The Woodshed

How much power?

1

So I have a question in regards to how much power a band needs?

I have a three piece band with powered mains. We typically don’t mic the drums but do on occasion. So it’s guitar, bass, a mixing board, my pedal board and two powered mains. A simple basic set up.

I’m questioning the amount of power we need to give the amps what they need.

we've never blown a breaker while playing, but I notice at some gigs the guitar and bass amp just sound horrible. The bass kinda farts and rattles, the same with my guitar amp. We played an outdoor gig today at a car show and had one extension cord available to pug into. The sound was just not great. Can having everything plugged into one outlet contribute to funky, poor sound?

2

So I’m guessing it’s way too much of a power requirement for one outlet. The mains are 1500w each and I believe the bass amp is around 400 or 500 watts. I use a 10 watt Vox but that pushes our total power usage up close to 3500 watts.

So again we don’t blow breakers, but does this contribute to poor sound? The PA seems to sound good. It’s the guitar and bass amp that get funky sounding.

3

Of course. Simply, add up the wattage draw of your amps (usually found at the spot the AC cord attaches at the amp), total it up, and go from there. I'd like to have at least two isolated 20 amp circuits, if not more. If you're unsure of what else is on the circuit, you may need more. A single extension cord will not carry enough power for your needs unless it's 12 gauge wire and you are the only thing plugged in to that circuit. Don't accept feeds from stage dimmer circuits or small generators, either. Any circuit that shares power with coolers, HVAC, neon or fluorescent lights is also suspect. That advice comes from personal experience---been there, done that. I've worked stage electrics for over forty years, thirty of those in one of the largest theaters in the country. Doing remote of site gigs was always a PITA due to lack of power.

4

A power anecdote..... One of my bands had a rather outsize system(for clubs, anyway). The mains were Peavey SP-4's and the subs were BIG Peavey 18's. I was setting it up for our first gig at a club, when the owner came over, saying that was a monster system for his bar and there'd be trouble if we were too loud. Knowing we had excellent control over stage and FOH volume, I smiled and said "Just because you have a 'Vette doesn't mean you drive 150 in a school zone". We were on the rotation there for 3-4 years after that. I DO like a lot of headroom!

5

The more current you pull on a power cord the more the voltage drops. Also, the longer the length the cable of a given size the less the current draw it can handle without significant voltage drop. 15 awg is good for 15 amps but at lengths longer than 50 ft you need to upgrade to 12 awg.

About 30 years ago a brother in law lost power to his house so he ran an extention cord from his refrigerator to neighbors house across the street. Well he burnt out the compressor in the refrigerator due to voltage drop.

6

The more current you pull on a power cord the more the voltage drops. Also, the longer the length the cable of a given size the less the current draw it can handle without significant voltage drop. 15 awg is good for 15 amps but at lengths longer than 50 ft you need to upgrade to 12 awg.

About 30 years ago a brother in law lost power to his house so he ran an extention cord from his refrigerator to neighbors house across the street. Well he burnt out the compressor in the refrigerator due to voltage drop.

– Bubbalou88

I've never heard of or seen odd number wire gauges for commercial home use. It's always even numbers. Odd numbers are only used for very special industrial purposes---high tension lines, telegraph and so on. That's how they often catch scavenger wire thieves.

Wire is also directional. Looking at the print on the wire jacket, the right hand end is always the male plug. If you have to cross the wires to make the connection properly, you're wiring the wrong end. The black, white and green wires should fit naturally into the connector.

Wire has resistance. The larger the gauge (the smaller the number) the less resistance. The longer the run, the higher the resistance. I'm not at all surprised the fridge motor burnt out.

7

Seventeen watts max! And wire is NOT directional. That's silly.

8

Seventeen watts max! And wire is NOT directional. That's silly.

– Billy Zoom

It is directional for wiring purposes. If you have to cross wires over, you're backwards. Wires should go in directly. Electronically, it makes no difference, but it's a mechanical thing when you're wiring it up.

10

In what industry?

– Billy Zoom

I'm a retired IATSE stagehand. Mostly did sound and lighting. I've made up miles of 12 gauge AC twistlock cables for stage power. I've worked with everything from43 gauge to 0000 3 phase feeders. Our main theater had over a million watts just for stage lighting, and more feeds for building needs, sound, and the other facilities. Elliot Hall of Music at Purdue, where I worked for 30 years (and a dozen other facilities on campus) is one of the largest theaters in the country. I've dealt with everything form millivolts to kilovolts, and feeds from delta and Y three phase power.

Like I said, electronically, there is no distinction. Mechanically, there is.


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