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previous: Mike No, I have eliminated the vibrato.<... -- 9/27/1999 10:10 PM View Thread

Re: 6AU6 Tube

10/1/1999 1:26 PM
Re: 6AU6 Tube
In triode connection, the 6AU6 should have an amplification factor (mu) of about 36, and can be run at 250v plate supply at a current of 10-12ma. You can use a 100k plate load resistor like the typical 12AX7 circuits we're used to, but the cathode bias resistor would be relatively small. A 330 ohm unit will give a grid bias voltage around -4v.  
How much of a voltage gain does the stage need to provide? I'm not familiar with the D.T. EFX loop circuit. Is the triode used as an output buffer to the effects, or a return amp with (possibly adjustable?) voltage gain capability? Most gain recovery stages don't need a VG of 10+. They can get by with less than 10. A 6AU6 in triode would provide a gain inbetween that of a 12AX7 and 12AU7.  
As Ned suggested, you could easily convert to a single triode having the same gain characteristics of a 12AX7 using a 6AV6, or a slightly lower gain but less microphonic 6AT6, use the D.T. component values and be done with it. But you could try the 6AU6 wired in triode first as an experiment.

Mike It's a parallel effects loop. I bel... -- 10/2/1999 3:16 PM