# Homebrew Amp Question

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Could someone please point me in the direction of a website/page that explains how to determine the output of an amplifier (or if you are willing to explain it here, that's fine too)? I know this is basic stuff to the EE's on board, but I am trying to learn as I go, mainly by reading and putting stuff together.

In other words, if I follow a schematic to build a 10 watt amp, how do I know it's actually 10 watts?

www.ax84.com

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Measure the output voltage of the amp while it's plugged into a correct speaker load.

Take the number you get, and square it.

Divide by 4.

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Measure the output voltage of the amp while it's plugged into a correct speaker load.

Take the number you get, and square it.

Divide by 4.

Well, pretty close - P=E^2/R, so square the AC voltage across the load and divide by the load resistance, 4 if it's 4 ohms, 8 if it's 8, etc. For a realistic figure, use a 1KHz sine wave input and measure the output just below the onset of clipping, using the rms AC voltage. Any legitimate wattage rating will include both the load impedance and the distortion level at the rated wattage.

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