Bew Box

[monte_carlo97 10+ year member]

i have built a total of 6 different boxes for my car.

This time i am going to make a good one so i don't have to make any for awhile.

 

[JimJ 5,000+ posts]

i dont understand how you can simply find the resonant frequency of your car, when your car is composed of so many different materials, each of which have different resonant frequencies....

Put the driver in a sealed box, take a cheap SPL meter like the Radio Shack variety, and simply run tones until you get the relatively loudest. You're just seeing what the resonance in-cabin is like, because that will depend on multiple factors, like the total airspace the sub is firing into.

 

[monte_carlo97 10+ year member]

so should i put the box in the trunk or in the cabin of the car.

 

[monte_carlo97 10+ year member]

also when i do get the loudest that is probably the hz that i will want to tune to?

Correct?

 

[bcarpenterfhl 10+ year member]

just curious, what subs are going in?

 

[Raven 10+ year member]

In the sweep, when you hit your peak SPL, that's your resonance frequency.

IF I remember rightly, you're supposed to tune just under it by like 2 or 3 hz, then play the test tone that's 2-3 hz above tuning. Don't quote me at that, try searching around the forums for a little more reliable wisdom.

 

[monte_carlo97 10+ year member]

just curious, what subs are going in?

the mofo's

 

[monte_carlo97 10+ year member]

In the sweep, when you hit your peak SPL, that's your resonance frequency.
IF I remember rightly, you're supposed to tune just under it by like 2 or 3 hz, then play the test tone that's 2-3 hz above tuning. Don't quote me at that, try searching around the forums for a little more reliable wisdom.

can anyone else disagree or agree with this.

 

[monte_carlo97 10+ year member]

any more opinions.

I mean what is average spl tuning.

Cause i was talking to a guy at my dealer show that had his truck there with a blow through and he had his tuned to 58 hz and it sounds d@mn good.

 

[monte_carlo97 10+ year member]

Put the driver in a sealed box, take a cheap SPL meter like the Radio Shack variety, and simply run tones until you get the relatively loudest. You're just seeing what the resonance in-cabin is like, because that will depend on multiple factors, like the total airspace the sub is firing into.

would i put the sub in the trunk or in the cabin. Then once i got the freq. how do i tune my box in relationship to that frequency.

 

[Goldtaz1 10+ year member]

can anyone else disagree or agree with this.

Jmac told me to tune a quarter octave lower than my resonant frequency. Whatever your res frequency turns out to be you will need to multiply by .875 and that will tune you a quarter octave lower.

 

[packerfan 10+ year member]

if someone would be willing to spend a little time with me designing a box, i would really appreciate it.
Basically i want to find out what volume will yield the most output and what to tune to.

Noone here is gonna know the perfect box for your situation, your gonna have to test, test and test some more. The TL if your friend...

 

[ruckus]

would i put the sub in the trunk or in the cabin. Then once i got the freq. how do i tune my box in relationship to that frequency.

If your competing I would think in the cabin. Dont they put the meter in the ac vent or dash? and most competition bodies dont allow you to remove your rear seat but you can fold it down if it folds stock.

 

[squeak9798 5,000+ posts]

Put the driver in a sealed box, take a cheap SPL meter like the Radio Shack variety, and simply run tones until you get the relatively loudest.

Just doing that doesn't actually tell you the res freq of the vehicle, since you aren't isolating the frequency response of the car from the frequency response of the box itself.

Take a subwoofer (10" or 12" or whatever, doesn't matter) and put it in a sealed enclosure (NOT ported). Set the box somewhere in an open area (like your yard, NOT somewhere in your house). Play a set of frequencies (say, 40hz - 80hz at 2hz or 5hz intervals..the smaller the intervals the better, but the more time consuming) through the sub while in the open area, measure the output level of each frequency with your meter and record on a sheet of paper each frequency and it's output level. Now, take that same sealed box and place it in your car. Play the same set of frequencies now with the box in your car, and again record the output level of each frequency. Now you need to compare the output levels of each respective frequency between the open area and in-car enviornments. The frequency that has the greatest difference in output between the two measurements (in-car and open area) is the frequency that your vehicle peaks at.

Or, you can do this method: http://www.bladeice.com/resfreq.htm

 

[monte_carlo97 10+ year member]

you wouldn't happen to have a mic would you squeak?