which route? WinISD or DD 16in^2 port to 1ft^3 box??
94tegRS
12-10-2004, 08:27 PM
I always used winisd to design my boxes and have always been happy, but I recently read on digital designs site that
(copied from site)"Most modeling programs that simulate box responses were written for home audio use. They are not suited for high output systems. The port area defaults are inadequate. The port area must be commensurate with cone area. If the port velocity gets too high, the port no longer functions as a port, you end up with a leaky sealed box, double bad.
Lets say we have a 12 inch speaker in a box, roughly 100 sqin of surface area. Many programs and manufacturer sites will suggest a 4" diameter port for a 12" vented box. A 4" diameter port has about 12 sqin of area. This is about an 8-1 ratio of cone area to port area. If the 12 inch cone moves 0.25", the port must move 2.0". It can handle this, but when the cone is moving 1.0", the port must move 8 inches! Now you've got a leaky sealed box.
You need more port area for a clean sounding, high output system. The DD port formula is this: 16 sqin of port area per cubic foot of box volume. The port should be 13 inches long. Remember, the port is tuned to the box volume, not the sub(s)."
so which route should I go, Im looking into building a 2-2.5 ft^3 ported box for my lum12, only gonna be powered by a small 200 watt amp cuz thats all I got and im putting it in the car Im selling to just get rid of them cuz they are justr sitting here taking up space.
(copied from site)"Most modeling programs that simulate box responses were written for home audio use. They are not suited for high output systems. The port area defaults are inadequate. The port area must be commensurate with cone area. If the port velocity gets too high, the port no longer functions as a port, you end up with a leaky sealed box, double bad.
Lets say we have a 12 inch speaker in a box, roughly 100 sqin of surface area. Many programs and manufacturer sites will suggest a 4" diameter port for a 12" vented box. A 4" diameter port has about 12 sqin of area. This is about an 8-1 ratio of cone area to port area. If the 12 inch cone moves 0.25", the port must move 2.0". It can handle this, but when the cone is moving 1.0", the port must move 8 inches! Now you've got a leaky sealed box.
You need more port area for a clean sounding, high output system. The DD port formula is this: 16 sqin of port area per cubic foot of box volume. The port should be 13 inches long. Remember, the port is tuned to the box volume, not the sub(s)."
so which route should I go, Im looking into building a 2-2.5 ft^3 ported box for my lum12, only gonna be powered by a small 200 watt amp cuz thats all I got and im putting it in the car Im selling to just get rid of them cuz they are justr sitting here taking up space.
GSteg
12-13-2004, 05:58 PM
go with what DD recommends.
WinISD has its faults and should never be used as the only tool for building boxes. They are theoretical-based. The magnitude versus frequency graph you see only accounts for an anehoic response. What you get in WinISD will NOT be your product.
WinISD has its faults and should never be used as the only tool for building boxes. They are theoretical-based. The magnitude versus frequency graph you see only accounts for an anehoic response. What you get in WinISD will NOT be your product.
94tegRS
12-13-2004, 06:40 PM
even if its not for a DD sub though? forgot to mention that part
GSteg
12-13-2004, 06:58 PM
even if its not for DD subs.
think of WinISD as an online 1/4th mile calculator where u just push in the weight and the hp and get the time. If the 1/4th calc. say you will run 6 seconds on the drag strip with a honda civic and some NAAWWSS, does it mean you'll get that time? Factors such as traction will come. In audio world, the car itself will factor it. What you see as a smooth response in WinISD will actually not be as smooth when it's in a car. :)
think of WinISD as an online 1/4th mile calculator where u just push in the weight and the hp and get the time. If the 1/4th calc. say you will run 6 seconds on the drag strip with a honda civic and some NAAWWSS, does it mean you'll get that time? Factors such as traction will come. In audio world, the car itself will factor it. What you see as a smooth response in WinISD will actually not be as smooth when it's in a car. :)
94tegRS
12-13-2004, 10:29 PM
so winisd is really just for home setups?
GSteg
12-13-2004, 10:37 PM
it'd probably be more realistic in home than in car.
but you're still going to get some gain inside a room. not to mention, WinISD does not now the limits of anything. WinISD is under the assumption that everything stays linear
but you're still going to get some gain inside a room. not to mention, WinISD does not now the limits of anything. WinISD is under the assumption that everything stays linear
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