Topic: Which channel was mid and which was side?

[Carrera2]

Well, I did my first multi-track live show the other night. In a addition to sharing and supplementing the house sound, I ran a mid-side pair. In all of the excitement, I didn't really think about the signal flow of the mid-side pair and consequently, really don't know which recorded to which track (I do know the track numbers for the pair, just not sure which is which.)

I can't really think of a way to tell which is which? Can you?

[yug du nord]

Unless you turned up the levels quite a bit on the side channel during the recording, the side channel is most likely quite a few db's quieter.

[stevetoney]

Well, I did my first multi-track live show the other night. In a addition to sharing and supplementing the house sound, I ran a mid-side pair. In all of the excitement, I didn't really think about the signal flow of the mid-side pair and consequently, really don't know which recorded to which track (I do know the track numbers for the pair, just not sure which is which.)

I can't really think of a way to tell which is which? Can you?

First I'd listen to each track through some good headphones.  You should be able to tell which mic was pointed directly at the stage and which picks up the sound coming from the sides.

If you can't tell from that, load both tracks into your DAW and then change the percentage of the left channel in the mix it to see if the stereo image changes...or simply listen for stereo separation in the two channels.  Without knowing for sure, I'm thinking that if you have it backwards and the figure 8 is assigned to the mid channel, you wouldn't hear any stereo imaging.

[Carrera2]

Yeah, thanks guys. After splitting the tracks to mono and AB'ing them back and forth (and looking at the levels), it is pretty apparent which is which. The side channel level is definitely a bit lower and the sound of each is much more distinctive than I expected. Thanks a lot.

[DSatz]

M/S became popular in the 1950s when stereo records and FM broadcasts were new, because it could deliver compatible mono and stereo recordings at the same time. The "M"-channel microphone (if placed and aimed properly) should provide a decent mono recording of all the direct sound sources with a good overall balance and a certain amount of natural room sound; it should neither be too "dry" nor too "echo-y." For LP mastering engineers back in the days of dual inventory, the "M" channel pickup by itself was the mono version of the recording.

The "S" channel on the other hand should contain far less direct sound, and it usually won't be a very acceptable mono signal when listened to on its own; of course that's not what it's for.

If you somehow misidentify the two signals and matrix them, you'll get a L/R stereo version with inverted polarity in one of the channels. If you've ever wired one loudspeaker of a stereo pair "out of phase" and listened to any coincident-mike stereo recordings that way, you should recognize the defective imaging fairly readily--there is no stable center to the image at all. Any signals that originated from center stage are reproduced identically but in opposite signal polarity by the two loudspeakers.

--best regards

[Patrick]

...what everyone else said.  It should be fairly obvious which mic is pointing towards the sound source and which mic is picking up the "side" of the stereo field.  In the future, it's easy to make L=mid and R=side.  That's pretty much the standard, and it's easy as hell to remember.