I was wondering if there is a need to have a 12AX7 in preamp slots 4 & 5? I ask this because in the Mesa Bass 400+ it is suggested to install a 12AU7 in the driver socket. If I am not mistaken, the driver is the same as a phase inverter? My understanding is that the 12AU7 has lower gain than a 12AX7, but will handle much more plate voltage.
I am not so concerned with the driver section as I am with trying one of these lower gain tubes in the effects loop section. It may be interesting in that a possible change would be being able to increase the channel volume more without clipping the effects loop. Also reducing amp noise overall.
If you were to use a 12AU7 in the phase inverter/driver socket could the tonal response of the amp be better? A drawback would be less voltage hitting the power tubes leading to a later saturation stage of the power tubes.
Any thoughts from you guys on this?
I am not so concerned with the driver section as I am with trying one of these lower gain tubes in the effects loop section. It may be interesting in that a possible change would be being able to increase the channel volume more without clipping the effects loop. Also reducing amp noise overall.
If you were to use a 12AU7 in the phase inverter/driver socket could the tonal response of the amp be better? A drawback would be less voltage hitting the power tubes leading to a later saturation stage of the power tubes.
Any thoughts from you guys on this?