Every other note is slightly pitched (when playing the same note over and over)

Hey everyone,

A couple of months ago I bought an OB-6 module and I loooove it.

However, since a few weeks ago, whenever I play a single note multiple times in a row, every other note seems slightly pitched lower. So first note sounds normal. Second note lower. Third note normal again, fourth lower, etc.

Even with a blank patch.

When I play 2 different notes after each other, they're both the same every time I play them. But a single note will sound different every other note.

I tried re-calibrating multiple times, even reset the global settings. But it does not seem to do much. One time after re-calibrating I thought it was fixed but a day later it sounded wrong again.

The room temperature is pretty stable where my OB-6 is.

Does anyone know what I might be doing that might cause this issue?

Cheers, John

By “calibration” do you mean the wheel calibration or the tuning routine (manual+0)?

The tuning tables do take a while to populate. If you’ve cleared them and then run the routine whenever there’s a tuning discrepancy, after a week or two they should be more stable.

Is it possible that the sounds had some vintage knob applied? This does introduce tuning variances by design.

Furthermore, with analogue oscillators, there is a bit of voice-to-voice variation anyway.

Hello John, and everyone else here..

I have updated to firmware 1.8 a few weeks ago and since a few days i notice the same phnenomenon you describe.

;If I press one note multiple times the pitch goes up and down by every hit.
When set to unison the pitch stays the same.

Did you find an answer to this yet i was wondering?


edit: I just calibrated the oscs and filter once again and for now it seems ok again. fingers crossed!
« Last Edit: January 21, 2024, 05:20:15 AM by Remco »

I thought I would post this here instead of starting a new thread since it is so similar to my new experience. Just purchased my Ob6 last night and noticed the volume loss in the same note in succession. To make matters even stranger, there are certain notes that take on a mind of their own. I've included a video below to document the odd behavior. Perhaps it's user error as I still need to learn it. Just never experienced anything like this on my P6:


Perform the calibration steps seen in the manual.
Sequential/DSI Equipment: Poly Evolver Keyboard, Evolver desktop,   Pro-2, Pro-3, OB6, P-12,


If any of you started experiencing these problems after updating to 1.8, that’s most likely the issue. It wrecked my unit till I downgraded. What it caused was:

1. Pitch problems nonstop, especially after warming up.

2. Hissy noise on notes 5 and 6, again, usually  after warming up.

3. Calibration hanging on 43, also after warming up. It would pass calibration if the unit was cool.

The fix is to email support and get a copy of 1.74 and reinstall it. Why a new OS would break certain units is beyond my knowledge but it clearly is happening. Hopefully they can make a newer update that works universally.

That is, if it even needs many updates at this point… Cheers.