[sdiy] Doepfer ribbon progress

[Scott Juskiw]

>So I got the dopefer ribbon hooked up to
>my Theremin Quantizer.
>
>I'm a little underwhelmed...
>
>1) The ribbon has pretty HIGH friction. OK
>if you want to tap, but if you want to gliss
>its pretty poor IMHO.  Compared to the Kurzweil
>its awful.

I fully agree with you here, they could have put something on the 
surface to make it easier to slide around on. I haven't tried the 
Kurzweil one, but the ribbon on my Andromeda has a much smoother 
surface than the Doepfer. I use the Doepfer ribbon more like a weapon 
than an instrument: wielding it over my head to scare my enemies.

>2) The pressure sensitivity is very noisy. Its OK if you
>play a note and press down... but sliding gives a very
>jerky response

Mine is the same. I don't think they intended us to apply pressure 
and then slide around while maintaining the same pressure. Especially 
not with the high friction surface. Maybe that's why they designed 
the new one (which I haven't tried). Anybody tried the newer one?

>3) I'm running voltage mode on the ribbon. Someone suggested current
>mode (ie it would allow you to have a true low note of high note
>priority)
>
>In fact... you could play two notes from the ribbon.  That might be
>cool.

I prefer current mode because it acts more like a keyboard when you 
accidentally touch the ribbon in two places at once. I tried a 
two-note output for a while but it was a bit unpredictable due to 
fingers not having zero width (it can't distinguish one fat thumb 
from two thin fingers in close proximity), and I didn't like trying 
to play it with fingernail tips only. But if you are quantizing the 
output then that's less of a concern.

>4) I have a current mode pressure circuit.  It has a sensitivity pot
>to change the response... and a zener to clamp the output at +5V
>
>That seems to work pretty well, except for the noise when sliding
>I'll probably put some filtering in there

I use your Morphlag circuit whenever I need to smoothen things out, 
works great.