Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Mason on October 14, 2023, 05:14:00 pm

Title: 12AU7 Tube Power Amp Pedal Questions
Post by: Mason on October 14, 2023, 05:14:00 pm

I've built a few tube preamp pedals recently and I wanted to try to build a power amp to use with them. The preamp pedals are powered using a switched-mode power supply and can be run off a 12-volt pedal power supply. Would it be possible to build a power amp using each side of a 12AU7 in a push-pull configuration for the power tube and a 12ax7 phase inverter using a switched-mode power supply? For reference, the power amp design would be similar to the one rob robinette uses here: https://robrobinette.com/Bassman_Micro.htm With maybe a couple of added options for switchable negative feedback and a depth control.

From my understanding, the current draw wouldn't be any more than the preamp pedals I've built using the same SMPS. Is there any reason why this wouldn't work?

Title: Re: 12AU7 Tube Power Amp Pedal Questions
Post by: JB on October 15, 2023, 04:54:01 am

I’d check some data sheets. If you’re using a 12AU7 as a power amp then it will pull a lot more current than a 12AX7. Maybe 10 times. That may or may not be a problem for your PSU.