[LAD] Getting the most out of onboard HDA

Justin Smith noisesmith at gmail.com
Fri Sep 12 19:14:39 UTC 2008


On Fri, Sep 12, 2008 at 11:28 AM, Jens M Andreasen
<jens.andreasen at comhem.se> wrote:
> Assuming a 7.1/192K/24bit $3:- chip onboard ... What next?
>
> First I will say, it actually will do the planned send and return
> to/from the two pieces of stereo outboard equipment I have (that is not
> going anywhere,) as well as do separate headphones and monitors. So I
> should be a happy camper ...
>
> Suppose one was to face the real world of playing live again? In my
> experience this can be a torturous venture into the realms of cheap
> lights and the evil thyristors and diacs of this world, all trying to
> make their voices heard through my equipment ...
>
>
> So, how about turning a single unbalanced stereo jack into a single
> balanced mono jack by converting a single mono signal to a stereo signal
> with inverted phase, would that be a good idea? If so, I believe this
> might work in a simalar way on microphone input as well.
>
> If the above holds and we then have two (instead of one) DAC's working
> push/pull on the line, would it be possible to take advantage of this?
>
> What I have in mind here is that, the lower you get in the "bittiness",
> the more the systenatic errors of distortion will be apparent.
>
> For starters, how about having one the phases at a level slightly below
> the other? This should ideally trigger transisitions between absolute
> levels at slightly different times for the two phases, giving us an
> extra 6dB of useable headroom.
>
>
> mvh // Jens M Andreasen
>
>
>
>
>
>
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>

It should not be so hard to make a ladspa plugin that takes a mono
signal and gives you a stereo signal meant to be composited into the
two sides of a balanced signal, giving you double the original
absolute amplitude in headroom. Or maybe this would be better as a
daemon that provided a jack sink to be placed before your system
outputs.

If you just did a simple phase inversion, you would lose half of the
information you could be sending to the dac, you could easily use an
algorithm that sets things up so you have full bit resolution (ie.
double the rated resolution of a single channel).



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