[sdiy] sequential multitrack schematics.

[mark verbos]

I'm talking about mixing a saw or tri wave in with the CV before going 
into the CV in on the CEM.

mixing a hi frequency saw or triangle wave with the CV would be pwm 
accross the thresholds in the chip, assuming the CEM can switch that 
fast. The amplitude of the saw wave determines the length of fade 
between waves. If the wave is above double audio range you should not 
hear any ring mod type sounds.

check out Grant Richter's Analog Tracking Generator
http://www.musicsynthesizer.com/DIY/Grant/CVtwister.html

Grant uses this technique to blend accross the steps of an LM3914

and Buchla's 257 control voltage processor
http://www.musicsynthesizer.com/Buchla/b257.jpg

Don uses this technique to make a voltage crossfader

Professor Nyquist told us that the dither oscilltor has to be at least 
twice the highest frequency you want to hear. You may still hear some 
aliasing, but if you run it was up high, it shouldn't be too bad.


Mark



harry bissell wrote:
> You can't use a saw or triangle... it would discrete switch them
> anyway, internally.  If the DC points of each wave were different, the
> result could be nasty.  You would have a kind of balanced modulator
> effect The internal waveforms would not have any bandwidth limiting
> so lots of high harmonics... and the waveform select would have lots
> of high harmonics... so I'd expect beating / aliasing.
> .
> The mod signal might also couple into the chip in unexpected ways
> (capacitance etc) and bleed through.
> 
> It would be worth the try... especially if you wanted a some ring
> mod or otherwise lo-fi effect
> 
> H^) harry
> 
> Michael Bacich wrote:
> 
>>
>> On Sep 27, 2006, at 3:50 PM, mark verbos wrote:
>>
>>> what if you used a hi frequency triangle or saw wave to dither the 
>>> CV, then you could get fading out of it. no?
>>
>>
>> What if you used a high frequency variable width pulse?  Then changing 
>> the pulse width would effectlvely control the "on time" of the 
>> triangle vs. saw, and modulating the pulse width with a voltage would 
>> change the mix/balance.  Of course, it would have to be way above the 
>> audio range in frequency, and you'd need some filtering to eliminate 
>> artifacts.  It might work...
>>
>>
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> 
>