The MIDI interface translates MIDI messages to trigger signals which can trigger the different TR82 modules. The MIDI channel can be selected by setting the jumpers on the PCB. Since the TR606 doesn’t have MIDI capabilities this module is a custom design, based on an Arduino board. The firmware is available in the download section.

The bass drum of the TR606 is basically a double Twin T oscillator which generates a simple but nice bass drum sound. There are a couple modifications which can be done here, I’ve chosen to add a Tune and a Tone mod here, giving some extra control over the sound.

Because the decay modification for the bass drum involves some drastic changes to the circuitry I’ve decided to add a second bass drum module. To make the decay work one of the Twin T oscillators is replaced with the decay mod circuitry.

The snare drum consists of a single Twin T oscillator which is complimented white noise from the noise generator. The noise is passed through a HPF. Since the noise circuit is also used in the Toms module, I've created a standalone daughterboard for it.

In the original TR606 the Toms circuits are placed on a separate board and to safe some space the low and high tom share a lot of components, essentially 'joining them at the hip'. The sounds consist of a single Twin T oscillator each which get complemented with a subtle rumble. This rumble is generated by passing the noise through a LPF. Because of the nature of the circuitry some of the modification will effect both sounds. I've also added a input with a selection switch to allow for external noise to be added instead of the internal noise source.

The hihats are bases around the HD14584 Schmitt trigger which generates 6 triangle waves at different frequencies. These signals are mixed together into 2 separate signals from which 1 is send to the HiHats circuit. Like the toms circuit, the hihats circuit also shares a lot of components with each other so some of the modifications effect both the Closed as the Open HiHat

The cymbal also uses the HD14584 Schmitt trigger triangle generator as a sound source. However, instead of 1 it uses both signals. The generator sounds is send through a HPF to generate the cymbal sound.

In the original TR606 all voices are routed to the output mixer and this module does exactly the same.