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Boston Acoustics A400 Buying/Repair Advice

Lastplace said:
Digging up this old thread. I have a pair of mint A-400s. I have never heard of changing the tweeter fluid. How difficult is this to do?

Almost sounds like changing the blinker fluid on a car.
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It's super easy and it's not "blinker fluid." It's more like muffler bearings. :D
 
Lastplace said:
Can you provide some basic instructions? I assume the tweeters are removed from the speakers. What then?
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Remove from cabinets, open them up, remove old ferrofluid, put new ferrofluid in, close them up, reinstall in cabinets.
There are several relevant short videos on YouTube worth watching first. :)
 
I just got a set of these with a mid with mild static. Everything is all original except for the surrounds (caps, drivers, etc,).

Has there ever been a solution for the distorting mids? Has anyone who had the issue fixed it?
 
Noskovus said:
I just got a set of these with a mid with mild static. Everything is all original except for the surrounds (caps, drivers, etc,).

Has there ever been a solution for the distorting mids? Has anyone who had the issue fixed it?
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Switch the mids and see if it follows the speaker, if not , it’s a crossover problem.
These speakers have really crappy crossovers, crappy electrolytic caps on hard cardboard , glued to the cabinet .
Use hair dryer to heat it up board, while peeling up.
My a400’s sounded awful when I got them but I was optimistic .
Most of the caps were out of spec so I replaced them.
One tweeter had tar like ferro fluid , replaced that too. They were great after that
I tried tri amping them , sounded fantastic too!
 
I’ve got ferrofluid on the way. I can redo the caps as well. I can already tell they sound good with a single amp.

I’ve heard conflicting things about tri-amping them. AI seems to think the crossover makes tri-amping and biamping the same.

I haven’t tried testing it very much until I get the driver cleaned up.

Thanks the the reply!
 
They will sound better with old caps . If you measure the old caps , you’ll find some that are simply out of spec.
Replace them - all.
There are no conflicting opinions on triamping them, it’s better , end of story .
AI is wrong . Right now , you’re forcing 50w through a maze of coils and caps that decide up the sound to the drivers .
Tri amp does this before signal even hits the power amps . It’s more efficient and cleaner sounding .
However , it requires extra amps, a $500 active crossover and you need to make sure you connect the right things to right drivers so you don’t destroy anything .
I suggest you rebuild stock crossover ( cost maybe $30 if you use film caps) then maybe explore tri amping down the road if you desire .
 
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