Using a powered USB hub


#1

Pardon me for asking a really basic question: How would you use a powered USB hub with the Directstream DAC? Is there a sound quality advantage if the hub is powered by a 5V linear power supply?


#2

My guess is that it would be helpful. If the DS is the only thing plugged into the hub then the USB power wouldn’t be too garbaged. Also using a short cable from the hub to the DS (say 3’ or so) might keep the USB data from corrupting the power as much.


#3

Thanks Ted. I’ll give this a go.

Can I use just the data leg between the mac and the hub and a standard USB cable between hub and DSD?


#4

I’m afraid I don’t know quite what you mean by using just the data leg - a cable that disconnects the 5V? Whether that works depends on the OS, drivers, hubs, etc. It won’t hurt to try it, but you could have problems installing drivers, powering up, coming out of suspend, etc. Some people seem to have found the recipe for when to connect the 5V and when you can disconnect it for their setups. My suspicion is that a hub with a linear supply will undo most of the interference from the 5V up to the hub so I wouldn’t bother, but YMMV.


#5

Ok. I’ll use a standard USB cable from mac to hub and hub to DSD.

Must buy a USB 2.0 hub first. Will post my results. Thanks.


#6

I had one successful session with a USB hub and thought I heard an improvement in SQ but would need to do some more critical listening to confirm.

However, I’ve encountered a problem and Ted … you may be able to advise. When I turned on the mac the next day the mac would not register the DAC - ie the DAC does not appear in Audio-midi.

The display on the DAC was reading 352k (normally 192k when I connect mac directly to DAC as I set Audio-midi on the mac to 192k max). The green light was on.

It seems as though the DAC sees the hub and doesn’t see the mac and defaults to 352k which the mac doesn’t like.

I had to restore the direct connection of the mac to the DAC and reboot the Directstream to be able to play again via USB.


#7

Actually all of the seeing and default rate settings, etc. come from the MAC (or PC), not from the DAC. I’m afraid I’m not much help in MAC land. And I’ve seen very little interference by (USB 2) HUBs in connection issues, etc. I personally must have more than a dozen (USB 2) hubs that all work fine with the DS (and everything else I normally use.)

The fact that the DS was showing a sample rate means that the last successful USB connection was at that sample rate. I don’t know if it’s helpful in figuring out what the current problem might be.

Hopefully someone who has experience with MACs and connection issues can help.


#8

I should have said tho that, just in case you didn’t try it: when ever I’m having USB problems I power off the DS (with the back panel switch), reboot the computer and after the computer’s up power the DS back on.