Phoenix Gold Phorum

anyone know how to test power of an amp (i have an m25) with a DMM for clean power ? dr. fosgate's tests of PG amps got me interested ..

http://www.soundbuggy.com/Eric/Car%20Au ... index.html

his amplifier has a long history, and ended up becoming my "reference" amplifier. It is the best sounding amp I have ever heard, and is also one of the most underrated. Rated for 25W x 2, this amp will do 100W x 2 into 4 ohm loads, with its 20V unclipped output capability.

wondering how the '20v' was measured and therefore converted into 100w rms

The '20v' Dr.Fosgate referred to was measured using a dmm set to read AC voltage on each individual channel of the amp. I would assume he used an oscilloscope to determine the clipping point. For this type of test you run a 0dB sine wave into the amp and make sure the appropriate frequency range isn't affected by any xovers or processing(deck, eq, processors, or amp). The frequency of this input signal is determined by how you intend to use the amp, typically a 1khz tone for full-range duties and a 60hz tone when the amp will power subwoofers.

After you get the ACV reading as described above it is simply a matter of using basic Ohm's law algebra to estimate the power output. P=E^2/R is the formula used in this process.
P being output power, E representing AC voltage, and R for resistance.