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Overcoming Pet Peeves on PR’s Reverb/Trem

Discussion in 'Amp Central Station' started by markesquire, May 1, 2020.

  1. markesquire

    markesquire Tele-Afflicted

    Sep 20, 2008
    The Princeton Reverb is just about perfect in my book. Blackface tone is my favorite, and spring reverb and tremolo are indispensable effects to me.

    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.

    Reverb: at least on my PRRI, the reverb has two problems. First, by the time the reverb mix is high enough to be noticeable, it’s making a very noticeable amount of hum. Multiple techs have looked at it and said it’s just part of the design, and while it feels stupid to use a pedal when I have a real spring reverb, the lack of noise makes a big difference. Second, the reverb effect and dwell doesn’t seem as strong/long as other amps (DR, TR). Is there a way to have much stronger reverb that is dead quiet (dedicated reverb tube, etc)?

    Tremolo: I love the bias vary trem on the PRRI, but have 2 problems with it. First, I really wish I could make it slower and deeper. I’ve seen a video here of someone who did this on a vintage PR, but that’s not possible on my PRRI. Also, when trem and reverb are both on, the fact that reverb comes before tremolo seems unnatural to have the reverb cut out (which wouldn’t happen in a real reverberated room). I wish there were a way to put the reverb after the trem.

    So, is there a way to buy/make a PR with deeper/slower trem that is before a dead-quiet strong/long reverb, or am I better off just using pedals?
  2. Uncle Daddy

    Uncle Daddy Tele-Afflicted

    Sep 26, 2015
    Maldon, England
    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.
  3. King Fan

    King Fan Poster Extraordinaire Ad Free Member

    Jan 1, 2013
    Salt Lake City
    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.
    BigDaddy23 likes this.
  4. Mart the Hat

    Mart the Hat Tele-Holic

    Feb 11, 2013
    Edinburgh, Scotland
    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.
    tubegeek likes this.
  5. schmee

    schmee Doctor of Teleocity

    Jun 2, 2003
    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! :D
  6. Mexitele Blues

    Mexitele Blues Tele-Afflicted

    Mar 7, 2018
    Westminster, CO
    The reverb will hum if any part of the tank or footswitch cables are unshielded. Are you using the stock foot switch?
  7. jhundt

    jhundt Doctor of Teleocity

    Mar 23, 2003
    sounds to me like you are trying too hard to like an amp that isn't the right amp for you.
    brookdalebill likes this.
  8. brookdalebill

    brookdalebill Tele Axpert Ad Free Member

    Nov 15, 2009
    Austin, Tx
    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.
  9. bradpdx

    bradpdx Friend of Leo's

    Jul 16, 2006
    Portland, OR
    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.
    Telecaster88 likes this.
  10. printer2

    printer2 Poster Extraordinaire

    May 24, 2010
    Hum is 60 Hz. No usable signal down there. It should be filtered out.
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