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Using USB 2.0 with USB 3.0 question...
Posted: Tue Feb 25, 2014 7:59 am
by FMiguelez
Hello.
This week I'm supposed to receive all my equipment (according to FedEx, it's in an airport somewhere in Toluca)!
The computer has USB 3.0 (4 ports).
Will they remain with USB 3 speed, or will they default to the lowest one detected by the computer (the USB 2)??
I'm planning on using a USB 2 hub for all the iLoks, Vienna Keys, etc. The monitors (USB 2) will take 2 ports. The remaining one I want to use it for an external disk for samples in USB3, so they get read fast.
Will this work, even if I combine USB 2 and USB 3 external components in the same computer?
Thanks.
Re: Using USB 2.0 with USB 3.0 question...
Posted: Tue Feb 25, 2014 3:20 pm
by mikehalloran
There are some threads on the subject but the short answer is that the usb 3 ports on a Mac have connectors that accept either usb 3 or usb 2.
A usb 2 / 1.1 cable cannot be used to carry usb 3. That will not work.
The longer answer:
Usb 2 and usb 3 use different terminals inside the plug and jack - for this reason, a standard usb 2/1.1 cable cannot carry usb 3. Some usb 3 hubs have separate jacks for each protocol and are wired for both only when sending the signal to your computer - it's cheaper to build them this way rather than wire every jack to accept both protocols.
It is also possible to wire a usb 3 cable that cannot carry usb 2 but I haven't seen those - yet. I'm certain that, if usb 3 becomes ubiquitous, we'll see cables wired this way. Why? Because it's less expensive.

Re: Using USB 2.0 with USB 3.0 question...
Posted: Tue Feb 25, 2014 8:59 pm
by Tonio
So best course of action is to get a USB 3 cable and/or a active USB hub that accepts USB 2 in and USB3 to computer> Is there such a monster?
Re: Using USB 2.0 with USB 3.0 question...
Posted: Tue Feb 25, 2014 9:03 pm
by Tonio
Re: Using USB 2.0 with USB 3.0 question...
Posted: Wed Feb 26, 2014 6:17 am
by FMiguelez
Thank you for chiming in, Mike.
I understood your explanation, and it cleared one of my concerns. But what I'm still not very clear about is if the 4 computer's USB3 connections are independent from each other in terms of bus speed.
Will the computer's USB3 connections remain at USB3 speeds, even if I connect USB2 devices as well (i.e. external HD connected via USB3 enclosure in USB connection A, and a slow USB2 Time Machine HD in connection B) ?
B won't affect A's speed capabilities, will it?
Re: Using USB 2.0 with USB 3.0 question...
Posted: Wed Feb 26, 2014 8:56 am
by mikehalloran
I don't know what Mac you have coming in. If the info is not readily available, you will see how many USB busses you have in the system profiler.
Although USB 2 and 3 share the same connector, they are separate busses and do not interact with each other - supposedly. What happens inside the intel chip set is above my pay grade.
Another thread is saying that the way around the stuck MIDI note issue with some Macs that have USB 3 is to plug your interface into a USB 2 hub such as your keyboard. The thing is that most Apple keyboards are USB 1.1, not 2. Hey, whatever works, works.