[openbeosmediakit] Re: Audio mixer alpha 2 ready

  • From: David McPaul <dmcpaul@xxxxxxxxxxxxxx>
  • To: openbeosmediakit@xxxxxxxxxxxxx
  • Date: Mon, 01 Sep 2003 19:12:21 +1000

> David McPaul <dmcpaul@xxxxxxxxxxxxxx> wrote:
> > 
> >     The mixer works here with a ymf744 card.
> > 
> >     However, there is a lot more distortion in it than with the R5 
> > mixer.
> > 
> >     Outputing 44.1 16bit using soundplay and changing the mixer 
> > gain I 
> > get more distortion using both mixers as I move the gain up but the 
> > alpha2 mixer is a lot worse.
> Initially the mixer is at a 0dB position, this means the factor 1 is 
> used for
> aplification. Moving it up will increase until factor 7 at the top.
> So amplifing audio in the mixer that is already loud will always 
> create distortion,
> since the data will be clipped by the DAC in the soundcard if you 
> amplify
> something that is already loud.
> There is nothing that the mixer can do about it, but sometimes you 
> need
> the high amplification if the input data is very silent.

Um, sure but I think you may have missed my point or maybe I missed 

Both mixers generate more distortion as the test sound is played and 
then amplified.  I expect this.

However, I believe there is more distortion generated by the Alpha 
mixer than there is by the R5 mixer.

Perhaps the R5 mixer is less linear or the R5 peak amplification is 
lower than the Alpha peak amplification.

At the normal levels I don't notice any difference and it is certainly 
hard to judge by switching back and forth between mixers and trying to 
remember how the other one sounded but I believe it is there.

Perhaps we can record the output at each level and compare the files?


Everything you know is wrong!

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