Why mono is better than stereo (sometimes)

Why mono is better than stereo (sometimes)

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An Audio Masterclass visitor asks why stereo is better than mono. But is that always the case?

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by David Mellor, Course Director of Audio Masterclass

Monday September 26, 2011

I made a short video about stereoizing an electric guitar recording, which you can see here...

By 'short' I mean it's just a single example based on some work that was sent in to us. There are lots of other ways to do it.

One viewer asked the question, "Can you explain the pros and cons of stereo?"

Well that's a simple question, but does it have a simple answer?

If asked in an elevator (the 'elevator question', like the 'elevator pitch'), I would say that it provides a more enveloping experience than mono, more akin to what we hear all around us in everyday life. So that in a nutshell, or in an elevator, is why it is better. I could say more, but I'd need all day, and a consultancy fee ;-)

But can mono sometimes be better than stereo? Now that's a more interesting question because stereo is pretty much universal. Stereo is also a more recent development than mono. Therefore stereo must automatically be better surely?

Well, not always. Here are a few examples...

Beatles-style mixes

I don't only mean the actual Beatles, I mean any record from the early 1960s that follows the philosophy that no effort is spared to get the mono mix absolutely perfect, and the stereo mix - done by the assistant after everyone else has gone home - is run off in a few minutes. Or a couple of hours for a full album. (This has been well-documented for The Beatles, but is also how mixes were made for other artists.)

In those days few potential buyers had stereo equipment, so this made a lot of sense.

So if you rummage around secondhand record stores, boot sales, yard sales and other likely outlets, you can find 1960s albums, and often the same album in mono and stereo versions. I can tell you that some of those mono mixes sound GREAT. If you focus your attention on mixing specifically for mono, then it is amazing how good it can sound.

The loudness war

Let's suppose someone high up in your own personal food chain has asked you to make a mix really loud. How can you get an extra 3 dB without sacrificing even one iota of sound quality?

Let's suppose you made a mix (normalized to 0 dBFS) that had a huge amount of stereo content. So much so that your phase meter bends over backwards much of the time. (If you display a stereo signal on an oscilloscope using the X-Y mode, a mono signal will show as a straight line angled at 45 degrees upwards to the right. A stereo signal will show a similarly angled ellipse. If you increase the stereo content this will tend towards a circle. If you add out-of-phase content, it will lean over to the left. Pure out-of-phase is a straight line angled upwards to the left.)

So you have audio coming out of the speakers on the left and you have audio coming out of the speakers on the right, but there isn't a great deal of correlation between the two.

Now mix the same track, but in mono (normalized to 0 dBFS). Suddenly you will find that the mix, played back on speakers, is 3 dB louder. That's because when two signals that are equal in level but uncorrelated are added together, the sum of the two is 3 dB greater than either signal alone. But when they are fully correlated, as in mono, the sum rises by 6 dB. It's three decibels for free! What's not to like?

In reality, there is always quite a lot of correlation between the two channels of a stereo mix, so the benefit is not the full 3 dB. It's still a reason however for panning bass instruments and kick drum center instead of hard left or right.

FM radio

Do people still listen on FM radio? Although we can now listen to digital radio via digital radio sets, satellite TV systems, Internet etc., many people have not scrapped their portable AM/FM radio and you will often find one playing in the kitchen of the house. And let us not forget the car! It will be a long time before no car is sold that has FM radio capability.

FM stereo was a great invention. It 'piggy backed' the difference between the two channels onto the mono signal, which is of course the sum of the two channels of a stereo signal. A decoder can easily turn this into left-right stereo while maintaining full compatibility with older mono sets. Genius.

The downside is that the difference signal doesn't have much of a signal-to-noise ratio, therefore if the broadcast signal is weak then the audio will be noisy. On some FM radio sets, you can switch to mono, when you will hear a much less noisy signal. It's a big difference. And most sets will do this automatically when the signal is really weak.

In consequence of this, many people listening while driving will be hearing a mono signal. If your mix doesn't sound good in mono, then hard luck - it either won't get broadcast in the first place, or listeners will desert the station.

Social listening

You can enjoy great stereo by sitting exactly between a pair of stereo loudspeakers, properly positioned. That is you as an individual. Invite some more people to the party and only a few of them will be well placed to hear stereo as it should be heard. Invite a few more and many of them won't get the stereo experience at all.

If your mix doesn't sound good when there is a whole party-load of people, chatting and downing drinks, then you can't say that it is entirely a good mix, however brilliant it sounds when properly heard in stereo.

In summary, there are situations where mono is unavoidable. And there are many examples of recordings that sound wonderful in mono.

Maybe mono isn't such a bad thing after all.

My question now to Audio Masterclass visitors, does anyone actually prefer mono to stereo?

By David Mellor, Course Director of Audio Masterclass
Monday September 26, 2011

Readers' comments on this article...

Da'soundz So'hard, Atlanta, USA
Thursday September 29, 2011

This song is very well put together. I agree with Ricky about the mix; can't wait to hear the repost. Keep up the good work; you'll have a future in this business..
Steve Ward, White Plains, Ny, USA
Monday September 26, 2011

As to Beatles mixes, you are correct that their early records were intended to be heard in mono. My understanding is that the "stereo" mix was not meant to be heard at all, but was intended to give the mastering engineer a little bit of flexibility. By having drums on one channel and Bass and vocals on the second, the mastering engineer could fine tune the balance of the two in the final mix. In Europe, early Beatles records were generally sold in mono. In the US the record companies took the two-channel master tapes and released them in stereo. By the time of their later albums, mixes were intended to be in stereo and were released that way.
Devon, Vienna, Austria
Monday September 26, 2011

To Lindsay, I think Mr Mellor was getting at the fact that in early stereo days, the mix was generally worked on for hours in mono as the main reference and then a quick stereo version was printed. The mono mix was much more difficult to achieve, and was the existing standard. Stereo was (as you suggest) more of a gimmick at the time. The seemingly absurd panning schemes was because I think they just didnt really know what to do with stereo yet. I also believe many of the hard-panned instruments come from some early consoles only having a left-center-right switch rather than a true variable pan pot. I think when Eddie Kramer working with Hendrix on Axis: Bold as Love was when they started to get the idea to record drums in stereo on 2 tracks. That, to me, is when stereo mixes started to make sense. To everyone else (and Lindsay) Now I still sit and wonder how they plan to mix a band in 5.1? To me, stereo is perfect for representing a musical performance from an audience perspective. in 5.1 (I mean on a studio album) where is the listener? In the band? Will the tom rolls pan around the room? I am sure some cool music could be created for 5.1, but I am talking about a band. and how the performers will convincingly use the acoustic space. That will be a whole other thing to explore and do absurd things with it until the next Eddie Kramer comes along and makes it make sense. But I guess thats getting off topic.
Lindsay, Australia
Monday September 26, 2011

That is not quite accurate for the "Beatles-style" example. Stereo was just coming in during that time and there were two things that were needed for people to ditch their mono players and to go stereo: a benefit to the user in terms of an enhanced listening experience and decently large range of support titles that would be available so the consumer knew that it would be something they would be able to enjoy into the future and not something that would be available for a handful of albums. The ways that the powers that be ensured that these two criteria was to create what can only be described as 'extreme' stereo mixes. Anyone just needs to listen to any Beatles album of that time to hear such absurd panning like the guitar panned in this ear, the drums in that one, John in one ear, Paul in the other and a lone bass bouncing along in the centre - and these pannings are not done by halves here, all to 100%. One of the big reason for this was not only to create a really distinctive sound for the average consumer to hear but in order to convince consumers that they should buy all their favourite mono records that they already own, again, is to make them completely different yet the same music that they have come to love. It is the 'extra bonus special collector's edition with extended featurettes BluRay special' of the vinyl years. Plus, they would walk into their local electrical retailer and listen to the demonstration system and "WOW! I can hear it all around me! First it is there and then there, at the same time! I never thought this band could sound any better - now they are around me!" So there is a lot more to the stereo/mono story in the glory days of vinyl than simply, it was the assistant's coffee boy's mix. :)…
Henry, Mcdonough, Georgia, USA
Monday September 26, 2011

Yes when listening alone and placed center stereo is best. When playing for a crowd (DJ) I will play in mono. The dancing crowd do not care and they get the same mix no matter where they are on the dance floor. I use two Bose personal speaker systems that radiate sound at 180 degrees and sound great.
Ithamar, Tel Aviv, Israel
Monday September 26, 2011

I'm a big fan of mono (-: I would like to add some more examples: 1. Live shows - similar to your Social listening argument. Many PA engineers (especially in large outdoor settings) will mix the live show in mono. It's a good way to make sure that everyone in the audience hears the same mix. 2. Dramatic effect - for example, have the intro and 1st verse mixed in mono, then go to full stereo in the chorus. (of course you'll have to compensate the master level by about 3 dB to get the effect right) 3. Focus in the mix - when placing elements in a mix, it's easier to create a realistic spatial illusion by using mono tracks. After all, most of the sounds that we hear in real life come from mono sources. Most sample libraries are in stereo, because the individual samples sound better that way - but that adds too much spatial information that may not be relevant for your arrangement. I haven't done any surround mixing yet, but my guess is that it's event more true for surround (soon we'll get to have surround sample libraries? hehehe)

 

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