The Matrix-6R is the rack version of the Matrix-6: a 6-voice analog synthesizer released by Oberheim in 1986.
Below are some Oberheim Matrix-6R patch files for download, and links to additional sounds for sale elsewhere.
Here are about 1000 sounds found originally at Synth Zone (as matrixpatch.zip), but the .MID files have been converted to .syx sysex files. They're organized into 11 files that categorize the sounds. The original ReadMe file is also included in the .zip:
the 11 banks of patches supplied on cassette with the Oberheim Matrix6 and 6r. Saved as sysex dumps to standard midi files.
These files can be sent directly to your Matrix-6R via a sysex transfer program, and they can also be imported directly into Patch Base.
Patch Base has a full-featured Oberheim Matrix-6R editor and librarian for both Mac and iPad. Try it out for free.