[LAU] status usb2 for sound

Dominic Sacré dominic.sacre at gmx.de
Sat Nov 7 12:21:46 EST 2009

On Friday 06 of November 2009 19:55:25 Martin Homuth-Rosemann wrote:
> you're right - the pcm2902 codec is broken by design. The internal
> voltage reference shows a terrible distortion because the 1 kHz usb
> clock isn't decoupled properly. The data sheet
> (http://focus.ti.com/lit/ds/symlink/pcm2902.pdf) recommends the use
> of an external voltage reference for "a high-performance application"
> (figure 37) - unfortunately Behringer uses the circuit for "a simple
> application" (like figure 39).
> I tested my UCA202 with Fons' jaaa and got a "nice" peak at 1 kHz -
> it went away after adding a REG103-A to my UCA (you can get free
> samples from TI).

Hi Martin,

How do you "add" a REG103-A? Do I need a deep knowledge of electronics, 
or would a soldering iron be enough? ;)

I've got a UCA202 which causes a very audible, pulsating noise at 
multiples of 1 kHz while running Jack. If there's a way to fix it, I'd 
like to try. Of course the device was cheap, and as it is it's pretty 
much useless to me, so I'm not all too afraid of breaking it...


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