After several hours ON, calibration resets to same miscalibration,RESTORE helps

[sander37]

I've noticed several times, after having the Polybrute power on for a 4-6 hours, suddenly the calibration is off.
Each time it's off in the same way, as if a faulty calibration preset has been recalled.

When this happens it's especially noticeable at the Steiner resonance, 4 voices sound more or less equal, one voice has way too much, an other voices way too less resonance, Steiner Frequency is also a bit off between voices and oscillators also sound a bit off, but not too obvious.
On one voice noise is not audible thru one of the filters, I believe it is the Ladder, but this does not occur every time the calib. is off.

Powering Off an On does not help in this situation.
The way to get a playable synth back again, is to enter Settings en go to 8.Misc/4.Voice Auto-tuning and select 4.Restore.
Now everything is back to normal again. The tuning of the Steiner filter could be better, but it's acceptable workable for now...


This behavior looks like a software problem to me.

Arturia, are you aware of this problem?

[DrJustice]

Just to be sure, did you run the calibration when it was fully warmed up, and what happens if you run the calibration after those 4-6 hours when it goes off?

[sander37]

I have the polybrute since 1 week now, the first time when this problem occurred, most Calibrations I tried ended in a calibration Time Out.

I've had one successful calibration, it had been warming up for 1 hour then, it also sounded correct after this calibration, but after a while the Steiner resonance and freq was offset between voices again.

The last few day's I didn't try a calibration any more, a RESTORE gives better results, but not every time.

edit:
The Polybrute is has been powered up for 20 hours now, and it's showing the same symptoms again.
1 voice has no VCO-2 thru Steiner Filter
the next voice has no noise thru Ladder-filter, and the Resonance of that voices Steiner Filter is too loud.

I will turn it off, let it cool down, and see if it will be ok again in a few hours.

[jgale]

I've owned my PB for about 3 weeks and have none of these issues.  I calibrated it once 2 weeks ago and now when I turn it on it is slightly out of tune by gets completely in tune after about 15 minutes of warming up. 

I even let it stay on for 14 hours to test for you what would happen and it stayed perfectly in tune. I'm not sure where you are located - but I am in NY and my ambient room temperature is only 65F - not sure if you are where it is warmer.

I think you may have a hardware issue.  You may want to try to reload the latest firmware one more time to see if that fixes it. If not - hopefully you can return it where you purchased it and get another unit.

Good luck!

John

[sander37]

After contacting Arturia support I decided to request a replacement from my dealer.

I received the replacement only 2 days afters sending mine in, thank you Bax-shop.nl

After connecting and powering up the new unit I was unpleasantness surprised.
The first 20 minutes there was no self resonance on the ladder filter on 2 voices. and no Steiner self resonance on another voice.

After warming up EVERYTIHING worked, as expected.

But, the next day started with the same symptoms.
Calibarations often fail in a timeout, but with this unit I do get a successful calibration sometimes.
Getting the message "calibation Done" does not mean it has been done well. (Filter tuning and resonance intensity can be way off)


Today after powering the PB up, I had no self resonance on Steiner filter of voice 6, resonance control has effect but it does not reach the level of self resonance.
After 10-20miin de resonance of voice 6 started being audible, but with frequency and intensity variations, (as if S&H was assigned to both frequency and resonance, but that was not case.

I suspected bad contacts, so I gave some taps with a finger on the front panel, just above the keyboard, from left to right.
Apparently voice 6 is located on the right, because the hessitant resonace of voice-6 muted when i gave a tap below the effect section. 10 minutes later, after warming up some more, the resonance of Steiner voice 6 started to return. At first it was still wobbly in freq and res intention, but now 3 hours later, all is in tune and working again.

So, this is my second unit with the same kind of problems, be it on different parameters.
I see a similarity.

I think this is caused by bad or hesitant connections internally, between  control and voice boards. What else could make this so time/temperature dependent.

DHL handles the delivery of my Polybrutes (unfortunaltely), I think method of board interconnectivity is not compatible with DHL transportation.
(there is a link on this forum to a Spanish review with pictures of the internals somewhere)

[DrJustice]

Does it ask for the cold calibration? I think the display says something like "PolyBrute is cold ... calibrate... OK / Cancel".

This calibration step is important, considering the symptoms, and it's different from the normal one that you run when the synth is warmed up. If doesn't ask for the cold calibration, let the synth cool down properly, maybe even opening a window for a while.

[sander37]

Th e PB has asked for Cold Calibration severals times.

I canceled the very first time, because it was still cold from transport.

Since then I've done several cold calibvrations (4 or 5 times over the weekend I think, maybe more, it felt like a "calibration weekend"), some ended in time out, and then most steiner resonaces would be very distorted, ladder filter resonance was sometimes down in voice 4 and 5, some ended in "calibratione Done" with variable results in tuning and resonance, over the voices. Certainly not what I would call calibratied. The same goes for calibrations I started from the menu.
I've updated to version 2.0, after this update the callbrations did not result in a DONE. after updating the 2.0 firmware for a second time, the calibrations started to have better results.
(maybe I need to update the firmware for a 3rd time to 2.0....)

The last few times I powered it up, it didn't ask for a Calibration anymore.

Both units are produced 08/2021

I really think there is a problem with the calibration procedures, my experience is that when the calibration is off, it is very hard to get it right again, as if the previous values are used as a base for the new calibration. keeping it in the same loop. 
I'm just making sort of educated guesses here, since the calibration doesn't give any feedback on what voice or segment failed.

My Oberheim Matrix 1000 never failed a calibration.


Al is in tune and working fine after a few hours of warm-up.....
(not what i hoped for.)



If it didn't sound as good as it does, i'd have just asked my money back.
But the problem is, my money doesn't sound as nice as the Polybrute.

[DrJustice]

It will ask for the cold calibration every time the synth is powered up in a somewhat lower temperature than for the last cold calibration. I.e. it will normally stop asking after a couple of times when the synth is in a fairly stable temperature, like being kept in a studio.

Some users have had to run a few calibrations before the synth settled down. After that it should be pretty much spot on though, in tune and with correct resonance right after power on. I'm sorry to hear yours isn't getting there, even with the second unit. Hope you can work it out with Arturia support. As you say, it sounds so nice that it's worth hanging in there until it's fixed. Keeping my fingers crossed for a solution!

[skysplitterink@yahoo.com]

I am experiencing the exact same thing, at this point it has done a cold calibration which got out to not be acting completely insane, but even then the steiner is still a bit out of tune and some of the patches that I have made just don't sound the same. I have yet to get it to actually perform an autotune of "ALL" and I think this is part of the problem as that seems to be the only time it calibrates the output level for the filters.

Man I love this thing and realllllly want it to come back to where it was this morning before I decided I just should Autotune!!!!