Switch box for channel switching modification of guitar amp

Discussion in 'The Projects Forum' started by aj7877, Jul 5, 2008.

  1. aj7877

    Thread Starter New Member

    Jul 5, 2008

    I’m an ex television technician (who hasn't look at anything electronic for 5 years) and I’m trying to design a circuit for the following.

    I have a guitar amplifier. It has 3 channels, clean, rhythm and lead. The channels are switched by footswitches that connect to the amp. These switches run on 12V and are SPST. At the moment, there are two switches which are able to switch between all 3 channels. These have leds to indicate the status as well.

    What I want to do is design a box with 3 switches on it, so I can control each channel by pressing the appropriate switch. I was thinking this might need momentary switches & some sort of latching with IC's but to be honest I have no idea where to start. At the moment each switch has a 2 core cable to connect it to the amp. I was also thinking about replacing the 2 cable set up for a single multi-core cable.

    This is how the switches combinations work at the moment:

    Switch 1: led on = clean channel, led off = lead channel

    Switch 2: if switch 1 has led off this switch has no effect, if switch one has led on then this switch will allow you to switch between the clean and rhythm channels.

    So to some up what I'm trying to do, I want to replace the current switches with one box with 3 switches on it. You press one switch you get lead channel, you press another switch you get clean channel etc.

    Any help or a point in the right direction would be good.

  2. bertus


    Apr 5, 2008

    Do you know the current configruation of the switches?
    Can you give a schematic for it?

    Besides I found a website specialized in guitar effects.

  3. aj7877

    Thread Starter New Member

    Jul 5, 2008
    I've attached the schematic that came with the amp.

    There's also a schematic here but it appears to be a little different to the one that came with the amp.


    At the moment there is one lead, which is a normal guitar cable (shield/earth + conductor), which attaches to one 1/4" jack on the amp and on the other end is one of the footswitches. It is just a SPST switch. With the switch open there is 12V on one side. So by closing the switch it must be completing a circuit.

    The setup is the same for second switch - 1/4" jack on amp, lead to switch etc.

    I opened the switches and did some measurements to find out what happens when.

    So when footswitch 1 is open - footswitch 2 has no effect. This activates lead channel.

    When footswitch 1 is closed - footswitch 2 then then has effect as follows; when footswitch 2 open then clean channel is activated. When footswitch 2 is closed, rhythm channel is active.

    I hope that helps.