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Tremolo bump

Discussion in 'Shock Brother's DIY Amps' started by Prophetsnake, Dec 13, 2020.

  1. Prophetsnake

    Prophetsnake Tele-Meister

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    I built a pair of Rick Tone stand alone Tremolos a couple of years ago, and they work well, but they both 'bump' when there's no signal from the guitar. I have heard that many of them do this, and it's just something that you live with, but these are both excessive. I've tinkered with resistor values and no change whatsoever.
    Any suggestions?
     
  2. DeepDangler

    DeepDangler Tele-Meister

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    It may be sacrilege but you could try running the trem unit the loop of a Boss NS-2 noise gate. It can separate dry signal from wet.
    9F1E6684-AE86-48E6-B5CE-4EED13059BAF.png
     
  3. Prophetsnake

    Prophetsnake Tele-Meister

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    Interesting. Made me think, anyhow. There really isn't a dry signal. It's either working or it's by-passed.

    This is the circuit. The voltages are pretty much in line with what's noted.

    I'd really like to be able to understand the whole concept of a tremolo in any case. I tinkered with the depth circuit a bit but no dice.


    [​IMG]
     
  4. DeepDangler

    DeepDangler Tele-Meister

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    Is the bump you talk about like a mild hum that sounds like 60 cycle but in step with the trem? It’s possible you have AC line noise causing it or a grounding issue somewhere in the unit. Does it do this when the unit is on but no guitar is connected?
     
  5. jmp81sc

    jmp81sc Tele-Meister

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    Here is a common fix for trem thump in Fender bias vary trem circuits.
    6G2 trem_thump_fix_diode.png

    And here is a video from Uncle Doug explaining bias vary trem circuits.



    Good luck
    John
     
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  6. Prophetsnake

    Prophetsnake Tele-Meister

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    Thanks. I'm not sure about it being hum if I am honest. I recorded it on my phone.



    I start out with max speed and intensity, then ease off on the intensity first, which cleans up the tone, but the bump is as strong as ever. Reducing speed seems to tame it a bit, but still - very noticeable. At :47 into the recording, I pull the guitar lead out and the bump is still there, and there I think you are probably right, it's a hum coming through.
     
  7. Prophetsnake

    Prophetsnake Tele-Meister

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    Ah! Thank you. I will try that.

    I've watched that Uncle Doug video a dozen times chasing this issue down and am still none the wiser. Normally his stuff is simple enough for me to understand, but I keep missing something with this one. None of the books I have are much help either.
     
  8. schmee

    schmee Doctor of Teleocity

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    Some pedals are like that for sure, Delays also have a clik/bump on some. Hard to figure how they sell them. Many can be fixed with a cap in the right location or the diode shown above.
     
  9. tubelectron

    tubelectron Tele-Afflicted

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    If I understand well, @Prophetsnake, what you call "bump" is the throb-thump effect due to the LFO modulation of the tremolo passing through the audio signal. Right ?

    A solution would be to add a steep slope HPF tuned very low at the signal chain output, in order to filter off the remaining LFO modulation from the signal. I had this problem on one of my tremolo circuit (solid state though) and that's what I did.

    [​IMG]

    Here is a short video showing the efficiency of the filter :



    Here is the tone of the tremolo - amplitude and harmonic - you do not hear throb-thump anymore :



    Here is the schematic of the output HPF used :

    [​IMG]

    And the built-in :

    [​IMG]

    If you look to the Gibson GA-40 amp circuit, you find HPF RC filters that are inserted for that purpose (5x.005 + 4x1M) :

    [​IMG]

    The same RC HPF filter exists in the VOX AC30 too :

    [​IMG]

    -tbln.
     
    Last edited: Dec 14, 2020
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  10. Prophetsnake

    Prophetsnake Tele-Meister

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    QUOTE="tubelectron,

    what you call "bump" is the throb-thump effect due to the LFO modulation of the tremolo passing through the audio signal. Right ?


    Absolutely. And that filter has gone a long way towards improving my understanding of what's going on here. I've been looking at the wrong end of the circuit to try and kill the noise. It might be better to clean it up at the output.
    Thank you for that very detailed reply!
     
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  11. Paul-T

    Paul-T Tele-Holic

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    @tubelectron , tell us about those LED/lenses, they look great.
     
  12. tubelectron

    tubelectron Tele-Afflicted

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    Oh, there's nothing amazing here : I used here pilot jewels caps coming from old pilot lights from the French brand "Dyna" in which I put a LED of the suitable color, maintained in place inside by a rubber grommet.

    I also did the same with new pilot jewels caps available as spare parts - this stompbox below uses Fender-like models :

    [​IMG]

    A+!
     
  13. Mongo Park

    Mongo Park Tele-Afflicted

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