JH's VCO, wavetable source

[Paul Maddox]

MB,

>
>...I don't think so. I personally don't like the idea of
>converting an analogue signal into digital domain and
>back.
>

DDL?

>
>I would say there are some subtle pros and cons. First
>of all, ADC is prone to quantization errors which accumulate
>with the nonlinearity errors and scale mismatch of the input
>saw waveform. Moreover, I think that the requirement of a
>precise and sufficiently fast ADC makes this approach more
>expensive one.
>

I agree, there are advantages and disadvantages to both ADC and HSVCO 
options, I chose the HSVCO, Grant chose the ADC, both work...
my main worry with the ADC route was getting a constant amplitude saw to 
drive it, else you would start dropping bits at higher frequencies.
Howevere, grant seems to have cracked this, well done grant.

>
>BTW, there might be a piece of RAM instead of the EPROM and
>a local microcontroller responsible to fill up the RAM with the
>transfer curve (my idea for a module - put some pots and an algorithm
>within a microcontroller generates a curve according to the position
>of the pots. For example some polynomial stuff.) You are not limited
>to fixed wavetables in this way.
>

something I intend to do with my polysynth...
2 VCO's..
1 switchable to wavetable.. this wavetable reads from RAM and as such this 
RAM can be programmed from the main CPU, giving the options of either 
wavetables/sample playback/morphing/whatever you wanna shove in it!

I wish to point out, Im still a fair way off this yet, about 12 months or 
so.

>regards,
>
>mb
>

TTFN
Paul



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