Your car's resonant freq?

[Randy Savage 5,000+ posts]

In all seriousness...from my wall building experience (I've built/had a hand in building a few), the only way to get em loud is to test test test...for one wall we had 4-5 different baffles (anywhere from 4"-10" thick)and ~5 or so different angles for the back wall and would swap em in and out until we got what worked best..

 

[Flipx99 5,000+ posts]

In all seriousness...from my wall building experience (I've built/had a hand in building a few), the only way to get em loud is to test test test...for one wall we had 4-5 different baffles (anywhere from 4"-10" thick)and ~5 or so different angles for the back wall and would swap em in and out until we got what worked best..

That's quite an investment in Mdf.

I am also concerned about weight. In a small car, does it cause structural damage because of the wieght?

 

[Mr. Opportunist 10+ year member]

use something lighter then mdf

 

[Randy Savage 5,000+ posts]

That's quite an investment in Mdf.
I am also concerned about weight. In a small car, does it cause structural damage because of the wieght?

Yep...was a ton of MDF...used 1" MDF. Even used 2" Trupan in a wall in an old Montero we did...sawzalled off the roof to make room for the wall, then welded the roof back in place //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Flipx99 5,000+ posts]

Yep...was a ton of MDF...used 1" MDF. Even used 2" Trupan in a wall in an old Montero we did...sawzalled off the roof to make room for the wall, then welded the roof back in place //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Not ready for that type of commitment. //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

 

[dleccord 5,000+ posts]

In all seriousness...from my wall building experience (I've built/had a hand in building a few), the only way to get em loud is to test test test...for one wall we had 4-5 different baffles (anywhere from 4"-10" thick)and ~5 or so different angles for the back wall and would swap em in and out until we got what worked best..

why are the baffles that thick? is it because just to hold the weight of the woofers?

 

[ntense702 10+ year member]

That's quite an investment in Mdf.
I am also concerned about weight. In a small car, does it cause structural damage because of the wieght?

in my escort we walled it off with 2 sx 15's with 9+ cubes of 3/4" mdf and it lowered the rear an inch or so. The car also acted wierd, the idle acceleration increased.

 

[Mr. Opportunist 10+ year member]

why are the baffles that thick? is it because just to hold the weight of the woofers?

changes note it peaks at....

 

[Chevyaudio 5,000+ posts]

Hmmm...this is interesting. I never knew some of these things about walls. ***writes in journal...I actually read an interesting thread on ca.com today***

 

[ntense702 10+ year member]

in all setups I've had in my car the peak note is always 40 hz, had a box tuned to 38 hz, then 40 hz, and currently 32 hz, and for some reason 40 hz still shines.

 

[Chevyaudio 5,000+ posts]

my single cab peaks at 41 hz....im interested in what your truck peaks at Tommy.

 

[tommyk90 5,000+ posts]

my single cab peaks at 41 hz....im interested in what your truck peaks at Tommy.

Is that what your BOX peaked at IN your truck, or is that the resonant frequency of your truck?

 

[luvinthebass 5,000+ posts]

in my car it peaked at 40 hz as well.

 

[Mr. Opportunist 10+ year member]

is that where your car peaks at or where that box peaks at?

 

[bigbassman Premium Member]

good lord what an explosion of..... well... alotta junk //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

if you decide to go down the road of "sealed box first" testing... you HAVE to use a .707 butterworth alignment, sealed...

why .707? because one of its characteristics... is a 12 db per octave rolloff below F3... I think its F3... we'll try it..

now its been well documented that 99% of vehicles exhibit a boost of roughly 12db per octave starting at the corner frequency, which is determined by the size of the cabin, and its characteristics at higher pressure. most corner frequencies are in the 60-80 hz area....

so simple math... 12 db per octave - 12 db per octave = 0ish... flat response down to Fb.. which in theory will allow the peak hunting to begin...

but there's a couple giant flaws..... one... as stated previously... most vehicles do not have any big peaks.....

two.... as pressure increases.... the vehicle will flex, and leak... and that throws a loop into the frequency finding...

so in short.. sealed box testing at a db level lower then what you'll be using... is a waste of time... but by all means go for it //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

now... onto box efficiency...

that's what you wanna spend your life testing.... finding the perfect combination of vehicle, port, volume, and wooferage....

unfortunately... there's no set way that works for everyone.... which is why "test, test, test" is usually said 20 times in the course of a thread like this...

speaking for myself... my grand prix walled off, didn't care what it played... it played exactly what I designed it to play.... and I've adjusted to play nearly every frequency from 30hz, up to 68hz, with no problems..

depending on the mic placement, certain tuning arrangements did better, due to wavelength propegation, and cancellation.. which again.. is why I've spent soo much time testing....

Loyd L.