PMPO

PMPO stands for Peak Momentary Performance Output. It is a dubious measure of the power output of a loudspeaker of more interest to writers of advertising copy than to consumers. The PMPO is calculated by the vendor or tester of the speakers as the maximum power in watts under perfect conditions that are impossible to achieve in practical use. No sound system can sustain its PMPO for more than a few milliseconds without being destroyed.

A much more serious and reliable measure is watts rms. Rms stands for root mean square. The rms power is found by taking several tests, then working out the average of maximum watts under worst conditions and best conditions.

To get an idea of the relationship between PMPO watts and watts rms, consider the following numbers advertised for some current loudspeakers. These models have been selected at random. Inclusion in or exclusion from this list is neither a recommendation nor a criticism.

• Teac PM-100 3D suround-sound speakers: 16W rms, 180 PMPO
• Kinyo "200W" PC speakers: 3W rms, 200W PMPO
• Philips Fun Power Plus MMS-102 PC speakers: 10W rms, 120W PMPO (to be fair to Philips, their data sheet mentions only the rms value; the PMPO value is claimed by retailers)