Problems with gain in my circuit

[jenks]

I've nearly finished designing my bass pre-amp & overdrive :-) The pre-amp has bass, mid and treble controls. Then there's a switch for you to choose between two overdrive stages where the signal is driven through 12AX7 thermionic valves.

The only problem I have with the whole circuit atm is the variation in amplitude I get from the various stages. The pre-amp section attenuates the signal by 16dB, the soft-overdrive adds 40dB and the MXR-overdrive attenuates the signal by 143dB!

What's the best way to solve this problem??

[Enzo]

Not sure what I am looking at, but it appears the outputs of U1, U2 are feeding into the OUTPUTs of the XBP things. SHouldn't that be to their INPUTs?

[Steve Conner]

Looks like a simulation problem to me. (sure it was 143dB, not 144? :P) We can't really help until you try building it for real and come back to us with some physical problems. A bunch of extra volume controls is what you would use to equalize the differences between stages.

[teemuk]

In the second figure the top opamp is powered from dual supply but it still references its input to 4.5 volts (through R4).

Third figure: The Opamp configuration is kind of odd. First of all, diode clipping won’t work well in non-inverting configuration. Does it have a reference to zero volts in the non-inverting input?