2. pc-audio
  3. 1150170453

any words of wisdom for usb noise problems?

i thought usb connections would be trouble-free after placing waveterminal u24 between my desktop pc and the dac in my panasonic reciever (office system). itunes runs dead quiet there. i am trying to implement a pc feed into my levinson preamp in main system. when the usb cable makes contact between my laptop pc and the u24 running into the preamp i get substantial noise, which is substantially worse when a usb hard drive is also attached.i googled "usb noise" and saw references to some midi users' and photo printer issues and some filter products (argh!- hope to avoid this step). also mention of computer screens as possible culprits any suggestions or similar experiences?
wkraft
wkraft OP
8 posts
 
to elaborate- the waveterminal running into the coax digital input of my panasonic sa-xr55 (i know many will turn up their noses at this class d based unit) results in dead quiet speaker and headphone output. this prompts me to wonder what in the receiver prevents the noise transmission. i see that most audiophiles are not using the u24 dac function, and i am thinking ahead- would implementing certain kinds of dac obviate the need to uncouple the u24 from the dac.
pardales
652 posts
 
I have used the Waveterminal for almost two years now. It a a great device but I am sure one f its short comings is that it draws its power from the PC via the USB cable. I have spent a lot of time listening to it as a DAC and it is phenomenally good sounding given its price. I am awaiting one of Empirical Audio's new wirless USB offramps. You can find info at their site.
vfoostdijka929
3 posts
 
This is clearly a design fault of the U24. They should have put a circuit inside to clean the power via usb and/or add the possibility to connect the U24 to an dedicated external power supply.

I tried an external USB-hub with it's own external power supply. Unfortunately the U24 isn't recognized by the computer when connected via the hub but maybe this is just a matter of reinstalling the U24 drivers.

I am thinking now of modificating the U24 to make it work with an external power supply. The easiest way is probably to cut the USB cable in two and connect pins 1 and 4 of the part which leads to the U24 to an external power supply.
ckorody
643 posts
 
Not a design fault - more likely a design decision, and by modern standards by now an old design. The U24 was built as a semi-pro recording studio product, not as an audiophile product. Recording studios are filled with all sorts of devices using less then optimum electronics.

BTW the hub may not be able to power it.

Using the Opticis fiber optic USB may give you that last degree of quiet you are looking for.
audioengr
3,282 posts
 
There are two fundamental problems with the Waveterminal:

1) it uses the power from the USB cable
2) it does not have any isolation to break the ground from the computer to the audio system

These things are difficult to get around without modding the thing. The Opticis will help with (2), but not (1).

steve N.
Empirical Audio
Manufacturer
More to discover