P.A. Systems

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P.A. Systems

The P.A. (a.k.a public address system. Pronounced pee a ) is the amp the singer sings through in practice. It's what you plug the microphone into. At a gig in a club or stadium, it's a bigger system, and the whole band is put through it. The drums are miked, the guitar amps are miked, and the bass amp, keyboards, and DJ's turntables are usually input through a small unit called a direct box.

NOTE

Michael Woody adds, "I understand the PA to be a complete system for amplifying acoustic sounds (vocals, pianos, percussion, etc.) and possibly for reinforcing already amplified instruments, including at least one vocal microphone, an amplifier , and the speakers . The various cables should go without saying, but who knows . A sound mixer is also typical and required when using more than one microphone."

The mikes and direct boxes on stage go through a snake, which is a box that routes all the cables to the soundboard, a.k.a mixing board, a.k.a. mixer, at the back of the room. This is where the soundman hangs out. The mixer has a number (usually 16 or 32) of inputs, a.k.a channels. Each one deals with a separate microphone or direct input, a.k.a line input. For instance, in a professional setting, the drum kit will have seven or more mikes on it: one each for bass drum, high hat, snare , both rack toms, and then two overhead to get the cymbals and overall sound of the kit. Each guitar amp will occupy one channel; same with each vocal. The soundman raises and lowers the volume and EQ of each channel to get a good mix.

Woody adds, "In my experience, a snake is a collection of several discrete cables within a single larger cable with a breakout box at one end (on stage) and loose connector at the other end that plugs directly into the sound mixer. It can send instrument signals from the stage to the mixer as well as send monitor signals back

Figure 5.4. Rack-mount graphic EQ.

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Figure 5.5. Close-up of master graphic EQ on a mixer.

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to the performers, assuming they have monitor speakers with built-in amplification. There are variations, but this is what is generally considered to be a snake."

EQ is equalization. This is the amount of high frequency, middle frequency, and low frequency sound in each channel. This is built in to each channel of the mixing board.

A mixer usually has a master EQ for the whole mix, also.

The mixing board will usually have several monitor mixes available. A monitor mix is the amount of each instrument going to each monitor speaker.

Monitors , a.k.a. monitor wedges, are the speakers on stage that face the band, rather than the audience, so the band can hear themselves. Different mixes are useful because one band member might need to have a different mix than another band member. For instance, usually the singers will need to hear more of themselves and less of the guitars. The bass player will often want a lot of the snare drum to help him stay in the pocket.

The mixing board usually has an effects send to a rack-mount reverb, which the soundman usually adds to the snare drum and the vocals only. Sometimes they'll add a lot of it to a singer if he sucks. You can't really cover up a lack of talent, but they will try.

Figure 5.6. Monitor.

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Figure 5.7. Singer with monitor.

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The soundman (or woman ) is in charge of running the P.A. He (hopefully) knows how to do a good sound check (the process of getting all the sounds gooddone before the gig when the venue is empty).

Keep in mind that the sound of the room changes when full of people. The sound is absorbed and responds differently than it did in sound check. A good soundman knows this and compensates.

In stadium situations, the soundman who runs the system feeding sound to the audience (the house mix) will be a different person than the one mixing the monitors, using a different mixing board. In a club, it's usually the same person on the same board.

Very professional bands will bring their own P.A. and soundman. Bands that are on their way but can't afford that yet will often bring their own monitors and monitor mixer soundman, so that at least they sound good to themselves on a consistent basis. This makes for a better performance and gives the band a modicum of control in a world where they are otherwise often powerless.

Smaller bands will sometimes have their own smaller P.A. system, which can be the entire P.A. ( mainly for vocals) in a small venue or anywhere that does not have a P.A., like a party (keep in mind that you'll need more power for the same volume outdoors).

A powered mixer is a good choice for this. It is a mixer that includes a power amp. You plug it directly into the speakers.

This system could also double as your monitor system in a bigger venue that has its own P.A. system.

Figure 5.8. Small portable powered mixer.

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Figure 5.9. Close-up of powered mixer.

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Figure 5.10. Another powered mixer.

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Figure 5.11. Speaker on small portable P.A. system.

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Figure 5.12. Bass speaker on small portable P.A. system.

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Figure 5.13. Cheap powered mixer.

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Figure 5.14. Back of cheap powered mixer.

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