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previous: Craig I almost forgot to mention the main... -- 9/24/1997 2:40 PM

Re: ...I almost forgot...

9/24/1997 8:12 PM
Gary	Re: ...I almost forgot... You might want to put a scope on the output of the amp and monitor for an ultrasonic oscillation when you get the volume up to 6 or 7 or more. You may or may not need an input signal depending on whether the circuit needs a signal to excite it into oscillation. Also, you may be able to see it on the input to the master volume. I've experienced this sort of problem but never to the severity that all audible sound was gone. If that's what it is you may need to check your layout again--maybe some more shielding (concentrate on the grid circuits). Does the level of the master have any effect on the sound loss(other than when it's all the way down)? Gary

9/24/1997 8:12 PM

Gary

Re: ...I almost forgot...

You might want to put a scope on the output of the amp and monitor for an ultrasonic oscillation when you get the volume up to 6 or 7 or more. You may or may not need an input signal depending on whether the circuit needs a signal to excite it into oscillation. Also, you may be able to see it on the input to the master volume. I've experienced this sort of problem but never to the severity that all audible sound was gone. If that's what it is you may need to check your layout again--maybe some more shielding (concentrate on the grid circuits). Does the level of the master have any effect on the sound loss(other than when it's all the way down)?
Gary