Wow, I am sorry workin'
I am not sure you really know what is going on at all, I know alot about speakers, sound reproducion, physics and engineering. There are many who know more than me but it is a simple concept that any educated person could explain:
Do you know why you barely ever see 12" or 18" drivers in speaker systems(or if you do see them they are often in cars or on sh!tty home stero systems)? It is for 2 reasons, first of all, the cone itself has to be made out of an extremely light weight material that is very very stiff, if it isnt stiff enough, the cone itself will form it's own sub-vibrations, or standing waves on itself. This happens with ALL drivers, most you cant hear it though. On larger bass drivers it is much easier for this to happen, thus discoloring the sound. The only way to prevent this from happening is to use a very very rigid material to make the cone from (carbon fiber, aluminum, Ti) and these are often very expensive. I, along with many other people dont want to spend that much money. Smaller drivers can sound cleaner for less money and can produce just as much bass. The second reason that speakers like this arent used as often is because it takes a higher quality amp to drive them accurately. I know that you know somthing about speakers, and thus physics. The thing that makes a speaker sound 'Fast' as many people like to say, is the ability to perfeclty reproduce the waves that are present in music. Imagine a 60Hz Sine wave. This is the signal going to the amplifier. Then the amplifier adds power to the voltage signal and sends it to the bass driver. First, lets pretend this is a crappy 10W amp (trust me, I have heard some INCRDIBLE 10 W amps, but lets assume this one has a bad DC converter and small caps) sends the signal to the sub at Max volume, thus the peaks of the sine waves are +/- 10 watts. Now, the woofer has 3 forces acting upon it, first, there is the natural tendency to move back to it's resting posion, there is the resistance of air as it moves (the magnitude of this vector foce is equal to the radius squared times the speed that it is moving. The direction is equal to the direction that the power suplied by the amplifier is trying to move it), the last force on the speaker is the force that the voice coil (this is an electromagnetic foce) puts on the cone of the speaker, moving it in and out. Now, if there isnt enough force made by the voice coil (which is directly related to the power supplied by the amp), the cone of the speaker wont make it all of the way out to where it is supposed to be. The first thing that many people would think is that this just makes the speaker not as loud. It effects the accuracy too. As the cone is moving out, it of course has momentum. This momentum prevents it from moving back in as it is supposed to. If you look at a graph of a simple sine wave compared to the SPL of a speaker that is underpowered, you can see this happening, as a matter of fact you can see this happeneing on ANY speaker, it is a simple limitation of speakers that may never be solved.
Theoreticaly, you are all right, an infinitely lightweight cone, with no air resistance could be powered by a really low powered amp, and perfectly reproduce music. this is not theoretical, there IS air resistance that resist's the movement of the cone, and a bigger cone has more air resistance. There IS momentum, a bigger speaker has more momentum. It takes more power to overcome these and move the speaker as it should be moved. Therefore I am right, more power can make a speaker more accurately reproduce sound, to a point of course.
You are also right in the fact that a larger diameter speaker is more efficent, in how it moves air, when talking about speakers, efficency is usually different, it has to do with how well the speaker does at turning the power from the amp into sound. Some speakers are very wastefull, power is lost to many thing, heat, staning waves on the cone, and just poor design in general.
In real life though, everything is all about balance. Although a 18" woffer has the ABILITY to make more bass, it takes more power. A 6-1/2" uses less power but also is limited by it's size because it can only move a certain amount of air. Coversly, it is easier to make a 6-1/2 accurate than it is to make a 18" accurate because of the power requirements.
It is all simple physics folks.
These are all of the reasons why I am going to go with 4 8" drivers instead of a single 15". I will be able to make do with a 250 watt amp on the 8" drivers and get very clean bass. The 18" would make more bass on the same amp, but I can garuntee that it wouldnt be as clean. They would probably cost about the same ammount too.
To answer Tom's question:
If you were to have 2 sine waves of different frequencies playing on two different speakers, it would sound the same as the two sine waves going into one speaker. As the waves combine, you dont really hear any difference, you just hear both at once. I cant think of a good way to describe this, but it just works out that way. When you hear an orchestra, there are millions of different waves that are hitting your ear drum at once. you single ear drum (imagine it being like a speaker as it moves in and out, except it is foced in and out by waves and then generates electrical pulses, like a speaker in reverse, or like a mic.) I cant think of a good way to explain this, it just works. The speaker re-creates all of these millions of waves layered on top of eachother and your ear hears it just the same.
Well,
I hope that this can straighten you out, If you have questions about this, ask me or someone that knows alot about physics, and they will tell you that I am right.
Paul Hilgeman
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