Re: [ecasound] can a soundcard generate pure DC output?

[Sergei S. <ser...@ya...>]

--- Michael Hellwig <mic...@un...> wrote:

> I need this info for a project (physics) I'm working on and you bunch
> here are the ones who know most about sound hardware and how to drive
> it, at least of the people I could think of.
> 
> So. Given some higher-level soundcard that supports 24bit/96kHz or even
> 192kHz (the DACs for that seem to be easily available at analog.com), is
> it possible with an existing audio driver (i.e. alsa) to tell such a
> card to output a certain DC voltage (at that 24bit precision) on a channel?
> 
> Because that would be really cool in that it would mean we wouldn't have
> to buy chips or evaluation bords and do a lot of development ourselves
> .. using existing stuff is of course always better.
> 
> I'm just a little doubtful since of course in audio work, DC signals are
> always to be avoided ...
> 
> thanks for any hints or thoughts!
> 
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Your question is too general, i.e. the answer depends on the soundcard
components.

First (last ?) of all, there can a DC decoupling capacitor at the output.

And there may be a buffer amplifier at the output which is also
decoupled from DAC output by DC decoupling capacitor.

Now, don't count on cheap 24 bits DAC to be a "real" DAC, most likely
it's sigma-delta DAC, and if yes, its ability to generate DC is iffy.

--Sergei.


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