[sdiy] Doepfer ribbon progress

[harrybissell]

Latest / greatest

1) I changed the circuit for current mode operation. I like it
better... otoh it is a tiny bit glitchy because the open circuit
condition is the highest note... instead of zero volts.  There is
a little 'chirp' you can hear in the quantized MIDI output...

In Volume mode (velocity is held at max) the chirp is very
clear with a quick attack

In Velocity mode (volume is held at max) the chirp s much less

In Velocity / Volume mode (pressure varies both parameters at the same
time)
it works very well.

2) I added a strip of .005 thick UHMW Polyethylene tape over
the sensor. At first it seemed to work better. After a while it seems to
work
'not quite' as well as it did initially. Did it degrade... or did I get
more
fussy (like the ladies often do :^) ???   I think it made the pressure
sensitiviy
a little worse.

I will experiment with some filtering on the pressure CV. Maybe the
Morphlag
is a good choice... and I just happen to have one :^P

Intersting... at work I'm working on a patten recogntion issue that has
a lot of similarities with the guitar synth problems. Are they lucky to
have me or what ??? :^P

Scott Juskiw wrote:
> 
> >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.