Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Smradek on March 06, 2024, 09:09:49 am

Title: Princtone Reverb No Tremolo with EL84's
Post by: Smradek on March 06, 2024, 09:09:49 am

Hello there!

How do I have to modify the Princtone Reverb No Tremolo
https://el34world.com/Hoffman/files/Hoffman_PrincetonReverb_NoTremolo.pdf
to use a pair of EL84's ?

Title: Re: Princtone Reverb No Tremolo with EL84's
Post by: Dave on March 06, 2024, 09:17:01 am

Look at the schematic for a Vox AC-15 or some other amp that uses El-84's at about the same power (Fender Blues Jr. is another) and copy the power section of that amp into your amp.


Dave

Title: Re: Princtone Reverb No Tremolo with EL84's
Post by: sluckey on March 06, 2024, 09:27:04 am

PT should have a secondary of 250-0-250. OT should have a primary Z of 8K. Bias range resistor should be changed to provide about -12v to -15v bias.

Title: Re: Princtone Reverb No Tremolo with EL84's
Post by: tdvt on March 06, 2024, 09:48:49 am

I am currently gathering parts for this very configuration.

I bought a Hammond transformer set for the Blues Jr & Mojo choke & reverb transformer.

Twin TMB tonestack, 2-tube reverb w/long tank, LTPI, EL84s

It's going into a Princeton Reverb cab (still to be built) but with a 12"