Doepfer

James,

you find my answers written inline.

Best regards
Dieter Doepfer
Doepfer Musikelektronik GmbH
hardware@doepfer.de
__________________________________________________________________

Doepfer Musikelektronik GmbH
based in Graefelfing/Germany
registered in Munich/Germany, commercial registry HRB 97 399
CEO's: Sibille Heller, Dieter Doepfer
European VAT ID No. DE129329318
website: www.doepfer.com
__________________________________________________________________

> Dieter-
> Ken Stone's Matrix mixer does the inversion thing without the multi-
> taped center terminal pots. His design is shown here:
> http://www.cgs.synth.net/modules/cgs33_matrix_mixer.html
>
> He has a switch to turn it from normal (off-on) to Bi-polar (full
> inverted-off-full non inverted) which is very nice.

yes, I know this principle (including the diodes that generate a "zero
plateau", the same principle is used in the A-174 Joy Stick module)

> You may be able to avoid the expensive pots my using some of his ideas (in
your own
> circuit of course). Maybe a taper can be found that would leave a wide
> "off" zone and then no detent would be needed either (especially if
> the mode can be switched from bi-polar to normal - the detent would be
> odd in the normal mode)

I think it will be more difficult to find a potentiometer with such a
special taper than a potentiometer with center detent and terminal. And it
would be odd to have a dead zone in the normal mode. But I think it's a good
idea to have the unipolar/bipolar switch available even with the drawbacks
in bipolar mode because of the missing center detent/terminal. Thank you for
this hint. I think we will start with a unipolar module (maybe with a switch
for unipolar/bipolar mode) and then release later the bipolar version with
the special potentiometers.

> I was wrong about the Buchla 205 - Looking at the schematics it
> appears to not do the inverting bit. That is a very nice function but
> if the cost/availability
> of the pots is a problem, the "normal" version is still quite usefull.
> -james