Midi controller for preamp (amplifier)

To be able to have independent control of amplifier with switches on the front panel footswitch and MIDI, you need to include intelligence between control switches and executive devices (relays). This is most easily done by using the MCU

The algorithm (pdf)

Here is a controller for the amplifier based on Bogner Ecstasy

It is implemented on the MCU ATMEGA128 and has 19 inputs for switches on the front panel, 6 inputs for switches in footswitch and MIDI interface. The program is implemented in such a way that it continually polls the state of the switches, and when any change sets the outputs to the corresponding condition. Current status of outputs can be saved into nonvolatile memory and then can be recalled by midi command.

Schematics (pdf)

Ready to transfer PCB (pdf)

Upper side assembly (pdf)

Bottom side assembly (pdf)

Upper side photo

Bottom side photo

Program