It wouldn't be that hard to do. It's been 2.5 years since I wrote my
trig-gate-cv delay but the basic concept is I have three 128 event
buffers. The first is used to timestamp an event (trigger high,
trigger low, etc.). The second buffer is to record a trigger or gate
transition (high or low). The third buffer is to record a CV value.
When I detect a trigger, I timestamp it with a 'delay' factor and put
the timestamp, trigger, gate, and CV in the buffer. The buffer is
circular and at 128 events long it never fills up.
Timer interrupts advance the timebase. When the timebase matches the
next timestamp in the buffer, I output the event. It would be pretty
easy to modify the concept to continue to record until some other
event (e.g. stop) and then simply playback the buffer. At the end of
the buffer you'd simply reset the timebase.
Note that this only works for discrete events such as a keyboard. It
won't record a continuously changing CV such as with a pitchbend.
Four channels would be tough since you'd need 12 outputs. A CVS with
an optional digial I2C expander could do it, though.
Maybe someday when I'm bored I'll give it a try.
Dave
--- In
ComputerVoltageSources@yahoogroups.com, "Grant Richter"
<grichter@...> wrote:
>
> I always thought it would be fun to have a 4 channel looper that
could loop the VCO CV,
> wave CV, filter CV and VCA CV. That way when you play a neat little
lick, you could hit
> "loop" and then have you hands free to twiddle the knobs.
>
> For Tangerine Dream kind of days (they did a lot of knob twiddling
over sequences that
> sound real good).
>
> The old ARP 1603 would do 4 bars of 4/4 (16) so only 16 to 32 actual
notes need to be
> stored. I saw pictures of them using 1603s and 2600s at some point.
>
> Just a thought.
>
> --- In ComputerVoltageSources@yahoogroups.com, "djbrow54" <davebr@>
wrote:
> >
> > Not exactly sure what you mean by a looper. It depends upon
whether
> > your CV is continuously variable or steps between discrete values.
> >
> > I did an arpeggiator where I would monitor the CV for a change
since
> > it was hard to detect a trigger (I since use edge interrupts).
With a
> > real-time clock, you just timestamp the CV value change. Ram use
is
> > minimal since you just have a record of the changes. Worked
great.
> >
> > I did something similar for a CV delay which can implement some
really
> > long delays. Sample the CV transitions and clock them out at a
> > variable delay later.
> >
> > Dave
> >
> > --- In ComputerVoltageSources@yahoogroups.com, "Grant Richter"
> > <grichter@> wrote:
> > >
> > > Has anyone experimented with doing a 4 channel recorder looper?
> > >
> > > I need one for an experiment.
> > >
> > > Any comments before I try to program one?
> > >
> >
>