Hello. I've owned an MT-32 for years and stumbled across this forum and the Wikipedia article today. I've got a 1st generation (no headphone jack) but has a serial #891264 so I assume it's a revision 01 board. I've never opened it up. Thanks to some of the information I've found here and on the Wikipedia page I now know why I had the "popping" when the volume was turned too high. I used it extensively to write my own music but became tired after a while with the stock sounds so I dug into the sysex and about 15 years ago wrote my own graphical patch editor using assembly language on the PC; had to write my own video, mouse, and MIDI drivers and everything. I've never gotten around to resurrecting that project though as I'd moved on to other synths (but still keep the MT-32 around).
On to my question: I remember reading in old issues of Electronic Musician and Keyboard, back in the classifieds section, someone was advertising an MT-32 "upgrade" ROM that added extra sounds and the ability to control a lot more of the parameters (especially the reverb parameters) from the front panel. Is anyone familiar with this or other optional firmware ROMs?
Until it went missing (stolen by an old roommate), I had a modded MT-32 I purchased from someone on Usenet. It even came with all of the original paperwork on the modifications made, including a very large number of electromechanical mods (improved backlight, additional resistor on the output to counter the horrible humming, solid capacitors, etc).
If I was sitting at a modded MT, I could probably remember everything, but I haven't touched one in ages.
Additions I can remember include additional internal memory for more sound banks, battery-backing for the internal memory, front-panel control of _all_ parameters through the use of button combinations, finer control of many parameters (which, to some degree, can screw with prior recordings), increased volume, etc.
IIRC, the additional instruments can only be accessed via the front-panel controls, without swapping.
There are several websites which detail various MT-32 mods, but I can't link to any of them as they usually contain the replacement ROMs. None of them are Roland property (they're the recodes), but better safe than sorry.