Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Jrusto on February 27, 2024, 06:01:24 pm

Title: Hoffman Princeton build in a PRRI Chassis
Post by: Jrusto on February 27, 2024, 06:01:24 pm
Moving along pretty good on my PRRI to Hoffman Princeton Reverb build but have hit a snag. 
I am trying to figure out how to the PRRI Rev/Trem pedal to work through a TRS system the PRRI came with.  I think I just hook the Trem wire as I have it but the Rev confuses me. 

On the PRRI both the Rev and Trem were on regardless of whether the pedal was plugged in or not. I kind of like that method of operation as I could just reach down and turn the knobs for the effect. 

The PRRI also came with caps between the tip/ring and ground on both the Rev and Trem.  I have them out in the photo and don't really understand their function.

So how do I go about hooking up the board to the TRS jack and where would the 220k resistor go.  It is twisting my brain so I thought I would reach out for some help. 

I have attached my amp build, a PRRI reverb schematic, and a link to the Hoffman Layout for reference.  https://el34world.com/Hoffman/files/Hoffman_PrincetonReverb.pdf .

Thanks for your help
Rusty
Title: Re: Hoffman Princeton build in a PRRI Chassis
Post by: WimWalther on February 28, 2024, 09:02:04 am
The 220pF caps look like contact snubbers, probably to prevent a "pop" when the foot switch is operated.

I'm not sure which 220K resistor you're discussing. What's its part #?
Title: Re: Hoffman Princeton build in a PRRI Chassis
Post by: sluckey on February 28, 2024, 09:53:13 am
You don't need the caps for Hoffmans PR, but you can put then on the F/S jack if you want to. The tip of your TSR F/S jack is for tremolo and the ring is for reverb. The 220K connects between ring and sleeve (ground) of the F/S jack. Notice the ring also connects to the reverb return jack.
Title: Re: Hoffman Princeton build in a PRRI Chassis
Post by: Jrusto on February 28, 2024, 11:40:55 am
Again thanks for the replies.  I put it togeather late last night on what I figured was right.  It was great to have Slukey confirm.  Thanks again.