The circuitbenders.co.uk drumBs module is a tweaked version of the Syntom II, an analogue percussion project first published nearly four decades ago in the April 1983 edition of the mighty Electronics & Music Maker Magazine.

ALL HAIL E&MM!

The drumBs PCB can create a wide range of basic analogue percussive sounds. Essentially these are the kind of sounds that relate to modern drum machines like an Analog Rytm, Alpha Base or Tempest in the same way as a Commodore 64 relates to the latest Apple Mac. On paper its sh*t in comparison, but it's cheap and fun, and theres a certain dirty basic DIY magic to it that you don't get in more complex machines. The drumBs synth section features both a VCO and a noise source, along with a resonant noise filter and an auto roll function. To drive the module you'll need a source of standard +5v trigger pulses or gates. This is the full eurorack panel and PCB set that includes the main PCB, the pots PCB and a panel in various colours. We usually have several different colour panels available, ranging from black with silver text, to a rather distressing dehydrated piss yellow!

The drumBs controls are:

DECAY: The decay of the percussion envelope.

BEND: The depth of percussion envelope applied to the pitch of the VCO and the filter cutoff of the noise source.

PITCH: The basic pitch of the VCO.

CUTOFF: The cutoff frequency for the noise filter.

REZ: The resonance of the noise filter.

PULSE: The level of an initial clicking attack at the start of the percussion sound.

MIX: The mix between the oscillator and the noise source.

ROLL: The repeat rate of the auto roll function.

TRIGGER INPUT: The trigger input accepts a standard +5v trigger pulse or gate to trigger the module.

ROLL GATE INPUT: The roll gate input activates the auto roll function whenever it receives a gate or longer trigger voltage. When the auto roll function is activated the module will automatically retrigger itself at a rate set by the roll knob for as long as the voltage is present at the input. This can be very useful for creating unusually timed fills and rolls, although at its highest trigger rate the roll function can sound like a constant VCO tone.

Theres nothing rare to get hold of and no difficult calibration to set the module up, so theres no reason why this shouldn't be a beginners project.

Below are two youtube demos of three of these modules in action:

DEMO1

DEMO2

You can download the build guide and the schematic from the documentation and design files links below.