[sdiy] VCO control Range

[thx1138]

On 8/28/09 7:25 PM, "Scott Gravenhorst" <music.maker at gte.net> wrote:

> Synth-diy at dropmix.xs4all.nl wrote:
>> "Laurie Biddulph" <elby_designs at ozemail.com.au> wrote:
>>> But what about the link up with MIDI?
>>> 
>>> MIDI starts at 0V and goes up from there. It doesn't support negative
>>> voltages. So if you set 0V to equate to MIDI Note 0 (8.176Hz) then you can
>>> only work with positive voltages.
>>> 
>>> So we have our VCO set for 0V = 8Hz and then we connect a CV controller that
>>> has a range of -10 to +10V, what do we do with the negative voltages?
>> 
>> Use a diode?  (c;
>> 
> 
> Ok, to be serious, I don't care whether oscillator frequencies obey some
> standard
> frequencies based on MIDI note number.  If I send a MIDI note the gives
> voltage X, then if
> I want to, I can sum -1.000 volts to drop the pitch an octave.  So while a
> particular MIDI
> to CV device may not give voltages below zero, I can generate them as I need
> or see fit.
> 
> -- ScottG
> ________________________________________________________________________
> -- Scott Gravenhorst
> -- FPGA MIDI Synthesizer Information: home1.gte.net/res0658s/FPGA_synth/
> -- FatMan: home1.gte.net/res0658s/fatman/
> -- NonFatMan: home1.gte.net/res0658s/electronics/
> -- When the going gets tough, the tough use the command line.
> 
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Hi All,

When I build a keyboard, I make the middle C re-assignable so that I can
have either more Bass or Treble range.

I can also split the keyboard and reallocate channel channels to either side
of the split.

Some of this is probably on Midi keyboards as well. It has been years since
I really looked at the Spec.

Scott is on the right path I believe. I need to get busy and build a new
Keyboard MCU card and let you guys play with this design stuff.

I will talk to my pals at work and see what we can put together for the SDIY
folks who really want to build this stuff.

M-Audio keyboards are what I use these days as they are down the Freeway
from my house. Faster than building my own stuff these days.

Best regards,

Terry