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Amperage draw from guitar amps


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Friend planing on running sound and wondering approx how much a 100w guitar amps or xwatts bass amps draws from the circuit.

 

Would it be ohms law ? (pretty sure but need to know if I have to factor in resistance

 

I = P / E ?

or

I = Square Root of (P / R)

or

I = E / R

 

Thanks !!

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The relevant forms of Ohm's Law would be P = R*I^2 or P = (V^2)/R however neither is going to tell you the power drawn by the amp. A "100W" amp means it delivers about 100W RMS to the speakers -- the power drawn is much higher. Many amps have the max power draw on the back near the power cord. You could also get a current or power meter between the amp and the socket. Obviously the max power draw only happens with the amp dimed, so a meter would be the best way to find the power drawn under given conditions. An amp running at at a low stage volume may only be putting 5W to the speaker and be drawing less than 50W from the wall even if it's a 150W amp.

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Ya kool ty for the info - doubt these guys are going to dime the amps so max prolly 20-30% draw - just want toi make sure the board pa amps can either handle the circuit provided or if i need more than one circuit 20amps

 

tyvm !

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Ya kool ty for the info - doubt these guys are going to dime the amps so max prolly 20-30% draw - just want toi make sure the board pa amps can either handle the circuit provided or if i need more than one circuit 20amps


tyvm !

 

 

You'll likely need more than a single 20A circuit no matter what if you're running any serious amount of wattage. A 20A circuit can handle about 2,400 watts of current draw (20A x 120V), so check the back of the power amps and make sure that you're not pulling more than that with just the PA amps.

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Excellent and helpful info - i really appreciate it guys !!!!

 

Its an outside fair - 4 bands - my buds sound setup so I dont know the details but I get 500 clams for helpin for the day :)

 

If i get any info I'll post it

 

TYVM

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put my amprobe on the hot line to the dedicated breaker and it was drawing 1.1amps dimed 100w marshall while mashing a few chords - should give me a general idea of what ill be dealing with amp wise

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