Analog and trigger sequencer with eight steps. Two CV rows with adjustable range, glide and sample and hold options.

Features of the analog rows (knobs):

• 8 potentiometers (knobs)
• lower row: Scale (knob)
• upper row: 1V/2V/4V (octave range switch for exact VCO control)
• Glide time (knob), same as portamento or slew limiter
• Glide Control (control input for switching glide on/off)
• S/H Control (control input for internal S and H, works like A-148)
• Pre Glide/S and H-Out (analog output before S/H and glide unit, especially required when external audio signals are used as inputs of the lower row)
• Post Glide/S and H-Out (analog output after S/H and glide unit)
• lower row: external inputs for the 8 steps (switched jack sockets), control signals or audio signals may be used as inputs (allowed voltage range -5V...+12V), the knobs of the lower row are working in this case as attenuators

Features of the trigger rows (switches):

• 4 Trigger/Gate tracks with 2 rows of switches
• toggle switches of 1-0-1 type (with middle position), which can be used to send a trigger/gate to the track above or below or to send no trigger/gate (middle position)
• 3 trigger rows (i.e. short pulse for each step set, pulse width corresponds to the pulse width of the clock/step input signal)
• 1 gate row (i.e. a high signal is applied during the length of the step set)

Control inputs and buttons:

• Step (defines the tempo of the sequence, same as clock or trigger input) - Reset (resets all rows to step 1)
• Start (starts the sequence at the momentary position)
• Stop (stops the sequence at the momentary position)

Step and Reset are compatible to the MIDI interface A-190, i.e. in combination with the A-190 the A-155 may be synchronized via MIDI. The quantizing module A-156 can be used to quantize the infinite analog voltages coming from A-155 into discrete semitone steps (multiples of 1/12V). Without MIDI interface e.g. a LFO rectangle output can be used to define the tempo of the sequence.

The sequencer controller A-154 adds a lot of new functions to the A-155 (e.g. voltage controlled addressing, forward/backward/pendulum/random mode, voltage control of first and last step, voltage controlled clock and gate length, step skipping, combination of several A-155 in parallel/serial mode and many more).