I have been running my SignaLink USB directly from my MacBook
Pro for two years now with no problem. I checked the Wikipedia
page for USB <http://en.wikipedia.org/wiki/USB> and I think it
has an explanation:
Power
...
A unit load is defined as 100 mA in USB 2.0, and 150 mA in
USB 3.0.
A device may draw a maximum of 5 unit loads (500 mA) from a
port in
USB 2.0; 6 (900 mA) in USB 3.0. ... Every device functions initially
as low-power but the device may request high-power and will
get it
if the power is available on the providing bus.
...
A bus-powered hub initializes itself at 1 unit load and transitions
to maximum unit loads after it completes hub configuration. Any
device connected to the hub will draw 1 unit load regardless
of the
current draw of devices connected to other ports of the hub (i.e.
one device connected on a four-port hub will draw only 1 unit load
despite the fact that more unit loads are being supplied to the
hub).
A self-powered hub will supply maximum supported unit loads
to any
device connected to it. ...
The MacBook Pro USB ports act as a powered hub. The SignaLink
probably won't work on a unpowered hub.
Cheers - Bill, AE6JV
On 12/31/12 at 8:21 AM, n...@yahoo.com (Bayard Coolidge) wrote:
BUT, you should be aware that the Signalink USB *does* require an external
powered
USB hub, because it draws close to 500mA, and says so in its specs, etc.
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