The most compact and powerful sequencing in the format. This one is also very accurate and precise. The output voltage is exactly what is shown on the display, which is a bit of a rarity amongst the available sequencing options out there.

This module is a powerhouse and does a lot of stuff. I've highlighted some of them below.

The 251e features four 50-stage sequencers, each with programmable pulse and control voltage outputs. A separate editing section is used for setting parameters in the selected sequence; sequences can be edited while running and follow the edit stage when stopped.

Intervals may be entered for each stage, with variable note values from a 1/32-note to whole notes. Triplets and dotted notes are readily accommodated. Pulse durations may be set to fractions of the intervals.

Output voltages range from 0.0 to 9.9 volts, conveniently accommodating oscillators with a sensitivity of .1 volts per semi-tone.

Tempo range from 10bpm to 250bpm is supported.

Additional features include:

Inter-sequencer triggering
Locks to incoming MIDI clock, selectable per channel!
50 stage (or less) envelope generator? Sure!
Variable start delay
Reversing capability
Multiple nested loops (sequence loops within loops)
Master voltage-controlled clock

With the 206e or 225e Preset Manager, the parameters of the 251e can be stored and retrieved as part of a preset. A 200e USB card is necessary to download new firmware for this module.