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Permalink Reply by samuel schold on October 5, 2014 at 11:10am

Hi Wayfinder! I only use the 9volt battery for power on these amplifiers. Every once in a while an amp works fine,but most often they buzz like hell .  

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Permalink Reply by robert jones on October 5, 2014 at 11:34am

Have you tried backing off the gain on the amp board?

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Permalink Reply by samuel schold on October 5, 2014 at 1:23pm

Hi Robert, yes I have tried to fix the problem by adjusting the gain pot on the circuit board. I am wondering if a .oo1uf capacitor in parallel with a 150K resistor across the output jack would help . especially at low volume?

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Permalink Reply by robert jones on October 6, 2014 at 1:12am

Worth a try, I would solder a non-polarized cap and a resistor together and use like a probe rather than hard wiring to the output.

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Permalink Reply by samuel schold on October 6, 2014 at 2:04am

Hi Robert! Thanks for the suggestion! I have done this before on input and output pots and it seemed to help a lot. I guess I have never tried it on amp circuits though. 

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Permalink Reply by robert jones on October 6, 2014 at 3:58am

Look up the caps on the amp board.

If cheap low quality caps were used that could be the source of the problem.

If that's the case you'll need to replace the caps as behavior would still be erratic even with an added filter.

Thing is once you get to the point of adding filters and replacing caps you might as well be building your own amp from scratch. Low power battery amps are EASY to build.

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