pitch instability

pitch instability
« on: October 29, 2021, 07:02:47 PM »
I have a new OB-6 when I first received the unit I calibrated the pitch manual + 0 button
a few days later the pitch has become completely unstable varying many pitches when holding down a key.
This worries me that the unit is flawed? I understand oscillators drift with Temperature , this is not just drift this is crazy varying pitch. I don't think I should have to calibrate unit every time I use it isn teh exact same temperature controlled studio? Just curious if anyone else has had this problem before I exchange?

Re: pitch instability
« Reply #1 on: October 30, 2021, 07:09:04 PM »
Run calibration again after itís warmed up.

Re: pitch instability
« Reply #2 on: October 31, 2021, 05:30:54 AM »
I'm sure there's a more detailed explanation elsewhere in the forums but there is most likely nothing wrong with your unit. This is normal behaviour as you need to calibrate over several sessions in order for the OB-6 (and other Sequential analog synths btw) to build up its tuning tables at different temperatures. It took mine about a week to stabilise. All of this is covered on page 65 of the manual.

Re: pitch instability
« Reply #3 on: December 07, 2021, 12:11:40 PM »
@echo44
Has this issue been resolved for you? I have received a brand new OB-6 today and am experiencing tuning issues as well:

Specifically, when holding a note, the pitch might shift up by ~25 cents after a while and back down again after a few more seconds. A while ago, I was using an older unit which I returned because a number of other issues, that seemed to show a similar behavior.

I have the suspicion that it might be a quantization issue with the temperature tables (such as switching between different sets of parameters when the measured temperature inside the unit slightly changes). The displayed temperature is a constant 47 degrees celsius. The firmware version is 1.6.8 (the used one I still had a few weeks ago was the currently downloadable version 1.6.6).

Edit: I have calibrated the unit a couple of times in warmed up condition but this did not change anything.

Re: pitch instability
« Reply #4 on: December 07, 2021, 04:48:41 PM »
@jmech
I got mine this week with a similar issue.
I followed advice of clearing the table, then running calibration. Worked fine ever since.
« Last Edit: December 07, 2021, 04:52:48 PM by Hyvai »

Re: pitch instability
« Reply #5 on: December 08, 2021, 08:24:21 AM »
Just a suggestion:  Don't know if this fix ever made it to manual, but if not,  it seems frequent enough to put in a trouble shooting addendum. 

 
Sequential/DSI Equipment: Poly Evolver Keyboard, Evolver desktop,   Pro-2, Pro-3, OB6, P-12,
 

https://Soundcloud.com/wavescape-1

Re: pitch instability
« Reply #6 on: December 10, 2021, 01:28:47 PM »
@Hyvai
Yes, I have reset the calibration table after posting my previous comment and the "pitch shifting" issue seems to have been gone since then.
I am wondering if it makes a difference if the initial calibration after the reset is done with a cold or a warmed up instrument as it is possible that the entries of the table are all initialized on the first run and refined on consecutive runs at different temperatures after that.
In my particular case the unit was warmed up.

Re: pitch instability
« Reply #7 on: December 21, 2021, 01:54:40 PM »
@Hyvai
Yes, I have reset the calibration table after posting my previous comment and the "pitch shifting" issue seems to have been gone since then.
I am wondering if it makes a difference if the initial calibration after the reset is done with a cold or a warmed up instrument as it is possible that the entries of the table are all initialized on the first run and refined on consecutive runs at different temperatures after that.
In my particular case the unit was warmed up.

I'm not sure, I ran another after it had been on for a while and again at peak temp. So I have 3 I presume now?
Glad yours is working now.

Re: pitch instability
« Reply #8 on: December 22, 2021, 10:13:23 AM »
This calibration is described elsewhere in the OB6 section of the forum.  Check out those posts.  It's a known issue on a certain percentage, but  easily fixed.   Prior to doing the reloading the cal table fix I was very dependent on warm up for stability.
Sequential/DSI Equipment: Poly Evolver Keyboard, Evolver desktop,   Pro-2, Pro-3, OB6, P-12,
 

https://Soundcloud.com/wavescape-1

Re: pitch instability
« Reply #9 on: March 20, 2022, 03:18:00 PM »
Just got a new OB6 and experiencing that myself, though I'm pretty sure it will resolve itself with repeated calibrations over the next few days. My P6 was similarly temperamental for the first while I had it but now is solid as a rock.