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Vintage Pioneer CS-33A woofer replacement

BTW, I think you made a good choice with the KLHs (plus it's hard to wrong with a pair of BAs for $35, even if they need refoaming). These are sort of a KLH/Infinity hybrid. At the time they were made, the same guy (Arnie Nudell) was running both KLH and Infinity. Those tweeters were the precursor to the Infinity EMIT.
 
Thanks. I’m really enjoying the KLHs. As for the BA A70s I refoamed them and then hooked them up and one woofer is blown. I’m not sure if I’m using the right term or if I can describe the sound well but it’s clearly not sounding right. The other speaker sounds great. I’m guessing I will need to replace the woofer. I found on eBay someone selling a pair of woofers manufactured just 3 months after mine. These both need to be refoamed as well. Should I replace both or just the one not working? The only other options I’m able to find are copies.
 
Before you do anything else, swap the woofers between the cabinets. Also, are you sure you refoamed them properly?
 
swechsler said:
Before you do anything else, swap the woofers between the cabinets. Also, are you sure you refoamed them properly?
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I can’t guarantee I refoamed correctly. It was my first time but I followed all the steps and I think I did OK. If anything I think the one with the sound issue was done a bit cleaner than the one without an issue.

I swapped the woofers between the cabinets and the woofer sounds just as bad in the opposite cabinet and the other still sounds fine. One thing I noticed was when I press on the cone the one with the issue makes a noise but the other does not. No sound when pushing down but sound when releasing. Actually I’m just now noticing that the sound only happens when pressing on one side. It’s hard to describe the sound. Could this mean there’s something that fell into the coil while reforming?
 
It could be that, but it's more likely that you didn't center it properly. Did you use shims or a test tone when gluing the surround?
 
swechsler said:
It could be that, but it's more likely that you didn't center it properly. Did you use shims or a test tone when gluing the surround?
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Thanks for quick response. I didn’t use shims I don’t know how that would work. I tried to center it as best as I could. Is there a YouTube video you’d recommend?
Does this mean my next step to refoam it again? If that’s the case I could do with some guidance so I don’t screw it up again. Also I guess I’ll need to purchase another kit and try to remove the previous one with alcohol to loosen the glue. I’m a bit concerned about the gasket that goes over the foam, maybe I can find those to purchase online?
 
FYI I used the simply speakers refoam kit. Rewatching the video I guess I didn’t exercise the cone well when glueing it together :(

I’m wondering if I can try to loosen the glue on either the cone or the frame to try and get it center and reglue? Or just remove it all and start over?
 
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There are tons of youtube videos; I don't recommend a specific one, but after you watch a few you should get the idea. You definitely need a way to center the voice coil, simply doing it by feel is not the way to go about it. Playing a 30hz tone through the speaker (using a tone generator app and amplifier) while gluing is one way; the other way is to remove the dust cap (generally via carefully cutting it away), and then using three shims (such a business card cut vertically into three pieces) between the voice coil and the magnet's pole piece. Of course the latter will require the replacement of the dust cap.

Regarding removing the surround, I'm not sure if it's possible to do that non-destructively.
 
I was planning on re-refoaming today. When I got the foam off I was expected that the rub noise would be gone but it’s not. If anything it seems worse. Does this mean the problem is more serious than a bad foam job?
 
It's kind of hard to tell when the foam is removed. What you can do is try moving the woofer cone in and out while varying the angle slightly. If there is no angle you can do it without rubbing then you might have a malformed voice coil. You can also try playing a 30hz tone through it, as I suggested above, and see if it makes any rubbing sounds. You need to do it with the woofer sitting flat on its magnet, facing up. If it's angled at all this won't work.
 
I finished refoaming and heard no rubbing anymore. I tried the 30hz test with the speaker flat on my table and it sounded good. I was hoping I’d be able to say everything was in good working order. Unfortunately when I reinstalled the speaker into the cabinet I’m getting the sound again at medium volumes. No matter how I press the cone I can’t cause any audible rubbing sounds. I redid the 30hz test with the speaker in the cabinet and I’m hearing the off sound. The good speaker in the cabinet makes no off noises. I recorded the sounds but I don’t think there is a way to share them here.
I’ll admit that I didn’t take the cone off and use shims. The kit I got doesn’t have those and says it’s not necessary. I did make sure to keep pressing around the cone throughout and make sure no rubbing noises were made. This is what the video that comes with my kit suggests to do. I didn’t think this was supposed to be that hard.

I will say that the off sounds when playing music are not as bad as they were after the first time I refoamed. Did I cause a problem by the bad refoam job or is this speaker just bad?
 
If it makes the sound only at higher levels ("medium" is not too definitive) it might be something else, such as a loose dust cap, surround or spider not fully glued down, or the tinsel leads hitting the cone.
 
swechsler said:
If it makes the sound only at higher levels ("medium" is not too definitive) it might be something else, such as a loose dust cap, surround or spider not fully glued down, or the tinsel leads hitting the cone.
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If it’s there at low volumes it’s really faint. But it doesn’t have to be very loud either. Sorry I don’t have a lot of experience here to help describe it better. Is there a couple of easy things to do to try and determine if any of these are the actual problem. I would guess loose dust cap or foam surround wouldn’t be too difficult to resolve but I’m not sure about the others.
 
Next thing I'd try is to remove the speaker from the cabinet again. Examine the tinsel wires between the woofer terminals and the cone, and see if they touch when the woofer is pressed in. Check inside the cabinet, make sure there's no way that the stuffing could be causing those wires (or anything else inside the cabinet) to touch the cone. Then try hooking up the speaker wires directly to the woofer, lay it on its back, and run some music through it. See if it still makes those sounds. If it doesn't, there's probably something in the cabinet that's causing it to happen; if it does, then it's the woofer.

One other thing you might want to do is play a slow, low frequency sweep through the woofer so you can narrow down the frequency at which it happens (it may be also be a range). This will make it easier to reproduce. The fact that it doesn't happen at 30 hz leads me to believe that it's probably not a voice coil centering issue.
 
swechsler said:
Next thing I'd try is to remove the speaker from the cabinet again. Examine the tinsel wires between the woofer terminals and the cone, and see if they touch when the woofer is pressed in. Check inside the cabinet, make sure there's no way that the stuffing could be causing those wires (or anything else inside the cabinet) to touch the cone. Then try hooking up the speaker wires directly to the woofer, lay it on its back, and run some music through it. See if it still makes those sounds. If it doesn't, there's probably something in the cabinet that's causing it to happen; if it does, then it's the woofer.

One other thing you might want to do is play a slow, low frequency sweep through the woofer so you can narrow down the frequency at which it happens (it may be also be a range). This will make it easier to reproduce. The fact that it doesn't happen at 30 hz leads me to believe that it's probably not a voice coil centering issue.
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It’s been a busy week but finally have gotten around to these tests you mentioned. I don’t think there’s anything touching either in the cabinet or outside. I got the speaker out of the cabinet and hooked directly to my receiver and went through the frequency sweep that you mentioned. There are off sounds between 48 and 198 hz. Outside of these I’m not hearing any noises at pretty high volume levels.
 
I still think the problem is that the voice coil isn't centered properly, but before you go and refoam again, I'd recommend starting a new thread here in the speakers forum, with details of how you refoamed, and what tests you've done so far. I don't think many people are paying attention to this thread any more, and it would be helpful to get some new eyes. You can also take a video of it making the sound, and then post it on YouTube and link it here using the Media icon (the one that looks like two strips of film).
 
swechsler said:
I still think the problem is that the voice coil isn't centered properly, but before you go and refoam again, I'd recommend starting a new thread here in the speakers forum, with details of how you refoamed, and what tests you've done so far. I don't think many people are paying attention to this thread any more, and it would be helpful to get some new eyes. You can also take a video of it making the sound, and then post it on YouTube and link it here using the Media icon (the one that looks like two strips of film).
Click to expand...

Thanks for the guidance, I've recorded a video that hopefully is helpful and posted to a new thread here https://audiokarma.org/forums/index.php?threads/boston-acoustics-a70-woofer-vibrations.959141/
 
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