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Seeking advice for Acoustic Research AR-5 restoration

M

mct

New Member
I will start this off by saying although I've dug through many threads about restoring, recapping, refoaming, repotting these speakers I am pretty much a total newbie to actually doing the things.

The other day I came across some pretty decent looking AR-5s on the local marketplace. Took em home, took off the grills, and the foam is gone. Alright, I can handle that.

Pull the woofers. One measures 6 ohm, which is fine I think, and the other, open. Not great! So I dig out the rockwool and look at the crossovers:

XO1.JPG
XO2.JPG

One appears to be fine, the other looks like where the resistor wire (?) is on the little board has basically burnt to a crisp including a bit of the surrounding insulation.

Burnt.JPG

I didn't remember to make not of which speaker came out of which cabinet but am I right to guess that the blown woofer probably came out of the cabinet with the fried resistor?

My questions are:
1. What might have happened here and what kind of damage may this have caused to the blown woofer, if in fact it came out of the same cabinet? Or are these things unrelated?
2. What might it cost to get this blown woofer fixed? I'm looking around and guessing I won't be able to find the right drop in part any time soon. I'm not far from Millersound, I'm guessing that is the best place to go for a repair.

Thoughts? Next move is going to be clean up the pots (or bypass) to see if the mids and tweets are functional. Thanks for any help
 
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I believe the AR 5 married the mid and tweeter of the 3 (maybe the 3a?) with the woofer of the 2 (actually, since it has a foam surround, it's probably the 2ax woofer). 2ax woofers are thick on the ground, and it might be cheaper to buy one than to have yours rebuilt.
One you sort it all out, you'll have a fine pair of speakers. Many listeners thought the 5 was actually better balanced than the 3 or 3a. Given the foam surrounds, yours are likely to have electrolytic caps, and these may have drifted out of spec, so it would be worth replacing them. Film caps are the usual recommendation, but in another thread, Bimasta has raised the question of whether new electrolytics might be a good choice - in spec, but with similar ESRs to the originals. I cannot offer any worthwhile advice other than noting that you can spend huge amounts of money on SUPER AUDIOPHILE!!!! caps, but it is not at all clear if there is any benefit over inexpensive film caps. Or new electrolytics.
 
Yeah I have head that about the 2ax woofer but I feel it might irk me too much to do this with mismatched woofers. Maybe I’ll get two. But the ones I’m seeing are 6 screw versions where my woofers have only 4 (1972 stamp, square magnet).

Caps I will deal with once I figure out the woofer issue and of course if the mids and tweeters still work, but no real preference besides the right values.
 
I bet lots of help will be coming soon enough. As long as your tweeters and miss are in good shape you have already won more than half the battle. With all of the AR 10 inch woofers produced you are bound to run across a pair that fit your cabinets. Did you test the suspected woofer across it’s terminals? The burnt part in your crossover (inductor?) may be in the woofer circuit.
 
Yeah, I pulled them and tested across the terminals. Very sad to have the one come up empty!
 
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