Buchla 281e Quad Function Generator


A function generator can be a modulation oscillator or an envelope generator, depending on the mode. The 281e contains four function generators organized in two pairs. Each pair can be used in quadrature mode for generating more complex CVs and it can be combined by a OR cicruit.


The 281e contains four indentical function generators (FGs) which fire an attack-decay cycle when receiving a pulse. After the cycle is finished a pulse is available at the pulse out.
Three modes determine the behavior:
- /\/\/: in this mode the AD cycle loops itself and we get an LFO. The attack and decay parameters not only control the waveform but also the frequency. A pulse at the input resets the LFO.
- /\ is an attack-decay envelope. The duration of an input pulse is ignored.
- /¯\ is an attack-sustain-release envelope. The duration of a pulse determines sustain length.

In quadrature mode which is activated with the green buttons, the FGs operate in pairs: A+B and/or C+D. The pulse input of the second FG in a pair is not used. The second FG will be triggered after the first has finished the attack stage. Attack stage works like a trigger delay.
The OR combiner at the bottom of the module mixes the signals of FGs A+B and C+D and blends between them. This function is int3eresting especially in the quadrature mode; #1 because of the delayed 2nd envelope and #2 because of the adjustable level relationship it is possible to generate multistage envelopes, e.g. similarto a classic ADSR. Use the first envelope as AD and the second as an ASR with lower level, this might do the trick.

Hint 1: patch the CV output into the CV input(s) of the time segments and change the curve form for this segment.
Hint 2: use the funtion generator as a clock divider: the length of the attack has to be longer than the time distance beteeen two clock signals.
Hint 3: In LFO mode the pulse output generates a square wave.


The setting of the potentiometers in the OR section can't be saved.


per channel: pulse input, attack CV in, decay CV in, pulse out, CV out

OR combiner CV outputs: for function generator pair A and B


4U Buchla form factor module, one panel wide (17.8 x 10.8cm or 7" x 4.25")

0,35 kg
Article Number
External Links

This item is discontinued or sold out and no longer available, please feel free to look for comparable new stuff in the following categories.