@pkane open input is catching 60Hz from the air by capacitive coupling to ambient mains frequency which is everywhere. So you have to close the input, as you did. 2nd, if you have enough dynamic range, open input will have more noise, because thermal noise of input impedance (47k or so) is amplified by the amplifier gain. Normally the signal source output impedance is much lower and effectively shunts amplifier's input.
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How to reduce 120Hz frequency at amp output?
- Thread starter pkane
- Start date
If these caps are rated 100v they could be wired in parallel in stead of in series.. This would lower the ripple considerably!
But now that think of it they are probably not wired in series but it looks like that as two of them are wired to get a positive and a negative voltage...
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