Originally Posted by TroysG
speakers themselves aren't loud. It's the signal that goes into them
Try listening to a wire. If you put a few gigawatts in there you might hear something.
The efficiency of a transducer is critical. Sound Pressure Level in dB measured from a reference point is what you measure sound with.
How sound you get per watt is very important indeed, and it varies.
Originally Posted by jcrobso
There is sensitivity rating for speakers
The way the units scale is not well known, and it highlights how important efficiency is.
To get twice the volume, you need 6dB more sound. Every 6dB it's twice as loud.
So a speaker with 84dB/[email protected]
will be half as loud as one that does 90dB/[email protected]
run off the same amplifier.
The usual efficiency of a speaker is between 80 and 90dB/[email protected]
Some of beyma's speakers are pushing the 100dB mark, which is unusual.
What's less well known is that to double the volume of a sound system, you need to multiply the amplifier volume by around 10. Watts are not a logarithmic scale.
So 1W is surprisingly loud, and 1000W is surprisingly quiet. For a home hifi of 50W, most of the time people are using under a watt, and that can still clip on loud peaks.
Improving speaker efficiency is a much easier way to get volume than throwing more amplifier watts at the matter. The difference between 500W and 1000W is minimal. There is also the issue of headroom. Lots of amps behave well in overload, so they'll carry on pushing well over the specified linear limit. It all depends on the design. It's best to run amplifiers well within their limits.
a 100dB speaker is 8 times as loud (18dB=3x6dB) as one that is 82dB efficient. To do the same on the amplifier end, you'd need to upgrade your 100W amplifier to 100,000W.
This is why PA manufacturers spend a lot of effort on getting the efficiency. It's the true access to volume, especially outdoors where the walls don't help to increase SPL. If you have to lug a 10 times as many generators onsite and burn 10 times as much diesel, you are not making friends, and the PA system has to be packing a punch. Usually the systems used outdoors rate in the high 90s *and* take 5kW per little cabinet.
Originally Posted by The Stimulation
Eh, sensitivity is a bunch of hobglobin crap. I've seen some rated lower than others and they outperform output wise.
Manufacturers quoting bullshit figures is one thing, a scientific measure of efficiency quoted with a specified tolerance of error is another. In the pro audio world, efficiency is not something people fudge.