[Techtalk] o great audio geeks... USB a/d converters

Carla Schroder carla at bratgrrl.com
Thu Aug 28 13:59:13 UTC 2008

On Friday 22 August 2008 15:58:38 Michelle Konzack wrote:
> Am 2008-08-11 10:23:51, schrieb Walt:
> > They replace the sound card, at least in my experience
> This is technical wrong, since it ADD a soundcard.  

Well sorry for not phrasing the question better, though I think it was clear I 
was asking if I still needed a soundcard when recording with a ADC/DAC USB 
device. The answer to that is no.

> So  if  you  have  a 
> 7-Port USB-Hub and add 7 Mictophones, for a Band,  you  will  get  seven
> /dev/dsp* and have the hell to set it up...  ALSA  does  only  recognize
> one by default so you have the get the ID's of the devices,  setup  UDEV
> rules to fixe it to a Device number and then setup  one  file  (you  can
> better add and remove it) per device in /etc/hotplug/...

That's not what happened with my new MobilePre. Plugged it in, opened 
Audacity, selected the recording and playback sources in the Audacity 
preferences, and it Just Worked. I had two mics and a guitar plugged in, and 
Audacity automatically opened a new track for each channel. The gain controls 
on the MobilePre controlled the volume for the mics. Plugged in a headphone 
for monitoring (lots of plugins on a little device!) and I was ready to rock.

BTW, anyone wanting a MobilePre be sure you get the new one, which is black 
and silver. The old one is blue and silver, and requires a firmware loader. 
There are instructions all over the web for configuring this on Linux; I'd 
rather just plug the thing in :)

Do you mean a 7-port USB ADC/DAC? Or do you really mean a hub? That many USB 
ports aren't going to do you any good anyway- the USB bus can't handle all 
those inputs without data collisions, so your sound quality goes to heck. You 
need Firewire for that kind of load. USB works fine for 1-4 channels on a 
reasonably powerful computer, and you don't do anything else while you're 

Carla Schroder
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