Ensoniq EPS
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The EPS (Ensoniq Performance Sampler) was one of the first few affordable samplers on the market. It was manufactured from 1988 to 1991 by Ensoniq in Malvern, Pennsylvania, USA. It was an update to the Mirage 8-bit sampler, as the EPS used a 13-bit sampling architecture.
The user interface was a single line vacuum fluorescent display. The EPS also used an integrated floppy disk drive (sourced from Sony or Matsushita), and an expansion bay that could be used to add RAM and a SCSI controller which supported SCSI hard disk and CD-ROM drives. Ensoniq offered its own Memory Expansion device with or without SCSI interface. Expanded RAM offers longer or higher quality samples. The EPS is also able to have up to eight instruments on reserve, and is able to play all instruments simultaneously. A company called Maartists offered 4 to 8 times memory expanders for the unit.
The EPS uses MIDI and can be used as a controller of other instruments, or linked to a PC or Macintosh.
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[edit] Construction
The keyboard is of thick plastic construction of a dark gray color with 61 weighted keys. There are assignable pitch, modulation dials, and patch select buttons. Accessing the interior of the unit is simplified by a swinging control panel secured by four hex screws.
The EPS had a straightforward interface that was easy to use, with configurable controls that were geared for live performance.
The whole unit was configurable through a custom operating system (latest version: 2.49). While the system boots from floppy, it flashes a "hands off" warning while it calibrates the keyboard.
An optional Output Expander module allowed you to access eight discrete mono outputs on the machine, allowing you to separately mix levels and effects for each loaded sample.
The key limitations of the EPS were its proprietary disk format, and a lack of support from Creative Technology, the current owner of Ensoniq. A 19" rack-mount version, the EPS-M, was also available in limited numbers.
This model was superseded by the Ensoniq EPS-16+, released in 1991. The EPS-16+ was pretty well identical to the EPS, with the addition of integrated DSP effects.
[edit] Use
The EPS is a performance sampler -- it contains two processors -- so you can continue playing while loading another sample. The one processor handles the IO while the other is responsible for keeping the audio running without interruption -- this made the EPS especially useful for live performance situations.
The interface, although operating through a single line fluorescent display, offered rapid access to all functions by the intelligent way that functionality was broken into Modes and Pages.
Modes were: Load, Command, and Edit.
Pages were: Instrument, Sequence, MIDI, and System.
In addition to eight soft instrument buttons, it had a number pad (0-9), four cursor buttons, a value slider, and 'Yes' - 'No' buttons.
Users could access pretty well any function with less than three clicks: Mode - Page - Number Pad.
There was also a dedicated button for Sampling, and setting the Keyboard range.
Three buttons (Record, Stop, Play) controlled the built-in sequencer (named sequences could be built into a Song)
[edit] Instrument
Instrument pages would be prefixed by clicking a Mode (Load, Command, or Edit) -- yielding functions relating to loading, editing, and tweaking EPS sampled instruments. Instruments could contain a number of discrete samples which were patched into Layers - each with their own ADSR envelopes and keyboard ranges. A simple loop editor that allowed you to define envelopes, cross-fades, and sample start-end, and loop points in real-time made the instrument flexible enough to recreate just about any sound you could hear.
[edit] Sequence
The Sequence pages allowed you to define sequences and songs. Simple quantitization was available, and a crude step-editor to tweak individual sequence elements. Sequences (with up to eight instruments playing simultaneously) could be assembled into Song Steps. In assembling songs, you could define the number of repetitions of each sequence that comrprised a song step. This made it relatively easy to score and arrange a song.
Sequences depended on having instruments being loaded into one of the eight instrument banks in the right order. You could save Banks of instruments which could be loaded in by a song sequence so that loading the song loaded up all the appropriate sounds into the right places so everything would just play when you started the sequencer.
[edit] Midi
The EPS supports polyphonic-aftertouch on its 61 keys, and therefore allows a fair amount of expression as a MIDI controller. It allows sys-ex messages to be passed over MIDI, and can transmit and receive on multiple MIDI channels simultaneously.
[edit] System
Because the EPS contained two processors -- sound generation and disk IO were handled separately. You could boot the EPS, load some sounds while playing the ones that are already loaded. Then sample in a new sound, only to find that you're out of floppies to save your precious sample to -- the EPS OS will allow you to go ahead, format another floppy disk, and save your new sound without the system function getting in the way of playing the audio.
One of the nice things about the EPS was that the boot disk contained everything needed to duplicate itself. You could create a bootable Ensoniq disk with a single command from the System page. Thus, if you had one boot disk, you had everything you needed to make another boot disk.
[edit] Repair Tips
Persistent key calibration (tuning) errors are usually fixed by reconnecting the interor connecting cable.
Problems with the cold solder connections can disable the vacuum fluorescent display; this is remedied by resoldering.
Since the ROM chips were in sockets -- sometimes after a couple years, the unit would fail to boot, and give strange characters on the display. Simply opening the unit and reseating the two ROM chips has saved it on more than one occasion.
