and Wet/Dry Balance @
Example 7.6: A drum set recorded with a near-coincident pair, above and slightly in front of the drum set. The image of the drum set is wide, and relatively tight and dry.
Example 7.7: The same drum set, with the same stereo mic array positioned 20 feet in front of the drum set. The drum set appears narrower, taking up less of the image width, but an increased amount of reverb takes up the entire width of the image.
7.8 SPILL – ENEMY OR CREATIVE TOOL?
Whenever multiple microphones are positioned close to each other, each one will pick up sound that’s not really intended for it. This spill is problematic if it does not sound good in itself, or if comb filtering and mono compatibility problems exist between multiple mics in the same room.
THE 3:1 RULE
In any multi-mic situation (including close drum mics, or recording multiple singers or a horn section with individual mics) the 3:1 rule should be used in order to reduce the level of spill relative to the desired sound in each mic. Figure 7.7 shows that the dis-tance between each mic should be three times the disdis-tance between each sound source and its mic. This will certainly not eliminate spill totally, but it will minimize its poten-tially negative effects.
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Spill is not always the enemy though. It can sound good.
One way to improve the sound of spill is to use mics that have better off-axis response.
Cheap mics may make sound sources on-axis to them sound good, but they usually compro-mise the sound of spill because of their poor sounding off-axis response.
When mixing rock and pop music, gates or strip silence features can be used to silence mic channels in-between drum hits. Gating out spill and removing the natural acoustical connection between the multiple instruments has a huge effect on the sound – it becomes ultra-clean and surgical. This may be stylistically and aesthetically desirable for some rock and pop projects because the drum set tends to be treated as a collection of individual, separate instruments. In jazz and some grungier pop styles though, the drum set is treated more as an organic whole and not as the sum of many individual parts – so a super clean, gated drum sound could be inappropriate and undesirable.
If gating is undesirable, less aggressive expansion can be used to reduce the level of the spill rather than eliminate it completely – however, ensuring good sounding spill is captured, or minimizing undesirable or bad sounding spill acoustically through mic technique and instrument location in a room is generally preferred to electronic solutions by most engineers working on acoustic music projects.
Good sounding spill is not the enemy. Bad sounding spill is. Strategies to “improve” the sound of spill include using mics with good sounding off-axis characteristics, directional polar patterns than put sources of spill in their null(s), and to record in a room with a good sound (because the sound of the room will be picked up by the mics). Spill can also be managed by exploring the position of the sound sources in the room – both the position of the sound sources relative to each other and their mics, and relative to the room itself. For example, a mic facing an instrument but pointing towards a reflective wall is going to pick up more reflected spill than a mic facing an instrument and pointing towards an absorptive wall surface. With the right mics and techniques, good spill can be a creative tool that shapes the sound and energy of the mix.
Fi g u r e 7.7 Applying the 3:1 rule when miking three singers.
3 1 1
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Example 7.9: A multi-miked drum set with the kick, snare, and tom tom mics gated to remove the significant spill in those mics. The sound is cleaner, tighter, and more focused. For some musical styles it might be considered too “bland.”
7.9 WHY MINOR CHANGES IN MIC POSITION CHANGE THE SOUND SO MUCH
All of the topics discussed in this and previous chapters related to microphones and stereo arrays have a combined effect on the sound a mic picks up. For example:
• Moving a microphone closer or further away affects proximity effect, distance perspec-tive, the direct vs reflected sound ratio, and the mic’s phase relationship with any other mics which also pick up the same sound source.
• Moving a microphone left, right, up, or down, affects the on-axis sound picked up, the spill picked up, and the mic’s phase relationship with other mics which also pick up the same sound source.
• Changing the angle of a mic affects not only the on-axis sound picked up, but also the off-axis spill picked up.
EQ cannot fix any phase related problems, such as the timbral shifts of comb filtering related to reflected sound or spill issues, so it is essential to listen critically to the sound produced by each mic, and the combination of all the mics set up in the same room before committing and proceeding with the recording session. EQ should be a last resort anyway.
If the sound produced by any mic isn’t right it should be corrected prior to tracking (through mic choice and placement) before relying on electronic “last resort” processes such as EQ.
7.10 EXPERIMENTATION AND EXPLORATION
Mic position X might have worked really well on guitar A in studio B when using mic C. But if any one of those variables are changed that mic position may not work as well, and time must be taken to experiment and explore until great sound is captured by the microphone(s).
In addition to changing mic position, some other things to experiment with include:
• Changing the instrument: Two different instruments of the same type may sound differ-ent, and propagate sound differently, necessitating different mic positions. The new instrument may sound so different that an alternate mic is desirable.
• Changing the recording room or the instrument’s position in a recording space will change how the instrument interacts with the room. Finding where the instrument natu-rally sounds best in the room may necessitate a change in mic position relative to the instrument, and/or a change in the microphone(s) used.
• Changing the mic will change both the on-axis direct sound and off-axis spill picked up, and a slightly different mic position may be necessary to get the best sound from the new mic and instrument combination.
It doesn’t take long to try a few different mic positions or to set up a few different mics.