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<DIV><FONT face=Arial size=2>Hi,</FONT></DIV>
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<DIV><FONT face=Arial size=2>for clarification : of course the noise level is
set to 0, and I also tested the circuit with not inserted noise-generating
opamps 7 & 8. No change, the hissing noise is there. As I said, it is a very
very low noise level, but it is audible and I dont like it.</FONT></DIV>
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<DIV><FONT face=Arial size=2>greetings, Joerg</FONT></DIV>
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<DIV><FONT face=Arial size=2>
<DIV><FONT face=Arial size=2>>at last I have managed to built my own TR909 -
bass drum pcb. It works prettty well (see ><A
href="http://www.analog-synth.de/synths/tr909/tr909.htm">http://www.analog-synth.de/synths/tr909/tr909.htm</A> for
details), but I found one problem :</FONT></DIV>
<DIV><FONT face=Arial size=2>>the output is a bit noisy. You can hear a
little hissing noise, which seems to correspond to >the envelope and
therefore VCA activity of the VCA between the output amplifier and
>distortion diodes (controlled by "decay").</FONT></DIV>
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<DIV><FONT face=Arial size=2>>What would you suggest to eliminate that (not
very loud) noise ? (Of course, this is not the >noise of the noise generator,
bleeding through somehow, this is tested...)</FONT></DIV>
<DIV><FONT face=Arial size=2>>Another opamp for the output-amplifier ?
Something better than the TL072 ? Something >better than the BC549 for
the VCA's ?</FONT></DIV>
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