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previous: Steve A. Mike: &nbs... -- 1/19/1998 12:26 AM

Re: Unused Triode as Gain Stage

1/19/1998 9:18 AM
Mike T	Re: Unused Triode as Gain Stage Thanks Steve...nice page. What I'm basically trying to do here is make my Champ sufficient for rehearsal. I punched it out for 1 more tube. Right now its pretty close to a AA964 Princeton without the vibrato circuit, with diodes for a rectifier, a cathode bias power section, a Celestion 35 watt 8 inch 4 ohm speaker, and a Fender Deluxe OT (Its an 8 ohm OT, but I don't think it will be a problem). It sounds good but it wont grind when cranked. Before I had the board wired as a 5F2-A Princeton with the output tubes in parallel with no PI but biased to about 45 mA idle per tube, and it sounded good and would grind real nice when cranked, but I knew there was more available power from 2 6V6s. So now more power is there, I think because of the PI and the fact that it is now biased to about 31mA per tube so it is running in 'AB'. Then I changed just the preamp section to a Champ AA764 with tone controls and the gain was gone. So now what I will try is circuit board wiring of a 6G2 Princeton without the vibrato, since the preamp is pretty much the same as the 5F2-A. I'm hoping this will restore the gain. I know that a cathodyne PI has unity gain, but I'm wondering if throughput is constant, that is if there is a stronger signal put into the PI if this same strength signal comes out... Mike

1/19/1998 9:18 AM

Mike T

Re: Unused Triode as Gain Stage

Thanks Steve...nice page. What I'm basically trying to do here is make my Champ sufficient for rehearsal. I punched it out for 1 more tube. Right now its pretty close to a AA964 Princeton without the vibrato circuit, with diodes for a rectifier, a cathode bias power section, a Celestion 35 watt 8 inch 4 ohm speaker, and a Fender Deluxe OT (Its an 8 ohm OT, but I don't think it will be a problem). It sounds good but it wont grind when cranked. Before I had the board wired as a 5F2-A Princeton with the output tubes in parallel with no PI but biased to about 45 mA idle per tube, and it sounded good and would grind real nice when cranked, but I knew there was more available power from 2 6V6s. So now more power is there, I think because of the PI and the fact that it is now biased to about 31mA per tube so it is running in 'AB'. Then I changed just the preamp section to a Champ AA764 with tone controls and the gain was gone. So now what I will try is circuit board wiring of a 6G2 Princeton without the vibrato, since the preamp is pretty much the same as the 5F2-A. I'm hoping this will restore the gain. I know that a cathodyne PI has unity gain, but I'm wondering if throughput is constant, that is if there is a stronger signal put into the PI if this same strength signal comes out...

Mike

Replies:

Bruce Mike, Are the two 6V6s cathode... -- 1/19/1998 6:46 PM
Craig I've been trying the same type of e... -- 1/20/1998 5:24 PM