Mono recording is recording from bother channels

I’m using 2.1.0 on win7 machine with usb sound blaster soundcard.
I have a 400mV tone going into the left channel and nothing on the right. When I record stereo I see around -16dB signal on left channel only as expected. When I change to record mono, I see only -22dB signal. I get the same thing if I move the input to the right channel. Seems when I set my recording to mono, it is mixing half power from left and half from right.
Is this something that is set in Windows? I haven’t seen this behavior before. Usually mono recording just record from left channel.

That’s one of the “normal” mono behaviors. The other thing you’re going to notice is your Left-Only signal overloads at -6dB.

This leads to my opinion that if you’re going to record mono, you should do it with a mono adapter. Adapters are not mixers. You can’t usually pick and choose which behavior you want.

Record your show with a -6dB peak goal, or record stereo, split to mono and delete the right channel.


Interesting that this is “normal”. I have another setup that completely isolates left and right channels. If I input my signal on the right channel it will not be recored when recording mono. Just curious if the difference is something within Audacity, portaudio or windows. Any way to configure it so all my systems work the same way?
I did recognize that recording in stereo and splitting the track will give me what I desire and is how I will proceed moving forward. Just curious of the root cause.

Thanks for the reply.

Interesting that this is “normal”.

It’s one of the “normals.” Recording a mono show with anything but a mono adapter is inviting a conversion. I count four possibilities: Just drop the right channel, jam the two together and don’t change the levels, jam the two together and drop the level 6dB to avoid overload, and fail. I have a stereo adapter which won’t connect in mono.

There was a recent posting from someone trying to record mono with a six track, multi-channel adapter. I don’t know we ever straightened that out, other than record everything and peel off anything you don’t need.

I don’t know that the “who” is easy, either. Audacity gets its sound from Windows, not the device. juggling device drivers can be a challenge.

Quick note, if you determine in the future to upgrade to Win10, device drivers have to be written for Windows 10 and say so. Windows 10 was the opportunity to peel off all those older and unsupported adapters and devices.


I’ve always assumed it was the driver…

The logic is - If you’re recording in mono from a 2-channel interface and channel-1 is hitting nearly 0dB and then you mix-in channel-2, the mixed digital signal could clip if you don’t cut both (digital) signals in half. And, the meters/clipping LEDs on the interface wouldn’t show either channel clipping… It would be a bummer if you didn’t know it was clipping 'till after you were done recording.

There’s no problem good engineering can’t make worse.

Statically, you don’t have to reduce the jammed together level by half. If you apply a mono signal to one channel, then all options are open, but if you apply a full stereo signal, then only a portion of the Left - Right show is going to “line up” to create a boosted volume condition. Classic Vocal Removal depends on this effect.

Chances of someone applying a mono show to both inputs is really small. You would have to go to the trouble to make a second channel or buy a “Y” cable.

So I propose a new standard where you add them together and only reduce the level by 3dB.


Thanks all for the wisdom. I’ve hit the default button and am just recording in stereo and looking at the channel of interest. This is obviously a more flexible approach. My thought that recording in mono would be quicker because I would only have one channel of data to deal with. Should have just paid for the burger today instead of waiting until Tuesday.

recording in stereo and looking at the channel of interest.

It’s easy to convert to mono. Use the drop-down menu on the left of the track > Split Stereo to Mono.

[X] Delete the silent track. The one remaining will be mono and play to both speakers.