Amplifier power requirements calculator
Provided by courtesy of Crown Audio, the pro-amplifier manufacturer which belongs to the Harman Group of companies. The said calculator is the 3rd template when you scroll down among the other system design tools for other useful applications. This calculator provides the required power wattage in an amplifier to produce the desired SPL.
There are 4 data points required to be provided:
Listener distance from the loudspeakers – This distance (meters) is measured between each loudspeaker's acoustic center (centerline) and the sweet spot (back of the chair). Generally, I feel the distance should not be more than 1.5 times the distance between each loudspeaker acoustic center and no less the 1.1 times the distance.
Desired level (SPL) at listener distance – I reckon, this should be between 75 to 80dB, 80dB is the recommended level of loudness for the audiophile and 85dB for the home theatre enthusiast.
Loudspeaker sensitivity rating (at 1m/1watt or 2.83V) – Check the loudspeaker specification sheet for this. It should be at 8 ohms nominal, otherwise, convert it using a relevant calculator or check with the manufacturer.
Amplifier headroom – Headroom is an important consideration to keep the amplifier from clipping when it runs out of juice. Not only will it produce distortion in the music, but may overheat the high-frequency loudspeaker voice coils, damaging them including the amplifier parts. Acquiring more headroom means using a higher-power wattage amplifier. Usually, POP/Rock-type music genres will require about 14dB and classical music requires around 20dB. We are not considering room loss which may typically be around 6dB because we are listening in the near field, moreover, two loudspeakers will gain around 1.5dB efficiency.
Once having input all the relevant data, just select ‘calculate’ and the required amplifier power will be revealed in watts per channel. For example, sitting away at 4.5 meters from the loudspeakers, desiring 80dB SPL at the listening seat with a loudspeaker rated at 89dB 1watt/1meter requires a power amplifier of at least 255watts RMS per channel.
https://www.crownaudio.com/en/tools/calculators
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