Convert stereo to mono

Hi all,
to convert an audio region from stereo to mono, after selecting an audio region, I do this:

Region -> Edit -> Make Mono Regions

…but nothing happens, it remains stereo.
Maybe I’m doing something wrong?
Alternatively can I use some plugin to get this stereo to mono conversion?
[Ardour 7.4.0 on Linux]
Thank you,

The mono regions are in the region list, so that you can drag them onto mono tracks (As opposed to your stereo track the source is on).



Ah, ok…Thank you.
So one has to: make the conversion, create a new mono track, then drag in the edited region, delete the old track.
It’s a somewhat cumbersome procedure… in Audacity the conversion from stereo to mono is achieved directly with a single step.


If you look carefully at how Seablade phrased his answer:

That menu selection creates two mono regions from the stereo track, one from left and one from right.
Depending on how the stereo track was originally created using only one of the two may be appropriate. If the material started out as a mono source and was panned into stereo without any separate processing of the left and right sides there should be no difference. If you have added processing like stereo chorus or separate delay settings on L and R sides, then you may want to mix the two channels together as one channel alone will not sound quite the same.

But two mono regions are not generated with that menu selection, nothing happens at all.
A single stereo region remains. It is not split into two mono regions. That was the problem.

Are you sure that two new regions do not show up in the region list? As Seablade explained that is the expected behavior as explained in the manual here:
Region menu page in the manual
Make Mono Regions: Creates mono regions out of a stereo or multichannel region by splitting it into its discrete channels. The created regions are added to the Editor List

Now I see that in the right panel, in the “sources” section, they are created.
So I have to create a new mono track, drag one of these in…
It always remains enough cumbersome. It could do it automatically directly creating two new separate tracks…

If I want to simulate what happens when a mono system plays a stereo track, what should I do?
What happens in that case, what does it do with the two channels (right and left)?

Thank you,

Hit the mono button on your monitor controller.
Ardour helpfully provides a software monitor controller.
Ardour monitor section

I suppose it depends on which exact mono system you mean, but I would expect mixing the L and R channel together would be the most reasonable thing to do. A less reasonable approach would just play one of the two channels (more likely to happen in something like a large venue with speakers placed too far apart, background music in a restaurant, friend offers to share one earbud, etc.).

Yes, I found it:

So it works.
Thank you.

Yes, so in this regard I think the plugin that in another discussion suggested to me x42 (Stereo Correlation Meter) is very useful to verify that one channel does not cancel the other.

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Suppose we have a project with 20 stereo audio tracks.
If I want to hear only one of these tracks in mono (all others remain in stereo), how do I do it (using monitor controller)?

The monitor section affects everything you hear: there’s no (sensible) way to use it to process only some tracks and not others. To easily switch individual stereo tracks to mono, it’s probably easiest to use a plugin such as the x42 Stereo Routing on each track.

Alternatively, if the panner on your stereo track is “Equal Power Stereo”, (The Ardour Manual - Panning) double-clicking the centre of the ‘width’ control of the panner will pan both the left and right channels to the centre. Double-clicking to the left of the width control will set the width back to the maximum possible. You can’t adjust the balance with this panner, however: you’ll need to add something like the x42 stereo balance control if you need to make balance adjustments to your stereo tracks as well.

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If instead of using the “Make Mono Regions” command, I do this:

  1. I create a new mono audio track

  2. I copy a stereo track and paste it into the new mono channel

  3. A new mono track has been created

What operations has Ardour done at this point?
Has mixed the left and right channels in the sense of a “sum” of the audio signals?
Thank you,

Is this plugin only for listening? Meaning if I export that track, it still remains stereo. Correct?

If you have a stereo track connected to a stereo master bus it will have a stereo panner instantiated by default. That panner has a width control, if you pull the L and R indicators together into the center it makes the signal mono.
Stereo Panner page in Ardour manual

No, the x42 stereo routing plugin (as all plugins) affects the signal that the track sends to its outputs: you’ll have to remember to switch it back to stereo before you export if you want your export to be stereo, unless you’re doing a ‘Stem Export’ and you’ve unticked ‘Apply track/bus processing’ in the ‘Channels’ tab of the stem export dialogue.

Thanks, I’ve just discovered that I can bring the left and right cursors together, this is very useful.

I exported a stereo track with that plugin (x42 stereo routing) inserted and activated, so it should export in mono (that’s what I want).
But the exported track remains stereo, with two channels.
‘Apply track/bus processing’ in the ‘Channels’ tab of the stem export dialogue is selected.

So I had to double check on this as I couldn’t remember, I usually do this manually as my needs vary depending on what I need to happen. In this case it would play only the first (left) channel of the stereo file.


Stem export with ‘Apply track/bus processing’ ticked will always export a file with the same number of channels as the track or bus has outputs; if it’s a stereo track that you’ve made mono with the plugin, the left & right of the exported file will be identical, and you can use either (or both) channels.

A perhaps silly question:
when the file is played what is the difference between having a mono track or having a stereo track with the two identical channels?
Will it always sound mono the same way?
So it might be useless to create a track with a single channel, I could keep the stereo one with the two identical channels. (A stereo system and a mono system will play it mono the same way).