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how much electricity is going thru speaker wires when music is playing?


Batmans Robin

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ok, so how much at high volume?

jsp

Assuming 'high volume' means 10 Watts RMS into an 8 Ohm speaker, the voltage would be approx. 8.94 V RMS and the current would be 1.12 Amperes or 1,112 mA.

100 Watts RMS into an 8 Ohm speaker would require 28.3 Volts. The current would be about 3.54 Amperes.

Power in Watts is equal to voltage in Volts multiplied by current in Amperes.

Fun with math...

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Thanks for the explanation; if one is really pushing the system with high volume (I would consider running my speakers at that power level extremely high since they are very efficient) then you would only be pushing less than 4 amps. If that is the case, then what is the needed wire gauge for stranded copper speaker wire? I run my power tools; many draw 15 amps on 12 ga. copper in my shop with no problem. Of course that is AC not DC - perhaps that is a factor in this calculation?

I guess what I'm getting at is what size speaker wire is really needed to carry the load to the speakers? I am using16 ga copper at the present time and it seems just fine. I see folks selling big monster type cables for big bucks all the time and question the necessity of such large cables and the often over hyped advertising BS. What is your opinion?


JSP
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It depends on the impedance of the speaker and the amount of voltage applied. Take for instance a pro amp driving a fairly inefficient subwoofer, that has a final load impedance of 4 ohms at 30 hz. The sub may have a spike in impedance up to 50 ohms above that, but at the impedance minimum, there can be a lot of amperage flowing through the coil.

3kw applied to a 4 ohm load would result in 109 volts applied, and over 27 amperes of current.

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Thanks for the explanation; if one is really pushing the system with high volume (I would consider running my speakers at that power level extremely high since they are very efficient) then you would only be pushing less than 4 amps. If that is the case, then what is the needed wire gauge for stranded copper speaker wire? I run my power tools; many draw 15 amps on 12 ga. copper in my shop with no problem. Of course that is AC not DC - perhaps that is a factor in this calculation?

I guess what I'm getting at is what size speaker wire is really needed to carry the load to the speakers? I am using16 ga copper at the present time and it seems just fine. I see folks selling big monster type cables for big bucks all the time and question the necessity of such large cables and the often over hyped advertising BS. What is your opinion?


JSP

There should be no DC on your speaker wires, it's all AC. DC carries no information and only heats up your voice coils. RMS voltage and current by definition is equivalent to DC in this context. Power line voltage is near sine wave, while music has a much lower average power content than a sine wave, in many cases less than 10%.

From an engineering standpoint best practice is to use a wire gauge that will accommodate the highest anticipated average current without appreciable heat loss or negative effects on amplifier damping.

IMO considering the average music power levels and distances found in a home environment, 12 to 16 ga copper speaker wire is adequate in most cases. The connections at the amplifier and speaker are the weakest links in the chain and should be checked on a regular basis.

John

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