Tube Guitar Amp Discussion Forums
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Is that value something that would be on the tube engineering reference data?zaphod_phil wrote:Yes, except you may need to change your cathode resistor value with a 12BZ7 to get it to bias correctly.
It is. The plate resistance on the 12BZ7 (31.8k) is about half that of 12AX7 (62.5k) and has twice the transconductance. That makes it equivalent of a paralleled 12AX7 (think liteII preamp). If you just drop it place of a 12ax7, it will bias quite a bit warmer, I think. My logic is usually suspect on Fridays. you would need to double the Rk value to keep the bias correct. The gain will also go up unless you halve the plate resistor. That's not necessarily a bad thing though.kedsinger wrote:Is that value something that would be on the tube engineering reference data?zaphod_phil wrote:Yes, except you may need to change your cathode resistor value with a 12BZ7 to get it to bias correctly.
