New box design HELP!

[soldiermedic 10+ year member]

Ok. planing for a new box design for a 12" sub. I'm using both WinISD and BassBoxPro. I am going to end up with a winding port, but for some reason, I am getting a couple different sets of numbers too far apart to find a safe median for. Which one is more accurate? Here is the sub and desired effects for the box:

Infinity 1262W

Ported box at 22hz (for flat response)

.75" MDF

ISD box volume computes for 3 cu ft (85 liters), and I'm unsure if that's internal or external; BassBoxPro computes for 2.3 cu ft internal.

ISD gives a port length of 59.7", BassBoxPro gives a port length of 90.73"

Any advice would help.

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[supermaxx123 10+ year member]

depends how much port area as far as how long it needs to be. I know it would be pretty **** long if you want 22hz. I've heard bassbox is better, but dont expect a flat response in a car either.

 

[branham1127 10+ year member]

Ok. planing for a new box design for a 12" sub. I'm using both WinISD and BassBoxPro. I am going to end up with a winding port, but for some reason, I am getting a couple different sets of numbers too far apart to find a safe median for. Which one is more accurate? Here is the sub and desired effects for the box: Infinity 1262W

Ported box at 22hz (for flat response)

.75" MDF

ISD box volume computes for 3 cu ft (85 liters), and I'm unsure if that's internal or external; BassBoxPro computes for 2.3 cu ft internal.

ISD gives a port length of 59.7", BassBoxPro gives a port length of 90.73"

Any advice would help.

Well if you are using two different sized enclosures and trying to get the same tuning, the ports will be different lengths. I'm not sure if you were questioning that part or not lol but just throwing it out there.

As for the rest, to make it easier you should just research what other people have done for the size with your specific sub and had good luck with and manually put the box size into winisd rather than letting it find the size for you. Then for that size, pick a proper sized port (12-16 sq inches per cubic foot of box) and manually plug those number in as well and set the tuning in the mid 30s, usually 32-35. 22 is quite low for the tuning..Then winisd will tell you how long the port needs to be to get the desired tuning the size of box that you picked.

 

[soldiermedic 10+ year member]

Thanks for all that, guys. I am only using one freq based on the gain plot in WinISD (22hz in this case), and once I get a general idea, I plot those numbers into BassBox. It's how I did my first box, and it worked pretty well for the wife's Trailblazer. I have the same truck, later model, and I listen to things she doesn't. So the 10" sub went in her car and I had it tuned to 26hz and had a winding port in it, but not nearly as long. Thing is, the numbers were almost in sync with both programs the first time with her box. I just can't get right with both of them this time, so which program should I lean more to?

BTW, Port width is 2.5", outer length was 14.5" based on the box being 16 " in height. I verified that the volumes were the same: 3 cu ft external.

 

[soldiermedic 10+ year member]

By the way, you all are awesome.

 

[RAM_Designs 5,000+ posts]

The http://www.carstereo.com calculator that I use is closer to the winISD length than the BBP6 length, given the two different box volumes. I got 61" long for a 3ft^3 tuned to 22hz with that port opening, and 82" for a 2.3ft^3 box. 22hz is too low in my opinion, but more power to you if you like it. I'd personally go with something like 2.5ft^3 at 30hz.