Can anybody identify this 15'' driver?
They are from the (Dr.) Böhm B250 PA speakers (~1985) but I could not find any additional information about the driver. I found a somewhat useful description in an old catalogue where they say, that the midrange horn goes from 1-5kHz and the tweeters from 5-20kHz. Nothing was stated about this driver tho except that the frequency response of the whole speaker starts at 35Hz.
Also after taking it apart it confused me even more because the 15 inch driver was connected without any crossover and the horn and tweeters were wired in parallel only with a 6.8 uF and 3.3 uF capacitor respectively. The horn even had a resistor (4.7 Ohm) soldered on the minus pole which was even more confusing.
Maybe someone can help me with this problem and I apologize for my English as it is not my first language.
They are from the (Dr.) Böhm B250 PA speakers (~1985) but I could not find any additional information about the driver. I found a somewhat useful description in an old catalogue where they say, that the midrange horn goes from 1-5kHz and the tweeters from 5-20kHz. Nothing was stated about this driver tho except that the frequency response of the whole speaker starts at 35Hz.
Also after taking it apart it confused me even more because the 15 inch driver was connected without any crossover and the horn and tweeters were wired in parallel only with a 6.8 uF and 3.3 uF capacitor respectively. The horn even had a resistor (4.7 Ohm) soldered on the minus pole which was even more confusing.
Maybe someone can help me with this problem and I apologize for my English as it is not my first language.
Attachments
Are there any numbers other than the 711 and the 4D you show? Even on the back of the cone?
1. It's a woofer, not a subwoofer.
2. The lack of xo material tells you this is an inexpensive sound reinforcement unit.
3. The resistor on the ( - ) is not unusual or confusing. It doesn't matter which side it's on.
1. It's a woofer, not a subwoofer.
2. The lack of xo material tells you this is an inexpensive sound reinforcement unit.
3. The resistor on the ( - ) is not unusual or confusing. It doesn't matter which side it's on.
Thank you so far!
No as far as I can see there is nothing on the inside of the cone but on the other speaker I have there is a 4 digit code printed on the back. My guess would be that it is some kind of old Foster driver as the other drivers in the system are all from Foster but that could be totally wrong.
1. Yeah that makes sense to me now. I was just confused because Böhm labeled it as a low range driver. I attached the translated catalogue specs I found online somewhere.
2. I was hoping this would not be the case but it seems more likely. The speaker was quite expensive back then (~900DM roughly the same buying power as €) so I thought it could be something good.
3. Thanks for clarifying!
No as far as I can see there is nothing on the inside of the cone but on the other speaker I have there is a 4 digit code printed on the back. My guess would be that it is some kind of old Foster driver as the other drivers in the system are all from Foster but that could be totally wrong.
1. Yeah that makes sense to me now. I was just confused because Böhm labeled it as a low range driver. I attached the translated catalogue specs I found online somewhere.
2. I was hoping this would not be the case but it seems more likely. The speaker was quite expensive back then (~900DM roughly the same buying power as €) so I thought it could be something good.
3. Thanks for clarifying!
Attachments
yanso,
Yes, the drivers you show are definitely middle of the road, not cheapies. Foster is usually the drivers made for OEM equipment whereby Fostex is when they sell raw drivers to the public, same company.
The speakers as a whole are the kind you would see in smaller canned music venues like pubs and the such. Not truly intended for sound reinforcement but made to put up with a little guff now and then. And yes, they often cost a pretty penny.
lene may have found the same/similar woofer, nice work.
Yes, the drivers you show are definitely middle of the road, not cheapies. Foster is usually the drivers made for OEM equipment whereby Fostex is when they sell raw drivers to the public, same company.
The speakers as a whole are the kind you would see in smaller canned music venues like pubs and the such. Not truly intended for sound reinforcement but made to put up with a little guff now and then. And yes, they often cost a pretty penny.
lene may have found the same/similar woofer, nice work.
Okay, so lene might have pulled that picture from the diyAudio site from 10 years ago.
https://www.diyaudio.com/community/threads/foster-fostex-what-a-speaker-15.239213/
It might just be a Fostex 15W200
https://www.hifido.co.jp/sold/?KW=15W200+FOSTEX&G=1&LNG=E&O=0&L=50&C=11-59585-04189-00
https://www.diyaudio.com/community/threads/foster-fostex-what-a-speaker-15.239213/
It might just be a Fostex 15W200
https://www.hifido.co.jp/sold/?KW=15W200+FOSTEX&G=1&LNG=E&O=0&L=50&C=11-59585-04189-00
This is a typical OEM woofer. Who made it is not that relevant, as it will be build customised to the customer's wishes. If you want to do something with it you will have to measure it first for T/S parameters and impendance/FR. No spec sheets of these will be availeble, and even availeble drivers that may be close with it on looks or look identical are not exact this one. That is how OEM works. It could be a great driver, it could be trash.
Oh. When I open with Chromium I see the woman. With Firefox I see the speaker.
So, none of us can be wrong when the site doesn't show the same thing depending on conditions we don't know... 🧐 A bit offtopic, but at least we saved some pics in case that's useful when the site turns into something else 🙂
