Any suggestions how to reduce the hiss of this circuit?
(The input of a diy bass amp)
I thought it was below the hum noise, testing at home with a small FR speaker and headphones.
Tuning the gain down and the master volume up - some residual hum noise from psu and the circuitry shows up.
Then I took the amp at the rehearsal room to the cabinet.
15" mid bass + a horn compression driver.
It started to pour out...
Plugging mate's headphones, plugging the line out into mixing console and through stereo speakers - the hiss is there but not that annoying.
Turning up the compression driver (bi-amping the bass cabinet) and it comes bold and loud
I just got an idea to lower the gain pot value and the preceding attenuator resistor, so eventually the hiss is lower...
There is a voltage divider cause the gain is way too much for a bass amp (6n1p) tube.
Otherwise I like the double triode topology, cause it adds grit when distortion just opens up slightly.
The first triode seems to need double less gain to do that without the attenuator resistor.
How to lower the gain ?
There is not much difference lowering the plate resistor on simulator.
(The input of a diy bass amp)
Tuning the gain down and the master volume up - some residual hum noise from psu and the circuitry shows up.
Then I took the amp at the rehearsal room to the cabinet.
15" mid bass + a horn compression driver.
It started to pour out...
Plugging mate's headphones, plugging the line out into mixing console and through stereo speakers - the hiss is there but not that annoying.
Turning up the compression driver (bi-amping the bass cabinet) and it comes bold and loud

I just got an idea to lower the gain pot value and the preceding attenuator resistor, so eventually the hiss is lower...
There is a voltage divider cause the gain is way too much for a bass amp (6n1p) tube.
Otherwise I like the double triode topology, cause it adds grit when distortion just opens up slightly.
The first triode seems to need double less gain to do that without the attenuator resistor.
How to lower the gain ?
There is not much difference lowering the plate resistor on simulator.
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