Tuning /calibration

valsolo · « **Reply #20 on:** April 24, 2017, 02:23:58 PM »

Hi guys,
I've got exactly the same problem. I've calibrated my synth many times but after a while I start getting this tune drift which makes the synth useless ... I recalibrate, it works for a while 5-10 minutes... then it starts again. Here's an example:

https://soundcloud.com/mjukost-1/weird

extempo · « **Reply #21 on:** April 24, 2017, 03:01:24 PM »

Quote from: valsolo on April 24, 2017, 02:23:58 PM

Hi guys,
I've got exactly the same problem. I've calibrated my synth many times but after a while I start getting this tune drift which makes the synth useless ... I recalibrate, it works for a while 5-10 minutes... then it starts again. Here's an example:

https://soundcloud.com/mjukost-1/weird

Hi Valsolo. Please see the previous posts in this thread from other DSI staff regarding calibration.

Jdoo · « **Reply #22 on:** April 24, 2017, 06:41:40 PM »

Quote from: valsolo on April 24, 2017, 02:23:58 PM

Hi guys,
I've got exactly the same problem. I've calibrated my synth many times but after a while I start getting this tune drift which makes the synth useless ... I recalibrate, it works for a while 5-10 minutes... then it starts again. Here's an example:

https://soundcloud.com/mjukost-1/weird

Something you can do, is check, and write down the internal temperature of your OB when it's drifted out of tune. It would give you a data point, if you think it's not holding tune at the same temps...

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...

I'm a horder.. when it comes to tips/BKMs...

teashea · « **Reply #23 on:** April 24, 2017, 08:04:27 PM »

I have run the calibration several times - my room temp stays very consistent. No problems - all works well.

syz-x · « **Reply #24 on:** May 22, 2017, 08:59:15 AM »

Valsolo: I have exactly the same issue with mine. I had it for two month's and I cant get it to stay in tune for more than a few minutes until I have to recalibrate. Done at least 200+ calibrations at different temperatures.

Been in contact with DSI support that kindly ask me to do further calibrations to solve the problem, meaning the instrument is somewhere in between two temperature tables and therefore "jumps" up and down in tuning.

I'm thinking of returning the instrument cause it is useless, cant even record a 5 min track without out of tune, and for live use.... forget it!

Have a few other VCO instruments in the same room without auto tuning, and temperature calibrations and such bells and whistles, and they stay perfectly in tune.

Morgenspaziergang · « **Reply #25 on:** May 23, 2017, 06:48:55 AM »

Yes you should absolutely return it if you keep having such issues and its useless to you.

DaveP6guy · « **Reply #26 on:** June 12, 2018, 07:16:17 AM »

Quote from: Soundquest on April 25, 2016, 08:48:20 AM

Have my OB6 about three weeks now. I've run the calibration as described in manual quite a few times over the last three weeks to give a sampling of room temperatures. My room doesn't vary widely, but after each power up/ warm up, I'm way out of tune. The quick and simple calibration procedure resolves this for me, but seems like I should be past this phase of calibrating every time I switch on.
Anyone else?

Wow. Some of the problems on this thread sound a little scary! I have a Prophet-6 and have not had this extent of problems. I've never actually played it with another synth so I should perhaps check that it's in tune with them!

I do however seem to have one voice that gets a little off compared to the others. I think it is one voice. However sometimes, it could be that this voice may be responsible for the real "sweetness" of the sound and some other wonderful quirks that I hear now and then that make me glad that I have a real analogue synthesizer.

I'm going to check my P6 against another synth. A digital one. They're useful for something!

AlainHubert · « **Reply #27 on:** June 12, 2018, 10:43:04 AM »

Just a heads up/follow up about tuning and temperatures. For months I had to wait for my OB6 to be warm-up to be stable, and even then after a while it would go out of tune. Not anymore. Because after clearing the temperatures reference table, and doing about a dozen calibrations as soon as it was out-of-tune, my OB6 is now flawless without the need for any further calibrations. It's in tune instantly, from cold to warm to hot transparently.
So if you have an OB6 that gets out-of-tune after a while, or is not in tune when powering it up, and you've already done many calibration calls to no avail, maybe clearing the temp table might be a solution. It was for me.

shmuelyosef · « **Reply #28 on:** June 12, 2018, 06:44:11 PM »

I got mine at the beginning of 2018. It took a while but settled down. I still occasionally notice a slow beat frequency when I first set up a new voice...very noticeable with two sawtooth waves in OSC1 and OSC2. A recal fixes it immediately.

tarekith · « **Reply #29 on:** June 12, 2018, 08:08:15 PM »

I had to erase the calibration table on mine when I first got it, even after a couple weeks of frequent recals it was still off more than I wanted each time I powered it on. After clearing the tables and doing a few more recals, it's been fine ever since.

pulsn · « **Reply #30 on:** September 14, 2020, 12:15:47 AM »

Is [Module+3] the same Key Combi on the Desktop Module as well to clear the calibration table? I pressed it and already calibrated during the past couple of days at least two or three dozen times but i keep having Tuning issues.

alexpen · « **Reply #31 on:** September 19, 2020, 08:55:24 AM »

Quote from: pulsn on September 14, 2020, 12:15:47 AM

Is [Module+3] the same Key Combi on the Desktop Module as well to clear the calibration table? I pressed it and already calibrated during the past couple of days at least two or three dozen times but i keep having Tuning issues.

Yes, Manual+3. You will get no feedback.
Before recalibrate, you can check the actual temperature by pressing Hold+Portamento+3. You will need to do recalibration on different temperatures. For example doing several recalibrations at one particular temperature will make no sense.

Soundquest · « **Reply #32 on:** February 06, 2021, 10:56:34 AM »

Quote from: AlainHubert on June 12, 2018, 10:43:04 AM

Just a heads up/follow up about tuning and temperatures. For months I had to wait for my OB6 to be warm-up to be stable, and even then after a while it would go out of tune. Not anymore. Because after clearing the temperatures reference table, and doing about a dozen calibrations as soon as it was out-of-tune, my OB6 is now flawless without the need for any further calibrations. It's in tune instantly, from cold to warm to hot transparently.
So if you have an OB6 that gets out-of-tune after a while, or is not in tune when powering it up, and you've already done many calibration calls to no avail, maybe clearing the temp table might be a solution. It was for me.

I went for years like this. It wasn't a big problem, but a problem that was noticeable as I always needed it to warm up. But when I updated OS last month I decided to give this "clearing the table" a try. I entered like 12 new calibrations at 12 different temps and the instrument is spot on ever since. I would recommend this for any new owner.

art507 · « **Reply #33 on:** November 11, 2025, 08:34:57 AM »

Hello, guys! I understand that this is an old and very common issue for this synth, I just wanted to confirm some similarities in how it works.

I bought a new OB6 two weeks ago. It already had the new firmware 1.8.0 installed.

Pros:
- All the voices sound quite similar in terms of filter opening and tuning.
- The 6 voices are VERY stable with each other in terms of tuning on VCO 1 (using VCO 2 the tuning between voices sometimes varies by 2-3 cents.) They are even more stable with each other than the 5 voices of my TEO 5.

Cons:
- I have a common problem where it's slightly out of tune after several calibrations

I wrote to Sequential's technical support and this is what they advised me:

“The best way to proceed is to leave the synth powered on and disconnected from MIDI/USB for several hours, running calibration whenever it goes out of tune from voice to voice.

Calibrate a minute or two after powering on for the first time.
Wait about 15-20 minutes, check tuning, then run another calibration if necessary.
After another 20-30 minutes have gone by, check tuning and run a calibration if necessary.
Peak temperature usually arrives at about an hour after powering on - check tuning and calibrate if necessary.”

mail:

“The purpose of calibration is to prevent the voices from changing significantly from baseline. When you run a calibration at a certain temperature, the microprocessor stores that data. When the synth next reaches that temperature the microprocessor offsets the CV to the oscillators and filter to maintain tuning stability. This is explained in detail here: https://support.sequential.com/hc/en...on-Calibration

The microprocessor is capable of interpolating between calibration data points. This is why you don't need to calibrate every second. That would be a lot of data, and a lot of CV offsets!”

I have done exactly what the technical support wrote to me, I have emptied the tables and created 4 new calibration points: 1) waiting 2 min when turning on the synth
2) 15 minutes latee
3) 20 minutes later
4) after having it turned on for 1 hour and 5 minutes.

As a result, I haven't observed any logical interpolation between calibration points. I recorded a video showing a huge jump and a quarter-tone difference in pitch between step 1 and step 2! It made no sense to have deleted the previous tables where I went degree by degree of internal temperature, starting from 40. At least in that case, there was a negligible OSC DRIFT of about 5-6 cents in the tuning

https://youtu.be/ir-cr-pjzEg?si=tYuZvr5JQG-M3mpR

art507 · « **Reply #34 on:** November 11, 2025, 08:37:20 AM »

I'm not quite sure if it's normal for the OB-6 to have a half-tone difference between being cold and fully warmed up (in approximately 1 hour to 1 hour 10 minutes). For example, I tried creating a single calibration chart when it was fully warmed up, and when I turned it back on, it was at a half-tone flat and then gradually increased to 440Hz. My TEO-5 only has about a 15-20 cent difference between being cold and warm.

It reminds me of my Moog Little Phatty when compared to the Sub 37. The latter was almost always in tune, but the LP needed about 45-60 minutes to be stable (otherwise it was almost 2 semitones flat when cold).

I don't understand the comments from Sequential's technical support saying that the OB6 doesn't need a warm-up for calibration. But in practice, it starts to stabilize after being powered on for an hour. Have you had the same experience?

Soundquest · « **Reply #35 on:** November 11, 2025, 10:02:54 AM »

Art507, Mines been quite good lately. Sounds like you are already detail oriented....but some mistakes ive made in past during cal....Make sure your room is stable when doing the cal points. Make sure wheels are zeroed. Make sure no effects when checking on the scope.

art507 · « **Reply #36 on:** November 11, 2025, 11:13:52 AM »

Quote from: Soundquest on November 11, 2025, 10:02:54 AM

Art507, Mines been quite good lately. Sounds like you are already detail oriented....but some mistakes ive made in past during cal....Make sure your room is stable when doing the cal points. Make sure wheels are zeroed. Make sure no effects when checking on the scope.

Yes, I'm quite observant

There are no added effects and the room has a stable temperature. This is the second Ob6 I've owned. I bought the first one three months ago and it gave me a lot of problems: the voices sounded different from each other, the number buttons failed every day, and in the end I returned it.

What doesn't make sense to me is that Sequential uses the same calibration protocol and advice for the Ob6 (a relatively old model) and for the Teo 5, for example (a recent model from last year). At least in my case, the Teo 5 is quite stable after just 10 minutes of warm-up, while the Ob6 needs an hour, so that tuning up and OSC drift do not appear.

BT · « **Reply #37 on:** November 11, 2025, 04:45:23 PM »

It's pretty simple actually. Run as many calibrations as it takes to achieve stable tuning, spaced across power-on time in a logical manner. On some instruments it takes fewer calibrations; on some it takes more. Different environments can influence the process. We provide general guidelines so you can understand the process and proceed appropriately.

art507 · « **Reply #38 on:** November 11, 2025, 05:11:53 PM »

Quote from: BT on November 11, 2025, 04:45:23 PM

It's pretty simple actually. Run as many calibrations as it takes to achieve stable tuning, spaced across power-on time in a logical manner. On some instruments it takes fewer calibrations; on some it takes more. Different environments can influence the process. We provide general guidelines so you can understand the process and proceed appropriately.

Thanks for the reply!
- Do you think it's normal for my Ob6 unity to have a full semitone difference in tuning when cold versus warmed up?
- I understand that I won't be able to completely avoid Pitch Shift or OSC Drift at some point, when I'm beetwen the calibration tables, whether I create just 2 or 20? It seems the synth is only completely stable once it's reached its maximum temperature…

generalkustard · « **Reply #39 on:** November 11, 2025, 09:23:03 PM »

Quote from: Soundquest on April 25, 2016, 08:48:20 AM

Have my OB6 about three weeks now. I've run the calibration as described in manual quite a few times over the last three weeks to give a sampling of room temperatures. My room doesn't vary widely, but after each power up/ warm up, I'm way out of tune. The quick and simple calibration procedure resolves this for me, but seems like I should be past this phase of calibrating every time I switch on.

Anyone else?

Try clearing the calibration tables (manual +3) then do a calibration. Recalibrate again tomorrow.