Source is mono 1 channel. What is the best way to make this stereo?

Teagan wrote on 7/19/2020, 3:06 PM

In the past I have just been duplicating the one mono channel from my Rode VideoMic Pro Plus by right clicking that channel and going to "Channels" > "Both" and that duplicates that mono channel to stereo in one track. That is good, it does what I need but I have came across some other ideas today including duplicating the tracks and panning one to the left and one to the right and another idea that involves that and also inverting the phase of one channel by going to right click > "Switches" > "Invert Phase", which sounds amazing somehow (and kind of weird), and I'm not sure if that phase inversion is doing something bad or something good. There was also another suggestion about the inverting phase option by delaying one channel by about 10ms so they don't cancel out in mono.

Any tips on what I should be doing, if not what I have been doing by just right click > "channels" > "Both" on my source track?

Another question, would it be worth it to try and pan the channels to try to make stereo, or even a 5.1 mix that I have been experimenting with? Where would I go to learn about that?

Comments

Dexcon wrote on 7/19/2020, 6:18 PM

YouTube has dozens of posts re this. Just go to YT and search something like 'convert mono to stereo'.

iZotope has a free plugin called Ozone Imager that might help you:

https://www.izotope.com/en/products/ozone-imager.html

lenard-p wrote on 7/19/2020, 6:41 PM

another simple thing to do is notch EQ left channel opposite to right channel. so left plus right gives the full audio. It's more simplistic. Used to be the basis of stereo expanders in the analogue days. I"m sure there are plugins or methods to better give life to mono now.

Musicvid wrote on 7/19/2020, 7:46 PM

Copy the mono audio to a second track, Pan one track full left,

Then if wanted, add a little delay and / or phase shift for spatial effect.

Bsharp wrote on 7/19/2020, 8:28 PM

If you have Soundforge, it is easily done there.

  • Just import the video or audio file
  • right-click the Channels box in the bottom status bar

  • Choose Stereo

3 options for destination choices will be in the drop-down-Menu  
Left channel
Right channel
Both

Choose both & you will have a stereo track

 

john_dennis wrote on 7/19/2020, 9:16 PM

@Teagan

"I'm not sure if that phase inversion is doing something bad or something good."

The answer is "Yes".

Turd wrote on 7/20/2020, 8:50 AM

In the past I have just been duplicating the one mono channel from my Rode VideoMic Pro Plus by right clicking that channel and going to "Channels" > "Both" and that duplicates that mono channel to stereo in one track. That is good, it does what I need but I have came across some other ideas today including duplicating the tracks and panning one to the left and one to the right and another idea that involves that and also inverting the phase of one channel by going to right click > "Switches" > "Invert Phase", which sounds amazing somehow (and kind of weird), and I'm not sure if that phase inversion is doing something bad or something good. There was also another suggestion about the inverting phase option by delaying one channel by about 10ms so they don't cancel out in mono.

Any tips on what I should be doing, if not what I have been doing by just right click > "channels" > "Both" on my source track?

Another question, would it be worth it to try and pan the channels to try to make stereo, or even a 5.1 mix that I have been experimenting with? Where would I go to learn about that?

Although what you're doing gives your audio an "amazing/weird" sound, it's a psychoacoustic effect. The biggest problem with your method is audio won't be heard by everyone who listens to it in a mono-mix scenario. What's happening is one track remains normal, while the other inverted track becomes it's evil-twin exact opposite. The two tracks, when blended together in mono, cancel each other. The more closely the volume on your two tracks match each other, the more they cancel each other. Try it. Listen to your audio in "mono" mode in Vegas. You'll see the meters bounce like crazy, but you'll barely hear it -- if you hear anything at all. Then try changing the volume on only one of the tracks. It doesn't matter which one. Even though you're LOWERING the volume, you'll hear it become LOUDER! That's because, by removing more and more of the cancellation from one track, you're allowing the opposite track to be heard. It's the basis for how noise cancelling headphones work.

A similar method is often used to remove vocals from a stereo song. Main vocal tracks are most often center-panned. If you isolate the two channels, then invert one, everything that's center-panned in the original song cancels and all you're left with is everything that was produced off-center. It's a far from perfect way to remove vocals, but it's sometimes good enough under the right conditions.

Note to self (everyone else please look away -- the note that follows is a reminder for mine eyes only): Figure out a clever, kick-booty signature that suggests I'm completely aware of how to properly and exhaustively party on and that I, in fact, engage in said act on a frequent and spontaneous basis.

rraud wrote on 7/20/2020, 9:46 AM

If the mono channel is interleaved to a two channel (dual-mono) event or file and the phase is reversed on one channel, cancellation will occur when summed to mono.

Voxengo's free "Stereo Touch" VST plug-in works good for 'simulating' stereo. I have used it on mixes splitting a mono rhythm guitar track to L-R. It is similar to splitting it with a delay one one channel, but has many more options.

Musicvid wrote on 7/20/2020, 10:32 AM

The problem with a simple phase shift for simulated stereo is that the ears simply adapt over a few minutes, and the spatial or "widening" effect is gone. One widely used technique is similar to Dolby Matrix, which does rely on a 90° shift in the source. It is so full of Q-Noise, however, that I was sadly disappointed when I bought my first PLII receiver, and never use it in my own work.

Another way to overcome the brain's cancellation of static phase shift is to use a subliminal phase rotation in one channel, the rightfully called Leslie Effect. Having taken Acoustics in college, and played a B3 with Leslies for two decades, I still marvel in Dopler Theory, and used it quite a bit.

So, in mixing my theatrical mics, which are of course all mono, and as many as 36 in number, I mixed down my L/R and delayed rear, then also delayed my Front Center main by ~15 ms, giving a Z-axis depth that is missing from most recordings, and the spatial effect was suddenly multiplied exponentially, as if sitting in the center of an auditorium with a curved stage. Here is an example, but it's a stereo mixdown.

 

Teagan wrote on 7/20/2020, 10:38 AM

If the mono channel is interleaved to a two channel (dual-mono) event or file and the phase is reversed on one channel, cancellation will occur when summed to mono.

Voxengo's free "Stereo Touch" VST plug-in works good for 'simulating' stereo. I have used it on mixes splitting a mono rhythm guitar track to L-R. It is similar to splitting it with a delay one one channel, but has many more options.

I got StereoTouch installed and it's really great. The Vocal Space option really makes it sound like true stereo. I just right click my audio and go to Channels > Both and then apply the plugin's vocal space option and that's it.

Thanks for the suggestion!!!

Can anyone explain what it's doing to make it sound like this or is it was MusicVid said?

I see on my master bus for the audio the L and R channels are getting slightly louder than each other over and over about every 2-3 seconds.

Musicvid wrote on 7/20/2020, 12:12 PM

Can anyone explain what it's doing to make it sound like this or is it was MusicVid said?

I have ways to check this out, and will download the plugin to check, time permitting.

I suspect it is something "like" what I described, but more refined.

rraud wrote on 7/20/2020, 12:49 PM

I would not use any kind of widening or stereo simulation on dialog unless for ADR or a special effect.. Sci-fi for instance.

rraud wrote on 7/20/2020, 1:51 PM
I see on my master bus for the audio the L and R channels are getting slightly louder than each other over and over about every 2-3 seconds.

Are you using it on a mono event or track or did you created 2-channel dual mono event prior to inserting the effect, I can also be used as an assignable effect (send-return). In any case I do not recall an occurrence of that sort. You may have a long secondary delay louder than the initial or excessive feedback

Teagan wrote on 7/20/2020, 1:58 PM
I see on my master bus for the audio the L and R channels are getting slightly louder than each other over and over about every 2-3 seconds.

Are you using it on a mono event or track or did you created 2-channel dual mono event prior to inserting the effect, I can also be used as an assignable effect (send-return). In any case I do not recall an occurrence of that sort. You may have a long secondary delay louder than the initial or excessive feedback

I started with mono on one track and turned that into stereo in one track with right click > channels > both and then applied that plugin's Vocal Space option.

It's so good compared to the original that I'm considering this for all my future work unless there's a reason I shouldn't.

john_dennis wrote on 7/20/2020, 2:02 PM

@Musicvid said:

"Another way to overcome the brain's cancellation of static phase shift is to use a subliminal phase rotation in one channel, the rightfully called Leslie Effect. Having taken Acoustics in college, and played a B3 with Leslies for two decades, I still marvel in Doppler Theory, and used it quite a bit."

I wondered at the time whether the background vocals in this recording: RIP Kenny Rogers

were played through a Leslie tone cabinet and added back to the mix, or if they just added a tremelo effect from a cheap Fender amp. Unfortunately, I got drafted and was distracted and never followed up on the subject. That was many years BG.

Brief Sample Audio:

Musicvid wrote on 7/20/2020, 2:35 PM

You should see the look on today's young people's faces when they listen to "Dark Side of the Moon" through their earbuds for the first time.

 

Musicvid wrote on 7/20/2020, 3:34 PM

Absolutely agree. Dialog is point source, and should be run dead center, or panned by subject position(s), but not split and separated. My technique is to delay the center slightly, as the l/r pit actually sounds closer, as in real life.

Musicvid wrote on 7/20/2020, 3:50 PM

@john_dennis Here's one I bet you haven't seen -- the Leslie 950 tower, which I ran with B-3, Rhodes, and Key Bass throughout the 70s. By the 80s, I had cut them down to four self-contained boxes without the psychedelia, and usually ran two for club gigs.

john_dennis wrote on 7/21/2020, 11:25 AM

@Musicvid

No, most of the Leslie tone cabinets I ever saw had a stained wood finish and no lights with the exception of the Fender Vibratone.

Musicvid wrote on 7/21/2020, 12:07 PM

A Hammond B3 and pair of Leslie 122 or147 cabinets. It was one of these that finished my back and my music career in early 2016.

https://en.wikipedia.org/wiki/Leslie_speaker#Sound_generation