Reverse Phasing a Stereo Mix

[SAtkins]

Hello all,

This is my fist attempt posting here, so greetings to you all and thanks in advance for any asssistance you all might be able to provide. Also, to the moderators, if this should be moved to a more appropriate location (I checked but didn't notice a more relevant area)please do so, or let me know how and I will do it.

K, here goes:

I am currently in the process of final Mastering some tunes prior to thier release on I-tunes. I'm using Audio Desk 3 and have bounced all of the tracks in each of the individual songs down to 2 stereo tracks. So now I'm basically in the "fine tuning- finishing" mode which requires very small tweaks and a light touch. In one of these tweaks I applied a "Trim" effect to to the Stereo mix, which not only allows you to set the max peak, but also permits you to make one side of the mix (either you chose) to be out of phase with the other side. I tested this with interesting results. It actually made the mix sound deeper, and more broad or stereophonic, giving the instruments a seemingly broader location in your hearing prespective, almost like they were located out beyond the actual range of the speakers you were listening to. It also seemed to throw certain instruments (in a high end vehicle sound system) into other speaker locations such as the rearmost, making you feel as if you were sitting in the middle of the music, not just having it come at you from the front. After rsearching a bit regarding these dynamics, I discovered this is an old trick used by sound designers for ages to produce these exact results. However there are some questions regarding this:

1.
I've also heard you can do this same trick by reversing the polarity in one of the stereo tracks. How would one accomplish this with Audio Desk. and what would the difference be?

2. Are there any drawbacks to this phased method? I know that in a mix with both mono and stereo tracks combined you can suffer drop outs in tracks due to this, does this affect a pure stereo track though? Am I losing anything here?

3. And finally, will this cause an issue when this isn't played on a regular stereo system, say a car or home system, but is transfered to an I-tune or Mp3 to be played on systems perhaps of lesser complexity?

Any assistance is most welcome.

TIA

S.

[Dwetmaster]

As far as I know, The Trim plug IS the way to do it. So I don't know of any other way that would be more effective to do it.

[HCMarkus]

Reversing phase and reversing polarity are, in this case, the same thing.

When you reverse phase/polarity on one channel of your stereo mix, if your music is ever played thru a mono system, all mono elements that are center-panned will disappear. As such, if you mix like most folks, all low-end will go away. Your lead vocal and snare drum will disappear. Mono elements that are not hard-panned one way or the other will be attenuated.

Out of phase information is moved around the faux-surround field by Dolby surround when synthesizing surround from stereo program material. MIght sound cool sometimes. Other times... meh.

Check mono-compatibility by using the fold-down feature of the Master Fader or your hardware controller. Then forget about reversing the phase on one channel.

[stephentayler]

I would recommend you do not do this. While it may sound tempting as it causes the sound to come from behind or around you, it really has an adverse effect, and particularly in mono, and people will generally think it is a fault. There are plugins that can help widen the sound field if you feel the need to do so, but this method of changing phase or polarity of one channel is not the way to go about it. It may sound interesting on your particular speakers, but you will have no idea how it may sound on other systems........

It may be used on a particular sound within a mix to send it outside the normal listening field as a special effect, but not on the whole mix.

In the days of vinyl it was completely a no-no to have out of phase material, it would make the stylus jump out of the groove!!

Cheers

Stephen

[stephentayler]

Oh, and welcome to the Forum!!!

SWT

[SAtkins]

Hey thanks guys. This helps alot. Its funny, after having a few different folks listen to the difference between the mix with, and the mix without this effect, most people preferred the one without it oddly enough. But what you all mentioned spoke directly to my concerns that bad mojo would come of using this technique, that may sound great on a high end BMW sound system, but then when played on an iphone with earbuds, may simply be missing pieces, or severely out of synch or eq. Verdict. I will not use it.

Now then, stephentayler you mentioned there are plugins that can help widen the stereo mix, or in essence gain some of what I liked about this effect but without screwing something else up in the process. What would they happen to be if you wouldn't mind sharing? And thanks for your warm welcome.

Please remember I am using Audio Desk " 3 I believe" on a Mac G4 in OSX.

Thanks guys!

PS. Isn't there something called stereo enhancer?

[stephentayler]

Hi there!

You can take this all with a pinch of salt, but here is what I believe.

Your systems are not particularly up to date, and unless you have a budget it is unlikely that you will find a stereo enhancer that is worthwhile (such as Izotope Ozone etc...) - and once again, I suggest that such treatment is appropriate for elements within a mix, not the whole thing......

The whole issue about stereo width is complex. We, as music-makers/producers/engineers spend a lot of our time in the 'sweet spot', perfecting our tracks so they sound great on our speakers or headphones. Usually paying attention to the tiniest details of stereo placement.

However, my biggest test as to whether a mix is happening or not boils down to the 'eavesdropping' test. While listening, I get up and walk around, down the corridor, into the next room, go and make a cup of tea (this applies to wherever I might be working - my place or any number of commercial or private studios). Read my email, concentrate on something else, see what pokes out and grabs my attention.

The sound of the record and the balance becomes completely clear to me at this point. Any finer details of the stereo picture are just a luxury now. If the balance is there, things can be shifted around to suit the stereo image according to taste.

But then again, most of these points relate to mixing, as opposed to mastering, which should only ever be about final relative levels and overall EQ, compression, loudness etc.

Just some of my thoughts!!

SWT

[Prime Mover]

I'm going to second that this is not a good idea. Keep in mind that there are still MANY devices that use "summed mono" outputs. Any time that your polarity inverted audio is summed to mono, it will be canceled out completely. Summing even happens naturally in various acoustic environments, especially when speakers are positioned very closely together. Even stereo recorded instruments will often become severely filtered and sonically unstable. It might sound fine in your space with a wide stereo field, but it suddenly might sound completely terrible on another system. So doing this will make your music sound completely unpredictable depending upon the equipment and space. That's counter to your goal of mastering, which is to make everything sound listenable in a broad range of situations.

Also, this kind of sound change generally is not the type of area you should be concentrating on during the mastering stage. Mastering is about taking what's there and making it smoother, more consistent, and more true to it's original intent, as well as fixing any last-minute problems. I would generally consider stereo-widening a creative process, slightly out of the bounds of these areas.

Fixing stereo problems and phase issues *IS* a common mastering task, but we're not talking about problems, rather than "beefing" a presumably okay stereo recording. No problem in wanting to make things wider, and there are plugins for doing that, but I would generally suggest doing these operations on individual tracks during the mixing stage. Take panned tracks and move them farther out, take stereo tracks and make sure they're panned hard. If that's not enough, use a stereo widening plugin.

One possible stereo-widening procedure that might work with the bundled plugins is to abuse the "Spacial Maximizer" plugin. This effect separates content that is identical in both channels, from content that is different in both channels, and allows you to process them separately. It does this through an ingeniously simple and 100% transparent process of polarity inversion and channel summing. I could go into a little more depth of HOW this is done, but you can look that up if you're interested, all you need to know is that it won't inherently introduce phasing or other artifacts. What might work is to gain-up the side content, and gain down the center content. This should emphasize the content that is different in the sides, and make the stereo field wider. Even though polarity-inversion is used to isolate the signals, in the end, it all gets inverted back again, so you won't have the phasing issues that come along polarity inversion. Again, though, I would only perform this on individual tracks, not a master. However, I've never actually done this, so I can't be sure of it's impact, but in theory, it should transparently widen your tracks without endangering the mix.

A word about "phase". Unfortunately, many audio hardware and software companies have used "phase" incorrectly to mean "polarity". There is no such thing as "phase inversion." Phase is a product of time, like taking a sine wave and moving it a quarter-cycle later. What they mean is "polarity" inversion, which is taking the positives and making them negative, and vice-versa. Any time you see a "phase" switch, you'll know it's the same thing as polarity, and the manufacturers were just being ignorant.

[stephentayler]

I'm currently working on a new version of an album I co-produced in 1980 - it was originally mixed to analogue tape for release on vinyl - the subsequent release(s) on CD were really compromised, so I have been experimenting with up-to-date techniques. So far I have taken the digitised files, and processed them through gentle de-essing with DP's dynamic EQ , Waves R-bass (push the low end a smudge), Slate VTM (put back some analogue character), NI (Softube Premium Tube - Manley EQ emulation - add some extreme high end sheen), some stereo widening in Izotope Ozone, and Waves L3 Multiband (even things out!) All very subtle changes, but this all adds some of the original character back - who knows if the artist will go for it, but to my ears it brings the project up to date.

In this instance I consider this to be pre-mastering.

I have always been lucky enough to trust this final stage to some of the world's best mastering experts. The exception has been on my solo album where I did not have the budget for such a luxury. In this case I have been very happy with my results!!

Cheers

SWT

[SAtkins]

Thanks guys. Again lots of good stuff to consider. I am definately wearing the mastering hat at this point as I do like the current spacial panning of the mix. Its really quite good as it stands, so only small tweaks and bounces of the stereo final are at hand. That being said, anything that can help me slightly broaden the stereo spaciality a bit is something I'm still experimenting with for this tune. Yes, I was aware that audio software often confuses phase with polarity, and that was what my first experiment enacted, a polarity reversal on one side of the stereo mix. It was altogether too sweeping and extreme as was indicated by your advices. So any suggestions as to what might give me a tad more breadth in spaciality is what I'm toying with here, but must be simply applied to the final stereo mixes, but not be too extreme. What do you all think about slightly panning the final stereo tracks a tad left and a tad right to broaden the spaciality, or do you think this might create a hole in the center? This is where experimetation can often glean you some neat results, so thanks for all the kind ideas!

S.

[philbrown]

For $49 there's this that seems like might help you toward your intended result at a reasonable price:
http://www.pspaudioware.com/plugins/too ... oenhancer/

Waves has one I like a bit better but it's pricey to buy it by itself (and it's Waves):
http://www.waves.com/Content.aspx?id=275

[stephentayler]

I like this - but it is part of Izotope Ozone 5 Advanced and costs a fortune!!

https://www.izotope.com/products/audio/ ... maging.asp

Cheers!

SWT

[SAtkins]

Thanks for the recommendations. Those look quite good, but unfortunately a bit steep. This is what I'm reviewing right now:

http://www.quikquak.com/Prod_UpStereo.html

If I find others, I will let you know. I think if carefully utilized, these might have some value.

S.

[kgdrum]

Well besides the price,as Stephen was explaining in an earlier post,most of the newer preferred apps will need a newer OS & Mac to use.

[mikehalloran]

I'll chime in here.

The reason the functionality exists in the Trim control is that, sometimes, it will solve problems. There are times when you want to remove track information. I used it recently to remove the bass and kick drum from a old direct to 2-track stereo recording from the 1970s. Sometimes you will encounter tracks that were recorded with microphones wired in reverse or a figure 8 where you don't know which side faced the singer.

One time, I was able to remove a fireworks show from a chamber music concert. The performers were in the church and none was centered in the stereo array. The fireworks were on the San Francisco Bay a few hundred yards away. It sounded like the 1812 Overture inside but, since those sounds were heard by the mic array as mono, they nulled when I reversed one channel and summed to mono. The recording was preserved and only the stereo image suffered. The composer thought I was a miracle worker. I got lucky.

Never do this without checking your mix in mono.