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Princeton Reverb Trem Intensity response

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  • Princeton Reverb Trem Intensity response

    Working on a PR amp and noticing that the Tremolo seems to be VERY weak when the Intensity pot is set to 5 or less. Almost like it disappears. I have seen some mods to change the Depth of the Trem (increasing the Trem cap values) but will that get me more usable range from the Intensity pot or will it just make the current usable range more intense?

  • #2
    Increasing capacitor values will slow the trem down but should not increase intensity. Though I'm not sure that increased intensity is what you want.?. The read seems to indicate that what you want is a faster increase of intensity relative to the knob adjustment. If that's the case you could try a 250k reverse audio taper pot for the intensity control. The overall inensity range would be the same but will be higher within that range sooner on the knob. About 20% log would be best I think though I don't know that you'll ever find one. I would go with an Alpha pot which will have a 15% log. The CTS and Bourns pots will have a 10% log and probably come up too fast.

    If what you want is actually more intensity you're probably out of luck. The PR uses the influence of a single triode oscillator design to modulate the bias and will not have the same influence as more elaborate two triode systems that reduce the impedance of the oscillator output.
    Last edited by Chuck H; 07-12-2024, 02:10 PM.
    "Take two placebos, works twice as well." Enzo

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "If you're not interested in opinions and the experience of others, why even start a thread?
    You can't just expect consent." Helmholtz

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    • #3
      Originally posted by Chuck H View Post
      The read seems to indicate that what you want is a faster increase of intensity relative to the knob adjustment..
      This is correct. I am not happy with the Intensity of the Trem/Vibe with the knob below 5. Between 5 and 10, I get great depth and a deep trem/vibe. Especially between 8-10. Below 5 it is anemic.
      As for the caps, after reseach I see that they have more influence on Speed so that is not my concern.

      So... the only recourse I see is to try different pot tapers for the Intensity pot huh?

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      • #4
        First step would be to verify that the pot you are using now is a linear pot. Disconnect any wires, measure the resistance from the wiper to each end to see if the resistance is equal when the pot is half way through it's rotation.
        WARNING! Musical Instrument amplifiers contain lethal voltages and can retain them even when unplugged. Refer service to qualified personnel.
        REMEMBER: Everybody knows that smokin' ain't allowed in school !

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        • #5
          THIS^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

          If it IS a linear pot then the reverse audio taper is an option.
          "Take two placebos, works twice as well." Enzo

          "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

          "If you're not interested in opinions and the experience of others, why even start a thread?
          You can't just expect consent." Helmholtz

          Comment

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