Originally Posted by
nevershouldhavesoldit;[URL="tel:1326965"
1326965[/URL]]The rated output is irrelevant. That’s the maximum output at its rated distortion (which, interestingly enough, is never provided for guitar amps but is a routine spec for audio amps). The input signal level determines the instantaneous output power. Class A and A/B amps with seriously overbuilt power supplies have even more headroom (but at higher distortion levels) above rated output. Most class D amps don’t have this luxury.
Most jazz players never push an amp beyond a few Watts, even on gigs. Speaker sensitivity (which is thankfully a routine spec in our world as well as the audiophile’s) tells the story. Many 12s generate 100 dB from a one Watt input, measuring SPL at one meter in front of them. SPL drops off about 6 dB for every doubling of the distance to a point source. Since speakers are somewhat directional, it’s a bit less depending on the radiation pattern of the speaker in question.
So 100 dB at 3 feet is about 95 at 6’, 90 at 12’, 85 at 24’ etc. The actual level may even be 2 or 3 dB higher, depending on the environment (reflecting, diffracting, and absorbing surfaces etc) and the speaker’s directivity. 85 dB is loud.
Normal conversation in our living rooms is about 60 dB and a home vacuum cleaner puts out about 70 dB at 10 feet. “Bedroom volume” is somewhere between them. So at home playing levels, even a “100 Watt” amp is putting well under a Watt into any speaker, including the least efficient ones (which make 85 dB or even a little less at a meter from a 1 Watt input).
The power level needed to sustain an unmic’ed 90 dB in the far reaches of a venue is another matter entirely. Sound energy is absorbed, reflected back at the source, and otherwise dissipated by everything and everyone in a room. Power level needed to achieve a given SPL also goes up exponentially with distance from the source. And a doubling of output in Watts means no more than a 3 dB increase in SPL at the same listening location. So getting 85 dB at the back of a crowded bar 50’ in greatest dimension could require 200 Watts from a guitar amp without sound reinforcement.
So you can safely and effectively use any amp for home playing. The output level will be the same regardless of its maximum potential.
Wright SoloEtte Travel Guitar
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