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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => AC Power and Grounding => Topic started by: John Calhoun on June 16, 2016, 12:39:04 pm

Title: Power consumption question from a novice
Post by: John Calhoun on June 16, 2016, 12:39:04 pm
Hello.

I have been slowly phasing out my passive rig for a powered rig. On the active speaker specs, it says "Power Consumption : 1.8 A" There's no way that means you can run this cab with just 1.8 amps, is there? If so, would that mean I could, conceivably, run the whole rig (2 active subs, 2 active tops, and 3 active monitors) off one 20 amp circuit.

Sorry if this sounds stupid, I am not too knowledgeable when it comes to this.

Just FYI. The speakers I'm using are EV EKX18SP subs and EV EXK15p mains and monitors.

Thanks for any help.
Title: Re: Power consumption question from a novice
Post by: Scott Olewiler on June 16, 2016, 01:55:05 pm
Hello.

I have been slowly phasing out my passive rig for a powered rig. On the active speaker specs, it says "Power Consumption : 1.8 A" There's no way that means you can run this cab with just 1.8 amps, is there? If so, would that mean I could, conceivably, run the whole rig (2 active subs, 2 active tops, and 3 active monitors) off one 20 amp circuit.

Sorry if this sounds stupid, I am not too knowledgeable when it comes to this.

Just FYI. The speakers I'm using are EV EKX18SP subs and EV EXK15p mains and monitors.

Thanks for any help.

I guarantee you can run that entire rig off of one 20 amp circuit.
Title: Re: Power consumption question from a novice
Post by: John Calhoun on June 16, 2016, 02:09:26 pm
I guarantee you can run that entire rig off of one 20 amp circuit.

Wow, seriously? I was worried about some of these smaller places we play, but I guess that isn't an issue.

I had been running (3) CS4080s and a CS2000 and that definitely had to be run off multiple 20 amp circuits.

Thank you so much for your help.
Title: Re: Power consumption question from a novice
Post by: Mike Sokol on June 16, 2016, 02:48:29 pm
Wow, seriously? I was worried about some of these smaller places we play, but I guess that isn't an issue.

I had been running (3) CS4080s and a CS2000 and that definitely had to be run off multiple 20 amp circuits.

Thank you so much for your help.

The key thing to remember is that audio isn't like lighting. If you have a 500 watt PAR, it's going to draw 500 watts continuously, so turning on 4 of them will draw 2,000 watts. That's 16 amperes continuous, which will take out any 15 amp breaker quickly, and probably a 20 amp breaker after a while.

On the other hand, audio has something called a Crest Factor, since there's usually a lot of dynamics in music (with the possible exception of EDM ;D). We generally figure that an amplifier will draw about 1/8 of its rated possible wattage. That suggests that 2,000 watts worth of amplifiers will likely draw around 250 watts of actual outlet power. So instead of drawing 16 amperes from the power line, it's probably more like 2 or 3 amperes of AVERAGE current. And average current is what heats up wires and trips circuit breakers (up to a point).

Again, EDM and DJ's can be the exception since they often drive huge amounts of bass at near 100% duty factor. In that case and amplifier can draw closed to its rated amperage from the power line.
Title: Re: Power consumption question from a novice
Post by: Scott Olewiler on June 16, 2016, 03:57:07 pm
Wow, seriously? I was worried about some of these smaller places we play, but I guess that isn't an issue.

I had been running (3) CS4080s and a CS2000 and that definitely had to be run off multiple 20 amp circuits.

Thank you so much for your help.

I would still split them up if I could, but if all you have is one outlet, you shouldn't have any issues. I have run (2) DSR112, (4) ELX112ps, (2)DXS-12 Subs , 2 guitar amps, a bass amp and mixer, etc all off  one 20 amp circuit more than once with no issues.
Title: Re: Power consumption question from a novice
Post by: John Calhoun on June 16, 2016, 10:53:11 pm
I appreciate all the input. We definitely don't do EDM... It's an oldies/classic rock n roll  band, so I think we're safe. hehe. But, in venues that are large enough, we still run a pretty hefty lighting rig (300 Watt par 56s). But, I have a 100 amp distro panel for that, so I think I'm good.

Again, thank for all the info.
Title: Re: Power consumption question from a novice
Post by: Lyle Williams on June 17, 2016, 01:21:00 am
Buy a cheap ($10-20) green power meter and plug everything through it for testing.  Then you will have real measurments.

But I agree with the above statements.  I have a similar (ETX) rig.
Title: Re: Power consumption question from a novice
Post by: Stephen Kirby on June 17, 2016, 05:27:00 pm
Yesterday I was running two DSR112s, a Crest Pro9200 into four Cubosubs (4 ohm load on that amp rates at 2200WPC), two QSC K10s, four Alto SXM112s, my Expression2 and a 5 piece band off of two 20A outlets.  If you added up the output power ratings of everything in the PA that would be 11,800 watts.  For less than headbanging music it's typical to use 1/8th of that which is only ~12 amps.  Plenty of headroom for lights (LED rig only pulls around 2A) and backline.
Title: Re: Power consumption question from a novice
Post by: John Calhoun on June 17, 2016, 11:34:41 pm
Thank you all so much for your input. I feel a lot more secure now  :)