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ra.ra

BA one-inch dome tweeter

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My questions are about this 1" dome tweeter, identical to the one shown in pics. I know very little about Boston Acoustics products, and I am just interested in gathering some information on this driver. I've had two of these for a couple years, and am curious whether they might be suitable for a DIY project at some point in the future. The face plate measures 3-3/8" x 4", and they measure between 5.5 and 5.8 ohms DCR. They have a heavy magnet with italicized "Boston" imprinted on the rear, and my pair have original stickers which date them to Feb 1983.

In which model numbers were these drivers used, and what was the corresponding tweeter crossover frequency? Used in two-way or three-way speakers? Also, are schematics available for any of those models, or at least is there any knowledge about the specific tweeter circuitry (i.e. cap value)? There is no urgent need for response here whatsoever, but reading some recent BA threads recently has made me curious to ask for some advice, opinions, or experienced knowledge. Thanks.        

 

BA 1%22 dome tweeter.jpg

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Thanks for both comments. From what little I have learned thus far, apparently the earliest versions of this series of speakers (circa 1980) employed a round Seas tweeter, which was then later changed to the rectangular BA tweeter shown. Also, I have contacted BA via email, but today I received a dispiriting note with the following comment: 

"There is no documentation or information going way back then on legacy products. We do apologize for any inconveniences."   

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I contacted one of my former colleagues from BA, who used to run the service dept. He told me this:

They look like CFT-3 tweeters. these are most likely A70's. A200's used the SEAS tweeter and A100/150 used CFT-5's I believe.

Steve F.

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Thank you, Steve, that's a helpful bit of info to move this along - - I previously had no info on tweeter part numbers. 

I have since found this interesting comment elsewhere on this site, made by s sislane from New Hampshire in 2008.

The A150 had the seas 241 tweeter (round, face+dome/coil from norway), the SERIES II had the CFT 1, and the series III had the CFT 5. All soft domes. The last two had rect face plates. The seas 241 was a very flat, natural sound, the CFT 1 had a similar sound, but all made at BA. When they got to the CFT 5, they added a slight trough/indentation in the face plate,around the dome, which spiked the output at a given frequency, making it just a hair brighter, but sounded amazing.

Pic of CFT-3 tweeter in an A60 is attached. Also, a composite pic of the various A150 models: series I, II, III, left to right. Not quite sure yet if my tweeters are CFT-1 or CFT-5, but apparently this same tweeter was also used in two-way models, like the A70 II shown. With this info, I'll continue to dig around for x-o schematics and product specs.

BA CFT-3 tweeter.jpg

BA A150 all.jpg

BA A70 II.jpg

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sislane from New Hampshire in 2008

This is Scott Sislane, who was the head of technical support for BA for many years. We overlapped during my time there. He would know this stuff, that's for sure.

Steve F.

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Thanks, Steve.....good to know that at least I was citing a knowledgeable source! 

 

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7 hours ago, ra.ra said:

Also stumbled on this site for BA parts - - no experience, no affiliation, no idea if legitimate. With the browser I was using, images of drivers did not appear. :(

http://www.pacparts.com/parts/list.cfm/MFG/Boston Acoustic/row/51

They seem legit. I've gotten obscure shortwave radio stuff from them in the past.

Images don't appear because they don't have them or stock on, say, an A70 tweeter,
Delivery depends on factory availability :-)

I got to them in the past because they're one of those suppliers that lists every part
available for a wide swath of consumer electronics, whether they ever have those
parts or not. I needed something (else) listed but unobtanium.

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The dome design looks very much like the SEAS that it replaced and I wouldn't

be surprised if it has a similar response.  Here are the specs on the SEAS:

 

Seas - H253 tweeter.pdf

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I think that tweeter was used in the A-100 Series 2 or perhaps 3.

Google for the A-100 and then click for images and you should find pictures showing them.

Those used a 6uF cap to a .5 mH inductor to ground to a 2 ohm resistor to the tweeter.

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On 3/9/2017 at 2:49 PM, Steve F said:

sislane from New Hampshire in 2008

This is Scott Sislane, who was the head of technical support for BA for many years. We overlapped during my time there. He would know this stuff, that's for sure.

Steve F.

Hi Steve!!

SEAS 241 used in A70 I, A100 I, A150 I, A200

CFT 1 used in A70 II, A100 II, A150 II, A400

CFT  5 was used in A100 III, A150 III, A1000 I/II, T930

CFT 3 was used in the A60, T830 and I forget what else. It was not a great tweeter.

These were the primary models, I may have missed some.

Scott Sislane

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The CFT 1 was a more natural sound (similar the SEAS tweeter but not identical), where as the following CFT 5 had a little depth added in the faceplate, which boosted some frequencies making it a brighter sound.

Scott

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