Primergy
Member
So I got my hands on an older Threshold preamp and started testing it on a secondary system.
I noticed a higher pitched tone when the USB is plugged into my DAC. This noise is volume level dependent (on preamp control) and becomes audible at around 30% volume, from there quickly reaches levels where it is a nuisance.
Setup:
Win7 laptop -> NuForce HDP USB DAC -> Threshold FET2 SII preamp -> Sony powe-amp.
Hmm:
https://discussions.apple.com/thread/2270209?start=0&tstart=0
Forgot to mention above that the laptop is sitting in a Dell dock with other devices attached.
Why is this not filtered away on a USB DAC that claims to have some reputation? (Possibly a rhetoric question?)
I noticed a higher pitched tone when the USB is plugged into my DAC. This noise is volume level dependent (on preamp control) and becomes audible at around 30% volume, from there quickly reaches levels where it is a nuisance.
Setup:
Win7 laptop -> NuForce HDP USB DAC -> Threshold FET2 SII preamp -> Sony powe-amp.
Hmm:
- The noise does NOT follow the preamp. If I plug the USB DAC straight into the power-amp, everything is fine.
- If I plug any other signal source into the any input on that preamp, everything is fine.
- The noise is not volume dependent using the volume control on this USB DAC. The noise level coming from the DAC is at a fix level.
- It does not matter if the USB DAC is on, or off. With the preamp in the mix, only unplugging the USB cable will stop it.
https://discussions.apple.com/thread/2270209?start=0&tstart=0
Forgot to mention above that the laptop is sitting in a Dell dock with other devices attached.
- Unplug all other USB devices, no changes.
- Unplugged laptop from dock, DAC in onboard USB - noise is gone.
- Laptop in dock, DAC in onboard USB - noise is back - well, that's a bit inconvenient!
There are a few other funky noises over the USB cord when I set the laptop to go to Sleep. No deviations in the noise observed during regular operartions
Why is this not filtered away on a USB DAC that claims to have some reputation? (Possibly a rhetoric question?)