Digital USB Sound Card isolation - Ground looping noise removal solution
We have made a solution for isolating the USB audio card from the PC - removing the ground loop noise, that you hear when attaching the 2-8 channels of line audios to your amplifier/receiver. It isolates the USB data and transfers power to the USB sound card through a transformer. All in a little USB stick that is put before the sound card.
The reason for making it was because I had the problem my self - SPDIF/Toslink only supporting 2 channels in commercial amplifiers and sound cards. So the only solution to get real 5.1 HD-DTS sound was to use a USB coundcard with 6 analog outputs at line level. Line level is 100mV (0.1V) and the way my amplifier works is it has 2 caps to ground from mains, resulting in 110V floating AC on the ground wire. The PC has grounding with a 3 plug. Common setup and common problem - 50Hz noise on the signal when amp is at 66% and sound signal is silent. Ground the amp. helped but the noise did not disapear. When using the USB2ISO - USB 2.0 Isolator - Isolated USB
the noise is gone.
Furthermore both amp and PC are protected when connecting / disconnecting which could have been a problem.
Please note: This product is for fullspeed USB devices. Some high-end USB sound cards allready have a sort of isolation build in.
Have fun and hope that this can help other in the same situation, thanx.