Oberheim OB-8 pot scanning resolution?

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Oberheim OB-8 pot scanning resolution?

Postby polyjuno » Tue Nov 26, 2013 1:07 am

I'm looking at the OB-8 MIDI specification (here), and in there it is a bit map of the OB-8 patch format. It seems that all parameters adjustable with pots, such as filter cutoff, envelope attack time etc. are stored using only 6 bits (that is, in 64 steps). That seems really low to me. Wouldn't stepping be audible on some parameters? I haven't seen anyone mention this anywhere, so I'm wondering if patches are really stored that way or just transferred via MIDI that way. Does anyone know anything about this?
Last edited by polyjuno on Tue Nov 26, 2013 10:27 am, edited 1 time in total.
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Re: Oberheim OB-8 pot scanning resolution

Postby adhmzaiusz » Tue Nov 26, 2013 3:35 am

I don't hear stepping other than the obvious oscillator tuning knobs.
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Re: Oberheim OB-8 pot scanning resolution?

Postby polyjuno » Tue Nov 26, 2013 1:30 pm

Yeah, I haven't seen anyone mentioning it anywhere really, so I guess it's not really noticeable. I guess if this is the case, it's only really noticeable on the filter cutoff when resonance is at a high value, and maybe pulse width and sustain levels. Do you hear any stepping on them? The rest either affect very small ranges (so stepping wouldn't be very audible) or affect things like modulation depth or envelope times, which I guess are OK at 64 steps. The reason I'm asking is that I'm thinking about getting one, and I wouldn't want this to be an issue (seeing that no one really mentions this as a weak spot I guess it isn't though).
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Re: Oberheim OB-8 pot scanning resolution?

Postby commodorejohn » Tue Nov 26, 2013 6:50 pm

polyjuno wrote:(seeing that no one really mentions this as a weak spot I guess it isn't though).

I think this is probably the important point - it's too easy to get caught up in technical wankery and forget about the main point: does it sound good? Obviously, since it's still sought-after and used to this day. This issue it may or may not have might make it less suitable for live-tweaking stuff, but as an instrument you only need to listen to some demos to know that it sounds pretty damn great.
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Re: Oberheim OB-8 pot scanning resolution?

Postby syntheticsolutions » Tue Nov 26, 2013 9:29 pm

The parameters on my OB-8 are silky smooth, they feel just like analogue pots to me.

I think you would need an oscilloscope to see the stepping, it is absolutely nothing like the parameters on the prophet 600
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Re: Oberheim OB-8 pot scanning resolution?

Postby polyjuno » Tue Nov 26, 2013 10:21 pm

Something like the Prophet 600's stepping (which I've heard examples of) was what I was picturing when I read it was 6 bits in the MIDI specs. I'm glad to hear it's not, or at least doesn't feel, like that. I guess patches are either stored with 6 bits per parameter then, or that only the six most significant bits are taken when a patch is transferred via MIDI. Both of these cases seem a bit weird, as there would be a loss of precision when storing or transferring a patch.

commodorejohn wrote:
polyjuno wrote:(seeing that no one really mentions this as a weak spot I guess it isn't though).

I think this is probably the important point - it's too easy to get caught up in technical wankery and forget about the main point: does it sound good? Obviously, since it's still sought-after and used to this day. This issue it may or may not have might make it less suitable for live-tweaking stuff, but as an instrument you only need to listen to some demos to know that it sounds pretty damn great.


Good points. It's just the engineering/programmer part of me that is/was having an issue with this really.
Last edited by polyjuno on Wed Nov 27, 2013 12:09 am, edited 1 time in total.
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Re: Oberheim OB-8 pot scanning resolution?

Postby commodorejohn » Tue Nov 26, 2013 10:38 pm

Yeah, I get you there, and it does seem odd that it would cut the resolution for either storage or transfer from what it actually uses, but whaddya gonna do, I guess...
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