RMS Power VS Peak Power

RMS Power

RMS (root mean square) power is the continuous power of equipment operated under AC (alternative current), an amplifier, a speaker, etc. The power output from an amplifier consumed by a speaker varies over the highs and downs of the music signal, and it is hard to measure the power of the amplifier and the speaker. RMS power applies in this situation.

How is RMS Power measured?

CTA (Consumer Technology Association) rates the RMS power of a power amplifier as below:

Drive the amplifier into a 4ohm load over the entire bandwidth while producing no greater than 1.0% THD+N.

Note: The THD+N shouldn't be higher than 1.0%.

Input source: 1k Hz sine wave signal for the full range amplifier;

50 Hz sine wave signal for the bass amplifier, usually the mono amplifier.

Monoblock amplifiers are often connected to a 1ohm load to get higher output for subwoofers, so it is common practice to rate the RMS power of a one-channel amplifier at 1ohm.

Peak Power

RMS x 4 = Peak Power

The peak power, often known as PMPO (peak music power output), can be reached when the system plays a big bass or a thunderous note. It's an instant power that a speaker can handle without damage.

Inferior manufacturers' amplifier may have 5% THD+N when it reaches the stated RMS power, or they may advertise Peak Power to mislead the Public.

Matching a System

Get amplifiers and speakers with true RMS power, or you'll do math with fake data.

Don't use peak power as a reference when configuring a system because it doesn't stand the equipment capability under everyday use. Select an amplifier with 1.5-2 times to the speaker's RMS power, so it can get the most out of the speaker without crooking it.