The purpose of these pages is to study and create an archive of drum synthesizers from the past and present. Specifically drum machines that used analogue techniques to model drum and percussive sounds. The focus is more on the way the sound is synthesized rather than drum machine control and sequencing.

Instead of just posting a load of badly scanned schematics and images found around the internet, I hope to analyse and re-draw each design ( or group of similar designs. ) and make mod suggestions and PCB / Strip-board layouts.

This page is still under development, it will gradually grow. So please bookmark and come back soon if you find a link does not work; content is being added all the time. Also if there is a machine you would like to see or you are looking for do not hesitate to email me.



Everything is freely available to download and use as you like.

Simple Modelling Filters

These types of drum have origins in the 60’s modelling drum sounds by sending pulses into simple resonant filters built from single transistors with inductors and capacitors. Of course the line blurs when you get to later Roland machines and they start using envelopes and other more complicated means.

  • Mini-pops, Doncamatic and other early Korg types

  • Early Roland

  • Panasonic - Rhythm Machine

  • Clicks out of custom chips, semi-integrated designs. Yamaha MR-10, Boss DR-55

Disco Drum / Drum Synthesizer

A method of drum synthesis synonymous with sweeping disco drum sound (boooooow) and the origin of dub sirens (long decay with modulation.) Seems to have been quite popular towards the end of the 70’s. The idea was to build a parametric drum sound that was modelled in much the same way as a basic subtractive synthesizer. Most seem to follow the same approximate pattern of Trigger > Decay Env > VCO < LFO Modulation - with slight variations of noise source (snare simulation) and VCF additions.  I suspect this kind of synthesis originated from modular synthesizers, the Moog drum controller for example. Circuit designers trying to mimic modular synth patches of disco professors.

  • Boss PC-2/Amdek PCK-100

  • Coron DS7/8

  • Drumfire DF-500

  • EHX Spacedrum, Sonic Boom

  • Pollard Syndrum

  • Pearl Syncussion

  • Star Synare 3

  • Simmons SDS 3 , SDSV

  • Tama Techstar TS204/TS305

Specific Sound Modelling

In the late 70’s to mid 80’s more sophisticated modelling of drum sounds were produced. Using the same basic elements as early drum machines adding the power of microprocessor control. The fact that components were cheaper, more compact and assembly was partially automated meant circuits could be more complex and therefore sound more “realistic”. There are some fantastic analogue models of tom tom’s!

  • Pearl Fightman

  • Roland 606,808,909, Boss DR110

  • The Hand Claps   

  • Simmons Claptrap

  • Roland Claps

  • EHX Claptrack

  • Tama TS Clap

  • Soviet Clap

If you have an old drum machine that is not listed here and would like to see info on it, do not hesitate to ask - I am always looking for analogue drum machines to scan and reverse engineer. I am also looking for any images if these machines so if you have one and would not mind me hosting it please contact me.

If you are looking for an original service manual, here is the list I currently have, please email me ben@clacktronics.co.uk and I will email it to you or send you the link were it is hosted by the originator.

 Boss DR-110
 Boss DR-55
 Boss HC-2
 Boss PC-2
 Coron DS7
 Coron DS8
 Drumfire DF-500
 EHX - Clap Trap
 EHX - Crashpad
 EHX - Rolling Thunder
 EHX - Spacedrum
 EHX Sequencer Drum and Clockworks
 EHX- Sonic Boomer
 Korg/Kieo Doncamatic Rockmate
 Korg KPR-77
 Korg Mini-pops 120
 Korg Mini-pops 7
 Korg Monotribe
 Lell Clap
 Lell Tom
 Lell UDS
 PAIA Drum
 Panasonic RD9844
 Pearl Syncussion
 Pearl Fightman
 Roland CR 5000 - 8000
 Roland CR-78
 Roland TR-606
 Roland TR-77
 Roland TR-808
 Roland TR-909
 Simmons SDS 3
 Simmons SDS V
 Soundmaster Rhythm 1
 Star Synare
 Pollard Syndrum 478 (the dual and single version are the same)
 Tama TS-204 / Tama TS-305
 Yamaha BK-20B
 Yamaha MR-10