no. i think its possible for someone to come up with an equation though, that has to do with box cuft, box tuning, and your cars cubic feet/and general shape of inside.
quick and 99 percent of the time correct way to find out resonance frequency is to get a flat frequency sweep audio C.D.(likemake it louder.com ) and then attach a multimeter to read AMPERES to any loudspeaker, inside or outside of a bass box(whatever). It should go:
Shut off any equalizers, epicenters, bass boosters, or any gains in your radio deck and amplifier boost switches.
1.sound amplifier black (-OUT) to loudspeaker black(-in).
2.Then sound amplifier red (+OUT) to AMPERE A.C. multimeter red (+IN) to AMPERE A.C. multimeter black (-IN) to loudspeaker red (+IN).
Click here to see a setup diagram
3.Play the frequency sweep starting from a low pitch(say 15 or 20 hertz) to higher pitch(100 hertz) slowly at a starting volume that makes the AMPERE meter read, say around 1.00 AMPERES alternating current at the start.
4. do NOT adjust the volume once you start the sweep.
The AMPERES will begin to drop automatically and go lower, to 1.00, 0.99, 0.98, 0.97 ect. until 0.33, 0.32, 0.32 it hits a low say 0.32 amperes, then it will begin to slowly go up again, 0.32, 0.33, 0.34, 0.35....
The point when the AMPERE meter reads the lowest AMPERES is your loudspeakers and or system frequency of resonance.
make it louder frequency sweep audio C.D. works really good for this because our sweep speed is (1 hertz per second = 1 hz/second). So starting the sweep at 10 hz, then begin play, 23 seconds later the AMPERES is at it's lowest reading, so this means your resonance is at 10 hz + 23 seconds = 33 hertz. This represents a "true resonance". As an example a 15 inch subwoofer with a resonant frequency of 25 hertz in a 6 cubic foot ported box tuned to 18 hertz, may measure 34 hertz "true". Sitting on a car with a "true" resonance of less than 31 hertz is quite fierce above 125 db.
The resonant frequency is not always your frequency db maximum.
This is because loudspeaker + box + amplifier + car = system. A system has a frequency at which the decibel level db is maximum, this is called the (Fdb). Use a frequency sweep disk to find out your Fdb, at about 10db lower than your maximum db, so you dont blow stuff up first.
yup thats how u can find the resonant frequency and heres another one but more complicated.
Get a db meter or download true rta on the internet free and get a sealed box, turn off equilizers, bass boost or anything related, put everything on flat, start playin test tones the louder the test tone at certain frequency will be your resonance frequency.
