resonance freq.

[Mr Bojangles 10+ year member]

Is there some kind of calculator or web site for figuring resonance freq. in diff types of vehicles? Or do you have to use the old take your boom box out, put it on the roof, measure hz, collect data, put the box back in the car and do the same thing...???

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[Mr Bojangles 10+ year member]

hmm... noone??

 

[Mr Bojangles 10+ year member]

Chuck Norris doesn't sleep, he waits

 

[Pyro_By_Nature 5,000+ posts]

Chuck Norris would give you at LEAST 4 roundhouse kicks to the face if he knew you were so stupid.

 

[Mr Bojangles 10+ year member]

Your just not good enough to have Chuck Norris avatar.. Jealous..

 

[dleccord 5,000+ posts]

this thread dies now.

 

[BassAddictJ 5,000+ posts]

lol..

put ur sub in a sealed enclosure............

take a small regular dB meter, in fact a analoge multimeter will probly do (jut dont crank the volume up)

keep volume constant and play differant frequencies and see which one has the higher dB for the given amount of volume. this freq should be a few to several dB's louder than the other ones...that peak freq is pretty much as **** close as ur gonan get to ur res freq wihtout doing anything else.......build and tune ur fartbox to that freq...ur good to go....... //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[BassAddictJ 5,000+ posts]

anything i miss or mess up?

 

[Immacomputer 10+ year member]

You need to do it twice. Meter the same frequencies inside the car and outside the car and see where your cabin gain starts. Also, measuring from the back of the vehicle to the windshield will give you an idea. This length will be roughly just less than 1/2 of the wavelength that your car will peak at.

For example, from my tailights to my dash is about 9 feet. To calculate the frequency of my estimated peak, I first take that length and multiply it by 2 to represent the full wave. Then, I take the speed of sound (in fps) and divide it by the number that I just found. This will give me a basic idea of where the car peaks.

Basically like this where the speed of sound in feet per second is ~1116.4:

(1116.4) / (2*L) = f

In my case, my peak came out to about 62hz and just below that is where my car peaks (around 59-60hz).

 

[squeak9798 5,000+ posts]

lol..
put ur sub in a sealed enclosure............

take a small regular dB meter, in fact a analoge multimeter will probly do (jut dont crank the volume up)

keep volume constant and play differant frequencies and see which one has the higher dB for the given amount of volume. this freq should be a few to several dB's louder than the other ones...that peak freq is pretty much as **** close as ur gonan get to ur res freq wihtout doing anything else.......build and tune ur fartbox to that freq...ur good to go....... //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

You need to do it both inside and outside the vehicle to elimate the response of the enclosure/speaker as a variable. The difference between the open air measurements and the in-car measurements will leave you with the acoustic affects of the vehicle itself.

That said....I don't know how many competitors actually go through this process......I don't pay much attention to SPL anymore and don't know the "best" method for "getting loud".

 

[CBFryman2 5,000+ posts]

Start wit ha presure box and keep making the ports shorter and shorter untill you reach a peak and start falling, then make new ports at the length of your peak SPL and go from there, box placement and what not. Then start changing other things and repeat the above.