Boston Acoustics A40 Refoam Project

I'm listening. :)

Actively watching your progress and hoping for the best. You'll get there!

Good to know I'm not talking to myself, at least. :)

Maybe you can answer a question for me; if I test my woofer with a multimeter and it tests within the threshold AND the woofer moves in both directions (depending on polarity) when I hook up a battery, can I be pretty sure that my voice coil is ok?

I'm starting to think it was rubbing pre-refoam but wouldn't know because I never hooked them up before I started working on them. I have 2 foams arriving and one bad speaker, so first I'm going to try the test tone. If the woofer still rubs after that, I'll bite the bullet and try shims. Shims make me really nervous, though!
 
Just discovered this thread. I also have A40s that I refoamed about a year and a half ago. My recommendation is that shims greatly help in keeping the voice coil from rubbing. I was also skeptical about shims at first, but I found they actually made the process much easier. Without doing this, it would be easy to accidentally install the foam off center and end up with the voice coil rubbing. Overall, it looks like you are doing a great job :thmbsp:
 
Just discovered this thread. I also have A40s that I refoamed about a year and a half ago. My recommendation is that shims greatly help in keeping the voice coil from rubbing. I was also skeptical about shims at first, but I found they actually made the process much easier. Without doing this, it would be easy to accidentally install the foam off center and end up with the voice coil rubbing. Overall, it looks like you are doing a great job :thmbsp:

Thanks, I appreciate the kind words. I'm discouraged that I've had to (almost) double my investment due to mistakes (and a little bit of poor planning), but I'm trying to tell myself that it's not so much how much I'm spending, but what I'm learning in the process.

I still think I'm going to try the test tone first, but only because I'll have an extra foam, 4 dust caps, and the leftover glue from the first kit in case I have to go with shims.
 
Were you waiting eagerly while I figured out how to work the internet? :D

HAHA!!! ...YUP! ...Actually I have a pair of 1st generation A40s that need some serious TLC. The boxes are in fine shape but the woofers look terrible and there are really no suitable replacements so I'm gonna have to do a re-foam if I ever want to listen to them. :music:

Did you do a re-cap while you have them all apart? ...It's in the AK contract! :deal:
 
I'm not going to recap unless I find I have to. I have a tweeter with low, but some, output that is testing ok on a multimeter, so I may have to.

I'm committed, though. No matter what I have to do, I'll get them working. Both of them.
 
The A40 speakers were the first I ever tried to recap, and I made a complete mess of it. Your job looks nice and neat. I've also had to refoam after discovering rubbing post-foaming. So I've been there too. I am sure you will come out fine. Best of luck!

FYI, I might have checked that 'dead' tweeter by swapping with the other 'good' one. You might find that the problem is in the crossover and not the tweeter itself.
 
That refoam job looks better than any others job that I did. Great work.:thmbsp:

Now, if it's rubbing, try to unglue the surround and shift it until there is no rubbing.

First refoam should be tried on budget speakers first, knowing the outcome
could be ( or couldn't ) successful...

Keep on going bud ! and he11fire those A40 ! Where with you !
 
he11fire-

If I were you, I'd just bit the bullet and recap these, especially while you have the cabs open and accessible. I *think* the A-40's have just a 3.3 uF cap and the crossover is mounted to the speaker cup/plate. You'll have to look and verify. However, if it is 3.3, a quick and cheap solution would be two of these (no affiliation):

http://www.madisoundspeakerstore.com/xxp-poly-cap-250vdc/bennic-poly-3.3-mfd/

Those caps have to be close to 30 years old now and probably drifted off spec. If they haven't drifted yet, they will. In the scheme of things, what's another ~$6-7?
 
The A40 speakers were the first I ever tried to recap, and I made a complete mess of it. Your job looks nice and neat. I've also had to refoam after discovering rubbing post-foaming. So I've been there too. I am sure you will come out fine. Best of luck!

FYI, I might have checked that 'dead' tweeter by swapping with the other 'good' one. You might find that the problem is in the crossover and not the tweeter itself.

I tend to be really particular (read: OCD) about this kind of thing, so I'm trying to keep it as neat and tidy as possibly. I scratched up the lip of the basket on the non-working woofer a bit when I was getting all the fresh glue off of it, but I'm hoping A. That will actually make the glue stick better, and B. You won't be able to see it because it will be covered with the surround.

I actually just got done doing the tweeter swap, and I'm happy to report that the tweeter is most definitely shot. As soon as I hooked it up all the highs from The Allman Brothers went bye bye. Switched it back, and it sounded great. I'm doing some of this stuff in an illogical order (IE: ordering a replacement tweeter before confirming that the tweeter was the problem), but that's just something I'll have to work on with my future projects. :)
 
That refoam job looks better than any others job that I did. Great work.:thmbsp:

Now, if it's rubbing, try to unglue the surround and shift it until there is no rubbing.

First refoam should be tried on budget speakers first, knowing the outcome
could be ( or couldn't ) successful...

Keep on going bud ! and he11fire those A40 ! Where with you !

Thanks to you and all for the kind words. I let the glue set too much to reposition the surround, although since if it didn't work I was going to have to pull it off, I did try rather forcefully to move it around.

I paid $30 for the A40s in the condition shown in the first pic. And I had to spend an hour or so driving back and forth to get them. I probably overpaid, but they were close so I didn't have to pay shipping, the only pair for sale at the time, and I wanted to do a refoam, so I jumped on it.

Thanks again for the encouragement!
 
he11fire-

If I were you, I'd just bit the bullet and recap these, especially while you have the cabs open and accessible. I *think* the A-40's have just a 3.3 uF cap and the crossover is mounted to the speaker cup/plate. You'll have to look and verify. However, if it is 3.3, a quick and cheap solution would be two of these (no affiliation):

http://www.madisoundspeakerstore.com/xxp-poly-cap-250vdc/bennic-poly-3.3-mfd/

Those caps have to be close to 30 years old now and probably drifted off spec. If they haven't drifted yet, they will. In the scheme of things, what's another ~$6-7?

I appreciate the hookup on the part numbers, but I'm going to handle one thing at a time. I inspected the crossovers and everything looks ok, no bulging caps or obvious scoring or anything, so I'll hold off for now. I have a set of KLH Model 20s that need recapped and that looks like an easier first try than removing all the glue and desoldering from a board like the A40s. Plus, I couldn't get the terminal cup out with the crossover attached, so I either overlooked some screws or I'd have to do the work inside the cabinet.
 
I appreciate the hookup on the part numbers, but I'm going to handle one thing at a time. I inspected the crossovers and everything looks ok, no bulging caps or obvious scoring or anything, so I'll hold off for now. I have a set of KLH Model 20s that need recapped and that looks like an easier first try than removing all the glue and desoldering from a board like the A40s. Plus, I couldn't get the terminal cup out with the crossover attached, so I either overlooked some screws or I'd have to do the work inside the cabinet.

The terminal cup should be screwed onto back of cabinet. Undo the screws and it'll pull out from the back. The glue is probably one large chunk that breaks away quite easily. If you *really* don't want to desolder from the board/pads, just snip the wires from the old caps, twist around the wires from the new caps and solder those together. Just use a little hot-glue to hold the cap firm against the terminal cup, slide it back in and re-screw.

FWIW, caps can look great but be well off value. I just redid some older KLH's (granted, these were probably from the 60's) and the caps looked brand-new but were WAY off of spec.

Do whatever you feel comfortable doing. They're your speakers and I'm not trying to be pushy. I usually just recap any speakers I'm working on since the caps are so cheap and it gives me peace-of-mind that everything is up to spec. Either way, enjoy 'em, they're fun little speakers. :thmbsp:
 
Well, my replacement tweeter showed up and I'm getting no output at all (from the "working" cabinet). Damn.

Edit: And it's not reading on my multimeter.
 
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Anybody got any leads on a replacement tweeter? BA doesn't carry any parts for the a40s anymore, there were 2 tweeters + 2 crossovers listed on eBay for $70 (!), and I don't see any on Oak Tree Vintage either. I contacted the guy selling the stuff on eBay about buying 1 tweeter or even 1 tweeter/crossover, so hopefully he's flexible since his listing ended with no bids.

Otherwise, it sounds like I might be out of luck until another replacement tweeter (or cheap pair, for parts) pop up somewhere.
 
Seems like he may have sent me the wrong tweeter. He still has the working one and is shipping it tomorrow morning. I have my fingers crossed.

EDIT: Also, I shimmed the voice coil last night on the remaining woofer. My logic is, rather than having 1 chance to screw up with the test tone and 1 chance with the shims, I'd rather have 2 chances at the shims. The voice coil magnet (is that right? The center piece that I'm preventing from touching the sides) is small in diameter and the shims are wide, is it ok that the shims overlap a little bit?
 
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I've been wanting to undertake a project like this - Its great to hear from a first-timer what sort of stuff might crop up! I'm keeping my fingers crossed for your new tweeter.
 
It's possible that there is just a broken tinsel on the tweeter and it can be repaired. I'm pretty sure that the lens around that tweeter will pull off (the plastic covering over the tweeter) which allows you to see the teeny-tiny copper tinsel. I had the exact same problem with one of my A-40's tweeters. I was too chicken to attempt to repair it (would have to solder the two pieces back together) so I just bought a used one off the bay. If you're feeling ambitious and/or bored, you could always attempt a repair on the original broken one (if it is, indeed, a snapped tinsel) for fun. Could at least hold you over until you got a new one.
 
It's possible that there is just a broken tinsel on the tweeter and it can be repaired. I'm pretty sure that the lens around that tweeter will pull off (the plastic covering over the tweeter) which allows you to see the teeny-tiny copper tinsel. I had the exact same problem with one of my A-40's tweeters. I was too chicken to attempt to repair it (would have to solder the two pieces back together) so I just bought a used one off the bay. If you're feeling ambitious and/or bored, you could always attempt a repair on the original broken one (if it is, indeed, a snapped tinsel) for fun. Could at least hold you over until you got a new one.

I'm definitely willing to try it, especially since I won't be out anything if I break it. Since I had the completely dead one that the eBay guy told me to keep, I tried to pry it off and broke a big chunk off of the magnet. I'll try a different approach on the low output one tonight since I have a few more days until the replacement (for the replacement) shows up.
 
I've been wanting to undertake a project like this - Its great to hear from a first-timer what sort of stuff might crop up! I'm keeping my fingers crossed for your new tweeter.

That's kind of why I did this. I know I was/am pretty intimidated by my first attempt, so I wanted to document it in case anyone else was in the same position. I wouldn't say any of it has been particularly difficult, just a little time consuming in spots. I'm a little impatient, so it would've been nice to get it all done at once, but hey, I'm learning.
 
I'm definitely willing to try it, especially since I won't be out anything if I break it. Since I had the completely dead one that the eBay guy told me to keep, I tried to pry it off and broke a big chunk off of the magnet. I'll try a different approach on the low output one tonight since I have a few more days until the replacement (for the replacement) shows up.

You shouldn't have to do any major prying to get the lens off. Should just be the plastic shell on the top/front that should pull off the lower assembly.
 
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