Originally published in Transoniq Hacker
Issue #33 (March 1988, p.6)

Mirage Super-MIDI Disk

Reviewed by Walter Daniel

FOR: Mirage PRODUCT: SM-1 Super-MIDI Disk PRICE: $39.95, $2.50 shipping FROM: Upward Concepts

The venerable Mirage is being upgraded by all those computer hackers out there. In this case, Dick Lord has produced a new Mirage operating system (OS) with an emphasis on performance features. This OS implements MIDI volume, controller mapping, overflow modes, and more. Sampling is disabled to make room for the extra commands, but this presents no problem since you should be sampling with MASOS. The samples on the disk are generic organ, brass, and sax(?) samples with short loops and no major program variations. There are some sequences on the disk, mostly baroque-type material. You should be buying this for the MIDI features anyway. Is this OS for you? Read on, and decide for yourself.

MIDI VOLUME

The Ensoniq OS 3.2 does not include MIDI control of volume. This disk implements MIDI volume by scaling the amplitude envelope of the Mirage voices. There is a drawback to this method in that lowering the volume decreases the resolution of the sample. Low MIDI volumes cause the sound to be gritty because only three or so bits (instead of the eight that are stored in memory) are all that describe the waveform. My experience was that mid- to full-volume output sounded fine. This limited amount of volume control is all that you should need, so the system used by this OS is certainly workable.

Volume control is sent as is any other MIDI controller (sustain pedal, mod wheel, etc.): a control change with a controller number and a value. The standard MIDI volume controller number is seven, but SM-1 allows different controller numbers. Parameter #76 is the controller number for MIDI volume of the lower sound, parameter #77 the number for the upper. You could, for example, assign an unused controller number to a slider on your master keyboard, then set #76 and #77 to that number. With such a setup, you could change the volume of the Mirage with the slider. There is a mode in which different controller numbers are saved with each upper or lower program. The documentation describes a parameter for "MIDI Controllers to Local," a feature that I could not figure out.

Where MIDI volume control really helps out is with MIDI guitars and wind controllers. If you're into wind controllers (and I am), you now can use the wind pressure to control volume directly. Even if you programmed your wind controller to send aftertouch information, all OS 3.2 could do with it was to control oscillator mix or LFO modulation. With SM-1, you can send the initial transient as velocity, lip pressure as LFO modulation, and wind pressure as volume. Be sure to program a wind controller to send a mid-level volume over MIDI to correspond to minimum wind pressure in order to avoid grittiness at low Mirage volumes. Although MIDI guitars send the strength of the string pluck as velocity information, some have separate MIDI volume control. It seems that it would be useful to have control of a MIDI module right on the guitar.

MORE MIDI

This OS has separate transmit and receive MIDI channels. With #30 (local) off, a keyboard Mirage (what I used in writing this review) becomes a separate sound module and MIDI keyboard controller. Parameter #73 controls transposition with a range of plus or minus two octaves in semitone steps. Remember the front panel commands sent as system exclusive messages? Once a part of the regular OS (but still in MASOS), they were banished by Ensoniq's version 3.0. Happily, SM-1 restores these commands. What this means is that all these extra parameters can now be controlled with a sequencer if that sequencer can send system exclusive commands.

MIDI EXPANSION MODES

Parameter #83 controls what appears at the MIDI Out jack of the Mirage. It can act as a simple MIDI Thru or Out, but there are four additional operating modes. One mode merges what appears at the Mirage MIDI In jack with local events (playing the Mirage keyboard, etc.) and passes the result to MIDI Out. If there is a transposition in effect, the OS will transpose both local notes AND incoming MIDI data! In fact, this "translation" is in effect for the final three modes: Overflow, Even Notes, and Odd Notes. Overflow mode passes any note beyond the eighth one to the MIDI Out. For example, if you are playing eight notes, playing a ninth one will not be sounded locally, rather sent to the MIDI Out. In Even Notes mode, the Mirage will respond to notes assigned even numbers by the MIDI protocol while passing on the odd-numbered notes to the MIDI Out. Odd Notes mode does the reverse.

What good is all this? The Merge/Transpose mode is great in that all the transpositions are set at the Mirage and translated for all units down the line. I had a DX7 driving a transposed Mirage with local off, then at the same time used the Mirage keyboard to drive a Casio CZ-101 which was on a different MIDI channel than the DX. Overflow mode is good if you have two Mirages; when playing involved parts with sustained sounds, notes won't be cut off to play the newest ones since there are now sixteen voices available. The Even and Odd Notes modes can be used to spread a part across the stereo field. I had great fun setting my Mirage to Even Notes mode with a string sample while a CZ-101 string patch played the odd notes. The not-quite-identical sounds really made the part sound as if it were played by an ensemble.

EVEN MORE MIDI

Parameter #89 now can be used to turn the footswitch into a sostenuto pedal. That's the one that lets you hold some notes with the pedal while playing others unsustained. In my experiments, I held high string chords with the pedal while pounding out staccato cello lines. The Sample Upper button advances both upper and lower program numbers by one, although there is no visual feedback from the display. Still, it's much easier than hitting the Prog button and number keys. And what performance-oriented OS would be complete without a panic button? The Sample Lower button sends an All Notes Off MIDI command and resets all MIDI volume values to full. It turns out that the All Notes Off is actually a MIDI control change -- there is a controller number reserved for the purpose.

SM-1 has some MIDI controller mapping options. The sustain and sostenuto pedal effects can be accomplished with external MIDI commands. Parameters #90 and #91 set the controller number for the Mirage to respond to such commands. If you use a keyboard that has assignable controller switches, you could set up one as the sostenuto "pedal" for the Mirage and use it as a chord hold function. The MIDI outputs of the Mirage footswitch and mod wheel can be assigned different controller numbers as well. I had my Mirage wheel controlling my CZ portamento time and turned the portamento on and off with the Mirage footswitch. Anything that responds to a MIDI control change is fair game. To check the MIDI volume on the Mirage, I did this: I programmed the mod wheel to controller #7, set the MIDI volume input controllers to #7, turned local (#30) off, then patched a MIDI cable from the Mirage MIDI Out to the Mirage MIDI In. With this setup, the mod wheel will control the volume.

DOCUMENTATION

There are really only five pages of documentation that come with the disk (the cover page doesn't count). Two pages briefly describe the features of the OS. One page is a convenient list of all the new parameters and what the settings are. Implementation notes for the OS (MIDI volume, sostenuto pedal, and expansion modes) are given on one page. The final page lists MIDI controller numbers and the front panel command sysex codes. The manual may be short, but it does get the job done.

CONCLUSIONS

If you're into live performance, you can gain a lot of control by switching to the SM-1 OS. All these new parameter settings are saved if you use parameter #14 to write the configuration file to disk (I tried). If you are touring, you may not want to entrust your show to one disk, so you'd be better off getting a disk utility that lets you put the OS on working disks. In fact, you can have a different configuration for every disk. Studio types can wring much more expressiveness out of their Mirages if they delve into this OS. Wind controller players and MIDI guitarists can fully use the capabilities of a Mirage with this disk. The drawback? You have to deal with more parameters. Yes, the Mirage keypad/display is annoying, but keep in mind that you can get at these settings with sysex commands. It's a lot cheaper to spend about $40 to get some more performance out of an older instrument than to spend the bucks to buy the latest new gizmo. There's likely to be a lot of Mirages on the used market in the near future (hopefully cheap), so a new OS like this one makes those old keyboards worth picking up or keeping. This is the great thing about software-based instruments -- they can remain useful for a long, long time.

Bio: Walter Daniel is an Assistant Professor of Aerospace Engineering at the U.S. Naval Academy in Annapolis, Maryland.
He can be contacted at the Compuserve ID of 75066, 164.

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