[Justin Uthadude]

The impetus for these questions comes from the recent purchase of a usb galvanic isolator that I installed in my laptop system. I was occasionally hearing noise, mostly during quiet sections of music, that would sound like very low static or hiss. I did the usual things, changed the power settings, checked the latency, rotated usb ports, disabled wi-fi, etc, etc. It got better, but wasn’t perfect. When I inserted the usb isolator between my laptop and dac, it got better. Not, radically “ wow, I didn’t know there was an organ in that song” better, but better like when I upgraded to a nicer dac. I feel there is more low level detail, a lower noise floor in quiet passages and between songs, more dynamic range and weirdly enough, better bass: like more obvious differences between the sound of a standup bass and an electric one. I realize this sounds like the observations in a review of a foo-foo cable, but I hear a distinctly better sound. I spent 4 hours last night trying to convince myself that it was the placebo effect, but I couldn’t. It was easy enough to A/B by plugging and unplugging the isolator from between the usb port on the computer and dac. It was harder to detect it when it was plugged in, because there wasn’t anything new to hear, but when I unplugged it, something came back that my brain recognizes as not music.
 
My understanding of dynamic range is the difference between the loudest signal and the quietest, usually limited at the extremes by the threshold of pain and ambient noise. This is further reduced when we turn the volume down to more normal listening levels, by lowering the softer passages down into the ambient room noise or noise floor of the playback system itself (including noise in the power source?). This particular usb isolator isolates both the data lines and the power line. Wouldn’t the removal of low level noise in the usb connection indeed improve dynamic range and coincidentally the s/n ratio?
 
As for the perceived better bass, my knowledge of ground loops and electronics in general is limited. Isn’t a ground loop more prevalent in the lower frequencies like a quiet hum? Would the removal of this clear up the ‘interference’ in the bass frequency range and let the bass stand out more? If any of you wear glasses, the improvement is kinda like going in for your routine eye exam. You didn’t go in because you were having trouble seeing, but you definitely notice you see better with the new glasses.
 
Does any of this make sense? Any ideas, help or explanations from the forum would be appreciated.

 

[nick_charles]

Can you take the analog outputs (with and without gizmo) and record them on a separate PC, then you could examine the samples using Audacity or similar and see to what extent the noise profile changes with the extra device in the circuit, this would be interesting.