Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: ALK2MT on January 21, 2026, 10:42:26 am

Title: Blues Jr Hoffman Circuit Adding Reverb
Post by: ALK2MT on January 21, 2026, 10:42:26 am
I have a question about connecting the solid state reverb circuit back into the Blues Jr Hoffman circuit. I am wanting some expertise on modding the circuit. Could I just attach the reverb circuit back in on either side of R18 like the original circuit? How do I delete meat control as well.

Thank you!

Alex


Title: Re: Blues Jr Hoffman Circuit Adding Reverb
Post by: stratomaster on January 21, 2026, 07:04:56 pm
You would also need to create a low voltage power supply for the IC to power to Reverb circuit.

The meat control can be deleted by simply not populating it and replacing it with a wire. Refer to the official Fender schematic.
Title: Re: Blues Jr Hoffman Circuit Adding Reverb
Post by: ALK2MT on March 27, 2026, 09:55:18 am
I’ll redraw this out, but in concept.

If I added the original 15/15 bias circuit back in, I would also need to accommodate for tube bias part of circuit and could replace R51 with a bias pot and come out ok?

I’m also drafting up the reverb circuit.


Title: Re: Blues Jr Hoffman Circuit Adding Reverb
Post by: stratomaster on March 27, 2026, 12:08:36 pm
Yes. You'd have to either adopt the whole circuit, adapt it while keeping the same topology, or use the 50vac tap for just the low voltage supply and derive your bias from the HT.

It's easiest to just crib Fender's proven design