Ultimate Guide To Going Live. Part 5: P.A. Systems

author: Backup Guitar date: 03/24/2004 category: the guide to
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Note: Before reading this article, I suggest that you first read the Amplification article in the Guide to Going Live series. As I touched upon before, P.A. systems are integral to being able to comfortably perform live. The whole theory behind P.A. systems is to have the volume in the room at a constant level, and that the performers don't need to have a wall of amplifiers just to have the people in the back hear some noise. Modern P.A. systems were pretty much engineered by a relatively small company, Yorkville Sound. Based in Toronto, Pete Traynor developed the portable P.A. cabinet and mixer, which caught on rapidly throughout local musicians, and soon demand increased across the American border. A full P.A. system contains several main components. First, there are the microphones which pick up amplifiers and vocals, which are then passed through a mixer (which often takes the convenient shape of a head), and then is passed through speakers. For a good P.A. head and two speakers, expect to pay $500 - although Squier and Kustom do make smaller P.A. systems which are available for less. In the end, price does matter, so don't be afraid to shell out a few extra bucks. A good mixer should have at least 4 channels, but 5, or even 6 (depending on you instrumentation) may be desired. There should be a three way EQ and volume for each channel, plus a master volume, and maybe a master EQ. Some P.A. heads also have reverb built in, which you may want to use with moderation, as this also puts reverb onto vocals, which usually don't require much reverb. A good speaker unit should be solidly built, with a rugged front grille. None of this cloth stuff, you need metal to protect your P.A. speakers. Your speakers need to be able to handle both bass and guitar frequencies. If you're going to be mic'ing up drums into the mix, you need even higher frequencies to allow for the high end sizzle of a cymbal. If you're using a simple four string bass, look for a low end of 40 Hz. Lower accordingly for a five or six string bass. You may have to get down to 20Hz. The high end sizzle of a cymbal can get up to around 10,000 Hz. If you want, a 212 P.A. unit can contain two speakers, with one of them optimized for high end frequencies, and the other for low end frequencies. It's really all up to you. Another option is to wire P.A. speaker units in series, which is fairly complicated, and requires a cable harness. It's really too much to bother thinking about. Wiring in parallel is the simplest way to go, and is easy to troubleshoot. Parallel simply means more than one cabinet is being used for one channel.

Hooking it Up

Hooking up your P.A. system is a very simple task. If you are going to use a microphone for the amplifiers, have the microphones within 5 inches of the speaker, just below the top of the speaker diameter. You can hang them upside down from the top of the amplifier, or use a small stand. Either way works fine. If you plan on hooking your amp up to the P.A. mix through a cable, make sure you use a preamp out jack, NEVER an external speaker out jack. Because the signal has been through a poweramp section after going through an external speaker out jack, the signal is so strong it will destroy the preamp section of the P.A. mixer. Also remember to use speaker cables, not instrument cables, when hooking up the P.A. mixer to the cabinets. The strength of the signal coming from a poweramp section will burn up a regular instrument cable. To find a good EQ mix for the P.A. mixer, put all your guitar EQ bands to five (or whatever happens to be middle number) and then modify the EQ on the P.A. mixer until you get a nice, even tone with all levels - bass, mid and treble and equal levels. You can then mix around with the EQ on the amplifier, and you should have an ideal mix. When you're going to use microphones, try to use a wind screen. You can build one yourself out of pantyhose (if you're too embarrassed to buy a pair yourself a the store, grab a ruined pair of your mom's) and a wire coathanger. Those are basically those screens you see used in recording studios. They help to eliminate the "puh" and "buh" sound you hear when those particular sounds are said. It also helps to eliminate any breathing noise coming in from the singer. When using dynamic mics, keep the microphone level to your mouth. Keeping the microphone end completely facing your mouth allows all of your voice to be picked up by the microphone. Have it tilted down at a slight angle to reduce the popping "p" sounds. If you are a fairly quiet singer, there are ways you can train yourself to sing louder. One of the best ways is to attempt to sing along with a song that you like through a stereo. Plug the microphone into the "microphone in" port on the stereo, and hook it up to a stand. Find a distance where you can sing at a comfortable level, that's heard at the level with the music. Then, move the microphone away one inch. Don't move your head closer, but sing louder into the microphone while still maintaining vocal balance. Trying this for a little bit each day helps to increase the strength of your vocal chords so they last longer when singing, and to improve your singing ability at louder volumes, not to mention allowing you to sing louder.

Projecting The Noise

Now, once you've got all your equipment hooked up into the P.A. mix, have someone stand in the room, walking around to different locations while the band plays normally. The sound should be heard quite clearly, with all vocals, guitars, drums and bass heard at a solid level where no one is drowning out the next person. If there is something wrong with the level, turn up the volume on the P.A. mixer for that particlar channel. In order to know which channels belong to a certain instrument, I suggest that you colour code each cable. For example, you could paint the lead singer's microphone with a green stripe at the end, the backup vocals with a blue, and so on. Make sure all colours can be easily seen in low light, and can be deciphered from one another. Keep all cords untangled and neat. Make sure that the sound is even across the room. Obviously, the front will experience some loud noise, but the back shouldn't be straining to hear you. As a performer, make sure you can hear the mix properly through the reference monitors, and your own amplifier's noise. Once you've got your noise spread evenly throughout the venue with good clarity, then you can start worrying about the dreaded F-word: Feedback.

Taming The Beast

Feedback can have its uses. Many artists like Kurt Cobain and Jimi Hendrix used feedback in their songs to add to the instrumentation. There's nothing particularly wrong with this, but when the audience is listening to an acoustic folk song, and a giant squeal cuts through the mix, nobody likes it. The most obvious cause of feedback comes from having the microphone pick up the speaker signal. To counter this, keep all reference monitors in front of the singers, in the opposite direction of where all microphones ointing. This reduces the chance of microphones being able to pick up signal from the speakers, and having it turn into feedback. If this still causes feedback, try spreading all the monitors and amplifiers further apart. You will still be able to hear them, but the microphones, being less sensitive than your ear, will not. While singing, make sure you're no more than 2-3 inches away from the microphone. This helps to block away outside noise, reducing feedback. If you ever cup your hands around the mic, this acts as a sort of parabolic dish, reflecting noise into the microphone, which can cause feedback. Another cause of feedback comes from the pickup pattern of the microphone. Refer to the owner's manual of your microphone to see what kind of pickup pattern is best used with your microphone. If you're selecting a microphone in the store, you can see what kind of pickup pattern your mic has by talking into the microphone from different directions. If the microphone picks your voice clearly while talking into the back of it, put it back. This means that the mic is likely to pick up stage noise from your speakers, taking you back to the first problem. You want the sound to be picked up from directly in front of the mic, where you will be singing into it, not from all around the mic. Feedback can have other sources too - your guitar and amplifier. If you're using your guitar (especially one with single coil pickups) close to your amp, you're going to hear a lot of humming. Use it at a high volume, and feedback can come up - even when you're at a distance of up to ten feet (I've been there and had it happen). The use of a noisegate can help to clear up this problem. Noisegates use a "threshold" parameter to help control sound below a certain volume level. More specific noise gates can suppress noise levels at specific frequency levels. Some noisegates are rackmountable, and can control the noise for up to 8 instruments at a time. Very handy. If you find that there is simply one problem instrument or microphone, and you can't get its feedback to go away, modern technology can save the day. Two feedback reducing devices, the Behringer DSP110, or Sabine's FBX Solo series can be used to solve feedback on one naughty microphone, or a group of specific mics. Also, make sure that the audience is gettting a good mix through the show. Have a friend with the band, or a groupie (they're meant to be taken advantage of) to walk through the bar a bit, and to check to see the sound is still good, clear, and not too quiet or loud. The audience came to the bar to hear you play, you didn't go to the bar to hear yourself play. Remember, that as a rule of thumb, the point of P.A. systems and reference monitors isn't to make the sound loud, its to carry on a seamless stream of sound. Your amplifiers mark the first point, to carry the sound across the stage to you, along with the reference monitors. The first row of P.A. enclosures is meant to carry sound to the audience. The next set of P.A. enclosures (if you have one) is to carry sound even farther back. One row of P.A. enclosures isn't enough to project sound out 100 metres. You'll need at least one additional row of P.A. enclosures to project sound the full 100 metres. If you plan to own your own P.A. system, there may be several different environments you find yourself in. For clubs that barely require a P.A. system, you will need about 100 watts, maybe a little less. These clubs are very small. If you're going to be playing a club where you seriously do need a P.A. system, and you even plan to mic up the drums to the system, you'll have to have more channels. 8 channels is plenty. It allows you to have two guitars, a bass, two vocals, and a few channels for drums (you may want cymbals to be quieter than the toms). Such P.A. systems will be in excess of 250 watts, which is definitely needed if you're going to be mic'ing the drums into the mix. Expect to pay over $1,000 for such high end P.A. systems. But, as I said before, almost all clubs will have P.A. systems of their own, which will be large enough to project sound through the venue. The volume level must be comfortable, especially for you. Don't forget to wear earplugs if your ears are at all hurting from the noise. Once the volume gets above 110 decibels, sustained exposure to the noise can result in ear damage. As I went over before, you don't want that happening to you. Remember to keep all your wires neat and tangle free. It helps to tape them down to the floor so that your performers don't trip on them. Use colour coded bands so that you know exactly which cable came from which port. There's no space for guessing in an atmosphere as lively and fast paced as being a live sound technician. One mistake can cut off sound from an important source, which makes the band - and the audience - mad at you. Keep organized, make sure you have your stage setup clearly drawn out so that even a complete newbie to the world of sound will be able to understand it, not that you'd ever trust an inexperienced person to your precious gear. Experience basically comes from experience. You'll only ever increase your P.A. skill as you continue to set up and set down your rig. Thanks for reading my article, and I hope anything you've learned will help you down the road. Sincerely, - Backup Guitar
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