7 Nov
2009
7 Nov
'09
1:48 p.m.
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...
Dominic