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Question on Dunlop Uni Vibe

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  • Question on Dunlop Uni Vibe

    I've got this Uni Vibe UV-1 that I am fixing up and I got the basic effects functional, but notice that there is a noticeable loss of treble (and maybe some distortion) in chorus mode and what seems like a boost in treble in tremolo mode. I don't know if this is "normal" or something to be addressed when I open it back up to replace the pots.

    This schematic has been accurate for my use so far. https://www.freestompboxes.org/membe...0%282-3%29.pdf

  • #2
    Glebert..... I just happen to have a Uni-Vibe in the house. But it is not something I am familiar with.

    In any event, when I listen to the dry signal and then compare it to the chorus, I do not hear any difference in the treble level. The same when I compare dry to vibrato. I also checked with the switch for the Vintage setting. I did not attach the controller pedal for this test.

    Hmmmm....

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    • #3
      Itīs an OLD circuit, and I bet input and output impedances are "wrong" by modern standards, thereīs a reason old pedals needed True bypass ... or else.

      I guess itīs affecting how your pickups sound, big time, and much worse, in an inconsistent way, as different pickups will react in a different way.
      Juan Manuel Fahey

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      • #4
        Originally posted by J M Fahey View Post
        Itīs an OLD circuit, and I bet input and output impedances are "wrong" by modern standards, thereīs a reason old pedals needed True bypass ... or else.

        I guess itīs affecting how your pickups sound, big time, and much worse, in an inconsistent way, as different pickups will react in a different way.
        I'm pretty sure the input and output buffering is the same for both tremolo and chorus mode, so I don't think it would be that.

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        • #5
          Originally posted by glebert View Post

          I'm pretty sure the input and output buffering is the same for both tremolo and chorus mode, so I don't think it would be that.
          That's what I thought at first.

          But if you look carefully, the input buffer is bypassed by the switching Opto-Fet (U9) in effect mode.

          You might try to use a stand-alone buffer or buffered pedal before the Univibe.
          - Own Opinions Only -

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          • #6
            Originally posted by Helmholtz View Post

            That's what I thought at first.

            But if you look carefully, the input buffer is bypassed by the switching Opto-Fet (U9) in effect mode.

            You might try to use a stand-alone buffer or buffered pedal before the Univibe.
            I do have a buffered pedal before the Univibe. I could see that bypassing might cause a difference between bypass and effects mode, but don't know how it would cause a difference between chorus mode and tremolo mode. I could live with the bump in treble in tremolo mode but the chorus mode sounds quite muffled.

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