N
NicolasKL
Full Audioholic
Is it just me or is this some of the most moronic marketing copy you've ever read:
Now the LS9 sensitivity is about 91db and the sensitivity of this sub is barely over 85. So we'll need to use two of them with double the power to get the same output levels, but lets set this aside too. Let's look at them as one speaker (one LS9) compared to one 12" sub. If we lay a 200 watt input on the 12" sub we only need about 50 watts of input on the LS6 to equal its output. But there are twelve woofers in the LS9 sharing the load so each woofer in the LS9 will only see 4.16 watts of power. Read that part again. Each woofer only sees 4.16 watts each. Now we send each of them a 25Hz note to play. The 12" sub with the 200 watt signal laid on it is playing very hard. It had to move way out there. It also has a lot of moving mass. The moving mass is 183.5 grams. That much mass put into motion has a lot of stored energy in the form of inertia. Suffice to say it takes it a while to stop.
Let's say that signal we sent was really a deep bass drum track. So we hear the initial strike of the drum but the decay of the drum is covered over by the much longer decay of the woofer. It goes boom, boom, hits real hard, but really sounds nothing like a real drum. The decay of the woofer totally smears the decay of the recorded drum. The LS9 on the other hand hit the same output level with each woofer only having to move a fraction the distance (less inertia) and the moving mass of each woofer is only 18.9 grams. By comparison the moving mass of the 12" woofer is nearly 10 times as much. So with the LS9 we hear the strike of the drum but now we hear the real decay of the drum and NOT the decay of the woofer. The LS9 plays it and stops immediately compared to the 12" woofer. It is not even close. It also takes more than three of the 12" woofers to equal the surface area of the twelve 6.5" woofers. Each of the LS woofers has a surface area of 137 sq cm. The 12" woofer has a surface area of 467.7 sq cm. Twelve of the LS woofers has a surface area of 1644 sq cm. So each of the twelve LS woofers has to move a much shorter distance to move the same amount of air. Big strokes (long excursions) also cause a lot more flexing of the cone (due to the air pressure loading on it), motor non-linearities, and much higher distortions. So the smaller woofers in the LS not only don't have to move as far, but have MUCH less mass, and on top of all of that will actually play lower than the 12" sub.
Now what would it take to match the speed and resolution of the LS9 in the low bass region using 12" sub woofers? First let's divide the input across 12 woofers (twelve 12" woofers) so that each woofer sees less power, has less distance to travel, and has less stored energy. 12 subs makes it even now right? We divide the load into 12 woofers on each speaker just like the LS9. Not really. Each of the 12 subs still has nearly 10 times the mass to move. The subs still have a lot more stored energy and inertia by comparison even though we reduced the amount of air (and travel distance) that each woofer had to move. I guess since we have nearly ten times the moving mass we can use ten times as many so that they only have to move 1/10th of the distance (this is a generalization). That will reduce the inertia to a level that it would be comparable to the LS9. Now we are close. Let's see now 12 subs per side times 10. That's 120 subs per side or 240 subs total. That might get you comparable sound quality.