How do you find the peak frequency of a vehicle?

[bunkerking09 10+ year member]

Do you just use a sealed box and sweep it on a meter? //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif//content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

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[fbi90909 5,000+ posts]

i believe it goes something like, build a box, get a term lab, run a bunch of sine waves, find which is the loudest freq in your car, build another box ported tuned to that freq, test again with sign waves, find highest freq, if freq is different build new box or adjust current box to freq, test again. find loudest freq. if close to past 2 freqs or so you are in a freq range of the vehicle.

now i'm not positive if this is how it works but i recall reading something of this nature.

 

[Tehgregzor 10+ year member]

I'm gonna agree with fbi. Sounds about right.

 

[bunkerking09 10+ year member]

i would like to make a box with adjustable ports, since i don't have a LOT of time to be building boxes constantly, but i would want to do it with aeros.

So how do i make aeros adjustable without sealing them with some type of glue?

 

[fbi90909 5,000+ posts]

uhhh just use PVC that can fit to the aero ports flares(if used) and use duct tape. or maybe hot glue and duct tape. that way if you ever need to remove them you can just heat up the pipe and the glue will losen up. then all you gotta do is clean off the glue after it cools.

 

[bunkerking09 10+ year member]

uhhh just use PVC that can fit to the aero ports flares(if used) and use duct tape. or maybe hot glue and duct tape. that way if you ever need to remove them you can just heat up the pipe and the glue will losen up. then all you gotta do is clean off the glue after it cools.

do you think this will really seal it that well? //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

 

[Rashaddd 5,000+ posts]

wouldn't metering a sub/box outside of a car and then putting it in and comparing where the car peaks vs where the sub/box peaks give you a pretty good idea

 

[Jeremy M 10+ year member]

wouldn't metering a sub/box outside of a car and then putting it in and comparing where the car peaks vs where the sub/box peaks give you a pretty good idea

yah i heard this is the fastest and more accurate way of finding the peak frequency.

 

[vehementSPL 10+ year member]

One thing about this though. With loud systems because of swelling of vehicle i do believe this varies the res freq

 

[TSGP]

You're vehicle is just like another enclosure.

Think of every install you do like a bandpass.

I don't believe in one single peak frequency.

Best thing to do is test on a termlab the day of a show, do around 3/4 volume, and start around your peak...give about 5 minutes between tests and go up 2 tracks.....5 minutes go up 2 tracks...keep records of every burp. Once you stop gaining go back down 3 tracks and that will get you inbetween the 2 loudest frequencies. Test that...if its quieter then play your loudest frequency.

Humidity, altitude, tempature, sun...how many times you farted in the car can make SPL change from day to day.

Also make sure you change NOTHING inbetween those tests. Seat positions, visor positions, ac vents ANYTHING, be SUPER anal about testing

 

[Rashaddd 5,000+ posts]

You're vehicle is just like another enclosure.
Think of every install you do like a bandpass.

I don't believe in one single peak frequency.

Best thing to do is test on a termlab the day of a show, do around 3/4 volume, and start around your peak...give about 5 minutes between tests and go up 2 tracks.....5 minutes go up 2 tracks...keep records of every burp. Once you stop gaining go back down 3 tracks and that will get you inbetween the 2 loudest frequencies. Test that...if its quieter then play your loudest frequency.

Humidity, altitude, tempature, sun...how many times you farted in the car can make SPL change from day to day.

Also make sure you change NOTHING inbetween those tests. Seat positions, visor positions, ac vents ANYTHING, be SUPER anal about testing

That doesn't necessarily tell you what your car actually peaks at though, because the box can hugely change how loud each individual note is in your car. Although...I've heard alot of times of people's always getting the loudest on a certain note regardless of what their box is tuned to...but still it should be taken into consideration.

 

[TSGP]

Thats why I never take vehicle resonant frequencies into consideration.

Because when you do, you try to make your enclosure peak there, but then if the weather totally changes and your car wants to play lower (my old truck used to drop from 49 to 44hz) so if the enclosure is peaking at 49....and the car wants to play 44...you're going to have an SPL loss and not know where the hell it went or be able to get it back until the situation where you tuned the first time is duplicated