The ESQ-1 is a "hybrid synthesizer" in that it has digital oscillators, but analog filters. Other synths with similar architecture are the Ensoniq SQ-80, Korg DW8000 (and DW6000), and Kawai K3 (and K3m).
The ESQ-1 has three digitally-controlled oscillators available per patch and its analog filters use Curtis CEM 3379 chips.
The Ensoniq ESQ-1 is known to have been used by Skinny Puppy, Jean-Michel Jarre, Front Line Assembly, John Carpenter, and Depeche Mode.
There are two sequencer expansions that have been produced for the Ensoniq ESQ-1. The SQX-10 expands the sequencer to a 10,000-note capacity, while the SQX-20 expands the sequencer to a 20,000-note capacity. Both are cartridges that plug into the mainboard via a slot in the back of the ESQ-1.
A handful of manufacturers released sound cartridges for the ESQ-1. Among the most popular were Ensoniq's Voice 80 series, Eye & I's Voice Crystal series, and Syntaur's Soundset series.
When you first turn on your ESQ1 the display will show the version number in the lower right just before it displays the patches.
The firmware is stored on two EEPROM chips, one containing the ""high"" and one containing the ""low"" ROM image. The low ROM chip is in the chip socket labeled ""U18"" on the main board, while the high ROM chip is in the socket labeled ""U17"" on the main board.
Known bugs in Version 1.7:
1. Selecting a different song while a sequence is running can cause a system crash.
2. Performing any of the following sequencer functions when there is very little sequencer memory remaining can cause a system crash:a. Saving or merging a track b. Erasing a track c. Recording a track
3. The system will occasionally lock up after loading data from MIDI. The data transferred intact, but the ESQ-1 never returns from flashing PLEASE WAIT. Turning the unit off and on again cures the problem.
4. The first time that MIDI data is loaded after powering up the unit, the unit has a tendency to fail to load; the display will read TARGET SYSTEM NOT RESPONDING, even though all connections are correct. The data load will be successful if tried again.
5. Due to ""jitter"" on the part of the Data Entry Slider, parameters on Programming pages and Tempo on Sequence pages will sometimes jump to the present value of the slider.
Known bugs in Version 2.0:
1. It is possible to set the pitch bend range outside the legal limit (49 to 63). It is necessary to re-initialize the unit to reset the pitch bend to the proper range of 0 to 12.
2. The sequencer sometimes fails to accurately record SUSTAIN pedal information.
3. The sequencer will sometimes play back key down events with velocity of 0 if the key had been recorded with a low velocity value.
4. In MIDI MONO mode, the ESQ-1 may not properly receive program changes on all channels.5. When syncing to tape, the sequencer will sometimes play the first note of the sequence as soon as the user presses play, putting the rest of the sequence out of sync.
Version 2.2 fixes/adds the following:
1. A parameter was added to allow the CV Pedal to be used as a volume pedal as well as a MOD Pedal.
2. Allowed data dumps to disk drives capable of accepting generic system exclusive messages.
3. Allowed compatibility with MIDI Guitar controller.
4. Ability to output a tape sync clock when syncing to MIDI clocks as well as when syncing to tape.
Version 2.3 fixes/adds the following:
1. 40 internal patches are loaded from the OS rom's after initialization.
2. Fixed a bug which caused erratic operation when using the LOCATE function by more than 16 bars.
Version 3.0 fixes/adds the following:
1. Added sequence editing features which allows addition and deletion of variable bars at any boundary within a sequence.
2. Ability to rename songs by pressing the soft button above the song name on the SONG EDIT page.
3. Allowed startup screen to automatically switch to last selected internal page.
4. VELOCITY parameter renamed to TOUCH.
Version 3.0 adds the following:
1. Ability to remain in SONG mode even after unit was turned off.
Version 3.4 fixes the following:
1. Corrected a sequencer problem which prevented the ESQ-1 from recording correctly with synchronized (SYNC=MIDI CLOCK) with units which send clocks continuously.
Version 3.5 includes the following:
1. Corrected waveform pointer in EPNO2 waveform.
2. Restored the values of the TOUCH parameters to their original and correct order, HARD, MEDIUM, SOFT.
If you are unable to re-initialize the unit due to scrambled software (i.e. the keyboard not responding), you can clear the RAM by following this procedure:
Make sure the power is off and the power cable is disconnected!
For METAL UNITS: short the right side lead of CR1 to C1.
For PLASTIC UNITS: short the right side lead of C18 to the left side of CR3.
The metal versions of the ESQ-1 don't have a heat sink on the back and have a serial number from 10000-24999 with a main board assembly number of 40900004001.
The plastic versions of the ESQ-1 have a heat sink on the back and have a serial number of 25000 and higher with a main board assembly number of 4090007001.
There are no interchangeable parts between the metal and plastic ESQ1's.
Year Released: 1986
Keyboard: 61 keys with velocity
Polyphony: 8 notes
Multitimbral: 8 parts
User Patches: 40
ROM: 64 KB (32 8-bit waveforms)
Sequencer Memory: 2,400 notes
Screen: 40 x 2 character fluorescent display
Patches: 40 (40 User-Programmable, Expandable to 120 With Memory Card)
Newest OS Version: 3.50