[sdiy] lookup table as expo converter

[Tim Ressel]

Mark,

I've been giving this some thought. I think one could
get away with having one entry per note (about 120)
and interpolating between the values for microtonal
and modulation. 

My first cut would probably use an ATMEL, and use the
internal ADC for sampling CV and mod inputs. A 120
note table of values would feed into a
Numeric-Controlled Oscillator. Another lookup table
would convert the inherently sawtooth output of the
NCO into other waveforms. Then an audio DAC provides
the noise.

I think the use of an oversampling DAC on the output
would take care of the sharp edges you get with was
and square waves. Since the DACs are almost all stereo
these days, you could have two simultaneous outputs.

--tr

--- mark verbos <mverbos at earthlink.net> wrote:
> I know it has been suggested before, but has anyone
> on here actually 
> ever used a digital look up table as an exponential
> converter? I'm just 
> curious. This would eliminate the temperature drift,
> but would be a bit 
> more complicated. It could have relatively high
> resolution if you used a 
> big EPROM and a high bit rate.
> 
> Mark
> 
> 
> 



	
		
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