Resonant Frequency Of Smd Tahoe

[Forevrbumpn]

Doesnt matter how large the sealed box as, as long as OUT OF CAR, it is a very flat response subwoofer system

What we used to do was get a 12" Dayton Titanic sealed, in 1.75cf I believe, that was a veryu FLAT response system, do test tones in cars, and it was ALWAYS accurate

[ISO]

^^^^I disagree^^^^

Your frequency will change depending on the size of the sealed box.

I will argue that just cause I'm bored.

Use the propper specs for the sub to build a box that will produce the flatest frequency response and use that to get a very close idea of the resonent frequency of the vehicle.

[banginAltima]

Well I still disagree, weither the box is to specs or not. If you build at box one cft or five cft... you will get a different freq. I know I tried it...

[banginAltima]

Plus to take it one step further... the size of the finished box in the vehicle will change the amount of air space which will change the freq. Now I am not just talking out of my ass. I spent about an hour with an instructor of the college I go talking about this stuff.

[ISO]

LOL if you want to get crazy I say go ahead and draw up your ported box the size you want becuase after that you just figure out the port witch on average is built into the box.

Go ahead and fill in that much cubic feet in the vehicle then mount a sub in a sealed box with the flatest response curve and have at it.

I'm confident you will be within 5 hertz of the resonance frequency of the vehicle.

Testing and trial and error are still going the be part of it but that should get you darn close.

Edit cause I can't get my thens and thes straighten out. LOLOLOL

[cnate777]

Actually, I was hoping Steve would be on so that he could answer. Not that I dont appreciate what everyone has said, and yes I agree with some of it and some of it I feel is wrong. But, none us built that Tahoe so it is pure speculation til you hear it from the horses mouth. HA

[meade916]

my box is tuned to 30.

with 2 18's it peaked at 37

with 4 18's the numbers dont change much from 41 to 46

its still tuned to 30 so it plays low but being a small box for 4 18's it doesnt go to the depths of hell like some systems can. I dont listen to much bass mechanic type music so it dont matter......everything i like is 30hz and up.

[banginAltima]

LOL if you want to get crazy I say go ahead and draw up your ported box the size you want becuase after that you just figure out the port witch on average is built into the box.

Go ahead and fill in that much cubic feet in the vehicle then mount a sub in a sealed box with the flatest response curve and have at it.

I'm confident you will be within 5 hertz of the resonance frequency of the vehicle.

Testing and trial and error are still going the be part of it but that should get you darn close.

Edit cause I can't get my thens and thes straighten out. LOLOLOL

I say skip all that and go straight to the testing-- trial and error is the best.

Plus being 5 hertz off peak freq was a difference of 3 db in my car...

[Forevrbumpn]

Plus to take it one step further... the size of the finished box in the vehicle will change the amount of air space which will change the freq. Now I am not just talking out of my ass. I spent about an hour with an instructor of the college I go talking about this stuff.

You are right, and not talkin out your ass, thats for sure... the main reason for tuning to cabin resonance is that is the vehicles 1/4 wave length

The size of box matters when it DOES effect the placement direction of woofers, and port location (there is other factors as total port area/cone area and area between the woofers/port and width of truck and length of the box- above box and side to side)

Location is everything.... if you did a wall that took up the last 2ft of the depth of the truck, and maybe cabin Fs raises to about 35hz, and then you try a wall built about the last 4 ft of the truck, and then the cabin Fs rasies to about 40hz, it is effected because the internal Depth of the vehicle changes... But now if you do a box no taller than the back seats, and woofer/port loaction is furthest back possible, you will get the lowest possible octave, at the highest DBs....

Your right, size of box matters, if you put in to consideration sub/port firing location... If the sub and port are dead in the middle of the vehicle, facing up, thats not exactly a great spl set up.... OR SQ/SQL

For the most part, I believe the cabin Res is about 30, not exactly 30, but from maybe 28-32hz depending on port sub location

Another thing to look at is, every octave above cabin Fs/Res, the octave gets stronger

30hz-60hz-120hz, ect ect

here is something to think about, for burping, or SPL, whatever your peak cabin Fs, if you double that, maybe swapable ports to double the tuning/Fs and if you can get a woofer to put out the same amount of air pressure- excursion, port velocity, etc, etc the meter will read higher due to the fact that the woofers cone/s are moving twice as fast as they are at the daily tuning, meaning more air movement, more SPL

Thats why all these HIGH spl people are using numbers like 80hz- cone is moving ALOT more

I studied this for 4years while at the speaker shop, we did almost daily RTAs on various cars finding the right octaves to do upgraded component systems, and factory replacement subwoofers- its really cool stuff, and I wish I had the money to do on such a larger scale than 6" and 8" subs

I have a Denali now, maybe with my $50 left over every paycheck, I may be able to do some serious building after 2 more years... lol

BTW- This is only if you dont have testing equipment, and need to do a rough guestimates on best numbers to use, if you dont have RTAs spl meters

like at home I didnt, but at the job, we used some pretty damn advanced $3000 software, not even counting the mics that costed $500 plus-Each, test amps, and everything else

[banginAltima]

You are right, and not talkin out your ass, thats for sure... the main reason for tuning to cabin resonance is that is the vehicles 1/4 wave length

The size of box matters when it DOES effect the placement direction of woofers, and port location (there is other factors as total port area/cone area and area between the woofers/port and width of truck and length of the box- above box and side to side)

Location is everything.... if you did a wall that took up the last 2ft of the depth of the truck, and maybe cabin Fs raises to about 35hz, and then you try a wall built about the last 4 ft of the truck, and then the cabin Fs rasies to about 40hz, it is effected because the internal Depth of the vehicle changes... But now if you do a box no taller than the back seats, and woofer/port loaction is furthest back possible, you will get the lowest possible octave, at the highest DBs....

Your right, size of box matters, if you put in to consideration sub/port firing location... If the sub and port are dead in the middle of the vehicle, facing up, thats not exactly a great spl set up.... OR SQ/SQL

For the most part, I believe the cabin Res is about 30, not exactly 30, but from maybe 28-32hz depending on port sub location

Another thing to look at is, every octave above cabin Fs/Res, the octave gets stronger

30hz-60hz-120hz, ect ect

here is something to think about, for burping, or SPL, whatever your peak cabin Fs, if you double that, maybe swapable ports to double the tuning/Fs and if you can get a woofer to put out the same amount of air pressure- excursion, port velocity, etc, etc the meter will read higher due to the fact that the woofers cone/s are moving twice as fast as they are at the daily tuning, meaning more air movement, more SPL

Thats why all these HIGH spl people are using numbers like 80hz- cone is moving ALOT more

I studied this for 4years while at the speaker shop, we did almost daily RTAs on various cars finding the right octaves to do upgraded component systems, and factory replacement subwoofers- its really cool stuff, and I wish I had the money to do on such a larger scale than 6" and 8" subs

I have a Denali now, maybe with my $50 left over every paycheck, I may be able to do some serious building after 2 more years... lol

BTW- This is only if you dont have testing equipment, and need to do a rough guestimates on best numbers to use, if you dont have RTAs spl meters

like at home I didnt, but at the job, we used some pretty damn advanced $3000 software, not even counting the mics that costed $500 plus-Each, test amps, and everything else

I just woke up a few minutes ago...so I am not thinking that clearly..... are you agreeing with me or insulting me.