Axiom Home Page Forums General Discussion Advice from Axiom Owners Which is easier to drive?

http://www.garnersclassics.com/wavs/gigawa.wav

93, welcome. One thing to note is that your Polks aren't any more "power hungry" than any other speakers of similar sensitivity. Also note that the numbers that you give for the Polks are sensitivities measured anechoically while the Axiom numbers that you quote are in-room. Typically, room reflections can add 3dB to the overall sound level at a certain "critical distance" and you should add 3dB to the Polk numbers to use a comparable standard. Doing that indicates that there's no appreciable difference in the sensitivities.

In any case, as Randy pointed out, this isn't something that requires great ooncern; clean power is plentiful and cheap these days. Those sensitivity figures that you quoted are of course using 1 watt, which is the standard. It's unlikely that most would be listening at at even the 90dB average level, which is quite loud indeed. Depending on the dynamic range of the program material(e.g. many classical compositions have a wider dynamic range than most pop recordings), brief peaks will hit about 20dB higher than the 1 watt reference level of around 90dB and would need about 100 watts for that instant. Even low cost units are widely available which have no problem with this.

Are we not taking into account that most don't listen to our systems at one meter? For every doubling of distance from the speakers do we not loose 6 db of output?

No, Rick, the 6dB decrease with doubling of distance would only apply in an anechoic environment and then only to an omnidirectional source where the sound would spread in a spherical manner. Since the surface area of a sphere is proportional to the square of its radius(4piR(squared))doubling the radius increases the area by a factor of four, which implies a decrease in sound level of 6dB at the surface of the expanding sphere. More directional sounds lose less direct level with distance. But the major factor that leads to far less than a 6dB actual loss of sound level with doubling of distance is the reflected ambient sound field in actual listening rooms(rather than an anechoic chamber)which becomes equal to the direct sound at the "critical distance"(about 3-4' in typical rooms)and makes the loss relatively small at the distances typically involved in the home.

An illustration of this can be found in fig. 10.4.1 in this discussion . Also see Linkwitz's explanation on his site; especially scroll down to reverberation distance and amplifier power calculation sections. The bottom line on all this is that a lot less power is required than the 6dB with doubling figure would imply.

I was going by this spl calculator which was showing the 6 Db decrease I had mentioned.

Here is another article writen by Alan that says there is a 6 db loss when doubling the distance from the loudspeaker.

Amazing how men can argue forever about things that are so easy to measure

Ok, pink noise on one M60, RS on slow, C-scale

1m 82db
2m 78db
4m 75 db

Result - in a 'typical' room (basement, 18x28x9, carpeted floor, drywall) the sound attenuated at about 3-4db with doubling of the distance at 'typical' listening distances.

Somewhat slower than the open space rule of 6db. This is the room effect that John was talking about.

I measured my own room and found similar results. Here is another site that states the same.

I’m with Rick. Starting to get tired of all this “one meter” referenced BS.

When listening to stereo music, I rarely have mine UNDER 90 db and I sure in the hell don’t sit three feet away from the speakers. I’m usually wandering around with a nail gun or tape measure.

To be real blunt, I don’t understand you folks that like to listen to music any quieter. Hell, it take 80 db before one can even hear all the instruments.

Movies on the other hand I listen to at much lower volumes.

I have better than average hearing for a human being too. Good enough to get weird looks from the doc every year when I get a physical.

Gee, I'm sorry I offended you by listening to my music on my system at less than ear bleeding levels. <rollseyes>