resonate frequency a vehicle
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=48314
Printed Date: July 18, 2025 at 11:49 AM
Topic: resonate frequency a vehicle
Posted By: jvillefinest
Subject: resonate frequency a vehicle
Date Posted: January 22, 2005 at 11:49 AM
I saw someone state this in a post in the comp sub topic. i was wondering how do you find this frequency and if someone could explain a little more what it means. Thanks ------------- 2007 Acura TSX
SQ setup in the works
Replies:
Posted By: DYohn
Date Posted: January 22, 2005 at 11:58 AM
Without access to an anechoic chamber and many sophisticated pieces of test equipment you will probably not be able to determine this. However, many auto manufacturers do determine their vehicles resonant frequency and often all you have to do is ask. What it means, in general, is the frequency at which the structural elements of the vehicle vibrate in resonance. Manufacturers want this number to be as low as possible so that the vehicle does not develop annoying rumbles at highway speeds. ------------- Support the12volt.com
Posted By: audeogod
Date Posted: January 22, 2005 at 2:04 PM
Why would anyone want to know this for car audio?? Can it be useful in someway??
Posted By: stevdart
Date Posted: January 22, 2005 at 3:20 PM
I think for SPL competitions. You would tune the sub enclosure to the vehicle resonance for max SPL (no sound quality intended!).
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Posted By: Ravendarat
Date Posted: January 22, 2005 at 7:28 PM
I was the one that was talking about this before, and it is intended only to be usefull for spl systems. I believe you can get a rough Idea using a RTA meter as well, but I can never remeber the exact steps to doing it.
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double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer
Posted By: DYohn
Date Posted: January 23, 2005 at 9:39 AM
Maybe we're talking about two different things. A vehicle's "resonate frequency" is a function of the materials, construction, suspension, welding quality, etc. and is like the Fs of a loudspeaker: it is the point where the system inherently tends to vibrate most readily. For most cars and trucks on the road, this number is down around 5 to 12 Hz - way below human hearing and not too useful for competition of any sort. Determining it is a very involved process and is way beyond the means of most car audio shops. But perhaps what you really mean is the frequency where the car exhibits the most cabin gain. This is a function of the interior materials and the vehicle's physical spaces and shapes, and is the frequency most "boosted" by the natural physics inside the vehicle. This is usually around 50-80 Hz and could be very useful to know for competitions. It can be fairly easily determined using an RTA. Is this what you mean? ------------- Support the12volt.com
Posted By: auex
Date Posted: January 23, 2005 at 11:03 AM
Speed of sound(calculate using your own needs, use google)/distance between cone of the sub to the microphone(wavelength) = Optimum frequency(hz). Also try going 1 or 2 octaves lower.
Basicly if you have 10 ft between the cone and where the microphone is then you would take 1126.8/10=112.68. This is the longest wave that you can actually hear in your vehicle without the sound being converted into pressure. This also is too high for most spl mics that are filtered. What I would do is build my enclosure so the the f3 or tuning frequency of the box is as close to 56 hz(1 octave lower) as possible. Then I would go to an rta and see what it would do trying 56 hz and 23 hz then start playing around.
Also it has been along time since I messed around with spl comps so if the info is a little off then what ever.
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Posted By: Ravendarat
Date Posted: January 23, 2005 at 8:45 PM
DYohn, thats exactly what I was talking about. I have always heard this refered to as either cabin gain or resonate frequency, as if it were one in the same. Obviously I was mistaken and am happy you have set me on the path to success oh great and smart one.  ------------- double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer
Posted By: jvillefinest
Date Posted: January 25, 2005 at 10:19 AM
What is an RTA ?
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2007 Acura TSX
SQ setup in the works
Posted By: DYohn
Date Posted: January 25, 2005 at 10:40 AM
jvillefinest wrote:
What is an RTA ?
Real Time Analyzer. A piece of test equipment. Here's one use for them. ------------- Support the12volt.com
Posted By: haemphyst
Date Posted: January 25, 2005 at 2:45 PM
DAMN, Dyohn... you didn't pick the cheap one did you!?!?  He could buy a laptop, mic and external mic power supply for that! AND add TrueRTA - the big boy, and take the remaining 7000 dollars and buy a whole new system - with installation! Wow, I had no idea they were STILL that expensive!
Just jabbin' at ya! ------------- It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: DYohn
Date Posted: January 25, 2005 at 2:53 PM
 Jab taken! Just trying to protect a little job security... ------------- Support the12volt.com
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