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Boston Acoustics A400 Buying/Repair Advice

I prefer the black. But then I never put grills on my speakers anyway. I cant get these on the wall in this room without having their path obscured by the sonus in front. I dont hear much difference against the wall. The Sonus lick em fairly but $6000 vs $300 ..... puts the a400 in an impressive light all the same.

Powered by the Yamaha A-S2100 if anyone is wondering. Great integrated that has powered all kinds of speakers including Dyns without a hitch.
 
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grillebilly said:
here is a newer BA with the polymer cone. Different model shown of course
http://www.usaudiomart.com/details/...c_hd_10_three_way_loudspeakers/images/343672/
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A while back I ordered some 8" replacement woofers from BA when they were still available. The ones they sent had plastic cones, and they were AWFULLY thin and flexible, not very impressive. I didn't use them; just refoamed the original (much more rigid) paper-cone units, which I think are a way better bet in the models that came originally with them. This includes all A200s and A400s.
 
MarkNC said:
A while back I ordered some 8" replacement woofers from BA when they were still available. The ones they sent had plastic cones, and they were AWFULLY thin and flexible, not very impressive. I didn't use them; just refoamed the original (much more rigid) paper-cone units, which I think are a way better bet in the models that came originally with them. This includes all A200s and A400s.
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They are definitely different material, Polymers are used in a lot of high end speakers so the material doesn't scare me. As far as rigidity goes, the surrounds are the only moving part and I think the flexibility of them is what effects sound. I may be mistaken, if anyone cares to correct me please do and tell me why.
 
The original 8" woofers in my T1000 were also a polymer material. In 2002, I ordered 4 new replacement woofers from BA when the surrounds deteriorated. (I was then unaware they could be re-surrounded). I bought the speakers new in 1989; surrounds lasted 13 years. Now, after 15 years, the surrounds are still excellent on the replacement woofers. I hope they stay that way.

Never had any problems with the midranges however.

A couple years ago, I disassembled the tweeters from the magnets and sure enough, the coils were completely wet with Ferrofluid so no problems there.

In the 27 years I've owned my T1000, I've been extremely happy with their performance overall. Their well balanced presentation I've found makes them perform admirably with almost any kind of music at generous listening levels without strain. My only complaint is that on high input of very low frequency can cause the woofers to breakup and distort badly. Fortunately this only occurs in a handful of passages in all the recorded material I own so it's a relatively minor issue and it should also be noted that these are pretty demanding passages that would test a lot of speakers' mettle.

For years I had used the T1000s with a Proton receiver that I bought new with the speakers and pretty much assumed that was all they had to give and put them in away for a while when I decided to try some other vintage speakers with my "new" vintage McIntosh tube gear, intending to sell the Bostons. When it turned out that nobody wanted the Bostons for the price I wanted, I decided to set them up again with the McIntosh tube gear. The transformation from the Proton to the McIntosh utterly transformed the T1000 to a different level entirely - and I do not make that statement lightly.

While I've never heard the A400, but if it sounds anything like the T1000, or better, I think it's a speaker I could enjoy forever.
 
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grillebilly said:
They are definitely different material, Polymers are used in a lot of high end speakers so the material doesn't scare me. As far as rigidity goes, the surrounds are the only moving part and I think the flexibility of them is what effects sound. I may be mistaken, if anyone cares to correct me please do and tell me why.
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I am not an engineer but stiffness is a huge factor. Thus the focal glass cone, flax cone, etc. Changing drivers to a different type from orig can destroy the sound because all things are designed as a unit in good speakers. Mass, location, cubic area inside. I know a few people that think they make speakers. They clone famous models but never get it right because the internal air must match the driver which must match the crossover ... etc. Thats where the $ comes in on things like Dynaudio C1 etc. Mighty expensive little bookshelves but so good sounding. Someone had to design it, drivers made for it, test, design again ..... that R&D is what makes a great speaker. sometimes things can be changed. Other times it destroys the outcome. The a400 is not particularly impressive in parts ... but someone engineered a working package. My replaced drivers supposedly came from Boston. I would like to get an original pair to A/B. Sometimes I think the bass is a little loose on the a400.
 
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Yamahaha said:
stiffness is a huge factor.
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Thanks for your explanation. I think it plays a bigger role in non-ported, sealed enclosures. With the cone attached on both ends, it would have to distort it's shape (flex?) to change the characteristics of speaker function. I am not an engineer either, and not disagreeing, but I assume since the surround is acting as a shock absorber of sorts, the cone would not change shape unless driven beyond it's limits. All the flexing should be taking place where it was designed to happen. I know a speaker builder who has won some awards...I will try to ask him. Thanks again for your input.
 
grillebilly said:
Thanks for your explanation. I think it plays a bigger role in non-ported, sealed enclosures. With the cone attached on both ends, it would have to distort it's shape (flex?) to change the characteristics of speaker function. I am not an engineer either, and not disagreeing, but I assume since the surround is acting as a shock absorber of sorts, the cone would not change shape unless driven beyond it's limits. All the flexing should be taking place where it was designed to happen. I know a speaker builder who has won some awards...I will try to ask him. Thanks again for your input.
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Yes without the knowledge its hard to say and the hype from manufacturers is often ... well just hype. I always wondered to just how much a cone could possible flex. After all some of the best speakers are good old paper cones. I even have two 12" Styrofoam cone speakers here I pulled out of an EV speaker. Been meaning to try them in a guitar cabinet just to see what they sound like.
 
Yamahaha said:
Yes without the knowledge its hard to say and the hype from manufacturers is often ....
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Ok, got a quick answer from the owner/builder at Customphile. Someone I don't know personally but is highly regarded. Here is his reply. Sounds like he has the same concerns you do.

The poly woofer likely has a different frequency response and could also have a lower sensitivity than the paper cone since they generally have a higher cone mass. Given this, you probably won't get the same frequency response if you were to change the woofer, resulting in a different sound. It's impossible to tell without measuring how different it might be, if at all. The other thing you might be asking about is my opinion on whether poly cones sound different than paper cones. If that is the case, I do think there are some small differences in tonality between the two materials. Poly cones have what I would call a slightly relaxed sound to them. I feel the midrange doesn't have the same liveliness other cones do.


 
Here is the other pair that was for sale. Refoamed not reconed but looks like some sloppy dustcap work to me.
Havent put them thru the ringer yet to see how they sound.

IMG_0044.JPG
 
DocStock said:
I'm not entirely sure what the issue is. The seller's description is that it's some sort of faint static sound coming from that midrange. Haven't heard it myself, so it's hard to say. The seller said he removed the midrange in question and rotated it before screwing it back into the cab in an attempt to see if changing the holes would provide a better seal. Perhaps the gasket is the source of the problem?
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I realize this post is older but did these speakers happen to be for sale in the St. Augustine Florida area? If so I bought them. The midrange has a bad voice coil and need repair. All four 8 inch woofers needed re-foamed.
 
Along these same lines (A400's) does anyone know the drop in replacement speaker for the 6.5 inch midranges? I can find other Boston Acoustic 6.5's with the round profile, I just don't know if they are the same as the ones used in the A400's. I think the T930's used a 6.5 round, but would it be the same drivers? Sure doesn't seem to be a lot of specs on the web about the A400's. Any help is greatly appreciated.
 
MannishBoy said:
Along these same lines (A400's) does anyone know the drop in replacement speaker for the 6.5 inch midranges? I can find other Boston Acoustic 6.5's with the round profile, I just don't know if they are the same as the ones used in the A400's. I think the T930's used a 6.5 round, but would it be the same drivers? Sure doesn't seem to be a lot of specs on the web about the A400's. Any help is greatly appreciated.
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My understanding is that particular driver is unique to the A400 and therefore rather more difficult to source replacements. I could be wrong here but information is pretty hard to come by concerning the A400's.
 
darkblue94 said:
My understanding is that particular driver is unique to the A400 and therefore rather more difficult to source replacements. I could be wrong here but information is pretty hard to come by concerning the A400's.
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I have also heard that the drivers are unique to the A400s.

Plus i believe they have a square magnet in the back.

I am looking for four replacement woofers for my A400's i picked up recently because for some reason all four were replaced with some cheap 8 inch woofers. Apparently the owner before didn't know you could refoam the speakers.

I think i've sourced two from eBay that were mis marked as A70's but they have the square magnet in the back and the date of manufacture is right in line with what i'm looking for.

Here's the link to what i've sourced so far. If these are indeed A400 speakers I am then looking for two more. Anyone have some laying around? ha...

http://www.ebay.com/itm/122136142803
 
Werne1nm said:
I have also heard that the drivers are unique to the A400s.

Plus i believe they have a square magnet in the back.

I am looking for four replacement woofers for my A400's i picked up recently because for some reason all four were replaced with some cheap 8 inch woofers. Apparently the owner before didn't know you could refoam the speakers.

I think i've sourced two from eBay that were mis marked as A70's but they have the square magnet in the back and the date of manufacture is right in line with what i'm looking for.

Here's the link to what i've sourced so far. If these are indeed A400 speakers I am then looking for two more. Anyone have some laying around? ha...

http://www.ebay.com/itm/122136142803
Click to expand...

I realize you posted 4 months ago and may have dealt with this already, but I have all of the drivers out of my A400s now to refoam, recap, and refinish them. Only the woofers have square magnets.

Photo 2017-08-26, 12 43 52 PM.jpg
 
MannishBoy said:
Along these same lines (A400's) does anyone know the drop in replacement speaker for the 6.5 inch midranges? I can find other Boston Acoustic 6.5's with the round profile, I just don't know if they are the same as the ones used in the A400's. I think the T930's used a 6.5 round, but would it be the same drivers? Sure doesn't seem to be a lot of specs on the web about the A400's. Any help is greatly appreciated.
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Hello; did you ever find any suitable replacement midrange? I am looking for same thing for my original purchased A-400's (2 midrange)
 
MarkNC said:
To the OP: If you end up with the 400s and you're up for a little project, it's worth replacing the ferrofluid (usually dried out and gummy at this point) in the tweeters. Parts Express sells a kit for a reasonable price, and it's not difficult to do. I did it on my A200s and believe it helps to get these vintage units back to original spec.
https://www.parts-express.com/ferrofluid-100ul-general-purpose-for-1-diameter-vc--340-540
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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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