The Official Sequential/DSI Forum


« on: April 20, 2021, 08:52:13 AM »
When I power on the OB6 it needs tuning twice every time. First time holds the tuning for 1/2 a minute or so. Then after re-tuning a 2nd time, sometimes a 3rd time, it hold its tune until powered off and not used for a while.

Is this normal for the rest of you guys?

I understand with VCOs tuning is part of the deal. I have no problem with this. I'm just not sure what is normal. I also understand temperature changes effect the tuning. My OB6 remains in the same location with minor temperature changes I suppose.

Also, I thought I saw in another tuning post that someone had tuning issues when they had a pedal plugged in. I do have pedals plugged in for sustain and filter cut off.

Re: Tuning
« Reply #1 on: April 20, 2021, 11:06:12 AM »
I thought I was going crazy, but I'm experiencing something similar.  I have the OB-6 Desktop and I'm controlling it with the Moog Matriarch.  I thought maybe the Matriarch was sending weird MIDI messages to it that were causing the pitch shifts (I still haven't ruled this out as the problem). 

They're very sudden, and several semitones of detuning.  After 20 minutes or so (I haven't timed it) everything seems to be fine.  Note that I don't retune anything, it just eventually goes back to normal.  I wasn't under the impression that the OB-6 needed any kind of "warm-up" period. 

Would appreciate any pointers on this weird problem!

Re: Tuning
« Reply #2 on: April 20, 2021, 11:58:29 AM »
Search "tuning/calibration" under this segment of the forum using the search function above.   See my Feb 6th post and read others contributions.  There is a pretty easy fix to this.

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

Re: Tuning
« Reply #3 on: April 20, 2021, 12:32:31 PM »
Looks like the post Soundquest is referring to is here...,475.20.html

Post number 22 reads...

What’s the OB’s current internal temperature?
Hold the "transpose" buttons and press the "3" button.   
If you have the desktop module, to display the internal temperature, press the "hold" and "portamento" buttons and press number 3.
Clear Internal Temperature Tables? (careful!)
   [MANUAL] + 3
Again- be careful doing this, as it will (may?) reset the internal calibration tables, and your OB will need to relearn temperature variations.   This last tip... I haven't done... for fear of whacking something out of kilter on my OB desktop.  Proceed at your own risk...

So basically reset the temperature table by holding the "Manual" button and "3".

Looks like there is no feedback that anything has actually been done. However, it did take longer to do a calibration. Not sure if this will fix the issue. I will try to remember to post back in the future the results.

Re: Tuning
« Reply #4 on: April 21, 2021, 08:17:54 AM »
Correct,  my most recent post (February) in that thread basically is saying that I cleared the calibration tables as described earlier in that thread, then re-ran a series of calibrations over several temperatures ranges.  It's been rock solid ever since I did this step.   I think I used a total of 12 calibration runs .

Prior to doing this easy fix it was always a craps shoot with how tuning was going to behave.   I think enough people have identified this problem over the years to warrant validity and an addendum to the manual as a possible trouble shooting pointer.  Its a minor inconvenience to fix, but an actual problem for those who've experienced the glitch, especially, I would think, if you are not privy to this forum.   
Sequential Equipment: Poly Evolver Keyboard, Evolver desktop,   Pro-2, OB6, P-12

Re: Tuning
« Reply #5 on: April 21, 2021, 09:23:07 AM »
Thanks, I'll give this a try.


  • ***
  • 567
Re: Tuning
« Reply #6 on: April 21, 2021, 12:56:00 PM »
It also never hurts to recalibrate the wheels.  Once on my P6 I was having some very subtle tuning issues that appeared on the surface to be temperature calibration related.  What I think may have happened is at some point I may have inadvertently hit preset + one of the numbers to recalibrate, which caused a partial (flawed) recalibrate, throwing off the tuning ever so slightly.  It happened after an OS update which was baffling, and I had literally tried everything else.

The manuals say you don't normally need to do this, and I'm sure that's true sans the mistake above, but if you've exhausted all other tuning troubleshooting methods (as I had), definitely give it a try. 
Prophet 10, Prophet 6, OB-6, Prophet 12m, Prophet Rev2-16, Toraiz AS-1, Moog SlimPhatty, Hydrasynth desktop, Korg Minilogue XDm, Roland SPD-30, Roland SPD-SX Special Edition, Roland KT-10, Maschine, Focusrite Scarlett 18i20 3rd Gen + Octopre, Strymon Pedals, Cubase Pro 11.

Re: Tuning
« Reply #7 on: April 22, 2021, 03:05:58 PM »
Just wanted to write back and say that following the advice in the thread linked above seems to have solved all of my issues.

  • Clear the temp tables: MANUAL + 3
  • Check the current temp: HOLD + Portamento + 3 (pretty much just to make sure you're not calibrating the same temp multiple times)
  • Calibrate for the current temp: MANUAL + 0

Rock solid now, and I swear it sounds even better than it did before!

I will note to be careful not to do HOLD + Potamento + 0... this wipes out presets 500 - 999 and replaces them with presets 000 - 499.  Whoops.

Re: Tuning
« Reply #8 on: April 23, 2021, 09:13:51 AM »
Good to hear Techsture,  Enjoy the machine.
Sequential Equipment: Poly Evolver Keyboard, Evolver desktop,   Pro-2, OB6, P-12

Re: Tuning
« Reply #9 on: April 28, 2021, 10:02:53 AM »
Tuning has been good at first power up after reseting the temperature table.

I agree with the post above about the manual should be updated with this info. My OB6 was new from unopened box so perhaps there is something in the factory settings with the temperature table that needs reseting upon first use.

Re: Tuning
« Reply #10 on: May 04, 2021, 04:43:07 AM »
I wasn't under the impression that the OB-6 needed any kind of "warm-up" period. 
From the operation manual:
How and When to Calibrate the Oscillators and Filters
The first time you use the OB-6, please run its built-in oscillator and filter calibration procedure. Let it warm up for several minutes and come to its normal operating temperature before doing so.