USB bus bandwidth and USB sound cards

**Merzbow** · 10-17-2005, 06:25 PM

Just a tip... USB bus bandwidth is more constrained than you think. I had my USB soundcard on the same USB hub as my USB hard drive from which I serve MP3s. I was wondering why my CPU usage would shoot to 50-100% during heavy sound. Well, I plugged the sound card directly into its own USB slot on the PC and CPU usage dropped way down. Apparently calls to the sound APIs in Windows would block synchronously waiting for I/O to be transferred to the sound card on the overloaded USB bus.

**DarquePervert** · 10-18-2005, 01:55 AM

USB 1.1 or USB 2.0?

And it's been known for some time that USB sound cards pas function calls off to the CPU, hence driving up the resources used. This isn't anything new.

**Merzbow** · 10-18-2005, 03:34 AM

Originally Posted by DarquePervert

USB 1.1 or USB 2.0?

And it's been known for some time that USB sound cards pas function calls off to the CPU, hence driving up the resources used. This isn't anything new.

USB 2.0. I wonder if I shouldn't have bought the firewire version of the IDE 3.5" drive bay I installed, my Xenarc does have a firewire port.

**Vero** · 10-18-2005, 02:13 PM

USB 1 and USB 2.0 both have the exact same bandwidth. USB 2.0 just uses a higher compression rate. Firewire does have a much higher bandwidth and will give you lower latency and better overall sound quality.

however you just cant argue with a good solid PCI card. i personally will be using my M-audio firewire 410 to run my audio off my mac mini, just as soon as i take delivery on my new car.