Here's an audio demonstration: in the first 4 bars, the snare's polarity is working against the kick. The last 4 bars I invert polarity of the snare:

http://www.audiosabre.com/music/mp3/PhaseIsMyFriend.mp3

I think it's important to always check out polarity (and/or phase) if something is awry.

its a good example the snare has more snap and feels a little more alive

If the track is i.e. a stereo synth you have to switch polarity (I'm using Live's Utility) for both L and R correct?

Ableton Live Utility (see bottom)

Is this an issue if you don't record instruments? If you are creating EDM completely in-the-box.. then do these phase or polarity issues occur??

Yes they can be there, if the creator of the stereo sample didn't take care it potentially could be out of phase with itself.

It is rare, but you can actually train yourself to hear if there are phase problems with a little practice. Most engineers are very sensitive to phase issues but it is an acquired talent.

Most people feel there is something weird going on with the sound, but can't pick their finger on it. You fix it and they are instantly relieved.
Lots of places have their speakers wired up out of phase, some friend's hi-fi systems (I gently correct it) supermarkets and shops (worst offenders), my local DVD rental shop (painful) and even cinemas (very ugly experience)


Phase is similar to tuning, after you get the hang of tuning a guitar, you can really hear when one is out of tune. The more you hear an "out of phase" problem the faster you recognize it.

So....

Take a mono sound, voice, piano, guitar, anything really. Pan it left

Create a second mono track, copy/paste the first sound at exactly the same start point. pan it right.

Then flip the waveform, or reverse or invert it depends on your DAW how it gets done

Give a listen, loop its playback to give it some time to sink in.

Does it feel strange, like a tickle in the ear, like your head has gone thru some sort of bisection?

"Invert" the sound again while playing back (if it is possible), what happens, it zooms into the middle and gets louder.

Repeat it until you get used to what that "out of phase" sounds like.


Most samples or instruments are OK, they use delay or pitch-shifting to create their "stereo".

But after training yourself to recognize an "out of phase" sound will allow you to recognize instantly if a problem exists. It is the same for all engineers, everybody starts at the beginning.

With the amount of Plug-ins and virtual instruments on the market, there are certainly going to be some with phase problems.

If you suspect it to be the case just solo it and check it out.

If you are not sure if you can hear whether it is "out of phase" or not, don't worry, try to collaspe it into mono by hitting a "sum to mono" button or automating the pans to the center.

If you hear big parts of the frequencies or all of the sound disappearing instead of getting louder then there is a "phase problem".

Record it to a stereo track Zoom in and take a look, if the waveforms take off in opposite direction and are the polar opposites of each all along the different parts of the waveform, there is a problem to correct.

This, of course only applies to stereo or 5.1 samples, a mono sample can't be out of phase with itself, keeping everything mono eliminates all the phase problems, but as we all have two ears to detect spatial information, it is nice to play with that "stereo" that are brains are programmed for.

I did this in Ableton and when I used the mono utility they completely canceled out, which is what I expected. I hit the mono button on my monitor switch and it got a lot quieter but I could still hear it. The best explanation I can come up with is that because it's gone out of the sound card and is now an analog signal, the two channels are slightly different and so don't cancel each other out completely. I guess you could say that's the "dirt" in my monitoring chain?

Also I was wondering how you would tell if the monitors are out of phase, but it's pretty obvious: when you play a mono sound it doesn't sound mono, but is instead this goofy stereo effect that disappears when you mono the monitors!

I was thinking about how to try to deal with this issue without chasing your tail and it seems to me you could just make it a policy to flip the phase every time you add a new track to an arrangement/mix and just listen for a few seconds to see if it improves.

Or if you set up a drum submix you can go through each of those and flip them both relative to each other and then relative to the whole mix. It would just take a second per track and you would avoid being stuck in a situation later on where you had 50+ tracks and you felt like one or two of them might have phase issues but you didn't know which. Might save you some headaches as you built up the mix, too.

Making sure the kick and bass are in phase is pretty essential for getting the "massive" sound that most of the super commercial guys have these days. Zoom in on the waveform of Green Velvet - Flash (Nicky Romero Remix), if you have it. You'll see that the kick and the bass fit together perfectly, it looks like one instrument.

Ah wait, I was actually showing it to a friend last week! This is just 1 beat.

"I did this in Ableton and when I used the mono utility they completely canceled out, which is what I expected. I hit the mono button on my monitor switch and it got a lot quieter but I could still hear it. The best explanation I can come up with is that because it's gone out of the sound card and is now an analog signal, the two channels are slightly different and so don't cancel each other out completely. I guess you could say that's the "dirt" in my monitoring chain?"

HMMMMMM

Don't know for sure, but there might be some "phase rotation" somewhere in the signal path.

Phase can be said to be 360° like a circle.

180° is halfway and that is the one that cancels with the original because it has a reversed polarity relative to the original.

If one waveform is delayed then then phase is rotated by degrees could 1°, 22° whatever...and there will be a leak and the signals won't nul.

If you are working with a stereo panned hard left and hard right it won't be a cause for concern, but combined in mono some frequencies can be affected depending on the position of on waveform vis à vis the other.


The outputs from the sound card should be coming out at an identical time.
If it is a lot quieter than I wouldn't be too concerned, it is not worth worrying about, nothing is perfect.

Phase relationships are the basis of a good recording and that extends to mixing. However there are many other factors other than phase that go towards a good mix down. Many of the decisions at the recording stage affect this. Of course with electronic music no such stage exists I would say sound source selection is one of the biggest factors in a good mix. Of course tonal balance, level balance, stereo image, transient punch, all play a very important factor too.

cheers

SafeandSound Mastering
online mastering studio

Yes they do, but you determine the tonal balance, stereo image, transient punch from the very beginning with the way one records the sample.

With electronic samples you are one step removed from this as it is not you who recorded (built the sample) it or coded the synth. They all output somewhere a waveform.

And as the majority of the "samples" are stereo, there is always a relationship between the left and right "samples" that is affected by phase.

If seems to be a audible problem then one should zoom in just to check it out.

If the "polarity" is reversed, one can "invert" then either delay or pitch-shift the result to be "mono-compatible" for people who might listen to the speakers of their iphone for example.

Just to avoid your essential synth in the tune disappearing or taking an unexpected volume hit for your listener.

The mastering will be better as well.

All of what has been said by far indicates that controlling phase/polarity is crucial. As that issue has been known for years I'm wondering why DAW manufacturers/devs don't include direct controls (more in depth rather than just polarity inverse or mono swithc) to DAWs mixer channels by default (like pan, mute etc). It would be more helpful rather than managing dozens of instances of the same plugin.

Just a thought...

I think it is because the DAW manufacturer and digital console manufacturer didn't want to be too up front about the inherent delays caused by inserting effects etc. as it was a derterrant to sales at the beginning of the DAW age.

A lot of progress has been made since then.

I'm pretty sure that most do. I know FL studio has a really nice section like that integrated into the mixer, and Live has "utility", which you can use to solve a lot of issues. Both have track delay options that you can fine-tune in fractions of milliseconds.

I use ProTools and before the "delay compensation" I was consulting the plug-in manufacturer Docs and off-setting the tracks to make up for the delay.