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"This is probably my favorite analog subtractive synth of all time.
The Matrix series descended directly from the OB-8, which signaled Oberheim's move away from raw voltage power toward more precise dependability & vast programming possibilities. The Matrix 6 is the perfect compromise of heavenly analog sound & modern control, for under $3k. What it lacked in knobs it more than made up for in features: 2 completely independently-controllable digitally-regulated analog oscillators with the rare ability to use 2 independently shapeable waveforms simultaneously for EACH, a juicy low pass filter capable of self-oscillation, 3 envelopes, 3 LFO's (plus another global vibrato LFO), a multitude of modulation configurations, osc sync, unison, portamento, filter FM, velocity, aftertouch, and the ability to stack two presets. All this and it still sounds so unbelievably good. It was sort of held back by poor MIDI implementation, but synthhacker heroes Gligli & Bob Grieb re-coded the operating system so you could tweak every parameter with a SYSEX controller in real time. Now, Stereoping makes a rack unit with a knob for every function to unleash the almost endless power of the Matrix synths.
This Matrix 6 was rescued from a dumpster sometime in the 90's. It was given a new lease on life by a wiz techno producer, who also happened to be a carpenter during the day, so it was given new wooden endcheeks too. I bought it from him a few years ago when he was downsizing his studio. It wasn't in the best place. 2 of the keys were cracked, the volume pot was broken, the firmware was outdated, the waveforms weren't calibrating right, the filters weren't staying in tune, and sometimes, it just wouldn't turn on. I rebuilt the power supply, fixed up some frayed wire connections, bought a new DAC chip, replaced a broken trimmer, bought a new volume pot, sourced 2 replacement keys from a guy who 3D-prints replicas in Croatia (everywhere else in the world has long been out of original Matrix 6 keys), calibrated the DAC, recalibrated the 3 oscillators that handle tuning for all the voices, updated the firmware to the latest OS that fixes all the bugs, restored full aftertouch sensitivity, and installed a memory battery holder for ease of future replacement. I've been fixing up Matrix series synths for years now and they all suffer from instability in the CEM3396 voice chips that leads to carefully constructed patches melting into muck. Users tend to just replace the CEM's instead of fixing the root problems, so there's a now dire shortage of these chips. I've done work to ensure the synth will soldier on and never give you any hell, as long as you're nice to it. You can trust that all the usual reliability issues that plague Oberheims won't bother this Matrix.
This listing comes with the synth, a power cord, a huge ZIP file of 30+ years worth of patches, and my guarantee as a trained tech."
