Making amp-options footswitchable?

Discussion in 'Amps and Cabs [BG]' started by Phyrexian, May 25, 2005.

  1. Hello everyone,

    since last week I'm the happy owner of an all tube Trace Elliot V8. It's an incredible amp! It's got two channels that are footswitchable as well as a compressor that can be put on or off with the same footswitch (typical marshall two button switcher).

    The amp also has a deep switch, a bright switch and a mid-shift switch. I was asking myself, would it be hard to make these three options footswitchable as well?

    thanks in advance,

  2. Joe P

    Joe P

    Jul 15, 2004
    Milwaukee, WI
    Being that these are in critical circuit paths, I doubt that you'd want to just tap into them and run a shielded cable out to a switch (especially if any of them have a couple hundred volts of plate potential on them!).

    The least invasive mod that I can think of would be to make a 'robot' that would actually activate a switch. This would be easiest, I'd think, if a switch were push-on/push-off. In this case a simple solenoid plunger could be aligned with the switch. These are perfect of this kind of purpose because the magnetically-activated plunger can only 'push so hard', and then it retracts back with a spring.

    Else you could install relays in place of the the switches. Then the footswitch - same as for the direct-solenoid method - would only need to provide control voltage for the relay solenoid.

  3. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    Hi Phyrexian,

    Ironically, the simplicity of what those switches do makes it hard to bring their functions out to a footswitch. They usually just switch a capacitor, resistor, or a combination of the two in or out of the circuit. These have signal going directly through them, so as Joe said, you wouldn't want to run these out through a cable to a footswitch box; I'll add that it would really open up the potential for picking up hum and noise.

    Using footswitch-controlled relays, as Joe also mentioned, would be doable but not a simple task, and you'd have to leave the switches always in a certain position (open or closed, depending on what each one does and how you interface the relay to it) to make it work. It's a cool idea, but the convenience might not be worth the effort.
  4. I'd like to see a foot switch for my DBX 120a sub-synth. It would be nice to cut it in/out on demand, without having to use hands on the controls.
  5. Thanks, good point. I never thought about that point.
  6. Joe P

    Joe P

    Jul 15, 2004
    Milwaukee, WI
    I'm tellin' you guys: if it's a push-on / push-off, a solenoid will do just what you want!

    You just need a way to physically line it up and hold it in place. There are many standard solenoids you can buy.

    It'd probably be easy for a rack mount device because you could make a bridge that goes across between the rack ear mounting screws.

  7. Thanks, but that external solenoid solution is not what I'm looking for. My amp is not in a rack as well so constructing this thingie could be quite a pain in the ass since it's got to be roadworthy (we gig a lot).

    I found a good and reliable amp tech over here in Belgium that says he can help me out. He says he's able to do integrate these extra switchings, even via midi. I'll check it out.