“Analog” Combinator TR808

I’m trying to emulate the TR-808 with a “Combinator” mainly containing some Thor synth and 2 Redrum beat box. Currently, I already have really convincing results with the “Kick”, the “Snare”, the “hit-hats”. I’m currently working on the “Handclaps” and the next one will be the “Cowbell”.

TR-808 “Handclap”

Roland’s handclap sound is made up of two elements layered together; the “strike” and the “reverb” portion. The circuitry has different sections for these, and both are triggered simultaneously. The strike is a fast envelope with four closely spaced peaks. Both the 808 and 909 use a similar scheme to generate this envelope. The strike envelope controls a VCA (using an OTA) to shape white noise. Its multiple peaks simulate a group of people clapping. The “reverb” part of the clap simulates sound bouncing off the walls of a room. Its so minimal – the white noise source is high-pass filtered, and fed to an envelope-generator and VCA… but the VCA in this case is just one transistor.

Source : Eric Archer

TR-808 “Cowbell”

The Roland TR808 cowbell is the 808’s cheeziest sound, but its design is interesting to study because Roland engineers were masters of minimal analog synth design. They rolled this one up tight! … with just 2 simple chips and 4 transistors, the 808 cowbell contains two square wave oscillators, two VCAs, a triggered envelope generator, Hi-Q bandpass filter, and buffer amp.

The square wave oscillators are the usual CMOS schmitt-trigger type that you can build with 4584, 40106, 4093, etc. The schematic specifies their period instead of frequency. But you know that frequency = 1/period, so what they’re really asking for is FREQ.1 = 540 Hz and FREQ.2 = 800 Hz. These frequencies are variable with internal trim controls TM1 and TM2. As specified, the ratio of FREQ2/FREQ1 is 1.48, a detuned perfect 5th. This seems like its intentionally out of tune to enrich the tone.

Source : Eric Archer

Here is a nice “Sound On Sound” article of year 2002 : SYNTH SECRETS

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