Pleppy's Place: PA Systems

Big DJ systems normally require a distro box because of the large power requirements of amps & lighting systems.

If you are not an electrician a power distribution box should not be attempted as DIY project. You should buy a pre-manufactured distro box or have a professional electrician build one for you.

The Furman ACD-100 & the Furman ACD-120 are two good distro boxes that are not too expensive.

Furman ASD-120 Sequenced Power Distributor demo video.
http://www.furmansound.com/video.php?id=28

Furman ACD-100 Power Distributor demo video.
http://www.furmansound.com/video.php?id=27

"The ACD-100 AC Power Distro is an extremely compact, low cost rack-mount power distribution system"

Furman ACD-100 (100 Amp) AC Power Distribution
http://www.furmansound.com/product.php?id=ACD-100

Furman ACD100 AC Power Distribution $500
http://www.samash.com/catalog/showitem.asp?SKU=FACD100

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You should use heavy duty extension cords. I'd go for at least two 100', two 50' & two 25' cords. (Plus a few short heavy duty cords.) Since you want to keep cords out of the way to prevent trip hazards, cord runs can become pretty long sometimes. (Taping cords on the floor next to the wall is one common way of running your power cords & speaker cables.)

10/3 100' Extension Cord $109.99
http://www.acehardwareoutlet.com/(rjaayla1zehh5e55urx4c445)/ProductDetails.aspx?SKU=3009065

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12/3 50' Extension Cord $59.99
http://www.acehardwareoutlet.com/(rjaayla1zehh5e55urx4c445)/ProductDetails.aspx?SKU=3087491

12/3 25' Extension Cord $13.99
http://www.acehardwareoutlet.com/(rjaayla1zehh5e55urx4c445)/ProductDetails.aspx?SKU=34083

Whenever possible hook your amps on one circuit & your lights on a separate circuit. Two electrical outlets may be far apart, but still be on the same circuit. So you need to check to be sure the outlets you are using are not on the same circuit.

You should use a power conditioner for your amp rack, (I recommend the Furman brand.) It will make it easier to keep you cords more neatly organized in your amp rack. And most importantly they allow you to have a switch on the front of your rack to turn on several components in your rack at once. Don't be confused by the term "power conditioner", that's purely marketing mumbo jumbo. Those cheap "power strips" at Wal-Mart & K-Mart with the on/off switch & the reset button are the same thing. A voltage regulator on the other hand is different, because they provide a constant voltage level. But they cost a lot more, so they aren't as popular as power conditioners & power strips.

Furman M-8 Power Conditioner $54.99
http://www.guitarcenter.com/shop/product/buy_furman_m8_power_conditioner?full_sku=103365284

Furman PL-8 II Power Conditioner $159.99
http://www.guitarcenter.com/shop/product/buy_furman_pl8_ii_power_conditioner?full_sku=102687027

Furman AR-15 II Voltage Regulator Power Conditioner $649.99
http://www.guitarcenter.com/shop/product/buy_furman_ar15_ii_voltage_regulator_power_conditioner?full_sku=181119

"The AR-15 II accepts any input voltage from 97V to 141V and transforms it to a constant 120V (+/- 5V)."

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It used to be you needed multiple components in your amp rack for signal processing. Equalizer, feedback eliminator, compressor/limiters & crossover. But now that can be more easily done with a DriveRack. A DriveRack handles all of your signal processing needs & does it very well while using less rack space in your amp rack.

The DriveRack 260 & the DriveRack 480 models are for larger systems, for most people the DriveRack PA is the model that is best suited for their system.

dbx DriveRack PA Processor $499.99
http://www.guitarcenter.com/shop/product/buy_dbx_driverack_pa_processor?full_sku=101779478

dbx RTA-M Reference Microphone for DriveRack PA $99.99
http://www.guitarcenter.com/shop/product/buy_dbx_rtam_reference_microphone_for_driverack_pa?full_sku=101863165

The higher notes are more directional than lower notes, so you want your tweeters to be slightly above the crowd's heads. You will need good solid speaker stands to accomplish this.

Ultimate TS-90B Black Telelock Tripod Speaker Stands $99.99 each
http://www.guitarcenter.com/shop/product/buy_ultimate_ts90b_telelock_tripod_speaker_stand?full_sku=100686369

It's important to have good heavy speaker cables in different lengths. You want to use the shortest cable length that will fit the application. Don't forget to secure the cables to the stands & run the cables on the floor in a manner that people won't trip on the cables. There are several methods you have to choose from to do this. One common way is to tape the cables to the floor & speaker stands.

Stay away from zip cord because it will get messy, it will never lay flat & it is damaged easily.

Remember that with wire, the higher the gauge number, the thinner the wire. So 12 gauge is a thicker wire than 16 gauge wire. 12 gauge is rated for more power than 16 gauge.

The reason for wanting lower gauge and therefore thicker wire, isn't so much about not melting the wires. You can use 16 gauge wire for 50 foot runs for a decent amount of power even for subs. However, where the problem is, is that the higher gauge wires (and therefore thinner wires) have higher resistance to electricity per linear foot.

Wire has electrical resistance. The thinner the wire is & the longer it is, the more resistance you have. This creates what is called a voltage divider with two resistive components seen by the output of your amp's speaker channels. One component is the speaker cabinet & the other is the speaker wire between the speaker cab & the amp. Part of the voltage across the amplifier's output is dropped across the speaker & part of the voltage is dropped across the speaker.

As long as you are using good low gauge wire, with as short of runs as possible, the amount of voltage drop across the wire is very, very small compared to the voltage drop across the speaker. This is a good thing, as you want the power being used up by the speaker, not the wire.

Now if you decided to use inexpensive high gauge wire (thin wire) & for a great distance, then you increase the amount of voltage being dropped across the wire, so that less of your power gets to the speaker. Obviously a bad thing. The thinner the wire & the longer the run, the more power is wasted in the wire, and not the speaker cabinet.

I suggest using 12 gauge speaker cables & preferably short runs.

12 Gauge Speakon Speaker Cables of various lengths.
$29.99 - $99.99 each
http://www.guitarcenter.com/shop/product/buy_corex2_speakon_speakon_speaker_cable?full_sku=332505%2e090

10" woofers & 12" woofers are better suited for handling midrange frequencies than 15" woofers. Since the subwoofers are handling all of the lows you don't want 15" woofers in the tops, they add extra unwanted bulk & weight. You can use a top with a 15" woofers if the tops are 3-way speakers with a mid-range speaker. One advantage to having 3-way tops with a 15" woofer is when playing smaller venues where you don't need a lot of bass, you don't need to take your subs to the gig.

It's usually best to place subs as close together as possible to prevent cancellation. Full cancellation occurs when the distance to a boundary is 1/4 wavelength, or when the distance to another source is 1/2 wavelength. A wavelength is the speed of sound (1130 feet per second) divided by frequency.

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$10,620 Speaker / Amp Combination

Two JBL SRX722 Speakers $1,509.99 each
http://www.guitarcenter.com/shop/product/buy_jbl_srx722_2way_dual_12_speaker_cabinet?full_sku=102969326