Hi All
I am looking for some comments advice on a recently acquired BGW8000 power amp.
I am looking to use it as a sub woofer amp in the near future.
In short its supposedly abt 225w per channel into 8ohms
and I believe was more aligned to PA type use in the past.
Looking at a couple of issues:
1. It works and works fine...
2. Turn off thump (not turn on) - at turn off there is a loud pop from one channel only - I am looking to hopefully find the cause. (it may be part of the trait of the amp - I dont know)
the pop is immediately at turn off and is loud enough to cause concern as well as illuminate the "overload" LED on the front panel 1 channel only.
I wonder if it may be some arcing of the power switch..? causing the issue
I have reviewed the schematics and see that in the German version there is a cap across the transformer primary - being down under I assume that this cap may not have been installed ..
I have not yet opened the amp to confirm.
I notice that there appears to be essentially nothing on the forum on BGW amps...?
I am also looking to replace the rather noisy cooling fan..no dramas there.
I also notice ton the schematic that there are no fuses on the supply rails ....
I wonder if some should be installed...? Didt he old PA amps have supply rail fuses generally or were they avoided so as to not have a amp failure during live concerts- i- built tough...
So in short :
Any ideas ?
Why the pop? and why only one channel ???
My old Phase Linear 400 from lifetime ago used to have a bad case of flatulence as the caps powered down (i also had an outboard capacity bank on the Phase 400 to the tube of apprx 80KuF)
I've been trying it out on some of B&W DM4's - and it essentially sounds fine - though playing Stevie Ray Vaughn's "Tin Pan Alley" at a useful level (not what I would call excessively loud at all) causes some stress on some of the explosive guitar transients. the amp was not sounding like it was clipping but rather the speakers were saying to turn it down a little.
Last time i heard a BGW was a 750 model probably in mid 1980's and it was unsuccessfully trying to destroy a large pair of JBL studio Monitors at a HiFI show
The SPL meter they had on hand was reading up to 115dB from memory...
All comments and suggestions gratefully received.
Cheers from down under
I am looking for some comments advice on a recently acquired BGW8000 power amp.
I am looking to use it as a sub woofer amp in the near future.
In short its supposedly abt 225w per channel into 8ohms
and I believe was more aligned to PA type use in the past.
Looking at a couple of issues:
1. It works and works fine...
2. Turn off thump (not turn on) - at turn off there is a loud pop from one channel only - I am looking to hopefully find the cause. (it may be part of the trait of the amp - I dont know)
the pop is immediately at turn off and is loud enough to cause concern as well as illuminate the "overload" LED on the front panel 1 channel only.
I wonder if it may be some arcing of the power switch..? causing the issue
I have reviewed the schematics and see that in the German version there is a cap across the transformer primary - being down under I assume that this cap may not have been installed ..
I have not yet opened the amp to confirm.
I notice that there appears to be essentially nothing on the forum on BGW amps...?
I am also looking to replace the rather noisy cooling fan..no dramas there.
I also notice ton the schematic that there are no fuses on the supply rails ....
I wonder if some should be installed...? Didt he old PA amps have supply rail fuses generally or were they avoided so as to not have a amp failure during live concerts- i- built tough...
So in short :
Any ideas ?
Why the pop? and why only one channel ???
My old Phase Linear 400 from lifetime ago used to have a bad case of flatulence as the caps powered down (i also had an outboard capacity bank on the Phase 400 to the tube of apprx 80KuF)
I've been trying it out on some of B&W DM4's - and it essentially sounds fine - though playing Stevie Ray Vaughn's "Tin Pan Alley" at a useful level (not what I would call excessively loud at all) causes some stress on some of the explosive guitar transients. the amp was not sounding like it was clipping but rather the speakers were saying to turn it down a little.
Last time i heard a BGW was a 750 model probably in mid 1980's and it was unsuccessfully trying to destroy a large pair of JBL studio Monitors at a HiFI show
The SPL meter they had on hand was reading up to 115dB from memory...
All comments and suggestions gratefully received.
Cheers from down under
I thought at first it was the circuit breaker but I see you have a "fast off " circuit which turns the current off in conjunction with the circuit breaker .
If only one channel is faulty then the connection between it and the fast off could be faulty .
I notice the DC speaker protection operate at (approx ) 8 volts this also is something that might need to be looked at .
This is a lot more common than you think and there are various threads on it on DIY Audio.
If only one channel is faulty then the connection between it and the fast off could be faulty .
I notice the DC speaker protection operate at (approx ) 8 volts this also is something that might need to be looked at .
This is a lot more common than you think and there are various threads on it on DIY Audio.
If you are lucky the designer of that amp will chime in. Duke is a member of diyAudio forum. Look for other BGW posts and I'm sure you'll see his name come up.
Craig
Craig
Hi George
The channel that POP's is BAD or has been modified.
No fuses are needed. The FAST OFF & SLOW ON circuit do work
Email me and I will send you a manual.
Duke duke.aguiar@ieee.org
The channel that POP's is BAD or has been modified.
No fuses are needed. The FAST OFF & SLOW ON circuit do work
Email me and I will send you a manual.
Duke duke.aguiar@ieee.org
BGW amplifiers were a sound reinforcement standard back in the 1970s and 80s. Since a BGW 8000 could be over 35 years old, have a look at the electrolytic caps. The designer, Brian G Wachner, died back in 1997 at age 52.
I still think Duke was the designer of the x000 series. He already replied to the OP so maybe he will confirm his role in that series.
Craig
Craig
Brian G Wachner was the Owner of BGW and did not do design work after 1974. I started 1977 and did electrical designs like 750B,C,D,E, 300, 600, 320,620, 100B, 75, 50, 7000, 7500, 8000 & many others.
Duke Aguiar.
Duke Aguiar.
Hi All
Well Duke did chime in and make suggestions via email as to where to start and in particular to look at the Fast Off circuit.
I did open up the beast and found to start with someone had been in there before myself...
But what i did find was a broken lead on one of two disc capacitors located across the.diode bridge to the power supply - on the Transformer side......
This was repaired and the turn off pop seems to at least for now disappeared...🙂
Assuming this works - this is great so thanks to all for your input - esp. Duke.
if not i'll go in further...
One lesson- when purchasing old equipment that may have had a rough life - check if you can for issues - what I essentially had was some 90v floating round in mid air- dangerously close to be metal / chassis..could have been spectacular!
Cheers to all
Well Duke did chime in and make suggestions via email as to where to start and in particular to look at the Fast Off circuit.
I did open up the beast and found to start with someone had been in there before myself...
But what i did find was a broken lead on one of two disc capacitors located across the.diode bridge to the power supply - on the Transformer side......
This was repaired and the turn off pop seems to at least for now disappeared...🙂
Assuming this works - this is great so thanks to all for your input - esp. Duke.
if not i'll go in further...
One lesson- when purchasing old equipment that may have had a rough life - check if you can for issues - what I essentially had was some 90v floating round in mid air- dangerously close to be metal / chassis..could have been spectacular!
Cheers to all