Originally Posted by mjg100
I agree with your post as long as we are talking about similar drivers. If not then there are many smaller drivers that can outperform larger drivers. Here is a 6.5" mid-bass driver that will outperform a lot of 8" drivers. It will hang with most any 8" driver in it's price range when it comes to SPL and sound quality. http://www.diycable.com/main/product...roducts_id=538
It is now $69. The introductory special was $49.
Remember that with bass frequencies, for a 6.5" driver to perform up to an 8" driver, it must move equal amounts
of air with it's cone. What is the only way to do that? Design a motor and surround for deeper xmax so it can have a longer 'throw'. What happens as a result? You need more amplifier power to move that bigger motor in and out enough times to duplicate the output of that 8-inch driver. That's a lot of extra engineering just to make up for a slightly different cone size and it's STILL less efficient than the 8-inch woofer at 80Hz and needs real good engineering to keep have the same distortion performance as a lesser 8-inch.
So, when comparing even close to similarly designed 6.5's and 8's, the 8's always win.
Oh, and here is the funniest FAIL of that link you posted:So what is the catch? What did we trade to achieve all of these attributes? The answer is nothing...
Fs = 45.8HZ
Qes = 0.48
Qms = 6.37
Qts = 0.44
Vas = 9.61L
Sd = 131cm^2
Xmax = 12.5 mm one-way
Re = 6.4 Ohms
Le = 0.84 mH
BL = 10.79 N/A
Power: 125W Approx: No IEC testing conductedSpl = 84.7 dB/1W/1M
Here is a pro 18" subwoofer:
Nominal Diameter: 380 mm (15 in)
Rated Impedance: 4 ohms (G)
8 ohms (H)
16 ohms (J)
Power Capacity1: 600 W AES continuous pink noiseSensitivity: 97 dB SPL, 1 W, 1 m
Frequency Range3: 30 Hz 2.5 kHz
at - 10 dB power (60 W): 0.7 dB
at - 3 dB power (300 W): 2.5 dB
at rated power (600 W): 4.6 dB
I don't think professionals will be using 6.5's anytime soon, no matter how well engineered they are. Just to let you know how big of a slam the difference is between these drivers? The pro driver will produce SPL with 1-WATT which that 6.5-inch driver will need 25-watts to produce. After that, things get REAL ugly for the 6.5 as the pro driver is rated for 600-watts with much more favorable power compression specs (less loss of volume at higher wattages). The 6.5 isn't just beaten, you could add two more of these 6.5's to equal the 18's surface area (still get only 90db sensitivity), but 3 of these 6.5's STILL wouldn't touch that paper cone pro 18-inch driver. So, the multiple driver idea isn't really a solid way to produce results on par with a larger driver. A larger driver is simply 'better' at bass frequencies everytime. There is no substitute for a larger driver, period. You can get 'in the ballpark' with multiple drivers but still not do better.
How many of those 6.5-inch "mini burgers" does it take to equal the bass output of the pro 18" driver? Lets do the math:
84db SPL at 1-watt
add a 2nd driver = 87db at 1-watt (for each driver, 2-watts total)
add a 3rd driver = 90db at 1-watt (for each driver, 3-watts total)
add a 4th driver = 93db at 1-watt (for each driver, 4-watts total)
add a 5th driver = 96db at 1-watt (for each driver, 5-watts total)
So, to equal the sheer bass output of the 18" pro driver, you have to use 5 (that's five) of those 6.5's PLUS 5 (that's five) amplifiers of equal power. And according to that power rating on those 6.5's, you STILL won't equal the maximum possible SPL of that single 18" pro driver. Five of those 6.5's would keep up for about the first 80-watts then start to poop out from power compression and thermal issues while the 18" would still be pumping out massive waves of thunder into the hundreds of watts. Again further proof that size DOES matter at high SPL outputs and even adding multple 'smaller' drivers is no real substitute.