How do you find out what the resonance of your car is?

Jstas

This goes along with the other thread.

Since I have not done this before, I'm trying to find out how to do it so I know if it's being done right.

Anybody know?

disneyjoe7

I'm thinking a speaker mounted in car, amp to power it, frequency generator to feed it a fixed Hz, a microphone, a o-scope to find peak in frequency heard? Just some ideas off my head, good luck.

BradimusMaximus

As I understand it you do exactly what Joe said but with one stipulation. You have to do it outside the car with the same enclosure and amp with the same settings. You need something to compare that peak against so if you run some nice long speaker wires from the amp you can set the box on some sort of platform out in the open and run the same tests. That is how I read to do it anyway.

Jstas

Where did you read this?

MacLeod

Try Elite Car Audio. Thats the premier car audio forum with experts-a-plenty. I guarantee ya somebody over there can give you way more information than you ever wanted!

http://forum.elitecaraudio.com/index.php

BradimusMaximus

I'll try and find that again and post it up for you.

http://www.caraudiomag.com/technical/0203cae_audio_speakers_basics/index.html

This link I posted earlier gives you a different method that uses some measurements and math to figure out the same thing.

exalted512

Well, like you said in your previous post, EVERYTHING effects this. Ideally, youd want your box in and loaded, any deadening your going to do be done, then test.

The cheap and easy way to do it is with a 10" sealed sub with as flat frequency response as you can get. Then get a CD with some test tones from say, 45-100, a spl meter (or rta) and let it play through. The frequency with the highest reading is your frequency.

Now thats not 100% accurate, but pretty damn close (usually has a standard error of about 6 Hz as I've been told). Either way, if your frequency is 62, tune at about 59 and go from there. Removable ports are a must.

Are you wanting to get back into the SPL lanes or just curious about the info? I can help you out more but I'd rather do it through PMs.
-Cody

Jstas

Well, the guys I was talking about in the previous post compete and they are at a loss as to how to get the car louder. They asked me for help and like I said, I related my thoughts and experiences on making cars go "boom" and they balked. So I wanted to find out more about how they did it and after learning more in the other post and reading all over the web, I think they tested wrong and are off on their resonant frequency. I know they are off on the box design because even Memphis Audio says the box should be about 4.5 cubic feet at the largest and not the 6 cubic foot beast he has now.

Building the box is easy. Getting the appropriate info to build the box properly is difficult. But they want me to "put my money where my mouth is" so to speak so my one friend and I are gonna put together a box for his subs and see what we can do. Even if I pick up 2 dB over the current setup, it's a success because he will be about 1.5 dB ahead of his next closest, local competitor. So yeah, I guess I am getting back in to the SPL lanes. I'd prefer the SQ lanes 'cause I know I can clean up there but there might be some employment in this for me too. So PM away if you want.

BradimusMaximus

Let us know what kind of numbers you get!

exalted512

What subs and amps does he have and what kind of vehicle? As well as, what are your buddies competing in and with? Also, do you know what numbers theyre hitting and on what meter?
-Cody

disneyjoe7

Does anyone wish to start a poll of what the resonance of a car would be?

My guess 43Hz to nearest one to a whole number wins, wins what?


Steve

Jstas

exalted512 wrote: »

What subs and amps does he have and what kind of vehicle? As well as, what are your buddies competing in and with? Also, do you know what numbers theyre hitting and on what meter?
-Cody

He has Memphis M3124D's, a pair of them. I forget what amp, I think it's also a Memphis. I don't know what class they are competing in but they will hit any show that shows up. IASCA...honestly, you name it. As far as microphones, don't know, gotta find that one out.

The car is a Jetta Sedan, early 2000's I think. They are in the 142-147 range depending on the microphone and test gear. He has another guy with a Honduh Cibbic hatch hitting a good 8-10 dB above him across the board. The box is smaller but the space inside the cabin is much bigger because of all the space in the rear greenhouse that comprises the hatch area. I'll get the rest of the info for you next week. They away visiting family this weekend.

Jstas

disneyjoe7 wrote: »

Does anyone wish to start a poll of what the resonance of a car would be?

My guess 43Hz to nearest one to a whole number wins, wins what?


Steve

Every car has a different resonance. You can take two, we'll say, 1999 Lincoln LS sedans. They can be "identical" Equal trim levels, equal options, equal drive trains and everything and test resonance on both of them and the will have different resonances.

exalted512

As well as have different resonances in different areas of the car.
-Cody

disneyjoe7

Jstas wrote: »

Every car has a different resonance. You can take two, we'll say, 1999 Lincoln LS sedans. They can be "identical" Equal trim levels, equal options, equal drive trains and everything and test resonance on both of them and the will have different resonances.

Really I would never think so on paper so to speak.

BradimusMaximus

So did you ever build a box Jstas?