interconnect cable, so I plan on making one. How necessary it is? Right now they are operating just like any standard set of speakers and sound great! The basses are deep without any hype, the trebles are clear but not piercing, and the midranges are natural sounding.

I might replace the electrolytics and upgrade the film caps, but for the time being I'll enjoy them as they are!

F1nut

There seems to be some magnet shift on the drivers, but it is only audible when hooked up to high powered amps. With my Harman HK930 or my Marantz 1070, they work just fine.

That makes no sense. What are the symptoms?

YES, you need the SDA cable!

gabasa

It probably doesn't make sense, lol. I hooked it up to a friend's receiver, much more wattage than mine, and at high volumes we heard some clicking noises. The first thing he said was that it might be magnet shift, but he really knows as little as I about speakers. Using my old Harman HK930, it doesn't make these noises.

gabasa

I feel like talking about the SDA cable, but perhaps I'll start a new topic because there's some more, different troubleshooting there. Thanks everyone for the advice, it's great!

gabasa

I'd have to find out, I'll get back to you on that.

F1nut

gabasa wrote: »

It probably doesn't make sense, lol. I hooked it up to a friend's receiver, much more wattage than mine, and at high volumes we heard some clicking noises. The first thing he said was that it might be magnet shift, but he really knows as little as I about speakers. Using my old Harman HK930, it doesn't make these noises.

Were they clicking or clacking noises. If clacking that could be a worn/damaged spider or a lack of driver control caused by an inferior power source.