Bummer, I 'saw' what I expected to see, 2 ft^3.Tuned to ~42 Hz, 8 ft^3 is close enough to a 42 Hz F3 and VC heating will flatten it out.
GM
That's what I thought.
You'll pardon my lack of ISD Pro (I'm running on a Macintosh ATM), but for a 40hz F3, what will excursion limit my output to? This is perhaps not the most ideal driver for a subwoofer, but it is quite cheap
That's what I thought.
You'll pardon my lack of ISD Pro (I'm running on a Macintosh ATM), but for a 40hz F3, what will excursion limit my output to? This is perhaps not the most ideal driver for a subwoofer, but it is quite cheap
Just as an aside Unibox is a nice program (free) that runs on excel. It's what I use on my Mac. It will model excursion.
Joe
One thing that won't work is that small port. The port will go into power compression long before 123dB is reached at 40Hz, My "educated" guess is 112dB will be about as loud as the port will go at 40Hz.
How about a sealed box of 8 cubic feet and this woofer?
Parts-Express.com:Eminence Sigma Pro-18A-2 18" Cast Frame Driver | sigma pro-18a subwoofer 18" subwoofer pa subwoofer 18" driver
This will produce about 121dB at 40Hz in reality and 200 watts of drive~ 40 volts.
Small ports still don't work! A port absolutely needs to have a minimum size of 1/3 the area of the driver so for a typical 18 that means AT LEAST a 9 inch round port. Half size is much better which is just over an 11 inch round hole.
Please do not make the port to small.
How about a sealed box of 8 cubic feet and this woofer?
Parts-Express.com:Eminence Sigma Pro-18A-2 18" Cast Frame Driver | sigma pro-18a subwoofer 18" subwoofer pa subwoofer 18" driver
This will produce about 121dB at 40Hz in reality and 200 watts of drive~ 40 volts.
Small ports still don't work! A port absolutely needs to have a minimum size of 1/3 the area of the driver so for a typical 18 that means AT LEAST a 9 inch round port. Half size is much better which is just over an 11 inch round hole.
Please do not make the port to small.
A 2' cube is about 6 cu ft net (allowing for an 8" dia x 7" long port, about 2.5L frame displacement, and 200 linear inches of 3" x .75" bracing).
40hz Fb
8" dia x 6.67" long (minimum suggested port for the Fb and driver x-max is 7.09" dia)
Fx=40hz
Qx=1.93 (5.7dB boost)
Will hit about 126dB at worst case x-max (around 63hz) with 500W input, and be -3dB at 40hz (with filter/EQ). 122dB thermally limited output (500W) at 40hz.
As long as you don't run sine sweeps, I think you could run 1KW on program into this box and tuning.
Note: most pro amps have about 3dB of headroom, so an amplifier rated at 1KW/4R would be about right for a pair of these drivers (make sure it has some sort of peak-clip limiting).
BassBox v6.0 used for above figures.
40hz Fb
8" dia x 6.67" long (minimum suggested port for the Fb and driver x-max is 7.09" dia)
Fx=40hz
Qx=1.93 (5.7dB boost)
Will hit about 126dB at worst case x-max (around 63hz) with 500W input, and be -3dB at 40hz (with filter/EQ). 122dB thermally limited output (500W) at 40hz.
As long as you don't run sine sweeps, I think you could run 1KW on program into this box and tuning.
Note: most pro amps have about 3dB of headroom, so an amplifier rated at 1KW/4R would be about right for a pair of these drivers (make sure it has some sort of peak-clip limiting).
BassBox v6.0 used for above figures.
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