an improved automated snare drum made to the order of Aphex Twin

Godfried-Willem RAES



This musical robot consists of a high quality Ludwig snare drum automated with 13 beaters hitting different spots of the membrane from the inside. Two solenoid driven drum sticks, mounted externally, take care of the rimshots. Of course, all beaters have a precise and wide range velocity control. The snares can be activated through a special dual solenoid driven mechanism, offering gradual control as well as some special effects. Controlling this robot is realized using a standard midi protocol. It was designed following the model of our <Snar> robot as a commission from Aphex Twin, who also delivered us the snare drum to be automated. One of the elements that forced us to recalculate and redraw the design was in the fact that this snaredrum has ten tuning pegs whereas <Snar> only had eight. Also, this snare drum is equipped with an internal controllable damping felt pad, occupying some space. Although possible, we decided not to automate this component. All these differences made placement of automation components in this snare drum a bit more complicated. This is a picture of the drum before any modifications, except taking the beater skin off to get access to the inside:

From an electronics point of view, there were no new problems to be solved in the development of this automate, except to a certain extend the snare push and release mechanism, involving gradual control using PWM on two separate solenoids.. The mechanics for the rimshot beaters are an improvement over the first design. Here we use heavy duty pull-type solenoids.

The height of the final robot is determined by the height of the drum itself, the height of the electronic components -in particular the hefty power supply- and the acoustical requirement that for preservation of the sound integrity of the drum a free space of about half the skin diameter had to be reserved between the resonance skin underneath and the electronic components on the base. For mechanical reasons, the drum should only be used in a fully horizontal position.


Power supply voltages and currents:

Midi Mapping and implementation:

Technical specifications:

Design and construction: dr.Godfried-Willem Raes

Collaborators on the construction of this robot:


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Construction Diary:

Composers Manual to the Robot Orchestra
A guide to all musical robots made by Godfried-Willem Raes up to 2015
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Technical drawings and data sheets:

Midi input board and PIC controller:

PIC-processor board: MidiPulseHold Rev.2, 2006.

Circuit drawing:

Power supply, circuit drawing:

Solenoid data:

Beaters: Linear tubular solenoids, push type, diameter 20 mm. Two types/brands can be used:

1.- Saia Burgess type 195225-229, STA, 9.4 V dc @ 100% - 7 Watt, nominal traject 5.1 mm, maximum traject 17.8 mm. Length:39 mm, Plunger: 15.3 g. Total weight: 87.3 g. DC-resistance: 12.8 Ohm. Maximum power @ 10% duty cycle: 70 Watt, 11.9 N. Mounting thread: M14 x 1.5.. Lifetime: 25 million cycles. (= 86 days uninterrupted rolls at 8 cycles a second). [This type used for <Snar>].

2.- Black Knight, type 121-420-620-620, 12V dc @ 100%. DC resistance: 20 Ohm. Mounting thread: 18UNF - 0.562" (13,8 mm) [This type used for Snar_2].

Beater-heads: Bakelite balls, with M3 thread, diameter 10mm.

Solenoids used for the snare pulling mechanism: Tremba Gmbh Zylinderhubmagnet ZMF-3864Z.001 24 V DC @ 100% Duty cycle. Conrad order nr. 542-162-17 (Anchors modified with fall through stopper).

Solenoids used for the rimshot sticks: Tremba Gmbh ZMF-3258Z.001 24 V DC @ 100% Duty cycle, pull type. ( On <Snar> we used: Saia Burgess type 195225-229, STA, 9.4 V dc @ 100% - 7 Watt).

Drumsticks: Premier M10, diameter 14 mm. If the drumsticks need replacement, first determine the pivoting point for optimum rimshot sound and drill a 3 mm hole at that point. Then the vertical hole, also 3 mm can be drilled for the solenoids drive mechanism. Finish the replacement by placing the counterweight ring on the drum stick. Secure its position with the M6 inbus setscrew provided.


PIC microcontrollers:

Datasheet for the 18F2525 and 18F4620 processors (PDF file from Microchip)

Wheels: building height 65 mm, with brakes.