Using USB external drive with MAC Mini & USB connected DS DAC


#1

I have read that using USB for a MAC Mini to connect to the DAC while also using a USB connected hard drive to the Mini is not the best configuration. I am currently using an external hard drive connected to a MAC Mini that is then connected to my DS DAC via USB. Under the MAC device tree I see that the external hard drive is connected via USB 3.1 to USB 3 on the Mini & the DS DAC is connected to the Mini via USB 2.0. Both of these USB ports appear to be on the same USB 3 Bus. The USB 3 hard drive connection was chosen because of the cable (USB 3.1 to USB 3) provided with the drive. I can order a Thunderbolt 3 to Thunderbolt 2 cable if I need to. The transfer speed is of no concern because of the drive’s transfer speed being the slowest in the chain. Should I look at getting the external drive onto the Thunderbolt bus?
Thanks,
Kev


#2

If you don’t mind the additional clutter I’d get a powered USB hub and only have the DS on the hub. That probably will give better isolation than using a different built in connection.


#3

Thanks Ted,
That configuration would still have the USB external drive & the USB output of the MAC Mini sharing the MAC USB bus. I read that this configuration can cause issues & that is what I was addressing. I will look info the powered hub in addition.

Kev


#4

I’m not trying to talk you into anything, but

My suggestion addresses the same issues - by having only the DS on the new hub and having that hub powered you are doing the same thing as using two different outputs from your MAC - you are isolating the USB power to the DS from the rest of the USB bus. In addition you have control of the quality of the USB power to the DS and by using a shorter cable you can decrease the coupling between the (remaining) power wires and the signal wire. The DS is less sensitive to jitter than most other DACs so any timing differences that might happen by sharing a USB connection on the MAC aren’t as important.

[edit: I should add that because you are using USB 2.0 for the DS and USB 3.0 for the drive they don’t interfere in time anyway so the only relevant issue is power signal interaction which the hub will help ameliorate.]


#5

I see. I was wondering if that was the case. They show to be sharing the same USB bus even when one is USB 3.0 & the other USB 2. I wanted to try using the Bridge 2 for this reason too. I would like to try a direct connection to the Bridge 2, just to satisfy my obsession with minimizing hardware. I have asked in several posts, but have had no help, for detailed instructions for setting up my MAC Mini & Bridge 2. I am not very network savvy, so I need the details for getting there on a MAC running High Sierra & JRiver MC23.
Regards,
Kev


#6

Just background: USB 3.0 is actually two separate trees: the USB 2.0 compatibility is handled by a complete USB 2.0 implementation using the same pins, wires, etc. that USB 2.0 would use. The USB 3.0 part is a parallel set of wires, pins, etc, that are designed for a higher data rate.