[sdiy] Micro as a Linear to Exponential converter?

[cheater cheater]

The best and simplest way to alleviate what Antti mentioned is to have
a very slow lag processor/LPF after the DAC output. It would have to
be reset (by for example quickly setting the time constant to very
short) every time you want your output to change. Then you can start
LPF'ing the signal from the DAC and turn the time constant up again,
and then 100 (dithered) samples later you can get a nice voltage
level. That still allows 2 ms latency at 48 kHz.

On the other hand you have amazing DACs nowadays like the ESS Sabre
which will provide 8 outputs at -132 dB DNR. That should be pretty
damn good for your expo. Because of the huge headroom they even
started making one that accepts 32 bit floating point input now.

D.

On Fri, Aug 14, 2009 at 10:48 AM, Antti Huovilainen<ajhuovil at cc.hut.fi> wrote:
> On Fri, 14 Aug 2009, Justin Owen wrote:
>
>> i.e. scaling - say MIDI Pitch info - on chip, to an Exponential CV output
>> (via a dedicated DAC), instead of outputting a linear CV and then using one
>> of the traditional discrete Lin to Exp conversion methods.
>>
>> Possible? Incredibly difficult? Stupid?
>
> The code part is trivial. The difficulty is in avoiding quantization,
> resolution error and aliasing. Basically it's all about ADC and DAC accuracy
> and speed.
>
> Antti
>
> "No boom today. Boom tomorrow. There's always a boom tomorrow"
>  -- Lt. Cmdr. Ivanova
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