Roland MT-32
Overview

LA: Linear Arithmetic

LA synthesis combines two synthesis - PCM and analog emulation (called Synthesizer).
All LA synths have 32 oscillators, which can be used both as PCM oscillator and as Synthesizer oscillator. A set of oscillator, filter (if available), amplifier and LFO is called Partial.
2 Partials interact with various signal routings and ring modulation. The routing is called Structure.
Up to 4 Partials can be Layered in a voice.

PCM Partial

The PCM Partial is a simple sample playback (See the figure below). It has no filter. Only the pitch and the amplitude can be controlled.

MT-32 has 54 waveforms - mainly one-shot attack segment of accoustic instruments and percussion samples. There are some looped waveforms as well.
There are "Spectrum" waves and various "Jam Loops" that combines several samples. They characterize LA Synths' Bell/Noise/SE sounds, which are still difficult to emulate today.

Roland hasn't clarified the size of MT-32's PCM ROM. As D-50 has 128KB (1M bit) ROM, and D-10 series has 256KB, MT-32 may have 128KB or less.

Roland LA PCM Sound Generator
PCM Partial

Synth Partial

Synth Partial has 2 waveforms - Saw and Pulse. Both can be modulated by Pulse Width parameter - though LFO PWM is impossible. Synth waveforms can then be processed by Resonant Filter, in contrast to PCM Partials.
Phasing problem often arises when 2 similar waves are layered - the sounds interact and often result in thinner sound.

Roland LA Synthesizer Sound Generator
Synth Partial

Structure

Structure combines 2 Partials with Ring Modulator. There are 2 Ring Modulation modes - One Partial's direct output can be added or muted.
Structure paramter can also be used to separate 2 partials to L/R outputs.

Filter and Amp

The Resonant Filter is only available for Synth Partials.
Various Keyboard scaling is available for both Filter and Amp.

Envelopes

Filters and Amps have its own 4-stage envelopes. The attack time can be modulated by Velocity. The envelope speed is not very fast, though not very slow, either.
There is one Pitch Envelope for each oscillator.

LFO

Each partial has 1 LFO that can only modulate the pitch - PWM is not available.
The LFO is not so fast, and its effect is not so deep.

Effect and others

There are 8 digital effects - reverbs and delays.
MT-32 is 8-part multi-timbral - its one of the earliest multi-timbre synthesizer with full MIDI control.
It has no aftertouch.

MT-32 has 1 drum-kit. Any synthesized voices can be assigned to any keys - it's the most advanced drum-kit architecture, still today.

Info about MIDI

It seems to interpret Panpot MIDI control change inversely: 0 for right and 127 for left. Thanks Cloudschatze for providing information!
If you have MT-32 compatibles, please take a look and see how the panpot works.



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Deep Synthesis: Home

4. 18. 2004
10. 30. 2005: Control Change information added