BlazedGlory

Has anybody taken the time to figure out or does anybody know what the resonant frequency of the Protege 5 is?

Just wondering...any guesses? Anyone know the resonant frequency of a similar car? (Civic Si, Matrix, Vibe, Focus...whatever)

Wondering so that I can get to work on a box for spl purposes...I want to have two boxes (this is for 2 12" Audiomobile Mass subs, 600-700 watts each). I will have a box (separate chambers) that is sealed with around 1.2 cu. ft. each. I'm trying to figure out what I should tune my spl box to though for maximum spl =).

bigwoofer

I metered my car today, and the resonant freq is around 45hz!!! I didn't go higher since my car is tuned for sq, but I imagine if you go another octave higher you will find another res. freq around 65-70 hz that may work for spl better.

P5s_LetsRoll

When I tested my car yesterday, I'm showing a sweet spot of between 45hz -51hz..

Which is excellent considering the HO12W7 is tuned to 31hz, and in car will produce best around 46 or 47hz. That is what the JL Engineer told me anyways..

Things are looking very good for SPL so far.. The 12w7 only has like 84 sq in. of cone area. Can you beleive that?

hihoslva

BlazedGlory:

If you are going for an SPL setup, sealed boxes are not the way to go.

You can certainly get plenty loud, but a ported box tuned to the approximate resonant frequnecy of the car is the way to big SPL numbers.

BTW - sealed boxes are not tuned. The frequency resonse of the sub changes due to box size, but there really is no way to "tune" a sealed enclosure to boost certain frequencies. That's what ported and bandpass boxes are for.

I am going to make an observation:

If you are bulding a sealed 1.2 cube box, you are not building an SPL enclosure. I'm not saying it won't be loud - but if you want TRUE SPL, you will need a properly built and tuned, big-*** ported box. I would look into using the WinISD box-modeling program to determine what box will best suit the SPL you're after. You enter all the TS (theile smalls) parameters for your sub (the program *might* have them already built in to its included database), plug in the amount of power you're working with, and it can help you design the box size, port area, and port length for max SPL.

~HH

P5s_LetsRoll

No, I was just using a sealed box to find a range of where the hightest resonant frequency was.

I know sealed boxes are more for SQ not SPL..

The box that I will be using at first will be the High Output box by JL tuned to 31Hz..

Will produce best SPL response around 45--47 which is perfect for SPL in these cars..

I'll let everyone know Friday morning a round about figure of what I will hit on Friday at competition. I'm dialing it in with a SPL meter Thursday night..