box design question

[jrobie79]

So i want to build a sub box, with the same basic set up as Lukes (ports fire into cabin) however I wanted to customize it to the driver I have, so its at its optimum.

Question is:

How do i calculate the optimum size and port length of the enclosure based on T/S parameters? are there formulas that you can plug these variables into. And i tried using winISD but i dont get what the graph means, and what is the most optimum graph shape. any help would be awesome...


btw the driver is an MB quart RWE302 reference series 12"

[stumble_t]

http://www.the12volt.com/caraudio/boxcalcs.asp

[jrobie79]

that site is awesome, but I can build the box and all that but I just want it optimized for my driver, based on the specs I got with it, I do not see anywhere to enter that information and also I do not see a calculator to find the best tuning frequency.

[dashboardmonkey]

http://www.the12volt.com/caraudio/boxcalcs.asp

best fucking site ever

I am on this site couuple times a week

[StereoInstaller1]

So i want to build a sub box, with the same basic set up as Lukes (ports fire into cabin) however I wanted to customize it to the driver I have, so its at its optimum.

Question is:

How do i calculate the optimum size and port length of the enclosure based on T/S parameters? are there formulas that you can plug these variables into. And i tried using winISD but i dont get what the graph means, and what is the most optimum graph shape. any help would be awesome...


btw the driver is an MB quart RWE302 reference series 12"

With a resonant frequency of 27 and a Qts of .56, you are going to have a HUGE peak at about 35Hz, and normal car tuning (in a 110 cubic foot car like the E30) is right around there...which is why I recommend finding a woofer that has a Qtc below .4, and a Fs around 25Hz.

Here is a link to the best basic calculator I have found online. It is the advanced section, and there are articles on several different designs of boxes, and tons of stuff to soak up.

If you can find Wayne Harris' TERMPRO, get it, learn it, use it.

There has been zillions of books on what to do with the numbers that help us design stuff, but 99.999% of all the "pros" out there basically know dick, but will be glad to tell you they know everything.

In the meantime, one of the things that fucks you is that the T/S parameters are basically garbage. It isn't like some chinese woofer manufacturer is gonna go through 40 hours of break in and then do a sophisticated test to measure accurate engineering specs, (ESPECIALLY the fucking hacks at Maxxonics, owners of the MB Quart name) so you basically are guessing no matter what you do...unless you do your own testing.

Testing subwoofer enclosures is a whole 'nother ballgame. I am not even gonna try and explain what or how to measure an impedance curve, but I will say it the #1 most important thing you can measure...for a subwoofer, if you can measure the impedance curve and port with relevance to that curve IN THAT SPECIFIC CAR, you are quite likely to get terrific sound. Since I have built about 15 different boxes (not counting the "Luke Boxes") and tried every option I know of, I can tell you this: if it sounds good sitting in your living room, it is not too likely to perform well in an E30.

These cars are nowhere near as weird as some (late 70's/early 80's Caprice? fuck off!) but build a few different boxes and get some testing materials (basic RTA can be done with an SPL meter and a copy of the original "Bass Mechanik" CD) and start learning what things are supposed to sound like....damn near 30 years as a professional installer and I STILL love this stuff!

Luke

[jrobie79]

thanks for the info about that, i was just going by cost of product

the only reason i chose that driver was because i found it for 69.99 on sonix i believe, or maybe woofersetc

can you recomend another that would work in a box like yours for under 100 bux?

ive read good reviews of the listed driver while none of the walmart ones so if you have any suggestions other than those, that would be greatly appreciated.