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Thread: MOSFET Vibro Champ Vibrato

  1. #1
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    MOSFET Vibro Champ Vibrato

    Hi, I'm looking for a tubeless MOSFET schematic of the Vibro Champ vibrato. I found a circuit with LND150s on the web, but I'm not quite sure whether it will work that way
    http://www.bilder-upload.eu/upload/9...1517691434.jpg
    Apparently there's a mistake in the LFO circuit using 100n caps instead of 10n but that might be a typo.
    Any ideas and suggestions much appreciated
    Zouto

  2. #2
    Senior Member uneumann's Avatar
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    Quote Originally Posted by Zouto View Post
    Hi, I'm looking for a tubeless MOSFET schematic of the Vibro Champ vibrato.
    Looks like that circuit could work. I find freq range and wave shape improves using a CS follower as in this example. The bottom of P5 goes to the bias supply and the wiper goes to the 220K resistors feeding 6V6 grids.

    tosc.jpg

    edit: I intended to show an osc example. Yes, in my case it drives a PP pair.
    Of course, you can adjust levels, freq for your SE needs.
    Last edited by uneumann; 02-13-2018 at 05:21 PM. Reason: clarity
    Old Tele man: Equations provide theoretical values, SPICE provides approximate values; but, the ears provide exact values.
    Hofstadter's Law: It always takes longer than you expect, even when you take into account Hofstadter's Law.

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  3. #3
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    I'm not sure I've ever seen a Vibro-Champ with more than one 6V6 grid or more than one 220K resistor or even a bias supply.

    The LND150 isn't a drop-in replacement for a 12AX7. As uneumann said, that circuit could work. But it would probably have the wrong frequency range and the wrong magnitude. That LND150 can practically swing the entire 340V, so the 68K would need to be increased in order to reduce the LF signal hitting V1B's cathode.

    I have drawn up an idea for an SS vibrato replacement based on other ones I have used in other applications. I don't have a Vibro-Champ to try it on, but it looks good on paper (to me, anyways).
    Attached Thumbnails Attached Thumbnails vibro-champ-ss-vibrato.gif  

  4. #4
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    Quote Originally Posted by 66 Kicks View Post
    I'm not sure I've ever seen a Vibro-Champ with more than one 6V6 grid or more than one 220K resistor or even a bias supply.

    The LND150 isn't a drop-in replacement for a 12AX7. As uneumann said, that circuit could work. But it would probably have the wrong frequency range and the wrong magnitude. That LND150 can practically swing the entire 340V, so the 68K would need to be increased in order to reduce the LF signal hitting V1B's cathode.

    I have drawn up an idea for an SS vibrato replacement based on other ones I have used in other applications. I don't have a Vibro-Champ to try it on, but it looks good on paper (to me, anyways).
    Thanks a lot for ideas and suggestions, Kicks you're right, I want to use the circuit in a SE amp with one 6V6. Frequency range and swing is indeed a problem to be solved. Since I'm not experienced with virtual SPICE Stuff, trial & error in real time seems a bit risky to me.
    Zouto

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