[sdiy] Verniers for Patch Recording

[Michael Boracci]

I am pretty sure that moving pots use an armature on the wiper which is
pulsed  to step along a rail of fixed magnets located along the side of the
device. Basically a linear stepper motor.


MB


-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of john mahoney
Sent: Wednesday, October 01, 2003 10:35 AM
To: harrybissell
Cc: Czech Martin; synth-diy at dropmix.xs4all.nl; Ian Fritz
Subject: Re: [sdiy] Verniers for Patch Recording


> The "digital" pots could be used for everything... that you could compress
into
> a 0-5V or 0-3.3V range. By prescaling with opamps... or (as JH might
propose
> -he has in the past) ... not making the signals larger than they need to
be in
> the first place
> maybe 0.5V amplitude... those digital pots could work fine.  No need for
VCAs to
> use them

This is a great point: design for programmability in the first place. But
who is doing so? We are saddled with years of tradition (mostly 0-5V).


> I bet a lot of you modular people would not be happy with 7 bit
resolution...
> the pots
> on a Prophet V are seven bit...and they zipper noticibly.  Willing to go
there
> with your modular.

No, that's not quite enough. The AD digipots have 6 and 8 bits, but you can
use coarse and fine pots in series to get around 11 or 12 bit resolution,
which is more control than most of us can manage with a standard pot.
(Separate coarse & fine analog pots may provide better than 12-bit
precision.)


> Pots are reasonably cheap, quiet, etc.

True, Harry, but pots are stupid! <G> There is no way easy to make them
programmable.


Does anybody know how moving faders are implemented on mixers? This
technology was once found only on the high end consoles (e.g., Neve's Flying
Faders (TM)), but costs have apparently come down. Still not cheap, I am
sure.

I'd also like to know how programmability was done on the Prophet -- has
anybody got a link to that?
--
john




____________________________________________________________
Free 20MB Web Site Hosting and Personalized E-mail Service!
Get It Now At Doteasy.com http://www.doteasy.com/et/