Reply To: USB to USB-B or Line Out to Line In for playback from PC to Qu-24

Forums Forums Qu Forums Qu general discussions USB to USB-B or Line Out to Line In for playback from PC to Qu-24 Reply To: USB to USB-B or Line Out to Line In for playback from PC to Qu-24

#52501
Profile photo of Andreas
Andreas
Moderator

Ok, some technical clarifications needed… 😉
The USB-B connection realizes a multi-channel, bidirectional audio stream of 32in-to-32out on a Qu32 (less on Qu24/Qu16). This is great for multichannel DAW operation but may be a nightmare to operate from non-multichannel-aware applications (i.e. iTunes), since it may be hard to get the audio streams to the channels you want them to go. And, for the same reason, if you need one or 32 channels, the physical link and driver always streams 32+32 channels (Qu32), and this is where the technical performance is required.
If you think you do DAW recording and and playback through the same USB-B connection but from different applications, this may easily fail, since the driver can not merge two audio streams (which requires some digital mixing which we purists do not want at all).
Consequence: Record via USB-B to the PC and choose something different for playback (i.e. stereo USB audio interface).

And if both, mixer and computer, are grounded on the mains side and have an additional ground connection on your audio link, you do have a perfect ground loop which is sensible to any kind of EM fields (i.e. transformators, switching power supplies, mobile phones…). I highly suggest to use some sort of line isolator in this setup (or check if your PC has a S/PDIF output).

You may try to use a pseudo differential connection between your PC line out and ST1/2 with connecting shield from the PC side to both rings on the Qu side and leave shield on the ST1/2 connectors open (or via some resistor to GND). Could help sometimes.