How to find resonant frequency

[IKnowImLost224]

How do you find the resonant frequency of your car? I built a box tuned to 33 hz and it sounds like shit lol. I then learned about needing to find resonant frequency. I think this would probably be a good thread to pin if someone can explain in detail

[skittlesRgood]

RF is really only useful for SPL. making your box peak at the same frequency your car peaks at. it wont make a good box sound like shit because tunings dont match. chances are, your box sounds bad because its a bad box or bad placement. thats something we can help with here if you post specs of the box and your equipment.

but to answer the question. you take a sealed 10" and play a sweep. the peak from that should be your resonant frequency. you might have to point it in different directions and get an average, i forget the smaller details.

[IKnowImLost224]

The outside dimensions are 20x30x15. Port is 1.5" wide and 16" long. The sub is facing up with an L port in a 2001 Malibu. Using a re xxx 15" dual 2 hooked up to a sundown SAZ-2500d @ 1 ohm. Tuned with the dd-1. The trunk is retarded which is why I made it face up. I'm guessing that's part of the problem but I'm not sure. Port corners are 45'ed

[skittlesRgood]

bingo. your port is WAAAYYYYYY too small. only 5 square inches per cubic foot when it needs to be closer to 14. you need to make that port something like 4.25"x16" with that same airspace. but that means the port needs to be longer so the box needs to be bigger. then it also needs at least 4" of clearance between the port opening and a panel in the trunk.

[IKnowImLost224]

I'm pretty close to max dimensions but I used Torres to tune the box

[neuspeedescort]

just because you used torres to tune doens't meand its done right. don't build vented boxes with less then 14 sq.in per cu.ft. simple. subs needs to breath!

NEUMAN

[IKnowImLost224]

So if it's a 4 cube box I would need 56 sq of port?

[LoudBimmer]

I got a <2cf box with ~36 sq in of port

[IKnowImLost224]

Now also when I make that port that much bigger that's going to make the tuning a lot higher right?

[skittlesRgood]

it would, yes. thats why the port needs to be longer. now you will find that your box is probably too small after port displacement.

when you use torres, it actually tells you that your port area should be within a certain range. it tells you the range. look at it again and see how far off you are. spend some time playing with it, get a design you think will work best for you. then take a screen shot of torres and post it in this thread. we can look at it and advise you before you build a new one.