Signal Arts: MIDI Analog Performance Sequencer

The Signal Arts MIDI Analog Performance Sequencer was specifically designed for experimental composition in the sense that it requires the user to focus on the sequencing process instead of the end product. Unlike modern matrix sequencers designed to chain preconceived sequences together to create a finished song, the MAPS makes it difficult to preconceive a final product. Contrary to traditionally- styled analog sequencers like the Analogue Solutions Oberkorn and the Doepfer MAQ 16/3 that only repeat synchronized sequences, the MAPS allows unquantized triggering so that sequences can run completely independently of each other. Although the MAPS can be programmed to launch chains of 16-step staccato sequences in unison like a matrix sequencer, or to randomize steps or create complex envelopes like a traditional analog sequencer, its real power is in its ability to use a set of relatively simple user-defined parameters to aggregate polyrhythmic counterpoint in real-time.

The deceptively simple building blocks of the MAPS are sixteen banks of eight sequences of eight steps. Each step has its own note duration, step duration, velocity, slew rate, and one other control message-all editable in real-time. Each sequence can be chained to another sequence, can be triggered from its own MIDI channel or trigger button, and can be sent to the same or another MIDI channel and one of the sequencer's three CV/Gate output pairs. Each sequence can be synchronized to the bar line so that the difference between the sum of its step durations and a full bar is added to or subtracted from the last step, or the sequence length can equal the sum of its step durations. What's more, a sequence's step parameter values can cross-modulate those of another sequence, providing the aleatoric transformation of sequence parameters over time. For example, a simple 8-step melodic sequence cross-modulated by a 7-step sequence with different velocity values can produce a 56-step rhythmic cycle.

Central to the MAPS's identity as a real time tool is its array of Trigger Modes that determine how each sequence reacts to a trigger. Trigger modes like RunStop and SeqReset exhaust the entire Run/Stop/Reset functionality of most analog sequencers, but the MAPS does much more with triggers. Release mode fires a second sequence at the trigger's release to facilitate complex envelopes and other two-stage events. Multiple mode fires a copy of the same sequence for each identical trigger received, creating rondo-like counterpoint on polyphonic synthesizers. In Duration Follow mode, the sequence's note durations track the trigger duration so that, for example, a legato sequence will follow a legato trigger. Sequences also track other properties of MIDI triggers, as they are pitch-transposed and vary dynamically respective to the trigger's MIDI note number and velocity.

The MAPS is intuitive and easy to navigate. It updates Roland's famous step- matrix interface, although sadly there are only eight step buttons instead of sixteen. But the MAPS compensates with a multifunctional, continuous, rotary controller for each step that quickly changes step or sequence parameters in real time. The MAPS also has extensive interfacing functionality. It sends MIDI clock, analog clock, and DIN sync. It also outputs CVs in an array of logarithmic and exponential curves scaled to either V/Oct or V/Hz. It can be configured to output Moog S-trig. It converts MIDI to CV. And it sends and receives SysEx and has a user-upgradeable OS.

With all its innovative functionality, it is unfortunate that the MAPS doesn't quite realize its analog potential. It only outputs quantized voltages and lacks the per-step gate outputs standardized by the seminal ARP Sequencer and Moog Sequential Controller. CV or trigger inputs could leverage the MAPS's functionality by allowing it to be configured as a sample-and-hold unit, pulse divider, shift register, or logic processor. The same input could provide analog access to the sequencer's individual steps as is the case with the multiplexer on board the Analogue Solutions Oberkorn or the CV/Clock input pair on Peter Grenader's Milton sequencer.

But rather than emulate the practice of traditional analog sequencing or the conventions of modern matrix sequencing, the hybrid MAPS draws the best from both traditions to facilitate a unique workflow. In this sense, the MAPS fills a niche that was previously vacant, and it's one of the rare tools designed specifically to generate new ideas rather than to regurgitate preconceived ones. ($799 direct; home.eol.ca/~jeffry/)