I having been using BBP 6 and WinISD to design a ported box for 2 Icon 12D1 and getting 2 different port lenghts. Could someone confirm which one is more accurate? My box will be made with 3/4 mdf 17 1/4 high 48 wide and 14 deep outside measurements. After sub and port displacement BBP 6 calculates this to be 4.043 cubs with a port 12.5 X 3 at 32 1/4 long tuned at 27h. WinISD says same specs with port length at 27.94. This is going in a 95 Mazda B3000 extra cab powered by a Sundown SAE 1200 for daily usage. I am fairly decent at box building but mainly just built sealed boxes. I want to try a properly designed tuned box for this new setup. Am I heading in the right direction, and could someone confirm which port length should be used? I know they are close but want it as close to perfect as possible. Or should I go for a little higher tuning? I know there is alot of knowledge on this site, I have been reading thru alot of it instead of making posts. So any help from the professionals on here will be greatly appreciated.

Why tune so low? Tune in the thirties. go for about 33. Get as close as you can and you'll be happy. Maybe someone else will see this and give you their opinion and you can put them all together and make your own.

I came up with 26.48 with a gross air space of 5.21. I used a different calculator then what you used. I don't know ^^^^^^

Edited April 4, 201015 yr by BIG JAY

You are tuning too low, as for which one is right I can't be sure without doing the same calculation. That is quite the difference though so I assume you have changed something.

In general I don't trust BBP at all but do WinISD; however, both are terrible at recommending enclosures. That you should play with on your own, but WinISD at least easily shows you excursion and the effect of your box.

I figured BBP would be a little closer to correct since it will take the port space out of the box when calculating the port size where WinISD doesn't. Would this not be a major factor when using a slot port? I will probably change the tune to 30h also.

BBP does not do slot port designs very well, last I checked. As said above, only use those tools for a general idea, not actual performance in your car.

WinISD just has you put in the net volume after port and sub displacement. So there won't be any error introduced like in BBP, which has to guess port displacement and may be off due to how you make the port or with what thickness of wood if slot ported.

I would tune to 30-32 hz and trust winISD.