Abstract: A user-customizable modular music effects pedal is described. The music effects pedal includes a base having an input, an output and a connector. The input receives a music signal. The connector is coupled with the input and has an electrical form factor and a physical form factor. The electrical form factor is configured to fit a corresponding electrical form factor of an effects cartridge. The physical form factor is configured to fit a corresponding physical form factor of the effects cartridge. The connector provides the music signal to the effects cartridge and receiving a processed signal from the effects cartridge. The effects cartridge includes effects electronics to provide the processed signal. The output is coupled with the connector and provides an output signal based on the processed signal from the effects cartridge.