Cannot perform stereo track to mono successfully

MacBook Pro, El Capitan, Audacity 2.1.1
I record audio talks using an Olympus digital recorder. The feed is direct output from an amp to the microphone port. Files are written as 128 kbps MP3 files. The one hour session files are usually large. I use Audacity to trim the files, compress if necessary, add Metadata, and export as smaller files for posting on a website. Currently, I am unable to convert the files from stereo to mono. The process runs, but the result is essentially no audio in the result track.

Why doesn’t this process run successfully? I have done it with older versions (of Audacity and Mac OS) with good results.

All Stereo to Mono does is smash the left and right together and divide by two (to keep the volume correct). If yours goes to a straight line when you do that, then the stereo left-right show wasn’t two near-copies of each other, they were mirror images (attached).

It’s well into the 99.9% certain that’s caused by a wiring error.

I record audio talks using an Olympus digital recorder.

Yes. I do that. Then I export the high quality WAV sound file into audacity (over the USB connection) edit my brains out, Save a WAV archive, convert to mono, export to MP3 and post it to the client.

What part of that do you not do?

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Oh, there is one more. Some Olympus recorders can do tricks with the microphones and you don’t record a plain, ordinary stereo sound show. Which model do you have?


Recorder is WS-822

I’ve looked at the image and I can imagine that the “tracks” may, in fact, be mirror images. I’m recording from a church setup and wonder if the on-again, off-again ability to perform this could be from the rats nest of cables from the main microphone and amplifier board.

I drop the original, high quality MP3 on the Audacity icon from the USB, edit my brains out and save it again as MP3 at about 10% the size of the original. Currently, that MP3 file is uploaded to the church site in a Joomla environment.

One real question might be this - is converting fake stereo (dual mono tracks) to mono going to gain anything in terms of file size reduction and/or audio clarity when the MP3 is play from the website link?

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My presumptive evidence of a mirror image…Do I need to look for some inverted wires?

My cable is an Angled 1/8 Stereo to Female XLR Cable.

You can Get Out Of Jail by splitting Stereo to Mono with the left-hand drop-down menu. Then delete one track with the little “x” on the left. Dust off hands. Drink tea. That may increase the microphone amplifier hiss noise of the final show a touch, but if you have to get the show out the door, that will do it.

Do I need to look for some inverted wires?

Certainly not. That would be too easy. I’m pretty sure your adapter is wrong.

I have the WS-823 which I specifically bought because it directly supports high quality WAV sound format in addition to surveillance, telephone and meeting recording. So far it’s been a sparkling success. I bought a second one.

There are variations, but the signals on the 1/8" plug are usually Left, Right and Protective Shield. Top illustration:

XLR connector pins are:
1 Protective Shield (so far so good)
2 Main Sound
3 Balanced Protection Signal (which is usually pin 2 upside down.)

Tell me again why you’re not transferring sound files around?

You can completely solve this in post production by splitting the stereo—but not to mono. Leave them L and R. Select one of the two and invert it: Effect > Invert. Now push them back together again with the drop-down menu. Make Stereo Track. That’s the stereo track you should have had, had you had the proper adapter (to overuse the subjunctive mood).


I’m now just waking up. Your problem is going from the mixer to the recorder, not the recorder to the computer. Good Morning.


You can get marginally better noise in the final show by using the split, invert, marry technique. You are, in software post production, creating the same noise cancellation that an XLR recorder has. If you don’t mind doing that for each show, that is a desirable thing to do.

That’s the whole thing about XLR cables. They carry their own noise cancellation around with them. That’s what lets you put XLR microphones on the stage 100 feet away.


And yes, converting to mono in Audacity should give you a half-size MP3 client file with little or no decrease in quality. Make sure the timeline says “MONO” before you export. That’s a single channel sound file that will play to both left and right speakers.

MP3 is not a good format for production. MP3 creates sound damage while it’s working and it creates even more when you edit and make a new one. That’s why I use WAV 44100, 16-bit for master recordings and then drop the quality to MP3 if that’s the requirement.

However, if you have a working pipeline, don’t listen to me.