BUG report in OB-6 Desktop tuning

[John01W]

Ok, I don't have a big problem with it keeping overall in tune...but what IS out of tune is the voices are not in tune with each other.

Here's an experiment for you to try OB6 users and test it for yourself, I believe it is a bug in the tuning.

Hit your calibration function, wait for it to tune....

Then hold manual and press write to give you a new patch....

to make it easy to hear put vco 1 on square and bring up the volume....put vco 2 on square and equal it's volume to osc 1...

detune the oscillators to taste.....I like to detune it to where there's slow motion beating on the lowest notes but not too much that it makes the high notes sound "squiggly"....the "sweet spot", so to speak.

Now, hit the same note repeatedly so you can hear the rate of the pulse of the two oscillators beating against each other.....the OB6 will "round-robbin" through the voice cards.....you'll notice that the tuning of these voice cards are out of tune from each other because the beating rate changes pretty drastically depending on which voice card is selected...  the voice cards are NOT in tune with each other...  So the effect of this is that detune of vco 2 effects some voice cards more than others.

So the effect of this is, getting your detuning just right like I described below sometimes the beating will be static, sometimes the beating will be fast, and other times medium.  The OB6 is not in tune with itself.

Sucks when you have the detune on the low notes just right and some times you hit that lowest note and it's just static....the opposite effect happens on the high notes...makes it impossible to hit that "sweet spot"

[John01W]

Basically, just saying the calibration doesn't tune all the voice cards together accurately enough(test it immediately after calibrating)...2 or so of them are a few or more cents off.  Wish the calibration was a bit tighter between the voice cards.

[autoy]

No, please don't make the tuning tighter between cards. Big reason to get the OB-6 is to have tuning a bit loosened up.

[John01W]

No, please don't make the tuning tighter between cards. Big reason to get the OB-6 is to have tuning a bit loosened up.

Did you test yours?  Good grief man,  I DON'T WANT super tight tuning between the cards, and I agree with you that it being slightly loosened up is a good thing and I already love the sound of the OB6, but 1 or 2 of the cards is much more so, so much that it "barks" from time to time(this is immediately after a calibration).  I can see I'll have to post clips to demonstrate. 


Again, did you test it?

[John01W]

Here is what mine is doing.  Test settings, hold manual, press write...then these settings vco 1 and 2 both sawtooth...NO detuning, same volume....no midi controllers/aftertouch enabled, no pedals plugged in...nothing else turned on...directly after a calibration:

voice card 1  nowhere above .5 cents difference (good, natural)
voice card 2   about the same(natural good variance, what we want)
voice card 3   about the same(same, good variance but not "out")
voice card 4  4/5 cents off(drives me NUTS when trying to get accurate detunes with rest of notes, it BARKS)
voice card 5   somewhere like first 4
voice card 6   1-2 cents off

as you can see, I LIKE the natural looseness...but this 4-5 cents off thing drives me NUTS!  By the time you bring up the detune on MOST of the voices just right,  the "BARKER" adds it's 4/5 cents to whatever detune you do and it can howl in the high/mid high ranges.  Is it just my unit?

[John01W]

No, please don't make the tuning tighter between cards. Big reason to get the OB-6 is to have tuning a bit loosened up.

BTW, I'll state it again....I AGREE with you.....I do not want to do anything that would change the OB6 sound(I LOVE IT), I just have some outlier voices in tuning  and I'm at the point of humoring the possibility that it MAY be a voice card possibly but I need to call the good folks at DSI before jumping to that conclusion......(OB6 is a masterpiece guys, inspires me to write/tweak sounds like no synth I've had before)

I'm with ya autoy!

[CMorg]

I've just noticed that in my OB-6 VCO 2 seems to be the only oscillator where the voices are out of tune with each other, varying from 0 to 5 or even 7 cents out of tune. This seems great for patches where you want VCO 2 to be detuned to VCO 1, but say you were using a patch where you had VCO 2 as the only oscillator (triangle wave for example), you would run into some tuning issues. That said if you run VCO 2 as a unison patch for bass or something its tuning is spot on because it's not round robining through the various slightly detuned voice cards. Can anyone else confirm that their OB-6 behaves this way?

Each VCO 1 voice card is perfectly in tune with the next on my synth, but not VCO 2, does anyone know if this is a deliberate design decision?

[John01W]

It would be great if there were some dedicated settings in the globals(per patch would be even better) for detune offsets by cent for each of the osc 2 voices so that folks who wanted more consistent detuning between the voices could have it or not if you like the way it is now(best of both worlds).  I reported mine as being in between 5 cents for some of the voices but I didn't hook up a tuner to it and accurately test it, it could be more for the extreme voices.
This would satisfy folks who like it currently and those who have a problem with it for some sounds.  It would kinda be like having the ability to calibrate manually like vintage synths.

[DaveP6guy]

I'm going to try that on my Prophet-6. I think my P6 has a similar problem that one voice (I think) is not always properly in tune with the others. So I occasionally get a sour (or an extra sweet) note - depending on how much it is out of tune when using the arpeggiator or when just playing manually. I wonder if I might need a replacement voice board but to be honest sometimes it sounds just fantastic. I have run the calibration routine about 6-7 times over about 3 months (there is some temperature variation in my room (no way could I call it a studio). I can't quite get a handle on when the tuning is out, i.e. whether it is if I start playing on switch on or whether it is when the unit has been on a long time.

I have no way to measure it at home but as long as it is not too bad, I don't care. It seems to be present more on some patches/sounds than others and I wonder if sometimes the waveform I am using makes a difference. Maybe something is fooling Dave's system for adjusting the control voltages in real time? I don't know. I sometimes wonder if they put 5 grade A voice cards and one grade B voice card in every machine to make them sound more real!

I get these occasions when one or more notes has a wonderful "buzz" running through it, sounds so analog, so "real" that I would not want to change anything on my P6 unless the de-tuning got worse. I think the rogue voice is the one that also produces these rally cool variations in the sound. My P6 sounds rustic, maybe that's not quite the right word, earthy then. Sometimes I can't believe how much I like the sound of the thing when it is on song. Great sounds (not the presets!) just seem to fall out of it when I experiment with it.

I don't know how to defeat a voice on my P-6 or even whether I can do it. Can anybody tell me if it is possible? Carson at DSI mentioned on his DSI YouTube tour that you can do it with the OB6 (as you could on the old OB8 I believe.)

Ok, I don't have a big problem with it keeping overall in tune...but what IS out of tune is the voices are not in tune with each other.

Now, hit the same note repeatedly so you can hear the rate of the pulse of the two oscillators beating against each other.....the OB6 will "round-robbin" through the voice cards.....you'll notice that the tuning of these voice cards are out of tune from each other because the beating rate changes pretty drastically depending on which voice card is selected...  the voice cards are NOT in tune with each other...  So the effect of this is that detune of vco 2 effects some voice cards more than others.