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Thread: How to "cheat" Reverb circuitry?

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    How to "cheat" Reverb circuitry?

    I have build custom all-aluminium housing for my Laney VH100R head. It is 5 Kg (about 10 Lbs) lighter then the original wooden box. Since I never use the spring Reverb I wanted to leave out the reverb tank also. The thing is: even when reverb pot is on zero, seems that tank does have some influence on sound because when I disconnect the tank's RCA leads sound gets really dry and dead and ugly.
    SO is there a way to cheat the circuitry?
    To leave out the tank but to put some resistor across the RCA leads / driver out??? Again I will NEVER use the reverb pot, it will always be on ZERO. I just want the circuitry to "think" that tank is connected.
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    Lifetime Member Enzo's Avatar
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    Isolate the problem. The amp sounds OK WITH the reverb pan? It sounds bad WITHOUT the reverb pan? Unplug only ONE of teh pan cords at a time. Pull only the INPUT (drive side) cord. Does that affect the sound? Return that cord and now pull the OUTPUT (return side) cord only. Does that affect the sound?

    Just guessing here, but my first thought is that when you unplug the reverb pan, you are leaving the high gain return circuit unterminated and it is free to oscillate. The simple cure for that would be to connect a short across that return connection.

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    Looks like the reverb is footswitchable. Does it help any if you disable the reverb via footswitch? It looks like there are separate op amps to drive the reverb so it seems like it should be isolated from the main circuit.

    Is your custom shell much smaller than the original that you can't fit the tank inside? Even if you don't use it and leave the knob at 0 it seems like the simplest thing is to just leave it in.

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    Quote Originally Posted by glebert View Post
    Is your custom shell much smaller than the original that you can't fit the tank inside? Even if you don't use it and leave the knob at 0 it seems like the simplest thing is to just leave it in.
    Well no, it's not smaller but I kind of use both shells, I know it's silly, but one is a snake skin foil, and the wooden one is a Burgundy Red tolex :-) The amp is like a drawer I just slide it in and fasten the few screws. So I use them intermittently. Maybe I could just find any tank to put in the aluminium one, but I didn't have any luck finding a reverb tank over here in Serbia. And moving the same tank from box to box each time is not an option, particle board on the original box would strip down fast.

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    Quote Originally Posted by glebert View Post
    Looks like the reverb is footswitchable. Does it help any if you disable the reverb via footswitch? It looks like there are separate op amps to drive the reverb so it seems like it should be isolated from the main circuit.
    Yes the reverb is footswitchable but it does not help if it's turned off on the footswitch, sound is still really dead and dry without the tank.

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    Quote Originally Posted by Enzo View Post
    Isolate the problem. The amp sounds OK WITH the reverb pan? It sounds bad WITHOUT the reverb pan? Unplug only ONE of teh pan cords at a time. Pull only the INPUT (drive side) cord. Does that affect the sound? Return that cord and now pull the OUTPUT (return side) cord only. Does that affect the sound?

    Just guessing here, but my first thought is that when you unplug the reverb pan, you are leaving the high gain return circuit unterminated and it is free to oscillate. The simple cure for that would be to connect a short across that return connection.
    Good thinking I will try your ideas next time I get to the practice pad, will report :-)

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    Quote Originally Posted by Emetal View Post
    And moving the same tank from box to box each time is not an option, particle board on the original box would strip down fast.
    You could have the tank in a bag and secure that to the shell with velcro or snaps.

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    Quote Originally Posted by glebert View Post
    You could have the tank in a bag and secure that to the shell with velcro or snaps.
    Hmmm interesting thought, well let me try to find some electronic solution and it everything else fails I guess that will be it :-)

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