SV: [sdiy] MIDI to CV (and PAiA Reverse SPAM)

[Dave Kendall]

I built a midi2CV8 a while ago, and it works well, but the MOD wheel and
Pitch bend have some zipper noise on the output. To fix this, put a simple
lag circuit on the output of the mod wheel. I used the core of this one.
<http://www5b.biglobe.ne.jp/~houshu/synth/glide0301.GIF>
Replacing the lag time pot with a fixed 62K resistor was quick enough for
mod wheel moves, and completely removed the zipper noise when opening up
filters for example. (59-60K was optimum - zipper gone, fastest response)

For the pitch wheel, there is a mod in the manual that brings the 10V range
down to ±2 semitones. Following this with an offset circuit centres the
wheel (The stock option is +5.33V at the centre detent, 0V at the bottom,
and +10 ish at the top!)
I added a second offset/scaler circuit with a pot to set depth, and a DPDT
switch to select between this and the ±2 semitone output.
(there is an old thread on [sdiy] "CV offset question" about this, sometime
around the end of last year)

The mods were well worth a bit of extra effort.

B.T.W. The Paia is a robust little beastie - it survived a short between -V
and GND which took *ages* to find. When the offending hair of solder was
removed it worked perfectly first time, and still does.

cheers,

Dave.

on 30/1/06 8:50, Colin Raffel at colin at experimentalistsanonymous.com wrote:

> I've been looking at MIDI-CV converters as well.  I think I am going
> with the PAiA kit just because I can choose between 24ppq with a gate/
> note output as well as having a polyphonic generator...  and I hear
> it is quite nice and does not look too bad to build.  Has anyone
> built one? Before I spring on the $96, does anyone have a kit they
> decided they don't want or a partly finished one they gave up on
> they'd be willing to sell me for a lower price?
> 
> Thanks
> -Colin
> On Jan 29, 2006, at 11:10 PM, Karl Ekdahl wrote:
> 
>> This one work's well and is really simple to build:
>> http://m.bareille.free.fr/mcv628/mcv628.html
>> It's made for the pic16f628 but it could probably be
>> cramed into the 627. Also check out the pic midi
>> tutorial on the site, it's really awesome in its
>> simplicity.
>> 
>> 
>> Karl
>> 
>> --- peter mcquain <pmcquain at tampabay.rr.com> skrev:
>> 
>>> Hi All,
>>> 
>>> 
>>> 
>>> As it looks like I'm not going to get my MIDI2CV
>>> module from EFM any time
>>> soon, I decided to try a scratch-built version. Can
>>> anyone recommend a
>>> project or schematic to get me started. I have
>>> searched around and not been
>>> able to find any complete descriptions, it seems
>>> that most don't want to
>>> share their PIC source code. I have several PIC
>>> 16F627A's hanging around, so
>>> if I can be picky, something that uses that family
>>> would be great :-)
>>> 
>>> 
>>> 
>>> Thanks in advance!
>>> 
>>> 
>>> 
>>> -pete-
>>> 
>>> 
>> 
>> 
>