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mickcordero
Mar 27, 2012, 10:54 AM
Just bought a pair of USB-powered for my 2011 MBA 13".

But when ever I pluck them in, I get a message that the USB device is drawing too much power. And the speakers are not working properly.

On my friends Macbook Pro 13" they work flawlessly.

Any suggestions?



Stealthipad
Mar 27, 2012, 11:11 AM
I assume you mean you also bought speakers.

It would suggest that the Air does not have the same amperage that the Mac Book Pro has.

mickcordero
Mar 27, 2012, 11:25 AM
Yes, sorry, forgot to write speakers :)

Apparently it looks like the MBA gives less power to the USB than the MBP.

I just wonder why it isn't stated anywhere? According to official Apple-specs, they should have the same amount of power?

M

bogatyr
Mar 27, 2012, 11:31 AM
It could be a power setting - is the MBA plugged in? I don't know about OS X but in Windows, power settings could reduce USB ports from powered to non-powered.

I have had no issues running USB powered devices off of my MBA. Though my devices have been limited to hard drives.

Dweez
Mar 27, 2012, 11:40 AM
Return them and pick up some which will run off the the headphone jack.

nufanec
Mar 27, 2012, 12:28 PM
Is it the same from both left and right USB ports? They run off separate busses so if it only happens on one then it is either that one of the USB ports is lower power than the other, or a faulty USB bus.

M-5
Mar 27, 2012, 12:30 PM
Does this occur when you plug it into the USB ports on both sides of the machine? Because from my experience, the USB port on the right side of the device (where the thunderbolt cable is) can supply more power than the left-hand side of the machine.

For instance, I've tried running a USB-powered external hard drive, and it only runs when I plug it into the right side of the mac. I took it to the genius for another issue, and I told him about the USB problem, and he said something along the lines of the Right hand side USB port is connected directly to the logic board or something like that, and that's why it can supply more power.

Stealthipad
Mar 27, 2012, 12:42 PM
Yes, sorry, forgot to write speakers :)

Apparently it looks like the MBA gives less power to the USB than the MBP.

I just wonder why it isn't stated anywhere? According to official Apple-specs, they should have the same amount of power?

M

Voltage would be the same but amps can vary from laptop to laptop, even desktop to desktop.

Like some others have said, make sure you are plugged into the charger and try the USB port on the other side.

mickcordero
Mar 27, 2012, 01:33 PM
I've tried both USB ports, and always with the magsafe plugged-in.

The message in Mac OS about the device drawing too much doesn't always pop-up, but the left speaker just does not work. I am guessing this is because the USB does not deliver enough power.

It works from the PC's and MBP I have tried it on. So my conclusion is that the MBA does don't deliver as much power as other laptops?

Stealthipad
Mar 27, 2012, 01:39 PM
I've tried both USB ports, and always with the magsafe plugged-in.

The message in Mac OS about the device drawing too much doesn't always pop-up, but the left speaker just does not work. I am guessing this is because the USB does not deliver enough power.

It works from the PC's and MBP I have tried it on. So my conclusion is that the MBA does don't deliver as much power as other laptops?

I would have to agree with your reasoning