Ensoniq ESQ-M Sound Module

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"In 1986 Ensoniq released the ESQ-1 synthesizer at a list of $1,395. The ESQ-1 became a big seller and continued the company’s good fortune they had with the Mirage. Due to this success, Ensoniq released the ESQ-M, a rack mount of the ESQ-1 which had all the features of the ESQ-1 except for the sequencer, 5 octave keyboard , and the 80 character display. However the ESQ-M allowed you to set individual volumes for each track (patch) of a mix.

The ESQ-M features eight voice polyphony and is eight part multitimbral with dynamic voice allocation. It can also do basic splits and layers which can be saved as part of a patch and split key is designated by the user. (Very impressive for a synth that was released in 86/87.) The unit features no on-board effects but does allow you program the pan position of a voice and the position may be modulated any modulation source. Also ingenious (other manufacturers please note) is that while you are playing a voice you may change the voice and the original will continue to sound and any new keys will reflected the newly selected voice. While using the unit in full multitimbral operation I did not notice audible delays in the machine’s performance.

Each voice features three digital oscillators, an analogue filter (a Curtis chip) three LFO’s, four envelopes, and four Digitally Controlled Amplifiers and a very serious modulation routing ability. This synth is a killer with these features.

The oscillators do feature a nice assortment of waveforms from the classic waveforms:. saw, bell, sine, square, pulse, and 3 noise waveforms, sampled waveforms: bass, piano, electric piano, voice 1 and 2, kick drum, reed, and organ, 3 additive synthesis waveforms, 5 formant waveforms, and 8 band limited waveforms, which as their name implies they have had their harmonic content restricted along certain lines. A few points to note: The noise waveforms are not random unlike white noise. The third noise waveform can be used to all random frequency components into a sound and reminds me a lot of a sound that can be achieved using the feedback on a Yamaha FM synth. The sampled waveforms are single cycle and remind me a lot of the Mirage sampler. The additive, formants, and band limited waveforms are very interesting and more sample playback units should put these type of waveforms on board their units. Oscillator two can be synced to oscillator one. Additionally oscillator one can use its amplitude to modulate the amplitude of oscillator two which results in the creation of side band frequencies (good for bell sounds, etc.).

Modulation is one of the best if not the best feature of the unit. The following are the modulation source: LFO1, LFO2, LFO3, ENV1, ENV2, ENV3, ENV4 (note: ENV4 always modulates DCA 4 however it can be routed to other destinations as well), VEL (2 curves - one linear, and one that that reaches the end of the modulation range quicker but levels off as it reaches the top.), keyboard tracking (2 types - one all positive over the full 88 key range and one negative as well as positive over a 5 octave range), wheel, voltage control, midi controller #, and aftertouch pressure (mono or poly). All these sources may be individually assigned to the following destinations: two sources to each of the three oscillators, two sources to each of the three DCA’s, two sources to filter cutoff in addition to velocity from the keyboard (it would be nice to modulate the amount of resonance), two sources to each of the LFO’s depth (would be nice to modulate the LFO’s speed but not an option), and the panning of the program within the stereo mix (excellent feature).

The envelopes (all four per voice) are a tad more complicated than the basic ADSR and offer the ability to assign negative levels to the envelope. The envelopes feature three levels and four time segments. The envelope begins a level 0 which is identical to the starting point of a standard ADSR and takes a fixed amount of time, as defined by time segment 1 to reach level 1. It then takes time segment 2 to reach level 2, time segment 3 to reach level 3 and time segment 4 to go back to zero which commences upon release of the held key. What is really neat is that the levels may be positive or negative. The envelope levels may be modulated by the keystroke velocity and separately the envelope attack time may be decreased via a faster velocity. Keyboard scaling of the envelopes is also offered with a full range from 0-63.

The LFO’s (all three per voice) offer triangle, rising sawtooth, square (positive only) and noise. Unfortunately the LFO frequency can not be modulated which would have been really nice. The LFO waves may be set to return to the beginning of its cycle each time a new key is struck or the LFO may be free-running. This option should be available on all synths. Additionally there is a human parameter which adds a random element to the LFO frequency which id quite nice. Additionally the LFO level offers two levels (level 1 and level 2) and a decay which determines the rate of change from level 1 to 2. This is much more powerful than the classic method of level 1 always being at zero as found on most synths.

The unit also offers some other interesting features such as: portamento, mono mode triggering which gives priority to the last note played and the envelope wont re-trigger as long as a key is held down when the new key is played. Unfortunately mono mode does not stack all eight voices, voice reset which allows you to decide if a same key is struck before its previous note has died away, whether it will be assigned the same voice or a new voice, envelope reset which decides based upon the same scenario if all four envelopes will reset or will re-start at the level they previously left off., full cycle which allows the envelope to run their full cycle regardless if you let go of the key before the envelope has completed its full cycle.

The MIDI implementation is really solid as the unit and includes the following:

* You can assign any midi controller #1-95 to act as a modulator.
* Midi overflow which is used to allow two ESQ-M’s to act like a single 16 voice synth.
* Aftertouch select off, mono, or polyphonic.
* MIDI mode; omni, poly, mono, and multi. Multi allows 9 separate patches to be assigned to 9 different midi channels that can play up to eight voices at once. Of course in total the unit can’t play more than eight voices anyway.
* The unit can receive controller data and program changes and system exclusive information which means you can record parameter changes on you sequencer and the ESQ-M will react to them, which is great.
* A single patch, the entire bank of 40 patches from either memory or the two banks of a cartridge may be sent or received via midi.

So How Does it Sound? The ESQM can sound really good but it takes some time and patience to program it to get it to sound good (There is a lot to keep track of!) Its really important to make full use of the tools that the unit provides you (i.e. four envelopes and three LFO’s per voice) and you can make some really interesting sounds with this much programming power. Also interesting to note is that with the additive, formant, and band limited waveforms you get some really FM or phase distortion (CZ) like sounds and you still have the voltage controlled filter to add another dimension. The sampled waveforms are fair and won’t pass for the real thing but 8 samplers seem to be somewhat in vogue as evidenced by the prices of a used Mirage but of course you can’t sample with the ESQ-M. The ability to modulate the stereo field with an LFO or Envelope is excellent and should have been implemented on more synths as it can do a lot interesting and different things."