cv to midi???

Harry Bissell harrybissell at prodigy.net
Tue Nov 9 06:46:55 CET 1999


Two things:

1: Potentiometers still aren't reliable for footpedals... maybe no problem for
Volume... but Wah pedals (OK guitar O.T.) get much higher use/wear...

2: Here's a neat "digital" idea. If you have a multi-timbral digital synth, with
separate left/right or other assignable output... Send a digital patch from
output 1 to a filter etc... and have the patch on output 2 go to an envelope
follower to drive the filter on channel 1.
All kinds of "cross mod" sounds can be had, etc ...
Use a high enough freq on channel 2 and there is very little bleedthrough from
the env. follower... use a low freq and get wierd effects.

:^) Harry (with the proteus MPS... 2 outputs....)

WeAreAs1 at aol.com wrote:

> In a message dated 11/8/99 7:37:03 AM, you wrote:
>
> <<  The DX-7 breath controller input jack provides three things: the ground
> ring, the "excitation voltage" on the tip, and it picks up the controller
> response voltage on the "middle ring".>>
>
> It should also be noted that the Yamaha Breath Controller unit itself
> contains active circuitry (a couple of opamp inverting gain stages, with gain
> and offset trimmers), and this circuit is powered from the "excitation
> voltage" part of the wire.  I think they use a resistive divider to derive a
> psuedo-bipolar supply for the opamps from the single -10v line.
>
> The original DX7 footpedals had some sort of light bulb, photoresistor, and
> moveable light shutter arrangement in them, which Yamaha had been using in
> their organs since the the late 1960's!  I have a Yamaha YC-30 organ, which
> was designed around 1968, which has almost the exact same volume pedal as
> those made for the DX7.  You always needed to bring a spare bulb to gigs,
> because if it burned out, you'd have no sound (although you could open the
> pedal and point a flashlight into it, in a pinch situation).  Obviously the
> light bulb was working on some kind of current loop - probably the same in
> the DX7.  The obvious advantage these pedals had was that they didn't have a
> moving potentiometer to wear out.  This was especially import back in the
> 60's, when potentiometer technology wasn't as good as it is today.
>
> For later model Yamaha keyboards, such as the DX7II and subsequent models,
> Yamaha came up with a more reliable passive potentiometer-based pedal, though
> these units still used the same three-conductor ground, voltage, and return
> arrangement.  Interestingly, you can use the new passive pedals on old model
> Yamaha's, but you cannot use the old photoresistor pedals on the new model
> yamaha's.  Maybe the new models have too much internal current limiting to
> properly ignite the light bulb?  (kind of like those pesky Korg's, with their
> temperamental MIDI outputs that refuse to provide power for cute little
> external MIDI boxes... Maybe they can sense it's not a Korg product.  "Pocket
> Pedal?  Sorry pal, we don't provide free power for CANADIANS.  Bring your own
> batteries, eh?")
>
> It would be good for us to do some kind of survey of the various CV input
> arrangements found in some of the most common MIDI keyboards, then maybe we
> could come up with a sort of universal CV input interface adaptor that would
> let us turn all our cold digital machines into useful parts of our warm and
> fuzzy analog modular systems.  As previously noted, Barry Klein really gets
> into this idea at length at his website, with discussion about using the DX7
> and Kurzweil K2000 as voltage-controlled "analog" synths.  (I think he should
> append the idea to include an analog Gate input as well.  It could be done by
> simply placing a couple of 4016 analog switches across the middle C key
> contacts.  You could even get voltage-controlled attack velocity if you made
> a little 555 timer arrangement to control a variable delay between the
> opening and closing time of the two key contacts)
>
> Michael Bacich




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