Thought dropping a pair of inputs on my breadboarded Deluxe 5E3 and making it a 3rd gain stage would be good, but ended up knocking it down so much with a 2nd vol pot and 1Meg grid stopper I decided to jumper out 1/2 an AX7. What a pleasant surprise! Still plenty loud, 43/42 mA on the 6V6s, took the vol pot to the PI out, and probably can back down the grid stopper. Well, I had to try it anyway! Now I have an xtra 1/2 AX7, to turn into a vibrato. Princeton AA964 here I come....
You could parallel the unused triode with the first gain stage making it quieter and this also halves the output impedance making the tone stack easier to drive.
Or you could direct couple the first gain stage to a cathode follower but this will change how the amp behaves by quite a bit.
Another thing to try is use the unused triode as a plate load CCS on the first gain stage. This would be more difficult because you would lose some voltage from your HV tap across the CCS. So your dropping resistor value would have to be lowered quite a bit to get enough voltage. You could also use the triode as a CCS in place of the large cathode resistor on the 6V6's.
You have lots of options, I myself hardly ever use vibrato but that is a classic option.
Or you could direct couple the first gain stage to a cathode follower but this will change how the amp behaves by quite a bit.
Another thing to try is use the unused triode as a plate load CCS on the first gain stage. This would be more difficult because you would lose some voltage from your HV tap across the CCS. So your dropping resistor value would have to be lowered quite a bit to get enough voltage. You could also use the triode as a CCS in place of the large cathode resistor on the 6V6's.
You have lots of options, I myself hardly ever use vibrato but that is a classic option.
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Constant Current Source....had to look that up before posting...new to me. Like the idea of lowering the impedance for the tone stack. Have read some on cathode followers (like the 5F6-A Bassman uses), might play with that. Got a tremelo ckt working, didn't like having to switch from cathode to fixed-bias, but it works OK. My son's band likes playing with my old Vibrochamp, so may build this Deluxe-now-Princeton into a 2x8 Crate amp cabinet I have waiting for a tube amp. Thanks for the ideas!
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