i have no tech knowledge at all so here is my question. i would like to know how to tell the wattage being put out by my integrated amp. i just got a r-tech integrated amp. that is made by rotel for the asian market. all it says on the back is 400 watt consumption max. there is no manual but i think it is 60 to 100 x 2 but with my new m3's, i don't want to find out the hard way. the amp and the speakers together are more than i can describe.
all i do is smile and knock the pictures off the neighbor's wall. i've had kef and paradine and nackamechi but these are the best. i dont't have a problem buying a meter but i don't know what kind or how to use it. please help me to keep my m3's in good shape for a long time. charles------------------------------------
Hello Charles,
I'm delighted you're pleased with the sound quality of your
Axiom M3s driven by the R-tech integrated amplifier.
It's actually quite complicated to do an accurate measurement of the output power of your amplifier in watts at just before the point of "clipping." Clipping is the point at which the power supply of the amplifier is exhausted and the output section starts to go into gross distortion, which flattens or "clips" the audio signal's waveform. You have to monitor the amplifier output on an oscilloscope while it drives a big fixed-load 8-ohm power resistor.
However--and this is a very rough speculation--since class A/B transistor amplifiers are typically about 50 to 60% efficient, you can assume that since your integrated amplifier is drawing 400 watts from the wall socket, its output power into an 8-ohm load would be somewhere between 100 and 150 watts per channel. Your
M3s would handle that kind of power on a momentary peak basis with music signals without damage.
If you really wanted to do a rough measurement--and I do NOT recommend you try this yourself--you'd have to get an AC voltmeter and measure the amplifier's output voltage across the amplifier's output terminals of one channel while you were powering your
M3 using a source CD with a single-frequency test signal or pink-noise signal. Trying to use music signals as a "test"
signal would be impossible as the voltmeter's readings would be jumping all over the place, given the constantly varying nature of music.
Once you measured the voltage at a fairly loud level, you could then use Ohm's Law to convert the voltage measured and the impedance (the
M3 is nominally an 8-ohm speaker) to determine the amplifier's power output in watts. The formula is Power (watts) = Voltage (squared) divided by the Impedance. So if your AC voltmeter measured 25 volts across the amplifier's positive and negative terminals while driving the
M3 (and we know the
M3 is nominally 8 ohms), then the power in watts into 8 ohms would be 25 X 25 = 625 divided by 8 ohms, which equals 78 watts.
Don't try this yourself, as it's very easy to damage your speaker using steady-state single-frequency signals or pink noise at extremely high levels. That is why bench tests of amplifiers use a large, fixed 8-ohm resistor to absorb the maximum power of the amplifier under test without risking damaging speakers.
Kind regards,
Alan
