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View Full Version : What does it mean to "tune" a box?



klepto
09-14-2006, 07:56 PM
Simple question here guys. Im just curious what it means when you build a ported box "tuned" to a certain frequency. What tunes/box sizes would you want for different applications. For example, what is the difference between a box tuned to 32hz and a box tuned to 28hz. Is the tune manipulated by the square inches of the port or by the size of the box? The reason im asking is because i will be doing my first ported box build for my SI Mag 12'' when it comes and i want to have everything perfect for my tastes.

mikey060
09-14-2006, 08:38 PM
determinded by port area, 28 would play lower then 32. less output too but it would shake yo nuts

lol i do beleive...i could be wrong

PV Audio
09-14-2006, 08:48 PM
Wrote this in a thread yesterday, hope this quicky helps:

Port tuning depends on three things: port area, port length, and internal volume. There's a relationship between the three. Given the same box for each experiment, here's what happens:

a. an increase in port area increases port tuning and requires either a longer port length (and conversely more Vb to compensate) or more internal volume

b. an increase in port length MAY and USUALLY does give you a lower tuning, but it lowers the Vb. If your box is already too small, increasing port length is futile because the more airspace u take away, the higher the tuning will get

c. an increase in internal volume will always lower port tuning no matter what the other two are doing

klepto
09-14-2006, 09:30 PM
Wrote this in a thread yesterday, hope this quicky helps:

Port tuning depends on three things: port area, port length, and internal volume. There's a relationship between the three. Given the same box for each experiment, here's what happens:

a. an increase in port area increases port tuning and requires either a longer port length (and conversely more Vb to compensate) or more internal volume

b. an increase in port length MAY and USUALLY does give you a lower tuning, but it lowers the Vb. If your box is already too small, increasing port length is futile because the more airspace u take away, the higher the tuning will get

c. an increase in internal volume will always lower port tuning no matter what the other two are doing

How do you determine this tuning, with some sort of program?

PV Audio
09-14-2006, 09:45 PM
There's a formula:

Lv = (23562.5*Dv^2*Np/(Fb^2*Vb))-(k*Dv)

where,

Dv = port diameter (cm)
Fb = tuning frequency (Hz)
Vb = net volume (litres)
Lv = length of each port (cm)
Np = number of ports
k = end correction (normally 0.732)

I use the formula still, but do most on the computer as the computer doesn't make pencil mistakes :)

Trey803
09-14-2006, 09:47 PM
I remeber thet first time I heard of tuning I had the same questions and was just as confused

jeepintn
09-14-2006, 09:49 PM
like i explain it to my friends... basicly, tuning will determine if u have a "late night tip" setup, or a "bia bia" setup

PV Audio
09-14-2006, 10:03 PM
like i explain it to my friends... basicly, tuning will determine if u have a "late night tip" setup, or a "bia bia" setup

What? :uhoh:

Lil_KB
09-14-2006, 10:08 PM
What? :uhoh:

I'm gonna guess and say he's talking about it will determine whether you hit the lows in late night tip or the higher tuned frequencies in bia bia better.

jeepintn
09-14-2006, 10:08 PM
What? :uhoh:

easily describing the difference in Hz that your system could be tuned to... if i were like "33 hz instead of 40 hz", they would be like "umm, ok, wtf does that mean? jsut making it simpler to undertand, the higher the number, the higher the note, hencer closer to the song "bia bia" than to "late night tip"

klepto
09-15-2006, 12:04 AM
So what is an average tuning freq, like around 32hz? Wahts the best frequency to play all types of music?

jeepintn
09-15-2006, 12:06 AM
its really all based on the individual man... i would suggest using round ports if your unsure of what u wanna tune to, so it would be easier to change your tuning and experiment a bit.

PV Audio
09-15-2006, 12:15 AM
So what is an average tuning freq, like around 32hz? Wahts the best frequency to play all types of music?

I'd do 30-32 depending on subs and what you have available.

And jeepin, I get ya now :)