I have four mics coming in through a PreSonus mixer via USB into my Windows 7 PC running Audicity 2.0.0. All input is currently going to only one track (channel). How do I enable Audacity to record the four discrete, independent vocal audio channels simultaneously?
p.s.: The four channels record independently with PreSonus’s Studio One, but I prefer to use Audacity as it is more familiar to me for editing and saving the recording in .mp3 format.
As a general, fuzzy idea, Audacity records one stereo show using Windows Drivers and software. People routinely complain that they have a bazillion channel sound source, but they are presented to Windows as multiple stereo pairs, and Audacity will only manage one stereo pair at a time.
Macs can manage two different microphones at once through the Aggregate Device software, but there are significant problems with that in a production environment.
You can prepare Audacity by compiling from the original salt, sugar, flour, butter, milk, etc. Bake your own Audacity Program. If you do that, you can bake in ASIO software support and your chances of multi-channel success go way up.
And yes, compiling Audacity – making a computer program – is as scary as it sounds.
http://wiki.audacityteam.org/wiki/CompilingAudacityForBeginners
I don’t know that the tools are available fort Audacity 2.0 yet.
Koz
Try setting the number of recording channels to 4. http://manual.audacityteam.org/man/Device_Toolbar
Steve,
No matter which combination of HOST and INPUT DEVICE I choose, the INPUT CHANNELS never changes from the two types: MONO or STEREO. I would expect to see “4 CHANNEL” pop up if it recognized the PreSonus mixer as having that capability, but Audicity doesn’t appear to have a configuration for that input device. Any other suggestions would be welcomed.
How could we have released a Windows build of Audacity 2.0.0 if we could not build it with Visual Studio (2008)? 
This is the correct help link for compiling Audacity on Windows
http://wiki.audacityteam.org/wiki/Developing_On_Windows .
Gale
It’s a “driver” issue.
I’ve got a 4 channel sound card myself, but the Windows (WDM) drivers make it appear as two stereo devices. Sadly Audacity can only access one recording device at a time (even if they are in the same box) so I can only record 1 or 2 channels at a time.
The “alternative” that Koz and Gale are talking about is to use ASIO drivers.
ASIO is not supported by Audacity out of the box due to licensing issues (Audacity is open source but ASIO is not).
ASIO drivers will usually support as many channels as the device has, so making all 4 channels available to Audacity. The problem is that the licensing issues mean that Audacity cannot be shipped with ASIO support (if it is to remain open source) so to get ASIO support it is necessary to build Audacity from the source code and build in ASIO support. This is perfectly legal provided that it is for personal use (may be commercial use but not distributed to others).
The instructions posted by Gale are for building Audacity from the source code. Additional information about adding ASIO support is here: http://wiki.audacityteam.org/wiki/ASIO_Audio_Interface but this is not for the faint hearted. It should be fairly straightforward for computer programmers but is definitely an “advanced” topic for most users.
The short answer is that you may not be able to get 4 simultaneous channels with Audacity unless you venture into compiling Audacity from the source (which on Windows is not very straightforward).