i found 2 resonant freqs for my car:( ???

[luv2bass 10+ year member]

i found 2 resonant freqs.1 was around 44hz and 1 more at 65hz.which of these should i use as resonance?

p.s. i made 2 tests

1)1 ported xxx15 at 31hz

2)the same xxx15 at same box but this time sealed(i muted the vent)

the peaks was almost the same around 44hz but at 65hz were identical!!!

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[Bill T. 10+ year member]

Isnt it typically 60~65Hz?

Bill T.

 

[Dbking 10+ year member]

mine was 47 hertz

 

[helotaxi 5,000+ posts]

the peaks was almost the same around 44hz but at 65hz were identical!!!

1/2 octave spread. It is not surprising that they were identical between the two boxes at the higher freq. The farther you get from resonance, the more a ported box behaves like a sealed one.

 

[Shaunly 10+ year member]

how do you find the resonace frequency.

 

[valant_94gt 10+ year member]

how do you find the resonace frequency.

^

^

I'm with stupid

 

[Dbking 10+ year member]

go to radio shack get the spl meter taht goes up to 125 db i beleive....make a test tones of sound clips from like 20 to 60 hertz or whatever u want. play the cd and meter it by the dash. then return the meter if ur cheap like me cuz i was never gonna need it again.

 

[B&R Innovation2 10+ year member]

Well with my experience I've never tested for RF with a ported enclosure. Using a sealed enclosure and lower to moderate volume levels finding a rf can be easily acomplished wiht a cheppy DB meter. As dbkin mentioned they can be had at radio shack but make sure you can set the listening frequency so it cuts off below your lowpass

 

[loserpunk 10+ year member]

All I did was buy this Bass Mekanik Cd that has A sine wave and a test from 10Hz all the way up to 100Hz. The loudest for my car was 55Hz so thats what I figured is the resonant frequency. The Cd goes by one Hz at a time from 10-100 so it gives you a very good idea of what the frequency is. The cd is called "Quad Maximus" by Bass Mekanik.

Get a radio shack meter. Have a single 10/12 inch sub in a SEALED box.

Place the sub outside the car take SPL with the meter from 35-80hz(It does not have to be at high volume, since the Radio Shack meter only goes up to 126db). Graph your results on a line graph.

Now place the sub in the car and do the same test with 35-80hz. Using the same graph, graph the results you got from inside your car with a different color pencil/pen.

Okay now look on your graph, the parts where your lines are FARTHEST apart, that is your resonant frequency

Now, if you want to tune a box according to the resonant frequency of your vehicle, you would want to tune the box so it would PEAK right at the frequency, which means it will have to be tuned a little under that frequency.

all that is courtesy of jmac i think...(might be someone else but i know james has posted on this topic b4)

 

[dflock 10+ year member]

Now, if you want to tune a box according to the resonant frequency of your vehicle, you would want to tune the box so it would PEAK right at the frequency, which means it will have to be tuned a little under that frequency.
all that is courtesy of jmac i think...(might be someone else but i know james has posted on this topic b4)

A little under, meaning a few HZs? So you peak at 44hz, you would tune it for 40hz? Or are you saying if it peaks at 44 tune it to 35?

Thanks for the good info.

... derek

 

[maniackilla 10+ year member]

why would u want it tuned to RF? why wouldnt you just tune it to what bass notes you want to pick up? whats the advantage? im uninformed on the RF so dont poke fun //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[loserpunk 10+ year member]

the closer you can tune to the RF the louder (as long as it's all done correctly) you will be able to get...but...vehicles RF's are usually fairly high....45 and above....tuning that high will lose sound quality...but you'll gain spl so it's a give and take situation..

and yes you want to tune(hertz wise) a few hz below the RF of the car....say 2-4...

all of these ideas work well but the best solution is trial and error //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif