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IamDeMan
09-21-2005, 07:59 PM
I am not sure how to determine what the sq in of the port face should be in a given enclosre. So here goes. The drivers are 18W3D4s friend has had them for awhile in his closet and wants to make a rather large low tuned home sub with them. their XMAX is like 13 and their SD is 186 sq in. Is there a way to determine what size it needs to be (Sq In) to avoid chuffing or any other port noise?

In the old WinISD I notice it has something it calls Vent Mach when creating a Ported enclosure with it. Is there a magic number of Mach to shoot for? or is this even related to my question in any fashiopn?

SSS 18734
09-21-2005, 08:15 PM
I am not sure how to determine what the sq in of the port face should be in a given enclosre. So here goes. The drivers are 18W3D4s friend has had them for awhile in his closet and wants to make a rather large low tuned home sub with them. their XMAX is like 13 and their SD is 186 sq in. Is there a way to determine what size it needs to be (Sq In) to avoid chuffing or any other port noise?

In the old WinISD I notice it has something it calls Vent Mach when creating a Ported enclosure with it. Is there a magic number of Mach to shoot for? or is this even related to my question in any fashion?

go to rear port velocity and remember to specify the max power you will be feeding your sub. aim to get most of the frequency response around below 17 m/s. That should guaruntee no port noise. If you have it above that point and at a very low or high frequency (20hz or 80hz for example), don't worry about it either.

Randy Savage
09-21-2005, 08:24 PM
In general, I like to stick to 12-15 sq. in. of port per ft^3 of enclosure.

IamDeMan
09-21-2005, 08:35 PM
In general, I like to stick to 12-15 sq. in. of port per ft^3 of enclosure.
Holy jeeebus. This enclosure is going to be huge. that port would be some thing else. 240-300 Sqin seems much.

IamDeMan
09-21-2005, 08:36 PM
go to rear port velocity and remember to specify the max power you will be feeding your sub. aim to get most of the frequency response around below 17 m/s. That should guaruntee no port noise. If you have it above that point and at a very low or high frequency (20hz or 80hz for example), don't worry about it either.
I don't see that anywhere in WinISD.

SSS 18734
09-21-2005, 08:48 PM
http://img398.imageshack.us/img398/6029/untitled1copy4vl.jpg (http://imageshack.us)

IamDeMan
09-21-2005, 08:50 PM
Ahaha excellent. Thanks mang. I'm still learning this thing.

DBfan187
09-21-2005, 08:58 PM
12cF w/ 100" of port tuned to 25Hz

IamDeMan
09-21-2005, 09:26 PM
12cF w/ 100" of port tuned to 25Hz
for 2x 18W3S? He was looking at over 20CF tuned to 20 hz or lower for an HT

IamDeMan
09-22-2005, 02:37 PM
PART 2

How accurate is WinISD at calculating the power handling? The box we are thinking of building shows 500 watts pushing the W3s to their XMAX at around 25hz in WinSID. However the rating of the subs is 500 ea. for 1000 total. Should he just get a 500 watt plate or use a 1000 watt plate? I know that power handling is greatly dependent on enclosure, but don't know how well WinISD calculates that.

tRiGgEr
09-22-2005, 03:25 PM
Minimum area - 86 square inches for a 20hz tunning. I would choose to use 137 square inches. Regardless of tunning.

IamDeMan
09-22-2005, 04:05 PM
Minimum area - 86 square inches for a 20hz tunning. I would choose to use 137 square inches. Regardless of tunning.
Ya, were going to keep the area up relatively high to insure no noise. Thanks for the input.