Resonant Frequency

[RisingX2004]

Does anyone know what the resonant freq. of a GA is? I have an idea its around the low 40's like 41 or 42Hz.

[tubpub11]

why do you want to know??

[Lash]

Tuning for SPL comps...thats why.

[RisingX2004]

Yup, just want to play the right tracks at a comp.

[Bumpin1OHM]

it varies in each car, one 96 gagt 3100 isnt the same as another 96 gagt 3100

and depending on how loud your system actually is, your res freq changes then, too!

see why its called a spl COMPETITION? its not easy :)

say if your running ported, the port makes the box peak, the woofer itself has a peak, the car has a peak, and the position of everything in the car can change that peak! your chasing your tail no matter what you do. its nothing but trial and error.

get yourself a termlab USB, a few hundred pounds of MDF< some good tools, and a calculator :)

have fun :)

[RisingX2004]

Haha that all makes perfect sense. I have competed before but not in a GA, it was in a neon and man it shook the hell out of it! Screw it, I'll just play a 80-30hz sweep. Wont be the best score but oh well, dont have a few hundred to throw down on a termlab - I'd rather get some wheels! O ya, thanks for the knowledge!

[tommymcc]

get a sub in a sealed box, play a variety of constant freq. and one of those notes is gonna cause your car to sound like its gonna fall apart, that is normally the freq you want, however when you put a larger or smaller box the freq will change, but not much, maybel ike 3-5 hz up or down

[CanadAM]

how do i mess with the SQL on my deck? its a kenwood.

[Lash]

Originally posted by tommymcc
get a sub in a sealed box, play a variety of constant freq. and one of those notes is gonna cause your car to sound like its gonna fall apart, that is normally the freq you want, however when you put a larger or smaller box the freq will change, but not much, maybel ike 3-5 hz up or down

Sealed and SPL comps dont mix very well...lol. ;)


They do make programs for laptops that can help you find the freq. of your car (ned a mic too). Not sure on how much they cost though.

[Bumpin1OHM]

the sealed box + sub is a good baseline, but say ur sealed box does 130db, and ur competition box does 136, the resonant frequency is gonna change as you get louder, quieter, etc...

experiment: get a sealed box, play ur resonant frequency tone that u found, say its 43hz. u start from no volume all the way to the max, different things will rattle, stop rattling, etc the more the volume is altered.

that is why its not just as easy as finding the res freq in a sealed box then burping that with any ol ported box, the box has to be tuned so that the box peaks with your car, and the positioning has to be right or else you get cancellation. read some competition forums if u want to become a competitor, because there is a lot of things that you are overlooking.

if your just going to see how loud you are, then with your current setup, play tones from id say 20-60 hz until u find the one thats loudest.

remember though, loudest to the ear is not always the loudest to the mic! :)

see, told u its tricky... (and expensive...)

[RisingX2004]

Thanks for the advice everyone. SQL is what I'm going for and thats where it is set up right now. A friend of mine has a meter from splmeter.com , the dBm2 and It hit 138.8 at the windshield on a 100-30hz sweep. Not my best score on that meter, which i'm sure it isnt as accurate. Good enough for me right now though. I need to fix the trunk seal as it leaks a bit. I have also put monster speaker wire in and it deffinitely seems cleaner and louder and i moved the box back toward the rear of the trunk and angled it slightly into the corner and that helped significantly. 140 and i will be happy

[dandragonrage]

You want something like this but for a car: http://www.behringer.com/DSP1124P/index.cfm?lang=ENG

[Bumpin1OHM]

uuum... how in the world does amplified feedback have anything to do with a vehicles resonant frequency?

[dandragonrage]

It will monitor the sound and automatically equalize as required so resonant frequency becomes a moot point.

[Bumpin1OHM]

if only that was true it would be used in every SPL competition in the world. read what it does bro... it cancels out mic feedback (like what happens when you put a mic too close to a speaker)

[dandragonrage]

Sounds like you know all about these things. Check www.diyaudio.com and see that they ARE used for what I said. And plenty of people do use similar things in the car.

[Bumpin1OHM]

they might be used for something in a home setting, but they are not used to find the resonant frequency of a vehicle to be used in SPL competitions.