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Hello everybody.
Very long time since i posted here, and equally long time since I built anything, but now I have completed my amp nr 4 and need some help.
The amp is a copy of a Marshall Plexi (Like Ceriatone Plexi 50 Lead) right up to the power tubes. The power tubes are a pair of 6L6's in UL - cathode biased. (Just have to change something, right?
) And it sounds great!
The problem is that the preamp is too loud. The volume controls works more or less like on/off switches, and anything above 2 = overdrive. Wether it's the PI or the power tubes that distort I don't really know, I don't have a scope. But the amp plays pretty loud.
What I've tried so far:
Double checked that the volume pots are audio taper.
Lowering the voltage to the first preamp tube
Lowering the voltage to both preamp tubes
In both cases I added a 10k resistor in the PSU in series with the ones allready there. This didn't help.
I tried a master volume pot after the EQ. The preamp doesn't distort before the volume pots are way up.
The PI cathode resistor tail is 470-10k-4k7 and the Presence is the "newer" 1987-design with a 22k pot.
Is there a good way to make the PI less sensitive or lower the preamp output, to get more control of things?
TIA
Jan
Very long time since i posted here, and equally long time since I built anything, but now I have completed my amp nr 4 and need some help.
The amp is a copy of a Marshall Plexi (Like Ceriatone Plexi 50 Lead) right up to the power tubes. The power tubes are a pair of 6L6's in UL - cathode biased. (Just have to change something, right?
) And it sounds great!The problem is that the preamp is too loud. The volume controls works more or less like on/off switches, and anything above 2 = overdrive. Wether it's the PI or the power tubes that distort I don't really know, I don't have a scope. But the amp plays pretty loud.
What I've tried so far:
Double checked that the volume pots are audio taper.
Lowering the voltage to the first preamp tube
Lowering the voltage to both preamp tubes
In both cases I added a 10k resistor in the PSU in series with the ones allready there. This didn't help.
I tried a master volume pot after the EQ. The preamp doesn't distort before the volume pots are way up.
The PI cathode resistor tail is 470-10k-4k7 and the Presence is the "newer" 1987-design with a 22k pot.
Is there a good way to make the PI less sensitive or lower the preamp output, to get more control of things?
TIA
Jan
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