Voices A4-A7 distort and only output on right channel.

[thrashhmusic]

Hello, I just picked up a 16 voice rev 2 today and unfortunately am already having problems with it.

Even on a new patch (and after calibrating osc/filters), voices 4-7 on the A side:

1. Only output on the right channel (even with output in MONO, strangely)
2. Seem to (at least partially) bypass the filter. I say partially because the sound does change, it almost sounds like there is a 50% mix knob applied to the filter for these voices. (I can still hear the high end but it is less loud when the filter cutoff is low) The more I listen to this the more it sounds like distortion adding high frequencies, not bypassing the filter. My theory based on output testing (details at bottom) is that L/R channels are being summed in the right channel and it's clipping somewhere in the signal path.

Seems like a hardware defect, and it happens regularly and predictably, across all patches, all notes, init patch, etc.

I'm able to tell which voices are the problem by clicking the "Global" button and watching it cycle through A/B voice #s in the bottom left. The weird behavior reliably happens on voices 4-7 on the A side.

I did buy it used, although I can tell that it was very lightly used. The previous owner said he bought it as a 16 voice, did not upgrade from 8 to 16 himself.

I'm running firmware v1.2.1

Some additional things I've tried:

- Calibrating Oscillators and Filters
- Resetting Global Parameters
- Upgrading to latest firmware (from v1.1.5.9 to v1.2.1)
- Using PHONES output instead of MAIN/A
- Unplugging USB midi cable
- Pulling my hair out

Thanks in advance for any advice. If there is a way to factory reset everything I'm willing to try that, although the previous owner imported some cool user patches I'd like to keep if possible

EDIT: Some more debugging that may be useful:

OUTPUT TESTING

when plugging into just one output at a time, A Left, A Right, B Left, B Right: (with only patch A playing)

A Left: Voices 0-3, 8-15 play, Voices 4-7 have no sound
A Right: All voices play, and voices 4-7 seem to be louder than the rest. Maybe voices 4-7 are summed to one channel and the "50% mix filter" I thought I was hearing is actually some sort of distortion caused by this summing?

B Left AND Right: Voices 0-7 make no sound, 8-15 do

Not at all sure what to make of this last bit..

[4dubs]

While I would recommend contacting Sequential's support team, I had a similar issue with a single voice not too long ago.  Recalibrating didn't fix the issue.  Sequential support recommended opening the unit and simply reseating the voice card that was at fault.  That fixed the issue instantly.  It's a simple procedure, but again, you might want to reach out to Sequential directly first to see what they think. 

[thrashhmusic]

4dubs, thank you so much for your reply.

I did contact support but they were a little slow and I was antsy to get this thing working so I tried reseating the voice expansion card and it did the trick (after another OSC/Filter calibration)

You're a G for suggesting that one, enjoy ur good karma.

[4dubs]

You know what?  Don't thank me so fast.  After I replied, I realized that the instrument I had the voice issue with was my Prophet 6, which has individual voice cards for each synth voice.  A REV2 will have 2 voice boards, one for each 8 voice layer.  I'm not sure if reseating those boards would fix your problem seeing as you're having difficulty with only 4 voices on the one board.

So sorry for remembering things incorrectly, but the problem you described was very similar to what I experienced.  I just got the two synths mixed up!  I'd be curious to hear what Sequential recommends.  They've always been very helpful.  Worst case scenario, you could always get a replacement voice board from them.  They're real easy to swap out.

[4dubs]

Oh man, I guess I didn't fully read your previous response.  Glad reseating the board worked out.

[thrashhmusic]

Sequential got back to me today and said to do exactly what you said: reseat the voice expansion card. So you def earned that thanks, got me an extra night with my new rev2 

[4dubs]

That's awesone.  Enjoy it!