Stereo is one of the most powerful tools we use to enhance a recording. However, there are a number of misconceptions when it comes to working with stereo sound.
Stereo is much more than sound coming out of two different speakers. In fact, the same sound split into a stereo track will still be heard as mono because it is the same source reaching your ears in the same manner. Differences in pitch, frequency, tone and timing determine whether you hear two separate channels as true stereo.
Some believe that everything should be recorded and mixed in stereo. That it allows the instruments to have a fuller more lush quality. It is true that using two microphones in stereo can capture more tonality of an instrument. But like many things in mixing and recording, it needs to be understood and handled with purpose.
Among the tracks that come across my mixing desk, I most often receive acoustic guitar recorded in stereo or two different takes of the same guitar part with the artist’s expectation that they will both be used, each track panned hard right and left, for a fuller sound. But there are a number of factors that contribute to whether or not this is a successful strategy.
It needs to be determined if all those lush frequencies are a help or hindrance to the overall mix. As discussed in a previous installment, if there are multiple instruments and frequencies competing for the same space, oftentimes something needs to be sacrificed. It’s nice for a mixing engineer to have the option of a lush stereo sound but don’t be totally surprised if they are not always used. It may turn out to be a much more effective strategy to record a second track using a different guitar or stringed instrument altogether. Or perhaps using a capo to add different voicings of the same chords. Sometimes being more creative with the arrangement is better than simply layering sounds on top of one another. That being said, a well recorded and mixed stereo acoustic guitar can sound fantastic!
Stereo can enhance a recording but it can also confuse the listener’s ears. Many instruments are designed to produce a sound that seems to come from everywhere. But in a recording with multiple instruments, having too many sounds coming from everywhere can be slightly disorienting. Those sounds can start to become lost in the mix. Much of this is determined by the overall arrangement and whether one particular instrument needs to be in stereo to be effective. If it’s a jazz trio, then the piano would greatly benefit from being recorded and mixed in stereo. However, a rock song with multiple guitars, drums, organ, synth and bass may not need a stereo piano and it would actually benefit the mix and the piano to have it as a mono track or panning the stereo more to one side.
Sometimes, recording in stereo can often add a hidden attribute that will have the opposite effect and cause the sound to be thin and weak. What I’m referring to is called “phasing.”
Sound is recorded in waves that travel up and down. If you zoom in on a track in a DAW or computer program you can see the actual waveform. When sound is recorded in stereo these waves should be traveling the same direction. As one wave goes up to a peak, so should the other. They are “in phase.” But when microphones are placed at various distances, the two tracks can become “out of phase.” Meaning, while one wave is traveling up the other is traveling down. Essentially making the sound work against itself. This can result in a strange thin hollow sound or, in extreme cases, the sound disappearing altogether.
This can be corrected by using a delay effect on one track, inverting the phase of one of the tracks or physically moving the track so that they are back “in phase.” Phase issues are less obvious when dealing with a stereo sound. So make it a habit to frequently check your mix in mono.
Anytime you are using multiple microphones to record a single source, phasing is something that needs to be looked at carefully. The milliseconds it takes for the sound to reach the mic can determine if you’ve captured a full stereo sound or two out of phase tracks that will essentially cancel each other out. It’s a precarious relationship. It’s this delay that determines how our ears perceive the stereo field. In fact, we often manipulated the delay to increase the sense of width in the stereo field.
How our ears perceive the stereo field can be effected by a combination of factors including depth, delay, EQ, panning and most of all the arrangement of instruments and vocals.
1) Consider the pros and cons of recording and mixing an instrument in stereo in relation to it’s benefits to the entire mix.
2) All tracks recorded with multiple microphones need to be checked to ensure they are in phase. This includes stereo tracks as well as instruments such as drums where microphones may be placed at various distances.
3) Don’t be afraid to eliminate one channel of a stereo track. It may increase the stereo field for the entire mix by allowing an instrument to be more defined.
4) Always check individual stereo tracks, as well as the entire mix, in mono. Listening and mixing in mono can be a great tool in determining phasing and other issues.
Blue Vision Music
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