via this auction
"This is the rackmountable version of the vintage analog matrix 6 synthesizer made in 1985. This is the original version (not the later remake. matrix 1000) made by Oberheim.

The matrix line of synthesizers were a step ahead of most other polyphonic synthesizers of the era due to the modulation matrix which enabled you to modulate almost any parameter by another parameter or source. This makes for very unique and complicated sounds.

The matrix 6r has a very brassy oberheim sound. Typical of the VCF CEM filters that it uses.
It can do almost any type of polyphonic sound you would ever need, ie leads basses pads and there are literally 1000s of patches available for you to try out.
I definitely say it has a strong presence. Whilst the oscillators are DCO's and don't noticeably drift, detuning and pulse width modulation on this synth are huge. It has some of the best strings, pads and brass sounds I have heard. I own a jupiter 8 and it is a noble competitor. It's no wonder that it has many patches named after the great synths CS-80, Prophet 5.. etc.

I've heard a lot of complaints that the matrix 6r is hard to edit etc. I personally used mine through software editors. It is quite easy to set midi controllers to adjust the filter cut off,resonance and envelope settings in real time without any lag or delay."