SDA-1C Right Channel No SDA Effect

PolksTillIDie · December 2020

Yeah, no shoebox full of cash, but also no head of someone's missing relative/spouse, etc. Having to bring in the cops would really slow things down...

The strange thing is that these speakers still sound so good. How did I get such great bass on the left when its inductor/coil was completely disconnected?

Playing some music now. The Who - Magic Bus. All tweeters work. One dimensional mw (upper dimensional) doesn't work on right. Only one mw on left (lower stereo) works! So no mystery why there's no right-channel SDA. But if I didn't know anything about SDA, and just walked in, I'd think these were some of the best speakers I'd been in front of.

So mw-wise, I only have one speaker's worth of working drivers, spread across two speakers. I guess that's a credit to these speakers and a Yamaha M-80.

So I guess I knew this was gonna end in me buying a multimeter.

Stay tuned ...

PolksTillIDie · December 2020

Just wanted to confirm my thinking on the midwoofers before I yank them out and begin testing them. They don't split some frequency ranges between them. So, again, playing a 30 or 40 Hz test tone should get them all firing equally, stereo and dimensional, all at the same time, right?

BlueBirdMusic · December 2020

Have you opened up the speaker that is working and compared its wiring/connections to the one not working?

PolksTillIDie · December 2020

Not yet, but there are non-working parts to both of them. Look two posts above for what works and what doesn't. Again, if I didn't expect SDA function, I'd think these sound great. Only when I felt each midwoofer did I realize they don't all fire and of course no SDA effect on the right. Going to guy a multimeter today and start testing.

pitdogg2 · December 2020

You do understand that the dimensional drivers do not play as loudly as the stereo drivers on some frequencies ...???

Your failure to understand SDA tech is impeding your ability to correctly diagnosed the problem.

The SDA driver fire basically a reverse signal to cancel crosstalk from the other speaker.

I cannot count how many times a new member has come here for advise to only find out that someone before him had tried to rewire the speakers internally to be a set of normal stereo speakers. I'm not saying that is your problem but you still do not know because you're stuck on test tones.

The first thing you should do is go to the vintage speaker section look for the SDA wiring and all that other stuff it's got a thread all of its own and you need to find sda1c wiring schematic for both left and right and follow that if that's not your problem then the problem can be only one other thing magnets that have started to slip and are impeding your speakers performance. Speakers that do not work at this age 99% of the time it's either a blown speaker or magnet slippage it's a well-known problem with magnet slippage. All the test tones in the world will not diagnose magnet slippage you can only diagnose that by either a multimeter or by gently pushing the drivers at the center carefully centering your fingers around the dust cap and pushing directly in slowly if you feel any scratchiness whatsoever chances are the magnet has started to slip.

PolksTillIDie · December 2020

Yes, the SDA drivers fire a 180 degree out of phase signal which acoustically cancels out crosstalk of the opposite stereo channel.

Please, I've had SDA speaks for 35 years, give me a break on all that and please check the post above. ("Just wanted to confirm my thinking...") Precisely because I wondered if all the mw's might not be working, I wanted to send a, yes, mono TEST TONE, of a given low frequency, which would/should activate all the mw's at once, so I can touch each one a tell where the problem is. That is the point of the inductor/coil, right? To enable all the midwoofers (and therefore the passive radiator) to play these low frequencies? Therefore, I'm trying to send an equal, prolonged, low frequency signal that's long enough, so I can get a finger on each of them to do a quick and dirty idea which work and which do not.

So, that being said, on the 1Cs, in a given enclosure, do the two stereo, and the two dimensional mw's, share the same frequency range or do they split up a range, like the tweeters do?

pitdogg2 · December 2020

35 yrs huh?
Well ok then you got this!! I'll leave you to it.
Have fun

PolksTillIDie · December 2020

pitdogg2, I've been looking over your posts to me and there's a lot of good advice. But even though I'm on my way to get a multimeter, I've never even touched one before, so you'll have to forgive me for trying to use what I do know to get a feel for what the problem is, so I can confirm it with what the multimeter says. No one's even told me what readings to expect from these midwoofers. Same with reading wiring diagrams. I'm an educated guy, so I'll figure it out, at least to the degree I need to ...

But I need to compress this work on my speakers to a small part of my day. I work like a dog at a hospital all day and these speakers are also the sound for my home theatre and sometimes you just wanna unwind with a game or a flick instead of staring at your disassembled speakers in silence on, for instance, a Sunday.

Know what I mean?

Gardenstater · December 2020

PolksTillIDie this should help some if you don't have it yet; the link to the manual for your speakers:

https://polksda.com/pdfs/SDA1C.pdf

Then you also have SDA Manual you can get information from:

https://us.v-cdn.net/5021930/uploads/editor/qx/d5a14j8apinc.pdf

You can get the DCR for each of your MW's from here:

PolksTillIDie · December 2020

Thanks Gardenstater. I had the manual, but not the handbook. Looks like my mw's are the 6510's and 6511's. As soon as I get the multimeter, I'll probably need help deciphering the specs for those two. What does DCR refer to?

If I truly do have some mw's that don't work, any use to keep any of them? Wouldn't it best, for matching if nothing else, to switch them all out?

Looks like I bought these speakers for parts and didn't know it.

Tony M · December 2020

So all the mid-woofer cones move freely when you push on them?

Forgive me if I forgot you mentioning this important first test. I'm going back to the beginning of your posts now...

audioluvr · December 2020

PolksTillIDie wrote: »

...if I didn't know anything about SDA, and just walked in, I'd think these were some of the best speakers I'd been in front of.

My recommendation is to just order all new crossover components and rebuild them or if that's not your thing send them to DHS Speaker and have Dave rebuild them for you. Odds are you have bad crossovers and if not you owe it to yourself to have them rebuilt anyways. If you like them now, your jaw will drop after that's done. The old cheap components degrade and fail.

Tony M · December 2020

F1nut wrote: »

There is no SDA signal to the tweeters.

You have something wired up incorrectly. Check that the red binding post is on the left for both speakers. If so, the problem is inside. The schematic is posted here, print it out and dive into each cabinet.

SDA wiring as follows:
Black or blue is positive
White or green is negative

I don't believe you told him the answer yet. Or did you? I'm going over the PROVEN scenarios that have plagued a few like me. Even I had a similar problem like yours with a set of SDA-CRS's that this forum's members helped me solve.

It WAS the RED wire nut being on the right side of the back of one the speakers. Somebody switched them somewhere in their past.

Going back to read more...

Tony M · December 2020

PolksTillIDie wrote: »

Yeah, no shoebox full of cash, but also no head of someone's missing relative/spouse, etc. Having to bring in the cops would really slow things down...

The strange thing is that these speakers still sound so good. How did I get such great bass on the left when its inductor/coil was completely disconnected?

Playing some music now. The Who - Magic Bus. All tweeters work. One dimensional mw (upper dimensional) doesn't work on right. Only one mw on left (lower stereo) works! So no mystery why there's no right-channel SDA. But if I didn't know anything about SDA, and just walked in, I'd think these were some of the best speakers I'd been in front of.

So mw-wise, I only have one speaker's worth of working drivers, spread across two speakers. I guess that's a credit to these speakers and a Yamaha M-80.

So I guess I knew this was gonna end in me buying a multimeter.

Stay tuned ...

I never thought about that.

Or the missing "hated" pet's head...

PolksTillIDie · December 2020

TonyM: Now we're getting somewhere. Yes, all the mw's I'd noted as not working have stiff-immovable cones.

audiolovr: And yeah, I already contacted DHS speaker about what I figured would end up being crossovers to rebuild. I was waiting on deciding how far to go on them. A friend of mine said the venerable Sonicaps aren't that expensive, so I thought I'd go that route.

I had to wait about three months to get my tweeters, so I wanted to figure out the mw situation so I can order them soon before that happens again.

So it looks like I don't need a multimeter at this point. I need all new mw's.

Thanks guys, you just saved me some money.

Gardenstater · December 2020

PolksTillIDie wrote: »

Thanks Gardenstater. I had the manual, but not the handbook. Looks like my mw's are the 6510's and 6511's. As soon as I get the multimeter, I'll probably need help deciphering the specs for those two. What does DCR refer to?

If I truly do have some mw's that don't work, any use to keep any of them? Wouldn't it best, for matching if nothing else, to switch them all out?

Looks like I bought these speakers for parts and didn't know it.

The MW6511's are the Stereo speakers which are on the inside of each speaker and they are DCR (DC resistance) of 3.130 Ohms

The MW6510's are the Dimensional speakers on the outside of each speaker and they are 6.570 Ohms.

There are some members that can repair shifted pole pieces/magnet assemblies and restore to proper working order. I wouldn't toss them.

They do seem to have their share of issues but you'll get it sorted

Don't forget to refer to the schematic I posted above. It isn't that hard to learn to read a simple one like that although it's intimidating at first.

audioluvr · December 2020

A failed MW is a concern of mine as the cause? If the "system" was overdriven or subjected to DC voltage that could have also stressed or damaged the crossovers. Replacing them may not solve the problem. Others here more experienced in this please respond as I don't want to appear to be an alarmist.

PolksTillIDie · December 2020

Yeah, I thinking about the way things are going I'll just get all new mw's. Unless these old ones are known to be better than the new ones. Midwest Speaker Repair has "replacement" mw's. They're not Polk OEM. Apparently Polk's not making them anymore. Any opinion on them? They're about $70 a piece, but then I'd know the speakers will have some future life on them.

audioluvr · December 2020

The correct originals are preferred.

Gardenstater · December 2020

I would definitely stick with the originals. They come up often enough in eBay. I would then seek out repair of your existing ones for backups on the forum if some capable members will help out. Make sure you have the correct models installed.

Those "closest replacement" polk "copies" on their site don't give me a lot of confidence. For one thing the Fs (resonant frequencies) are way higher than the Polk OEM's.

PolksTillIDie · December 2020

audiolovr: Hmmm...ok. Just looked at Midwest and the 6511 replacement is "closest replacement". Doesn't inspire a lot of confidence, does it? Ok, thanks for the info.

Okay, know the member who repairs these midwoofers? Gardenstater, any idea?

Thanks guys, avoiding a lot of pitfalls today...

PolksTillIDie · December 2020

Gardenstater: OK, to clarify there are occasionally new or used ones available? As long as the cones move, they're ok? Should I mix my present working ones with used ones I find on eBay?

Tony M · December 2020

You should still get a multi-meter. Harbor Freight has them for 5.00 or free w/purchase sometimes.

Are ALL of your mid-woofers frozen in place?

Are both Red terminal nuts positioned on the left? Black ones of course on the right.

I've had this point on my mind since you started this thread/inquire;
You say you play music loud. Real loud.
Polk audio speakers CAN play loud but NOT PRO-DJ loud. I hope you're not trying to get 110+ dbs from these 1Cs.

Can you get/borrow a Decibel meter to show how loud your playing?

Anything around 90 dbs is LOUD!

spongebobsquarepants · December 2020

Used is much more common than new old stock for these on eBay. I recently had a mw6510 driver that the cone moved freely, but made a terrible farty noise at higher volumes.

F1nut · December 2020

spongebobsquarepants wrote: »

Used is much more common than new old stock for these on eBay. I recently had a mw6510 driver that the cone moved freely, but made a terrible farty noise at higher volumes.

Probably a separated spider.

PolksTillIDie · December 2020

OK. Lemme get to your questions.

I'll probably get a multimeter anyway, to test what I end up with, but I was literally keys in hand ready to leave and get one when TonyM suggested pushing on the mw's. A revelation ... and a confirmation.

I'm listening to jazz right now at my usual level. Its about 60 dB 10 ft away.
And about the same (65 dB) on net radio listening to random rock, etc. Funny, I'd swear its louder....
But when I said loud, I meant for 10p in an apartment.

No, not all my midwoofers are frozen, just half of them.

Really.
Right channel - the upper dimensional is frozen.
Left channel - both dimensional are frozen, upper stereo is frozen.
That's four out of eight mw's !!
So the mystery of why no SDA effect on right side is solved, no working SDAs on left.
And that M-80's even more powerful than I thought!

Yes, the red binding posts are on the left on both speakers.

So what's my best play for these mw's? Get the broken ones repaired and keep the others? Or buy some new/used ones on eBay. Of course, if I could find new ones on eBay I'd snatch them up.

Oh, just found three MW6510's on eBay. That would get me the three dimensionals .... just bought 'em.

Now, somebody make me feel good about buying $180 worth of used mw's !

Guess I need to find just one MW6511. Well, the night's young.

Thanks guys for the help. I'll keep you posted as usual ...

Gardenstater · December 2020

If the eBay seller says they are in proper working order or no issues or the like, I'm pretty sure you might be covered through eBay if that turns out not to be the case, but I have never had that happen yet. I've bought 4 MW6500's with no issues so far. Good luck. It's good to have backups so you might still try to get your drivers repaired by someone if possible.

PolksTillIDie · December 2020

Thanks Gardenstater. I just bought a single MW6511 and that's all I had left that I needed mw-wise. They were reported to be in excellent working condition and to check out properly with an ohm-meter (as were the MW6510's).

So if that's the case I should be good for the time being. But rebuilding the crossovers with SoniCaps is also going to be in the budget.

Thanks for the help.

Tony M · December 2020

Thanks for the answers.

If your frozen woofers still TRY to produce sound, they most likely are easily repairable by a person who has the tool and skills to do so.
Don't throw them away just yet.

Sounds like you listen at normal levels for your 1Cs to easily handle whatever you throw at them. Good deal.

With you ordering original replacements, you're in for a treat when you hear them sound the way they will.

I can't wait for your descriptions of their sound in the coming weeks. Your journey is about to be rewarded like you wouldn't believe.

You could then take new readings and show us new sound graphs with all the woofers playing like they should. Those new graphs should be quite impressive. I hope you can find the time to share them with us.

I know you're very busy with other things too so we'll be patient. We ALL know what you're about to experience. We're all smiling on this side of web for you.

One more thing...I'm a BIG Yamaha Amp/Receiver fan as are others on this Forum.

PolksTillIDie · December 2020

Thanks TonyM. Please note these are used Polk mw's. At least for now. And, yeah, the Yamaha twins have been really good to me.

I just popped of the right speaker passive radiator to look inside. Both good and maybe bad...

Wide view:

Closer view:

The crossover's still attached to the inductor and the inductor's wires are hooked up. One of the reasons (along with working drivers) that the left channel SDA effect is still there. This crossover looks older than the left channel one with I think different caps, no? Maybe OEM? But will be eventually getting new crossovers anyway.

SDA-1C Right Channel No SDA Effect

Answers