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Hoffman Amps Forum image Author Topic: Princtone Reverb No Tremolo with EL84's  (Read 1838 times)

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Offline Smradek

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Princtone Reverb No Tremolo with EL84's
« 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 ?


Offline Dave

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Re: Princtone Reverb No Tremolo with EL84's
« Reply #1 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
« Last Edit: March 06, 2024, 09:19:06 am by Dave »

Offline sluckey

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Re: Princtone Reverb No Tremolo with EL84's
« Reply #2 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.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline tdvt

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Re: Princtone Reverb No Tremolo with EL84's
« Reply #3 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"

 


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