All USB ports aren't created equal

Remember my theory about 10.5.2 causing poor audio quality in Skype?


Remember my theory about 10.5.2 causing poor audio quality in Skype? I pretty much convinced that 10.5.2 is the culprit, but there's another theory floating around out there – that it's related to USB ports.

The problem manifested itself most recently in the MacBreak Weekly podcast (episode 88) where Andy Ihnatko and Alex Lindsay sound like Cylons. They attribute the poor Skype audio to a lack of USB power – apparently, not all USB ports are created equally.

Their consensus is that the Skype problem is a symptom of being plugged into an under-powered USB port. It seems that only the front USB port on the MacBook offers a full powered, full speed bus. On the MacBook Pro the magic USB port is the left one, the right one is hubbed.

According to Andy, via Wired's Gadget Lab blog:


The rear USB port, the one nearest the screen, is in fact already on an internal hub, shared with everything USB inside the case: the keyboard, the Bluetooth, the trackpad, the iSight camera and the infra-red receiver. Adding a four way hub to this is bound to end in disaster.

While changing USB ports seems to work for Andy and Alex, my USB mic was connected the (supposedly good) left USB port on my MBP and my audio still borged out. The fix for me was rolling back to Tiger (10.4.11). Chuck Freedman has been running fine with 10.5.1, so I'm still convinced that it's 10.5.2.

(Top picture courtesy MacUser.)