Question about LCD readout

Tips and techniques for Minimoog Analog Synthesizers
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restlessboy
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Question about LCD readout

Post by restlessboy » Fri Feb 15, 2013 6:07 am

So I’ve had the Voyager for a week and a bit and have been twiddling the knobs like there’s no tomorrow. I notice that sometimes I can turn something a good mm or so before the LCD notices that there’s a change in value. Also sometimes I’ll move a knob as far as it can go left or right, but the display will show 002 or 001 when there’s clearly no more give.

Is this any reason for concern? I’m choosing to believe that the actual sound producing bits are doing their job right, that the filter isn’t sticking at almost fully open/closed, and that it’s the LCD readout that’s not quite up to the task of monitoring the infinite resolution of analogue components.

I just notice that the readout on my Prophet 08 is a bit quicker to take notice of pot movement, albeit they’re much smaller pots so a smaller turn probably produces greater change in value.

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thealien666
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Re: Question about LCD readout

Post by thealien666 » Fri Feb 15, 2013 10:18 am

The actual high resolution values of the knobs are averaged by the display. They are 14 bits internally (16384 possible values) averaged down to 8 bits for display purposes (256 values). So it takes more than 64 actual value change before it is reflected on the display. (that's the reason why there is absolutely no audible stair stepping, even on sensitive parameters like cutoff with a self resonating filter)

"It is mentioned in the owner's manual, btw."
EDIT After reviewing the pdf version of the unified Voyager User Manual Combo, there seems to be no mention anymore about this fact. I distinctly remember that it WAS mentioned in my EB model paper version manual... Strange...


So everything seems normal with your beloved Voyager. Enjoy ! :mrgreen:
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unfiltered37
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Re: Question about LCD readout

Post by unfiltered37 » Sat Feb 16, 2013 1:08 am

So, the knobs are actually digital? I always thought the knobs were continuous. Not that it really matters, even my mp-201 has no audible stepping with lag, just didn't know that. I know they are real pots, but essentially they output a digital value only?

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Voltor07
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Re: Question about LCD readout

Post by Voltor07 » Sat Feb 16, 2013 1:36 am

unfiltered37 wrote:So, the knobs are actually digital? I always thought the knobs were continuous. Not that it really matters, even my mp-201 has no audible stepping with lag, just didn't know that. I know they are real pots, but essentially they output a digital value only?
More like they output analog signals, which are converted to digital signals for MIDI purposes.
Minitaur, CP-251, EHX #1 Echo, EHX Space Drums/Crash Pads, QSC GX-3, Pyramid stereo power amp, Miracle Pianos, Walking Stick ribbon controller, Synthutron.com, 1983 Hammond organ, dot com modular.

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thealien666
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Re: Question about LCD readout

Post by thealien666 » Sat Feb 16, 2013 3:45 am

Voltor is partly right.

The big digital board (not so big anymore since the SMT version) is complex because of the high precision analog to digital conversion of the potentiometers. All of their values are stored internally with 14 bits resolution. So high a resolution in fact, that one would be hard pressed to notice any stair stepping with 16384 values for one turn of a knob !

But their position (analog voltage output) is converted to digital before being re-converted back to analog control voltage to be sent to the analog sound generating board inside the Voyager. That's how pot mapping is made possible, I think. Rudi will correct me if I'm wrong about that...

The only fully analog Voyager is the Old School version. Although its keyboard scanning is digital, but quickly converted to analog pitch CV right under the keys, on that small circuit board.
Moog Minimoog D (1975)
DSI OB6
DSI Prophet REV2
Oberheim Matrix-6
Ensoniq SQ-80
Korg DW8000
Behringer DeepMind 12
Alesis Ion

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