When a recording is sold for retail sale the public ears two channels of audio; one for the left and one for the right, but when music is being created in the studio, the standard procedure since the 1960's has been to capture the music on separate tracks. This is the same concept as a stereo (2 channel) recording except there are many more channels of audio. The standard for analog recording is 24 channels or tracks of audio. Some digital setups are capable of up to 128 independent tracks of audio. Let's take a brief look at what this means for the music and for the musicians who play it.
The great advantage of multi-track recording is that each individual track (usually a single instrument) can be manipulated after the musicians have played the performance. For example, a trumpet could have made brighter with EQ, or a snare drum that is too loud can be turned down in the mix. Compression could also be added to a lead vocal that is too dynamic. When a vocal is too dynamic in relation to the instruments quiet lyrics can get lost and loud ones can overpower the band. Multi-track recording has been an incredible benefit to modern recording, allowing engineers to achieve a clear and distinct sound for each instrument that is nearly impossible to achieve with mono or stereo recording techniques. The only down side to this is that some engineers and producers can get lazy. Instead of capturing a good sound to tape they might decide to “fix it in the mix.” Although that can save a mediocre recording when the original musicians are not available, it is always inferior to capturing the music correctly in the first place.
Multi-track recording also offers the musicians a chance to go back and fix poorly played notes. When the bass, for example, is recorded directly (no microphone) to its own separate track, the player can go back and record just a small section again. In this way it is possible to assemble a recording that a particular player may not have been able to perform in one pass. Many studios have separate rooms to isolate instruments that are recorded with a microphone. This way other instruments in the room do not bleed into mics that are not on them directly. There are, however, consequences to this style of recording. You will never see a live performance with each musician in their own little isolated room. Imagine trying to emotionally connect with someone with a wall between you and them. Would not it be easier without the wall? The consequence of this practice of separating musicians is that the communication aspect has been devalued in modern music. Listeners often do not even know what they are missing because they have never been exposed to a band that is really playing together and not just at the same time.
Before multi-track recording was common, musicians knew exactly what was expected of them; a performance as close to perfect as possible from beginning all the way to the end. This is a lot of pressure to be under, but that pressure creates excitement and energy among the band. This energy is crucial to the feel of the track. The best way to preserve this energy is to place all of the musicians together in the room, just like they are accredited to when playing live. In this setting it is easy to make eye contact, give signals, and hear the other players. The best, most organic sounding performances will come from a band that literally plays together. In this scenario there will be bleed from other instruments into the microphones and depending on the amount of bleed it is still able to go back and fix mistakes. In certain situations this does not work. Drums can easily over power a softer instrument such as upright bass. The listener will not notice bleed from the drums into the bass mic and it can actually serve to help the drum sound, but when the bass player needs to go back and fix a note by himself, the new recording will not have the drums in it . This ends up sounding like part of the drums are missing only at the place where the bass player fixed his mistake.
Many of today's musicians will enter the studio expecting to overdub, punch, and edit and had not even been planning on trying for a perfect take. A recording can be made in this manner, but where is the excitment? Where is the energy? And what happens to the same musician when he or she tries to perform the piece in public? The audience is not going to be very happy when they stop the song so they can go back and fix a mistake. Multi-track recording is a double-edged sword with intense capabilities, but it is very easy to get lost chasing perfection and loose the excitation and emotion of a song. Only experience will tell you when you are about to step over the line.