Boston Acoustics A400 - Distortion in Midrange

[Marv S.]

I think if you take the dust cap off you will see the two thin wire leads. At this point you have nothing to lose to remove it and look, it will also give you the opportunity to check for VC rubbing.
Look at this link and how they cut the cap. I've done this a bunch of times on BA's. Yeah, it looks a little sloppy when glued back on, but who cares. They are fantastic speakers that are worth more in your listening room than the money they bring if you sold them.
http://www.decware.com/newsite/refoam.htm

I shim every pair I do. Not that you have to but it virtually guarantees perfect VC alignment. The mid IIRC is much tighter than the woofer and that makes it even more critical.

That is very, very useful as for the first time I can visualize what's involved in removing the dust cap. Thank you. I'll do it and take a look tomorrow. I agree that they are far more valuable in-house than sold.

 

[crispycircuit]

If the glue holding the coil of wire to the former dries out, The coil can break loose and add a buzzy sound. No fixes for this. Either a new driver or recone. Sometime when play your music loud. The voice coil heats up and breaks loose from the former thats attached to the cone. I'm sure a used one will pop up on Ebay..

 

[Marv S.]

Thanks to all, especially those who said, "Your voice coil is off-center," and to Grillebille who relieved my anxiety about dust cap removal. In spite of my assurance that there was no rubbing, I did in fact re-foam the offending midrange and this time I removed the dust cap and shimmed the pole. The result, that did it, and it sounds beautiful.

FYI:
In the interim, I stuck in this cheap 6.5-inch midrange from Amazon and to my surprise it did not immediately nauseate me. It was, to me, not as open sounding, a bit harsher, but for $27.00 it was liveable for a short time.

In any case, I am happily enjoying my June 1983 vintage A400s again. Thanks for all your help!