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more bass from master volume? Help

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2/18/1998 11:22 AM

more bass from master volume? Help

Hello all,
I have a Rivera-era Fender Concert I have modded, and I'm having trouble getting some tone from the distortion circuit when the master volume is set to low levels. Once I get the knob past 3 or so it sounds great. Lower than that and there is no bass response - the sound is thin, trebley, grating. The distortion circuit for this amp now looks like this:

1st (shared) gain stage
volume knob
2nd gain stage (switchable cathode cap)
"gain" knob
3rd gain stage (no cathode cap)
4th gain stage (no cathode cap)
tone stack
master volume

I still have one half of a 12AX7 available. My question is: Would it help if I converted the last triode and drove the tone stack (or the master volume) with a cathode follower (a la Bassman/Marshall) to lower the impedance and thus diminish the loading caused by the tone stack/master volume? Any other ideas?

Thanks,
Michael

2/20/1998 12:14 AM

Try adding a 100k resistor between the wiper of the master volume and the coupling cap to the phase-splitter. I am assumeing that the grid leak resistor to the phase-splitter is 1M. This will attenuate the signal a bit, but it should not be all that noticeable. I have only used this trick in Marshalls with the cathode follower before the tone stack, so let me know how this works for you.

Later...
GVB

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