Filter cutoff varies noticeably across voices despite running calibrations

I have a brand new OB 6. Performing a tuning calibration resolves pitch drift as expected but does not seem to calibrate the filters across the voices. If I turn resonance all the way up and play the same note six times, I get six different resonance pitches. I use the triangle waveshape for this since it's easiest to hear the actual filter. Repeating this, they are off by the same amounts each time it cycles through the six voices so it's clear the calibration isn't working correctly on filter cutoff per voice. Is this normal? If not, will it get better with time and more calibrations?

Unfortunately I noticed the same issue with two OB-6s that I bought and returned because of it (besides wobbly knobs and an improperly working button). Both were already running fw 1.74.

The first OB-6 I had ever tried and fell in love with did not seem to have those particular problems but it was an older revision, still showing the DSI branding and running fw 1.66 iirc.

When comparing the sound of a few factory presets to recordings I made with the older one, I noticed that the recent OB-6s sounded noticeably brighter/fizzier.

Recent OB-6s seem to have blueish voice cards in contrast to the older green ones. No idea if the “phenomenon” could be caused by subtle changes within the hardware or the firmware.

Frankly, I grew tired of being disappointed by the quality of a product at this price point.
« Last Edit: April 21, 2022, 01:56:02 PM by jmech »

LPF83

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What's described here to me sounds like the (optional) vintage knob behavior is turned on.  Hold Bank and press Globals (this is a third globals page with two lights).  Press 4.   Does it say "On"?   If so Vintage knob mode is turned on so the detune control creates variation in envelopes, tuning etc across voices.  Its round-robin voice allocation, so each note is going to a different voice.  Turn off vintage mode or lessen detune to see if it helps.
Prophet 10, Prophet 6, OB-6, Prophet 12m, Prophet Rev2-16, Toraiz AS-1, Virus TI2, Moog SlimPhatty, Hydrasynth desktop, Korg Minilogue XDm, Roland JP-8080, Roland System-8, Roland SPD-SX SE / Octapad, Maschine, Cubase

What's described here to me sounds like the (optional) vintage knob behavior is turned on.  Hold Bank and press Globals (this is a third globals page with two lights).  Press 4.   Does it say "On"?   If so Vintage knob mode is turned on so the detune control creates variation in envelopes, tuning etc across voices.  Its round-robin voice allocation, so each note is going to a different voice.  Turn off vintage mode or lessen detune to see if it helps.

Hi. Thanks for the reply. Yeah, as a P6 owner I'm familiar with the vintage mode but this happens irrespective of that setting. I should have updated this post that I've since done extensive troubleshooting with Sequential, including resetting calibration tables, numerous calibrations and even a replacement voice card, all without much improvement.

The tech is basically saying, they are designed to behave this way, so I guess I just need to decide if this is the synth for me or not. I get the idea of some variation between voices but what I'm experiencing seems more extreme than I'd expect, even from a VCO synth.

Unfortunately I noticed the same issue with two OB-6s that I bought and returned because of it (besides wobbly knobs and an improperly working button). Both were already running fw 1.74.

The first OB-6 I had ever tried and fell in love with did not seem to have those particular problems but it was an older revision, still showing the DSI branding and running fw 1.66 iirc.

When comparing the sound of a few factory presets to recordings I made with the older one, I noticed that the recent OB-6s sounded noticeably brighter/fizzier.

Recent OB-6s seem to have blueish voice cards in contrast to the older green ones. No idea if the “phenomenon” could be caused by subtle changes within the hardware or the firmware.

Frankly, I grew tired of being disappointed by the quality of a product at this price point.

Exactly. Since my first post I've done extensive troubleshooting with Sequential support and have basically been told that this is just how the OB6 is and that it's what people wanted. So if that's true I guess I just need to decide if it's right for me or not. I'm beyond my return window at the retailer anyway so I guess I can take my time seeing if I warm up to it. Otherwise, I can sell it and should be able to break even since I got a good deal on it.

Bummer for sure.... thought I was gonna love this synth
« Last Edit: April 21, 2022, 04:42:21 PM by synthwave4ever »

I've mentioned in my other replies here that I've been working with Sequential support. I just want to take the time to say that experience has been great. The tech has been extremely thorough and responsive and seems to be doing everything in his power to help me. Whether or not I keep the OB, I wanted to shout out the good support from Sequential. The buzz you hear about their support is 100% true.

LPF83

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What's described here to me sounds like the (optional) vintage knob behavior is turned on.  Hold Bank and press Globals (this is a third globals page with two lights).  Press 4.   Does it say "On"?   If so Vintage knob mode is turned on so the detune control creates variation in envelopes, tuning etc across voices.  Its round-robin voice allocation, so each note is going to a different voice.  Turn off vintage mode or lessen detune to see if it helps.

Hi. Thanks for the reply. Yeah, as a P6 owner I'm familiar with the vintage mode but this happens irrespective of that setting. I should have updated this post that I've since done extensive troubleshooting with Sequential, including resetting calibration tables, numerous calibrations and even a replacement voice card, all without much improvement.

The tech is basically saying, they are designed to behave this way, so I guess I just need to decide if this is the synth for me or not. I get the idea of some variation between voices but what I'm experiencing seems more extreme than I'd expect, even from a VCO synth.

Yes, there is a certain amount of variation from voice to voice even before the vintage knob update on the OB-6 compared to the P6 or other synths -- I always assumed it was done that way to give it the sound of the older models it was inspired by (they were pretty messy in this regard).   I may have assumed you were talking about some of the more  extreme behavior that's obtained with higher vintage knob settings.
Prophet 10, Prophet 6, OB-6, Prophet 12m, Prophet Rev2-16, Toraiz AS-1, Virus TI2, Moog SlimPhatty, Hydrasynth desktop, Korg Minilogue XDm, Roland JP-8080, Roland System-8, Roland SPD-SX SE / Octapad, Maschine, Cubase

Sorry, I should have mentioned explicitly that I have done the whole dance with resetting tuning tables multiple times and also excluded other sources of variations like the detune/vintage parameter.
In my experience it is fixed to the voice number / card which, at least for me, sticks out like a sore thumb once you noticed the difference for the first time.
If five out of six voices behave identically and one very noticeably different, I highly doubt this is intended in order to make it sound “more vintage”…but more likely either the result of tolerated component variation, or a level of quality control that, at least from my perspective, seems questionable.

LPF83

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Sorry, I should have mentioned explicitly that I have done the whole dance with resetting tuning tables multiple times and also excluded other sources of variations like the detune/vintage parameter.
In my experience it is fixed to the voice number / card which, at least for me, sticks out like a sore thumb once you noticed the difference for the first time.
If five out of six voices behave identically and one very noticeably different, I highly doubt this is intended in order to make it sound “more vintage”…but more likely either the result of tolerated component variation, or a level of quality control that, at least from my perspective, seems questionable.

I totally agree, if one voice out of six seems wildly different than the others, it tends to point more to a bad voice card IMHO.   I will say that for whatever reason, my OB6 seems especially prone to weird behavior involving individual voice variation if I'm not careful about things like MIDI loops (leaving local on, and having track monitor enabled in the DAW for example). 

By that I mean I have a number of Sequential synths, and occasionally have these "false positive" conditions where I think the hardware is starting to fail, and yet every time, it turns out to be something about my own configuration that is set wrong.  But, this false positive syndrome seems to occur much more often on the OB6 than my other gear.

My relationship with the OB6 has been interesting..  Sometimes in the discovery of false positives, it has felt a little like the type of girlfriend that always manages to make me feel like the bad guy even when my behavior is well within norms by everyone else's standard :).   I regard it as sort of an impish little demon of a synth with plenty of "character".... yet because the false positives have always turned out to be my fault and had a clear explanation for why they occurred, it remains a highly regarded piece of gear in my setup.

Oberheim products (at least the ones the OB6 was patterned after) are notorious for misbehavior, no where near as refined as Prophets.

But the symptoms of a bad voice board are what they are on any synth.  Do you have a video showing the behavior you could share? 

Prophet 10, Prophet 6, OB-6, Prophet 12m, Prophet Rev2-16, Toraiz AS-1, Virus TI2, Moog SlimPhatty, Hydrasynth desktop, Korg Minilogue XDm, Roland JP-8080, Roland System-8, Roland SPD-SX SE / Octapad, Maschine, Cubase

I totally agree, if one voice out of six seems wildly different than the others, it tends to point more to a bad voice card IMHO.   I will say that for whatever reason, my OB6 seems especially prone to weird behavior involving individual voice variation if I'm not careful about things like MIDI loops (leaving local on, and having track monitor enabled in the DAW for example). 

By that I mean I have a number of Sequential synths, and occasionally have these "false positive" conditions where I think the hardware is starting to fail, and yet every time, it turns out to be something about my own configuration that is set wrong.  But, this false positive syndrome seems to occur much more often on the OB6 than my other gear.

My relationship with the OB6 has been interesting..  Sometimes in the discovery of false positives, it has felt a little like the type of girlfriend that always manages to make me feel like the bad guy even when my behavior is well within norms by everyone else's standard :).   I regard it as sort of an impish little demon of a synth with plenty of "character".... yet because the false positives have always turned out to be my fault and had a clear explanation for why they occurred, it remains a highly regarded piece of gear in my setup.

Oberheim products (at least the ones the OB6 was patterned after) are notorious for misbehavior, no where near as refined as Prophets.

But the symptoms of a bad voice board are what they are on any synth.  Do you have a video showing the behavior you could share?

I can totally relate to the statement about the "false positives", I just had the experience last weekend with a different synth...  ;D

However, with the OB-6 I am pretty sure that I have methodically excluded any sources of error w.r.t. that particular problem (e.g. it was not even connected via MIDI or USB). It is on its way back to the store now anyways...