Buchla - 251e Quad Sequential Voltage Source

The 251e is an extremely powerful quad sequencer. Sequences can consist of up to 50 steps and contain both loops and nested loops. Parameters such as step or pulse length can be edited per step and are not global values. The sequencers can start each other, re-sync each other, run at the same tempo or act completely independently. Various sync modes change the behavior of the individual sequencers to start and stop pulses or activate the internal or MIDI clock. A voltage controlled Master Clock parameter changes the tempo of all sequencers by a factor of 0.5 to 1.5.

The 251e consists of four identical sequencers called A, B, C and D. Each sequencer has its own start and stop pulse input as well as a pulse and CV output. The edit/display switch of each sequencer activates or deactivates the edit mode for this sequencer. If the edit mode is activated for a sequencer, the settings of the SEQ have an effect. EDIT and STAGE EDIT sections only affect this sequencer.

In the SEQ.EDIT section, global settings such as tempo and playback direction are edited, which affect all steps. It also determines whether the sequence starts immediately or after an adjustable delay. The "sync next" button can be used to start or reset the next adjacent sequencer. If this parameter is used in sequencer D, it will also affect sequencer A. The SEQ.EDIT section also determines which step of the sequence is the last and whether the sequence stops automatically at this point or starts again from the beginning.

In the STAGE EDIT section the parameters of the individual steps are set. For each step the length of the step as well as the length of a possibly programmed pulse can be set. Note values can be normal, dotted or triplet. The parameter "c.v.out" controls which voltage the step outputs at the CV output of the sequencer. It is set in steps of 0.1V, which corresponds to a semitone step at 1.2 V/octave, or in millivolts, which leads to a change of the pitch of 1/100 semitone = 1 cent. Loops are also programmed in this section. A loop consists not only of information for the first and last step of the loop, but also a loop counter that defines how often the loop is played before it jumps to the next step after the end of the loop. This way you can also create loops within loops, so called "nested loops".

Irrespective of the set tempo of the sequencers, all sequencers can be manipulated simultaneously in tempo via the global parameter "Masterclock". The parameter is also CV-controllable and the scaling factor ranges from 0.5 to 1.5. The sequencers can create their own clock, which is controlled in BPM. They can also be synchronized via analog pulse signals or to MIDI clock. If the synchronization is carried out via pulse signals, there are various modes here such as how pulses in the start or stop input influence the sequence.  While in one mode, for example, a trigger at the start input jumps to the next step, and a trigger at the stop input returns to the previous step, there are also modes in which the steps can be addressed directly via CV.

Please note: Buchla 200e products may have lengthy waiting times, as they are manufactured in small quantities only.