Roland M-GS64
Thirty-two parts of GS/GM sound in a single-rackspace box, with two MIDI inputs, because sixteen channels were never going to be enough.
Overview
The number to know is 32. The M-GS64 divides its voices into two banks of sixteen Parts - Group A (A01-A16) and Group B (B01-B16) - and to feed all of them it has two separate MIDI IN jacks, MIDI IN A and MIDI IN B. A single cable only carries sixteen MIDI channels, so a second input is the only way to address Parts beyond the sixteenth. Owners report that the factory configuration maps Group A to MIDI IN A and Group B to MIDI IN B, so a message on channel 5 arriving at MIDI IN B plays Part B05. The routing is not fixed, though. A matrix parameter called In Mode governs how data from the two inputs is distributed, and SysEx received on MIDI IN A can be redirected to Group B depending on the address it carries.
The parameter set is deeper than the rack-ear footprint suggests. Each Part gets its own reverb level and chorus level, both on a 0-127 scale. The chorus thickens a sound, adds width, and makes a thin patch sit up in the mix. Key Shift transposes any Part across a ±24-semitone range, which is two full octaves in either direction, one unit per half-step, twelve per octave. A global Tune parameter pulls the entire instrument's A4 anywhere from 415.3 Hz to 466.2 Hz. That lets the M-GS64 sit with period instruments, or with a session where the piano has drifted sharp, without resampling anything. There is also a per-Part Detune on a -100.0 to +100.0 cent scale. Collectors pass around a trick: put two Parts on the same MIDI channel with slightly different Detune values and let them play in unison. The beating between them reads as a single, much richer voice.
Output routing is where the M-GS64 gets useful in a studio rather than just a stage rack. Each Part can be assigned to OUT 1, OUT 2, OUT 2L, or OUT 2R. Assign it to OUT 1 and the sound arrives in stereo with effects applied. Assign it to OUT 2 and you get the dry signal in stereo, no effects, ready for your own processing. OUT 2L and OUT 2R push the dry signal to a single side and ignore pan settings entirely, so each is a mono tap for a specific Part. Know this before you buy: the headphone jack carries the same signal as Output 1, so anything assigned to Output 2 will not be heard in the phones. The whole assignment scheme also only takes effect if the system Output Mode is set to "Selected". Leave it on "Fixed" and every per-Part routing is ignored. From the factory, all Parts are assigned to OUT 1.
Two more system-level details trip people up. The rear-panel MIDI OUT/THRU connector is switchable, and when set to THRU it passes only what arrives at MIDI IN A. Data received at MIDI IN B is not retransmitted regardless of the In Mode setting. Changing that switch makes the display blink, and the new setting does not take hold until the unit is powered off and back on. Sys Ex reception has its own on/off switch, and if it is off, nothing exclusive gets through, including bulk dumps. The Device ID runs 1-32, and for correct playback of General MIDI or GS song data it needs to be set to 17, with GM/GS reception switched on. Those two settings ship correctly from the factory, which is why so many secondhand units "just work" until someone goes menu-diving and changes them.
Parameter transfer shows the M-GS64's lineage and its limits at the same time. The unit's data is compatible with GS-compatible devices in both directions, but because the M-GS64 carries new parameters, the musical result on another GS box can differ. Send M-GS64 data to a plain GS device and it may throw an "Address Error". That is just the newer addresses going unrecognized, not a fault, and the parameters the receiving unit does understand will have been set correctly. Bulk dump between mismatched GS gear is best preceded by initializing the M-GS64 before retransmitting. Standard GS exclusive data for sixteen Parts begins at address 40 00 00, and Roland placed the M-GS64's remaining sixteen Parts starting at 50 00 00. Both blocks can be sent down a single MIDI IN if you use the upper address range. The lower range goes to Group A, the upper to Group B. That addressing behavior for SysEx is unaffected by the In Mode parameter, which makes it the exception to the rule.
Front panel operation is plain. A Patch button with an indicator drops the unit into patch selection. A Mute button silences a Part, and a Monitor button inverts the logic, so only Parts whose indicator is lit will sound. The Part button, held while pressing a Value button, steps through Parts, and the current selection shows on the display. Value buttons change parameters, and holding one while pressing the other accelerates the scroll, which helps a lot when you are deep in a parameter list. The function buttons double as level indicators. A rotary volume wheel controls Output 1 L/R and the phones, but not Output 2 L/R, which have no level control at all.
Mute Lock solves a real annoyance. When you replay a sequence, the mute settings you made can be wiped out by reset data at the top of the song, such as a General MIDI System On or GS Reset message arriving before the first note. Turn Mute Lock on and your mute settings survive those reset messages, so you are not redoing your mix every time you hit play.
In period terms, the UK trade press listed the M-GS64 at £599 in 1996. One reviewer noted the retail price of £499 would have been easier to swallow if Roland had put even rudimentary edit knobs on the front panel, with envelope and brightness control being the specific wish. Sounds are edited via SysEx, not from the panel, so the M-GS64 is a player's module and a programmer's homework assignment in equal measure. The same reviewer drew a direct line between the drum kits in the Sound Expansion Series, which are electronic sounds pulled from the TR808, TR909, and Compurhythm sets, and the character of the M-GS64's GM/GS voice set.
The M-GS64 is not one of the JV/XP-derived Sound Expansion modules that EQ Magazine (November 1995, p.18) covered when the series launched. That range drew its sounds from the JV and XP synthesizers, while the M-GS64 is the GM/GS member of the family. Sound on Sound (October 1995, p.142) framed the series as offering instant gratification in a rack, and the M-GS64 is the utilitarian end of that idea: the box for when a sequence calls for General MIDI compatibility, not for designing a sound from scratch.
eBay Listings
As an eBay Partner, we earn from qualifying purchases. This helps support our independent vintage technology research.