Yet another creation

chew* · Post by chew* » December 29th, 2006, 10:36 pm

Well I seem to have a lot of time on my hands so my buddy from Gforce and I worked on another enclosure for some subs that I blew last season. Memphis was cool and had sent me new subs to replace the ones i literally scorched with 4 times the rated power. So we cranked out a high output box tuned to 30hz. And heres the finished product. We used yellow suede on the front. I think it compliments the subs quite well. Note the large 5" port. The port per sub is actually 2.5" and it folds along the back as to tune it to 30 hz you need quite a long port.

92blackmx3 · Post by **92blackmx3** » December 29th, 2006, 10:56 pm

that looks really nice
u guys can call me really stupid but how do u know what your box is tuned to for hz

chew* · Post by chew* » December 29th, 2006, 11:25 pm

Well we use the thiele parameters ( know as TS specifications ) of the subs and use a box building program. The size of the box, and the length,width and height of the port are all factors. The depth of the port is the most crucial determing factor though. Of course this applies to ported enclosures. With sealed enclosures what matters most is the q factor. Q factor is manipulated by box volume in sealed applications.

lakersfan1 · Post by **lakersfan1** » December 30th, 2006, 6:23 pm

92blackmx3 wrote:that looks really nice
u guys can call me really stupid but how do u know what your box is tuned to for hz

It's not for newbies to do themselves. But if you've been around car stereo for a while, and can afford a few mistakes and time to redo things, you'd need a box building program like the one at Linearteam.org and the Thiele-Small parameters of your particular subwoofer. It'd also help to understand the theory of transfer function (corner loading) in a car, and how it affects the frequency response of the subwoofer. Most newbies make the mistake of designing a box for flat response anocheic, then wondering why it sounds like a-- in the car.

chew* · Post by chew* » December 30th, 2006, 6:56 pm

well put lakersfan1

92blackmx3 · Post by **92blackmx3** » December 30th, 2006, 9:38 pm

im not gonna even touch my box lol i got a kenwood made dual bandpass box it sounds good i was just wonderin tho lol

chew* · Post by chew* » December 30th, 2006, 10:34 pm

Well bandpass is even more frequency specific than ported, in fact there are different types of bandpass. For instance a 5th order bandpass tuned to the resonant frequency of a car will hit incredibly loud at that one single frequency however falls off at all other frequencies. That kind of bass is described as bass that feels like someone pounding the back of your head with a baseball bat. Unfortunately it requires a very large enclosure and is very hard to tune to an exact frequency as you have to account for the rise time of the sub. With ported you have to take this in account also but there is room for error. With bandpass there is no room for error.

I like to break it down like this.

For sound quality use sealed and sometimes ported if your really good with programming a box and have experience. I can tune a ported box quite well for sound quality. Sealed requires about 25% more power to get the same output as ported.

For higher output with less power and less subs use ported. Mainly this is the bang for buck solution.

For SPL use ported or bandpass if your really really good at box tuning and can live with frequency specific bass.