Guitar Amps

Miking a Rock Band Getting great live sound is the result of many factors. Not the least of these is mic placement. So if you're not playing arenas with a full sound crew well versed in these techniques, we can help with some useful tips and guidelines. In this issue, we'll look at a typical rock line-up - guitar, keyboards, sax and drums. We'll also include information you'll find useful when thinking in general terms about microphone placement - the 3:1 Rule. . And while these guidelines are widely accepted in live sound performances, remember that it's all about experimentation. What sounds right to you and your band, if you have one, is … what's right for you and your band. Ready to get started? Let's go!
A good place to start is by listening to the sound of the instrument or the amplifier you are miking. How does the sound radiate? Listen up close, and then a few feet away. Place your finger in one ear, then listen to the sound source with the other ear until you find a spot that sounds good, Put the mic there, In some cases, more than one mic is required for an instrument that emanates sound from a number of places at once (a piano is one example). The closer a microphone is placed to the instrument (to maximize signal level and reduce pick-up of unwanted sounds), the more important placement becomes. Every instrument and microphone has its own characteristics. Every musician has his or her own idea of what sounds good. Experiment and listen. How many mics? The number of mics you have to work with plays a pretty big role in your mic placement strategy. If there are only a couple of mics available and there are singers in the band, that pretty much settles it. Guitar and bass players are next in line and with drums and keyboard, particularly if you're playing small venues, last. Use as few microphones as possible. Every time the number of microphones doubles, the Potential Acoustic Gain of the sound system decreases by 3 dB. (Check the sidebar feature in this issue for more about decibels.) This means the volume level of the system must be turned down for every extra mic added. The more microphones you have on stage, the more likely you are to experience feedback. Using fewer microphones will allow more volume before feedback happens.
When multiple microphones are used, the distance between microphones should be three times the distance from each microphone to its intended sound source. This prevents the unpleasant hollow effect called comb filtering, which occurs when two or more microphones pick up the same sound source. This technique is known as the 3-to-1 Rule. Many of the same microphone rules used in recording apply just as well for live sound. The law of physics doesn't change for sound reinforcement.
General Rules for Placement A major difference between miking for live sound versus recording is proximity to the sound source. The goal in live sound is to get the mic as close as possible to the source for two reasons: 1. Placing microphones as close as possible achieves maximum sound level before feedback occurs. 2. Close-miking reduces leakage and pick-up of unwanted sources.
You'll probably be using unidirectional microphones in most applications because they're so good at isolating sound sources and avoiding feedback. If you're using stage monitors, you may want the tighter pickup patterns, and consequently better gain-before-feedback, of supercardioid mics. The type of instrument you're miking and the sound you're going for will tell you whether you need the frequency response of a condenser mic or a dynamic mic. Miking the Band Veteran sound engineers seem to agree on the following favorite microphone techniques. Remember, though, that these are suggestions … intended only to give you a starting point for your own audio adventures. Electric Guitar Amp The electric guitar has sound characteristics, believe it or not, similar to the human voice. Here are some guidelines to follow, depending on your sound preferences.
1. Place microphone as close as practical to sound source 2. Place microphone as far as practical from unwanted sound sources such as loudspeakers and other instruments 3. Aim unidirectional microphones toward desired sound source (on-axis) 4. Aim unidirectional microphones away from undesired sound sources 5. Use a minimum number of microphones
	Here's something to keep in mind: each instrument has its own dynamic range (the difference between the loudest and quietest sound an instrument can make). And one way to understand that is to look at its intensity level measured in decibels. If all of the instruments are fairly loud and the venue is of moderate size with good acoustics, no reinforcement may be necessary. One the other hand, if you're playing in a large hall or outdoors, even amplified instruments like electric guitars may need to be amplified further. Finally, if there's a big difference in the dynamic range among the instruments (like an acoustic guitar in a loud rock band), mic techniques can balance the scales. Remember, too, that the maximum volume of the PA is limited by the maximum gain before feedback of the softest instrument.
Drum Kit In most live sound systems, the drum set is miked with each drum having its own mic. Using microphones with tight polar patterns on toms helps to isolate the sound from each drum. It's possible to share one mic with two toms, but then, a microphone with a wider polar pattern should be used. The snare requires a mic that can handle a very high SPL (sound pressure level) so a dynamic mic is usually the choice. To avoid picking up the hi-hat in the snare mic, aim the null of the snare mic toward the hi-hat. The brilliance and high frequencies of cymbals are picked up best by a flat-response condenser mic.
Drums
Keyboards This category represents a wide spectrum of acoustic, electric and electronic instruments, each with its own special sound requirements. Listed here are some of the most traditional miking techniques. Upright Piano Open the lid and aim a condenser microphone just over the top, above the treble strings.
Grand Piano Use two flat-response condenser microphones; one positioned 12 inches above the treble strings and the other above the lower strings. Both mics should be about 8" from the hammers.
Electric Piano Amp Since most electronic keyboards can be plugged right into an amplifier, you can follow suggestions for electric guitar.
Hammond Organ/Leslie Speaker For a natural and well-balanced sound, mike the top louvers and bottom bass speaker 3" to 1" away. If you want to capture the Leslie's gutsiness, you might want to try a dynamic mic. For a clearer sound, try a condenser mic. To combat the Leslie's wind noise, use a wind screen or a pop filter. Shure Mic: SM57, Beta 52
Saxophone Like the electric guitar, the sax has sound characteristics similar to the human voice. And that's why the shaped response of a dynamic microphone is generally preferred. However, a miniature condenser microphone mounted on the bell often does the trick. The sound is fairly well distributed between the finger holes and the bell. Miking close to the finger holes produces key noises, so generally mics are placed toward the middle of the instrument. (Note: this technique does not apply to the soprano sax, since its bell does not curve upward - therefore, miking in the middle of the instrument won't pick up sounds from both the key holes and the bell.)
And here's the best advice we can give you The best way to determine the right approach is to trust your ears. Use the tips we've presented as guidelines, then experiment. Like almost everything else that has to do with music, there are no absolutes. There's only what works for you. For more information about mic placement, visit the K-Base on shure.com or request free publications at the Literature Cart.