Oberheim Matrix-6r Voice Distortion

[alinear]

Hello,

Have an unusual problem with a Matrix-6r. The first of the six voices (confirmed since the LED lights up to show which voice is being triggered as you play) produces an unusual sort of distortion that is not present on the other 5 voices. It sounds like it is somehow completely overgained and distorting, but only on voice 1. I thought at first that the filter was somehow not working for voice 1 (since it sounds 'brighter' when triggered), but was suspicious because it was also in some cases much louder than the other voices...

In going through the patch editor I found that the filter, envelopes, etc. for voice 1 still contour the sound. It is simply distorted. No parameter I could change in the sound editing process would really alleviate the distortion. The real telltales are (1) if the DCO's are all shut completely off, as I trigger voices they naturally produce a small bit of noise. Voice 1 produces MUCH more and louder noise over the rest, and almost sounds like a noise generator... and (2) if a pulse waveform is chosen voice 1 becomes massively loud. I am guessing this is because a pulse wave is so clipped to begin with. Sawtooth doesn't actually distort so much - it just gets more buzzy and sounds unfiltered. Any sounds that use pulse are virtually worthless to play since every 6th note is loud as piss.

So, before I attack this thing with a soldering iron and/or sell it for parts I am wondering if anybody has any insight as to what the problem might be... if there is some particular component that is known to cause this issue with these synths, or if there is somehow a magical firmware upgrade that might fix it. I tried running the software calibration on it to no avail.

Any insight appreciated. For what I paid for this ($200), I am partly tempted to just let it go for parts and replace it with a 1000...

Thanks!

[Z]

That's a very common problem with the M6's. Not sure what the casue is, but can be fixed by replacing the voice chip for that voice. I had that problem in the early 90's and was able to get a new chip from Oberheim/Gibson. Originally, they sent me the chip for a M-1000 - same chip, only 2/3 narrower. It may be difficult finding the correct width chip for the M6, but I hear there are socket adapters. I have not seen them myself, so if anyone could shed some light on that, I would (and I'm sure OP would, too) be most appreciative. My M6R has another bad voice and I've got a M1000 at the shop that won't power up correctly, so hopefully I can pull its chips to keep my M6R alive.

[alinear]

Thanks! Hopefully I can find some without having to pull them out of another synth myself. I may replace the 6r with a 1000 or a couple of 1000s anyway. The built in editing really doesn't help much - and it takes up way more rack space, despite looking cooler.

[alinear]

For the record -- found some here:
http://www.synthtech.com/testcart/index ... x&cPath=68

They have CEMs for both the 1000 and 6/6r -- I guess they are the same model but different form factor. Now to practice my desoldering.