All recordings of concerts are artificial. But once you’ve gotten that out of the way – you simply accept that you can never reproduce the actual sound of a live performance – you have to approach the question of how these recordings should be mixed. Not only are there questions of the volume of individual voices, instruments or groups of instruments, but also where they should be in the soundscape.
In the simplest type of live recording, you have one performer playing a solo instrument; say, a guitar. That instrument is centered in the soundstage, and there are no problems. Add a singer to the guitar, and it’s still simple to position.
But move to a slightly more complex instrument, such as a piano. There are two ways to record a piano, using microphones or a pickup. With the former, you can position microphones around the piano – most often, this is just two microphones placed facing the open lid – or you can use a pickup, which is transducers placed on the soundboard inside the piano. (There are many ways you can combine these devices, or use multiple microphones, both inside and outside the piano.) But a recording engineer faces a dilemma: do they place the piano in the center of the soundscape, or do they try to position it so the different keys are heard in different locations? I’ve heard recordings which are made to sound as though the listener is sitting in front of the keyboard; the lower notes are to the left, and the higher notes to the right. This is essentially false, because no one other than the performer hears a piano in this way. However, it does give the piano a bit more “life,” and makes the sound less static.
When there are multiple performers, the questions become much different. Generally, you want to have the performers sound as though they are in their appropriate position on stage. So a string quartet will have two instruments more on the left channel, and the other two on the right (generally the two violins are on the left and the viola and cello on the right). But I’ve heard string quartet recordings where the two instruments on the left are almost entirely on the left channel, and the same for the instruments on the right. This approximates what it would sound like to be in the middle of the string quartet, but no one ever sits there.
A jazz piano trio is an interesting group. Generally, the piano is on the left, the bass in the middle, and the drums on the right. This leads to many recordings trying to replicate this positioning. For example, listen to Brad Mehldau’s The Art Of The Trio Volume 2: Live At The Village Vanguard . (You can listen to samples of the recordings I cite by following the Amazon links.) The piano is far to the left, the drums to the right, and the bass in the middle, as they are on stage. However, you would only hear a performance like this if you were sitting in the first row, dead center. This gives a certain artificiality to these recordings, which is compounded if you listen on headphones. In fact, I find this approach very annoying on headphones, and generally don’t listen to recordings like this except on speakers. (Though even with speakers, the positioning is very obvious.)
Take the same artist when he’s in the studio. On Songs: The Art Of The Trio, Volume Three, recorded in the studio, the piano is centered, and the drums are quite creatively spread across the soundstage, while the bass is also centered. Musically, this is much more interesting than if the instruments were positioned laterally.
This positioning is even more obvious in the recent Grateful Dead releases from the band’s Europe 72 tour. You can hear this clearly on the Europe ’72 Vol. 2 release, notably on Dark Star. When the Grateful Dead performed, Jerry Garcia was stage left, Bob Weir in the center, and Phil Lesh stage right. Garcia’s guitar, in these new mixes, is far to the left, but Weir’s guitar is on the right channel. Lesh’s bass is in the center; I agree that the bass should be centered no matter what, but the positioning of the guitars is simply odd. No one would have heard the music like that, unless they were in the first few rows, and even then, the resonance of the halls would attenuate that positioning greatly. Add to that the fact that the vocals are centered. This is logical, but having Jerry’s guitar far to the left and his voice in the center is a bit jarring.
The Grateful Dead’s recent release of some music from their Spring 1990 tour follows this approach. But the drums are more spread out than in the Europe 72 mixes (probably because the multi-tracking used in 1990 allowed for this giving more tracks to the drums), and the keyboards are also far to the right (keyboardist Brent Mydland did sit on the right, as did keyboardist Keith Godchaux, in 1972). But on these recordings, Bob Weir’s guitar is in the center, which is more logical.
No matter what, an engineer has to establish a soundspace. All I’m saying here is that sometimes this soundspace is too artificial; in attempting to reproduce some of a band’s positioning, it creates music that doesn’t sound realistic. You certainly don’t want all the instruments in the center, but putting them far to either side can sound strange. Could it be that these recordings are mixed for people who keep their speakers very close together? I don’t; I have speakers on my desk that are a couple of feet to either side of my head, and my living room stereo’s speakers are fairly far apart. This speaker positioning makes sense for most recordings – especially those of an orchestra – but for some recent recordings, it just sounds weird.