Watts explained (amplifier power)
Watts (W) measure power output. But watts don't translate 1:1 to loudness - doubling watts adds only 3 dB (barely audibly louder). 100W amp isn't twice as loud as a 50W amp with the same speakers - it just has more headroom before clipping.
Watts measure electrical power output of an amplifier. But how watts translate to real-world loudness surprises most first-time buyers.
The 3 dB rule
Doubling amplifier power = 3 dB increase in speaker output. 3 dB is a JUST perceptibly louder difference. To sound “twice as loud” (10 dB SPL increase) you need 10x more power – 100W amp vs 10W amp.
What watts actually give you
- Headroom for dynamic peaks – orchestral crescendos, drum hits can peak 20 dB above average
- Ability to drive difficult speakers – low-sensitivity or low-impedance loads
- Cleanliness at loud volume – not running the amp near clipping
How much do you need?
90 dB sensitivity speakers, 12×12 room, moderate listening: 20W is plenty. Same room, dynamic music at concert levels: 50-100W. Large room + low-sensitivity speakers + loud listening: 150W+. See Speaker Sensitivity.
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