[sdiy] lookup table as expo converter

[Tim Ressel]

Yo,

<caveman>
Tim don't know compression. Tim just bang rocks
together and make wavetable.
</caveman>

Seriously, I have some other ideas in mind for the
lookup table scheme. Like doing distortion and stuff.
By the time I get to it, it will change I'm sure.

--(others don't call him) Tim

--- ASSI <Stromeko at compuserve.de> wrote:
> On Monday 24 May 2004 20:24, Paul Schreiber wrote:
> > MOTM-520 Cloud VCO does use a look-up table for
> the expo converter
> > (16-bit, 64K entries!)
> 
> This seems wasteful unless you do something else
> (like nonlinearity 
> correction) with that lookup table at the same time.
>  You can split the 
> linear code, convert the MS part with a first DAC
> and feed the 
> resulting CV into the multiplying input of another
> DAC handling the LS 
> part. Further compression of the table can be
> achieved by interpolation 
> via d/dx 2^x = 2^x ln2. Some constants can be folded
> into the reference 
> of the multiplying DAC to further simplify the
> lookup. Since 2^x is a 
> simple n:1 decoding function, you may never need an
> actual lookup table 
> or at least not a very large one.
> 
> 
> Achim.
> -- 
> +<[Q+ Matrix-12 WAVE#46 microQkb/Omega Andromeda
> XTk/30 sonic heaven]>+
> 
> SD adaptation for Waldorf rackAttack V1.04R1:
> http://homepages.compuserve.de/Stromeko#WaldorfSDada
> 
> 



	
		
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