Stereo versus mono

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maxman65

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Been trying to imagine what's happening. As I understand it a stereo recording of an instrument will contain more sonic information than an identical mono capture of the same thing. ? Can someone explain how there is more and what there is more of . Presumably both contain the same frequencies and density of material for an identical performance on the identical instrument . Like where's the extra coming from ? Is it simply to think in terms of double the same thing ?
 
You have two ears. With them, your brain has sufficient information so that with your eyes closed you can point to sound sources and estimate size and distance. People with only one ear working lose the spacial content and therefore distances are less easy and direction impossible without turning your head.

In sound systems trying to capture this, there are two main components that change. Level (amplitude) and time (as in sounds arrive at your two ears at different times)
Two channels gives you left and right. Oddly, nobody is interested in up and down! If you record with two channels and add them together, convention dictates this is mono. In fact, it is not as accurate - a single channel has very precise timing. Two channels, mixed together into mono blurs the time arrival differences into one less precise one.
 
Ok but say I record a piano out of a keyboard as stereo two track left and right is that taking up more sound space for other tracks to compete with than a recorded single track out of the left (stereo sum )
 
Let us say you record a singer in a nice concert hall with a pair of crossed figure 8 mics at a 'sensible' distance.
You will capture not only the singer but much* of the ambient information that makes the hall sound "nice". If you now process that stereo recording with an MS plug in you will see that the signals resolve into two components. A mono sum component and a difference component. If you mono the signal you lose the difference component and so yes, mono'ing a stereo signal throws away information ("they SAY "information cannot be destroyed" but I wish "they" could tell WTF that difference signal has gone! )

This is how old FM stereo worked. The station broadcast the sum part which kept the vast majority (then) of mono listeners happy (the station however had to be careful about such things as mic phase/polarity) they put the difference signal on a 38kHz 'sub carrier'. A bit of simple electronic algebra reconstructed the stereo signal.

*much but not all. To capture almost all the qualities of such a space you need a special "Ambisonic" mic and encoder.

Further reading? Google "Haffler"

Meant to say, "sounds out of a keyboard" ain't really "stereo". Unless of course they a recorded, stereo samples.

Dave.
 
It is said that you shouldn't use the 'stereo' coming out of a keyboard.
That stereo is just one perspective from the player's position, with bass notes louder on the left, and treble notes louder on the right.
But that is not what the audience would hear.
The argument is that you should record keyboards in mono, and then place it in a stereo field during mixing.
I don't know, but whatever sounds good to you is going to be ther right way.
I'm still experimenting.
 
I feel like folks are over-complicating this. A stereo signal is either a single signal doubled, or two signals panned to opposite sides. In the first case, there is not more information; it's just the same data twice. It will sound exactly the same as a mono signal because your stereo playback system will automatically copy a mono signal into both speakers/headphones

The stereo out on your electric piano is designed to mimic the sound of two microphones positioned at opposite ends of an acoustic piano. If you record both signals and then listen to them one-at-a-time, you'll notice that one emphasizes the bass notes, and the other emphasizes the treble. This doesn't mean that it's taking up more space in the audio spectrum, but that each track will take up different space from the other.
 
I'm convinced many keyboards just use a bit of high cut on the left output and low cut on the right output. When I am home, I might experiment with this one. If you close mic a piano with two mics, you usually blend the two together and adjust the pan on the two channels to be realistic, or you end up with a piano the same width as your monitors - which might be good, or bad. I wonder if one mic and stereo reverb might sound better than two mics and the same reverb plugin?
 
Well, “stereo” implies more information because it’s assumed that it is capturing a space with at least two microphones that are specifically placed to capture the differences between left and right. This is obvious in the construction of a “stereo microphone” which will have the 2 (or more!) elements aiming in different directions, as coincident XY or possibly Mid-Side or even a Blumlein pair. These kinds of placement, or even others when using separate microphones, will always have some information in their assigned tracks that is different from the other mic’s track. The digital file wile be larger than that of a mono/single mic recording, and if you would mix those stereo tracks down to a single mono track, it will not sound the same, and you will not be able to recover the stereo tracks from that mono mix, i.e., information will have been lost.

Now, MAYBE, a pair of omni-directional mics in a coincident setup might be very similar to one of the same kind of mic, but it still will have some differences, though likely not much interesting.
 
The two channels of a stereo recording will often have much in common, like general frequency content, but the specifics will be different. For a spaced pair, the differences will include arrival times of certain sounds. Even with a coincident pair, if the sounds coming from different directions (lower vs. higher strings) are different, the information in the audio will be different. A null test can reveal this nicely (or solo the side mic of an M-S pair).
 
To my ears it's a kind of trade off . Keyboard pianos are ok but not great even the better ones are a bit cardboard . Stereo gives more ambience with them. .more candy I guess .but attempting one in mono might allow more space for other components to come through . I also find that timing wise things can sound a bit more direct and tighter in mono .
 
Listen to the world with one finger plugging up your left ear, or put in one foam ear plug. Do you want to hear like that all the time?
 
Can I remind everyone that "stereo" actually means "solid" and has little to do with "two"?

Two channels, properly arranged, is the minimum necessary for the illusion of ambience and positioning but more is better!
I recall the BBC's experimental broadcasts of stereo on two stations sometime before the Zenith GE stereo multiplex standard was introduced.

Also "omnis" are, AFAIK used for 'spaced pair' stereo recording. Does not I think give as good mono compatibility* as co-i directional mics?
I have always regarded "true stereo" as a recording of an acoustical "event" with (matched if poss) pairs of mics? A "snapshot" of a room and instruments if you will. "In the Box" mixes are pan potted mono simulations.

*Not nearly AS important theses days.

Dave.
 
In the 90s, I tried the Sennheiser dummy head mic and the Jecklin disk. I note Neumann still make a version, if you have 7 grand spare!
 
Perhaps we would be if we had an ear under our chin and one on the top of our head. :-)
I have 5 ears. The 5th being on the back of my head. Without it I wouldn't be able to discern that it's the car behind me honking its horn at me telling me that the stop light turned green. ?
 
Listen to the world with one finger plugging up your left ear, or put in one foam ear plug. Do you want to hear like that all the time?
Mixing has little to do with real world situations - unless you are trying for real world feedback - a mix is however you want it to be - including Stereo.
 
I have 5 ears. The 5th being on the back of my head. Without it I wouldn't be able to discern that it's the car behind me honking its horn at me telling me that the stop light turned green. ?
Quite: we do not lack the "receiving apparatus" to determine the direction of sound in 360 degrees and to a more limited extent in the vertical plane. What is lacking is a speaker radiation pattern to exploit it. Microphones are also almost only ever setup to deliver horizontal, frontal information (although some rear information IS locked into a two mic rig, especially if fig 8 mics are used)

But, since orchestras have historically only ever been arranged across the front of the audience, with admittedly some venues rising at the rear, there is little point in capturing vertical information because almost no one at home has a rig to reproduce it. The coming of Atmos sound and the spacial "tricks" rock bands use now means this will change perhaps?

If you read reviews of monitor speakers and especially those in Hi Fi mags (gave THEM up years ago!) There is often talk of "good rendition of depth information". This is actually subjective bollocks since there is no acoustic 'mechanism' in a conventional stereo signal to portray 'depth'. I don't doubt the guys hear "something"? But then they have to write SOMETHING about the stuff to earn their daily!

Dave.
 
Can I remind everyone that "stereo" actually means "solid" and has little to do with "two"?

Two channels, properly arranged, is the minimum necessary for the illusion of ambience and positioning but more is better!
I recall the BBC's experimental broadcasts of stereo on two stations sometime before the Zenith GE stereo multiplex standard was introduced.

Also "omnis" are, AFAIK used for 'spaced pair' stereo recording. Does not I think give as good mono compatibility* as co-i directional mics?
I have always regarded "true stereo" as a recording of an acoustical "event" with (matched if poss) pairs of mics? A "snapshot" of a room and instruments if you will. "In the Box" mixes are pan potted mono simulations.

*Not nearly AS important theses days.

Dave.
Solid in the sense of "3-dimensional", it turns out: https://www.etymonline.com/word/stereo-

So pedantically, 2 signals is the minimum required to create the sense of a 3-dimensional space, but I don't think I've ever heard an arrangement with more channels being referred to as "stereo[phonic]"
 
Solid in the sense of "3-dimensional", it turns out: https://www.etymonline.com/word/stereo-

So pedantically, 2 signals is the minimum required to create the sense of a 3-dimensional space, but I don't think I've ever heard an arrangement with more channels being referred to as "stereo[phonic]"
In the earliest days of stereo there was a debate over whether it should have two or three channels. It was easier to sell the more affordable two channel systems, so they won out. When the idea of more channels came back around, stereo was associated with two channels, so terms like quadrophonic and surround were invented to distinguish them. But there's no technical reason you couldn't call them stereophonic.
 
Quite: we do not lack the "receiving apparatus" to determine the direction of sound in 360 degrees and to a more limited extent in the vertical plane.
Thank you for confirming it that being born with only two ears on our heads we all can determine the direction of sounds that reach our 2 ears, side to side, up or down, in front or behind.

When I hear thunder....I look up.?
 
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