Duplicate tracks from mono

Sorry to be such a wuss, but it’s a long time since I used Audacity. My input is a mono mic. I want my recordings to have two identical L/R tracks. How?

Record the mono track. Then duplicate that track (Edit…Duplicate). Then, from the title bar of the upper of the two identical tracks, “Make Stereo Track”.

Thanks PGA. That indeed works, but I thought that I could set it to record that way as a matter of course. If I use Amadeus instead it produces two identical tracks straight off (though I don’t want to use Amadeus with its limited facilities).

What setting do you have in “Edit…Preferences…Devices…Channels”?

Thanks. If I have 1-channel (mono) I get 1 track. If I have 2-channel (stereo) I get two tracks but there is only data on one of them. The level monitors at the top show signal only in the LH channel. (?)

I think that means that your hardware (probably the mic) is delivering only one channel (i.e. a mono signal). Your only option using what you have would seem to be Duplicate followed by Make Stereo as previously suggested.

Why do you want 2 identical tracks?
It will sound exactly the same as having one mono track but will take up twice as much disk space.

I’m sorry to be a bore on this - but if I use Amadeus 2 I can choose to have two tracks and assign the input for each - in this case assign both track to the mono input channel. The monitor then shows active levels in both tracks and I get what I want (for personal purposes when editing). If I can’t do this in Audacity I suggest it is a major disadvantage in what is otherwise a great programme.

Audacity is not Amadeus 2 so it is reasonable to expect some features to work differently in Audacity.

Audacity records sound from the sound card via the sound card drivers. Some sound cards will deliver a mono signal as 2 identical audio channels, whereas other sound cards will deliver a mono signal as one (mono) audio channel. Which of these two behaviours occur depends on the sound card hardware and the sound card drivers. If the sound card drivers deliver a single channel mono signal (as appears to be the case on your computer), then that is exactly what Audacity will record.

Interestingly, professional level audio devices will invariably deliver mono as a single channel. 2 channel mono generally only occurs with some low quality consumer level equipment.

I disagree because recording duplicate data would be a very inefficient method of working. I would also be suspicious of a recording application that modified the audio data before recording it. Audacity records the data that is sent to it.

If you really need 2 channel mono (and there are occasions when 2 channel mono is required) then it is a very simple matter to convert a true mono track into a 2 channel mono track. One of the quickest ways to do this is to duplicate the track (select the track then Command+D), then select “Make Stereo Track” from the track drop down menu of the top copy. However in most cases this would not be desirable because it reduces the number of tracks that will fit on the screen, it slows down processing (because there is twice as much data to process), it reduces system performance and it uses twice as much disk space.

Thank you everybody. I accept what you say. However - for whatever reason - I still find twin track mono recordings sound significantly better than one track, and I’m not really concerned about file size especially as files compressed to Apple lossless still sound that good.

My input is a mono mic.

How did you do that? In detail.

If I select the internal mic on my Macbook Pro and stereo on the Audacity drop-down tool bar, Audacity will record that mono microphone in two-track.

I think you can do that trick with a mono USB microphone, too. If you’re using an external mixer and enter the Mac via the stereo analog input, I think you’re stuck with left-only or mono. I need to check that when morning actually comes.


If they really do sound different then there is something wrong with your system. They should sound identical because the data is identical.
If that’s not clear, here’s a simple example of what should happen:

  1. Single channel mono track containing the following data:
    When played back, the data is sent to the left and right channels of the sound card as:
    L. 10110100…
    R. 10110100…

  2. 2 channel mono track containing the following data:
    L. 10110100…
    R. 10110100…
    When played back, the data is sent to the left and right channels of the sound card as:
    L. 10110100…
    R. 10110100…

Nope. I plugged in my Blue Snowball USB microphone and the choices are Mono and Mono. Koz