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2 weeks ago
#1
Here for the gear

Powering small monitors off-grid

Hi all,

I am helping a friend to prepare a small live-set in a place where we won't have power. The idea is not to play loud (it is not really a party, we will only be a small crew), just to have some sound to make the experience nice.

I did some research online over the past days, including on this very helpful forum, but I haven't really been able to find a satisfying answer. I'm mostly concerned to do something wrong (burn the amps or something), as I have never done this before.

We will be using small studio monitors, either the KRK Rokit 6 or 10-3, which have a power output of around 100W and 300W respectively, per speaker. So that's 200W and 600W for each pair respectively. As I was reading through different threads I understood that the actual power consumption would be lower than this (as this describes the power rating and not the "1/8 power consumption"). I couldn't find much info on the actual power consumption. Whichever speakers we use, I don't think we would be using them at more than 50-70% of the volume, but to be on the safe side let's assume we'd be playing them louder. Beyond these studio monitors, we would only be using a laptop and a traktor controller (the latter can be powered by the laptop, so we can disregard it).

I am wondering 4 things:

1) Is it safe to use a generator for this setting, without risking any damage to the gear?
2) Would we need any additional equipment beyond the generator, a power cable, and a power strip?
4) if yes, how should I calculate the size of the generator that I require? I know I should have a safety margin of 1.5-2x the power consumption. Since I don't know if I can use the power output to measure this, I don't know if I can simply calculate 2x300W (assuming the larger KRK system) + around 100W for the computer = 700 W; multiplied by 2 we are at 1400W. For the smaller KRK we would be at around (2x100W+100W)x2=600W.
4) Would another option than a generator be safer, for example connecting it to a car with an inverter or so? Please keep in mind that we have little to no technical experience with electronics so whatever is easier is best. We also want to do this in 2 days so won't have time to buy a lot of things (we were planning on renting a generator the same day).

Any tips would be much appreciated!
2 weeks ago
#2
Lives for gear

Generators are safe for electronics if you use them properly--mostly not connecting (plugging in or turning on) the load until it's up and running, and disconnecting it before shutting the generator down. Inexpensive inverters are very often "modified sine wave" inverters and you don't want to use one of those for audio stuff; it's very very noisy power, and you're likely to have nasty noise due to the inverter.

Pretty much any generator will be much larger than needed to supply your power needs, which realistically are no more than a couple hundred watts. The smallest AC power generators I can think of offhand are around 600 watts, and practically all are at least 1000 watts. You don't need to upsize too much for this load; there aren't any big motors with large startup current requirements, for instance.

Be aware that there are tremendous differences in how loud various generators are. In particular, inverter generators are much, much quieter than open-frame contractor style generators, especially under a low load. Honda inverter generators are among the best, and should be available for rental with a little looking around. You don't need anything other than the generator and power cords (and gas for the generator).

A car battery with an inverter isn't a great option because car batteries are not really designed for that kind of load; they're designed mainly to supply a big, quick burst of energy to start the engine, and don't have a huge capacity nor survive well with deep discharges. You'd probably have to run the car some to keep the battery somewhat charged, and most car alternators aren't all that effective at idle speed, so this isn't an especially efficient or satisfactory way of doing things. For a one-off, I'd suggest renting the generator as the easiest and simplest way...just make sure it's a quiet generator, and maybe have them demonstrate how loud it is before renting it if you are unsure about that.
2 weeks ago
#3
Here for the gear

Hi DrewE,

Many thanks for your prompt, clear and comprehensive answer. This is reassuring and we will thus indeed go for a small generator, inverter if we find it. Assuming larger generators might also be louder (assuming both inverter), we will try not to upsize too much as you recommended.

Much appreciated!

EDIT: we have just booked a Honda EU20i which seems to be a very silent inverter generator. I thought I'd mention it in case this can be useful to future readers.
2 weeks ago
#4
Gear Maniac

Honda EU generator

The model you booked is an excellent choice IMO. I have run my PA on Honda EU3000IS' (same series, just the next size up) and have had zero issues.

My local Home Depot rents the EU2000's for \$50.00 per 24 hour period, I believe.

The Honda inverters are pretty quiet as generators go but they are not silent.

I suggest a fairly long extension cord (no smaller than 14 gauge) and maybe even locate the gen behind a car/truck or some other fairly solid structure.
2 weeks ago
#5
Lives for gear

I agree, the EU2000i is a great option for what you're doing.

The bigger Honda generators (in that series) are not really much if any louder at minimal load, but they also aren't substantially quieter. With a heavier load, the larger ones of course are not being pushed as hard and for that reason end up being quieter, but I don't think it would make much difference in your case, and you'd have a more expensive and heavier and bulkier generator to contend with, and probably use a bit more fuel.
2 weeks ago
#6
Lives for gear
Quote:
Originally Posted by licancab
Hi DrewE,

Many thanks for your prompt, clear and comprehensive answer. This is reassuring and we will thus indeed go for a small generator, inverter if we find it. Assuming larger generators might also be louder (assuming both inverter), we will try not to upsize too much as you recommended.

Much appreciated!

EDIT: we have just booked a Honda EU20i which seems to be a very silent inverter generator. I thought I'd mention it in case this can be useful to future readers.
Great choice!
Since you are going to use a generator for the first time, I'd like to warn you about a few things:
-generator should be grounded
-carbon monoxide is denser than air, make sure that the generator is positioned in such a way that CO won't accumulate where people are
-there are some more things that you should be aware of - read the manual
1 week ago
#7
Here for the gear

Many thanks for all the replies! We now have the generator and are ready to try it out. The fact that the generator must be grounded.. what does it exactly mean? Should I connect the grounding screw from the generator to something metallic positioned on the ground? How important is this and how delicate is it to do it right..?
1 week ago
#8
Gear Guru

Quote:
Originally Posted by licancab
Many thanks for all the replies! We now have the generator and are ready to try it out. The fact that the generator must be grounded.. what does it exactly mean? Should I connect the grounding screw from the generator to something metallic positioned on the ground? How important is this and how delicate is it to do it right..?
All the info you need is here https://www.osha.gov/OshDoc/data_Hur...generator.html
1 week ago
#9
Lives for gear

Quote:
Originally Posted by Thomas W. Bethe
Note that this basically says that if you only plug stuff directly into the generator, the generator's frame is deemed to be an adequate ground and there's no need to earth the generator. It doesn't matter that, as is the case of many inverter generators, the frame is enclosed inside a plastic outer shell or otherwise electrically insulated from the earth.

In other words, you just need to plug stuff into the generator, and use normal electrical safety practices. Interconnecting the generator with the electrical system of a house or other fixed structure is a much more complicated situation.
1 week ago
#10
Here for the gear

Thank you all. We have used the generator without grounding as, as was indicated in my OP, we simply used it to power a music Soundsystem, a computer, and a couple of phones. Everything worked seamlessly!
1 week ago
#11
Lives for gear

Seems like I'm late to the party, but for future reference, something I've done in the past is used a 300W power inverter and a car battery to power PA speakers. PA speakers are much more efficient than studio monitors, so in your situation they're only going to draw maybe 20W each. I've yanked the battery out of my van, driven two PA speakers, a digital mixer (60W), and some 13W LED lights for a ~90 minute acoustic performance. The battery still started my van when I put it back, but I have a booster anyway. Also returned the inverter for full refund when I was done Way cheaper and less hassle than a generator, totally silent too.
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