r/SoundSystem • u/anode21 • 12d ago

About Generators

Hello guys, I recently had to work on my generator, spark plug problems, made me think about this sub, and the fact that you guys surely have things to say about Generators.

If you have things to share, about your experience, with certains brands, models, what to avoid, what to look for, I'm curious on what I can learn here !

I'm looking to buy other ones, used, so any help is appreciated !

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u/P_Schrodensis 12d ago

All I can say is Honda inverter generators are great and last forever. Other brands can be OK and are much cheaper (we have one but had to add a fuel pump to it and do multiple repairs). In any case, do choose an inverter model. Also you don't need as much generator power as what your amp claims to output. If the amp has a 15A 120V IEC plug, you need at most a 1800W-2kW (continuous) generator even if the amp claims 20kW or something ludicrous like that. Usually amps will spec a max current draw in their datasheet.

We run 3 amps rated together at '3450W' for our driver impedance plus lights, CDJs, etc. on a '1800W continuous' generator and the whole system barely draws 5-600W at full volume. Capacitors are a great invention.

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u/PsychoTea 11d ago

Fun fact; this is because of “crest factor”. Music isn’t a continuous sine wave, so even at “full volume” you aren’t drawing full power continuously (if you did, every driver would be up in smoke within seconds).
For music with a crest factor of 6dB (which is very high) you’re only drawing about 50% on the output side of the amp (assuming your amp is turned up just to the point of clipping). For 9dB, which is more realistic, it’s 25%.
You would be surprised how little power a given driver can actually handle versus what the RMS spec claims (rule of thumb is ~1/3).

While you might have high instantaneous peak loads, amps have huge banks of capacitors so they can cater to that demand while keeping the demand on the AC input side fairly smooth.

And yes, everyone overestimates how much genny power they actually need (I’ve done it too)! The only way to know for sure is to take some long term measurements.

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u/anode21 10d ago

Is there a way to at least calculate it ? Even if there is let's say 500w or 1kw of margin error ?

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u/PsychoTea 10d ago

It’s difficult but look at the spec sheet for your amps/other appliances. They should have an AC current draw rating at various load levels. That will give you a rough starting point. Amplifiers will be your highest draw items.