Resonant Frequency Questions ?

[Fish Chris]

First off, does anybody know what the resonant frequency of an F150 Supercab would be ? {not a Super crew cab.... but still, a pretty big, extended cab}

Secondly, if not, how would one find out what it is ?

Finally, once I do find out what it is, tell me again how this should influence my enclosure tuning ? It's something like, you want to tune a little higher, or lower, than the vehicle resonant frequency, to avoid a really "peaky" type of setup, correct ?

Anybody ?

Thank you,

Fish

[smokeumtires]

X2 i would like to know how to get the RF of my truck as well

[Forevrbumpn]

2 ways to do it, the generic quarter wave technique, or getting a sub with a known freq response, in a certain box, and meter wioth a sine sweep from 20hz-100hz, and see where the DB gain is in comparison to the original freq reponse

basically sealed sub if possible with a very flat freq response, install in the truck, and see the difference afterwords

[Fish Chris]

Well Forevr, first off, thank you. Since the second option might be kind of hard for me to accomplish, how would one go about performing the > generic quarter wave technique < ???

Of course, I can think of 1 other way..... which would be to ask somebody who owns our exact vehicle and who's into SQ systems.

Come to think about it, I wonder if this info exists "somewhere" on the internet ? Hey, it might be in my favor, that F150's are the most popular vehicles (not just trucks.... but litterally, most numerous vehicles) on the road today.....

Hmmmm,

Fish

2 ways to do it, the generic quarter wave technique, or getting a sub with a known freq response, in a certain box, and meter wioth a sine sweep from 20hz-100hz, and see where the DB gain is in comparison to the original freq reponse

basically sealed sub if possible with a very flat freq response, install in the truck, and see the difference afterwords

[Forevrbumpn]

yeah, find someone who has that truck and competes with it

the quarter wave technique is pretty much finding out where all your sound will be directed FROM, then measure that distance to where the microphone/sensor will be metered at

[banginAltima]

My 97 F150 always wanted to peak at 49.

[banginAltima]

The simplest but takes the most time is to build the box, start with it tuned low, then with a TL start cut a half inch at a time. You would want your box tuning lower then the vehicles freq. Your box will peak higher then tuning. Example: box for my car...tuned to 32ish car peaks at 40. Your box freq is rising to the vehicle freq. Once you match your box tuning (with the rise) to the res. freq of the vehicle, you should be good to go.

Granted this is all general.

[E a r t h]

Measure from the firewall to rear in feet.

1130 divided by your # in feet divided by 2 = wave resonance So 1130/ feet / 2

1130 divided by your # in feet divided by 4 = 1/4 wave resonance So 1130 / feet / 4

The above is a rough estimate to start

Play tones above and below this frequency area to find peak using a TL on both wave and 1/4 wave

Hope this helps

[Fish Chris]

Thanks again guys.

BTW Altima, what cab size was your 97 F150 ? I had actually planned to tune my box pretty low... like 30-32hz, as I'm more interested in hitting the low notes, than in getting super loud.... so this might work out okay then, huh ?

Hey Earthman, I'll try that too.

Peace,

Fish

My 97 F150 always wanted to peak at 49.

[banginAltima]

Thanks again guys.

BTW Altima, what cab size was your 97 F150 ? I had actually planned to tune my box pretty low... like 30-32hz, as I'm more interested in hitting the low notes, than in getting super loud.... so this might work out okay then, huh ?

Hey Earthman, I'll try that too.

Peace,

Fish

It was the Supercab or extended cap, what ever you call it...