A bunch – 3 dB represents a modest change in sound level, yet a 3 dB increase requires the amplifier to generate twice the power.
So every time you turn it up “a little”, you are doubling the power to the loudspeaker. No wonder so many loudspeakers succumb to the last song of the evening.
5) How much of an amplifier’s rated power will the amplifier likely have to generate in a music playback system?
Not much. Given a typical crest factor of 20 dB for live music, the amplifier’s output power could, on average, be about one watt per 100 watts of rated power.
That kilowatt monster that you bought with the home improvement loan will likely need to generate about 10 watts continuous. If you break out the compressor/limiter, you may get this up to 100 watts, but that’s about it.
6) So why buy a big amplifier? After all, they’re expensive!
Loudness and generated power are all about area. Clarity is all about headroom. If program peaks get clipped by a small amplifier, it sounds like trash.
Amplifiers must be oversized relative to their average output power by a factor of 10 to 100 to allow for signal peaks. This translates into 10 to 20 dB of headroom. If you have deep pockets and an understanding wife, go for 20 dB.
If not, spend some of the money saved on a hard limiter to make the program peaks “fit” though the amplifier. All of this makes sense only if you look at power using the decibel.
7) Which subwoofer is better? One that handles 100 watts or 500 watts?
You simply can’t tell from the power rating alone. It’s just a “waste disposal” number. How much sound can each produce? This is the efficiency rating.
A 15-inch bass horn sitting in a corner and consuming 100 watts continuous could easily be much louder than an 18-inch in a sealed box hanging in free space and consuming 500 watts continuous.
It’s not what’s fed in, it’s what comes out. See the stock market question (Question 2, above) for an object lesson on this.
8) Can a 30-pound amplifier really keep up with a 300-pound amplifier? My chiropractor wants to know.
Maybe. It depends on what it’s asked to do. Power (like hot water) can be generated “on demand” or it can be pulled from storage.
This is why “Anywhere Gas and Electric Company” dams up rivers to create huge reservoirs for turning hydraulic turbines.
The water flow can remain constant even through the dry season so that the lights don’t dim when the creek gets dry.
Amplifiers with large, heavy power supplies can typically maintain a more constant current flow under severe conditions – like reproducing low frequency synth tones through subwoofers that can peel paint (see question 1) at 100 feet.
Percussive sounds at mid/high frequencies aren’t nearly as “meaty”. You can save your back and your wallet with smaller, lighter amplifiers.
9) Can the loudspeaker’s power rating be trusted? The “Killbox 5000” is rated at 5 kW and the “Lighttones 100” is only rated at 100 watts.