Audacity Forum

I was successful at doing this. I had a mic plugged into the line-in jack on the computer and a mic plugged into my Fast Track Ultra which is connected via USB. I created an aggregate device using "Built-In Line Input" and "M-Audio Fast Track Ultra". This made a device that had 10 inputs (the FTU has 8 and line-in has 2).

I went into Audacity, selected the "Aggregate Device" and set the number of channels to 10 since that's how many there really was.

And Audacity was able to record from both mics at once. Unfortunately it created 8 empty tracks in addition to the 2 tracks from the microphones, but at least it worked.

This was using the latest CVS build of Audacity.

(Sorry, don't have to USB audio devs...)

Leland

Bravo! I downloaded Audacity beta 1.3.9 and it was able to select and use my already aggregated pair of USB mics for inputs.

For those of you who don't know, by aggregating inputs you can plug several USB mics directly into your Mac's USB ports and avoid using an external mixer/combiner. Just plug them in, go to Utilities< Audio Midi Setup< Audio on the Menu< Open Aggregate Device Editor. Now select the mics to be aggregated, assign Channel 1 to the left and Channel 2 to the right for both input and output, and save. (You can rename the aggregated device if you wish.)

The combined mics are now selectable for recording. If you need to adjust the gain on the mics individually and are unable to do this when the aggregated device is selected, you can go to the Audio MIDI Setup utility and individually adjust their gain there. You can also select different sample rates, etc. in the same utility. (You may need to set the bit-rate of your recording software to match the bit-rate of your mics if there are problems.)

Wonder if this nifty trick should be posted on the Mac beta forum?

Thanks for all the feedback!

DWJ wrote:Bravo! I downloaded Audacity beta 1.3.9 and it was able to select and use my already aggregated pair of USB mics for inputs... by aggregating inputs you can plug several USB mics directly into your Mac's USB ports and avoid using an external mixer/combiner...

Excellent. We're often asked if you can use two USB mics to record (for example) a stereo interview in Audacity. You can't on Windows, unless we allowed Audacity to record from multiple devices simultaneously. Our usual answer to that request is that recording from multiple devices on Windows would lead to the tracks drifting apart over time due to clock differences.

I'm not sure if JACK on Linux would let you aggregate inputs in this way - Steve might know. Either way I don't personally know any hardware mixer that lets you combine two *USB* inputs into an audio stream to send to a computer (no problem with combining wired inputs).

DWJ wrote:Wonder if this nifty trick should be posted on the Mac beta forum?

I think a possible solution might be to work it into this section of our so-called Mac Bugs page on the Wiki. When 2.0 comes out and many of the issues on that page should be consigned to history, it might be worth renaming it to "Mac platform" or similar.

Thanks


Gale