Overcoming Pet Peeves on PR’s Reverb/Trem

Check the code on the reverb tank. Mine is fairly noticeable at 2.5, and just gets stronger from there. The hum only happens near the end of the dial.

There are mods to slow the trem, resistor, capacitor or control pot. All involve a trip to the tec unless you're competent inside an amp.

 

I'll let smart folks talk about your reverb hum, but there's something wrong with any PR that can't kill rodents with the amount of verb available.

For 'deep' trem, have your bias checked -- and see if they can set it around 60% dissipation. (Hmm, I forget if the PRRI has bias adjust; if so this should be simple).

For slow trem, you just need to replace one of the (two) .01 caps in the trem circuit with .02. I haven't looked at the PCB in these, but I picture someone here will know where that is and how hard it is to replace.

 

A power tube bias varying tremolo will inevitably be last in the signal chain, so there's not really a way to put the reverb after it. There are simple capacitor and resistor value changes that can slow and deepen the tremolo, which should be equally applicable on the reissue version.

 

I too think you have a problem when it comes to amount of reverb. It should be strong. I wonder if a spring came off in your tank?

But noise in both the RI DR and PR is a known issue in some.

The strength and speed mod for Tremelo is easy on a vintage one, I imagine it would just be a matter of finding that cap and resistor on your circuit board. But remember your power tube bias setting effects Tremelo in a Princeton also.

I understand your frustration, but the statement: "The Princeton Reverb is just about perfect in my book. Blackface tone is my favorite,....But the reverb and tremolo on my PRRI bother me, to the point that I consider just selling it and buying a BF Champ with a Strymon Flint."
Makes no sense. A Champ will not sound anything like a PR. If you like the PR and can't fix the issues buy the Flint for the PR!

 

The reverb will hum if any part of the tank or footswitch cables are unshielded. Are you using the stock foot switch?

 

sounds to me like you are trying too hard to like an amp that isn't the right amp for you.

 

This, IMO!
You might be better served with something else.
The Vox AC15 has a “darker”, less splashy/surfy reverb than the PR.
The tremelo is different, too.
I greatly prefer the Vox.
It rocks way harder, too.

 

Stock Princetons often have a weak tremolo. I used to modify old ones all the time to have greater depth, it involves changing the value of 1 resistor. Note: the 68 CPR already incorporates this mod, shown below on a schematic.



Reverb hum is common in both the PRRI and 68 CPR. It's the tank coils picking up hum radiated by the power transformer, which is closer due to the smaller amp size when compared with DR/SR/TR. I made it better on my 68 CPR by doing some careful shielding and repositioning of the tank - I flipped it backwards relative to the original installation.

 

Hum is 60 Hz. No usable signal down there. It should be filtered out.