Example, a mono block that pushes 1000 watts rms needs a 4 gauge power cable, but the speaker cable that actually transfers power to the woofer is much smaller.
In: Engineering
The power feeding the amp is usually DC and low voltage.
The power feeding the speakers is AC and high(er) voltage, so it requires a lot less current.
1. the power may be transferred at a higher voltage, therefore reducing current losses (I^2 * R).
2. the amplifier will burn some power. different amplifier have different efficiencies. it might take 1kW to push out 150W at the other end if it was only 15% efficient.
Is this in a car? The gauge wire is determined by the number of amps of current. Cars use 12V electrical systems so P=I*V means the current in the power cable is 1000/12=83 amps which is a lot of current and requires a very thick wire to avoid getting super hot. For the speaker wire, use P=I^(2)*R, assuming 4ohm speakers, the current is √(1000/4) = 16 amps which is still a lot of current but a lot less than 83, so it can use a less thick wire. Also, that puts the voltage in the speaker wire at 63V, so that’s another way to look at why it can be thinner – it’s using higher voltage to carry less amps.
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