exardus

Hey guys, i have a phoenix gold 10d sub that i want to make a ported enclosure for. and i have a few questions on designing of the box.

First of all i found that Vb is the required internal volume of the enclosure from some audio site, and it's equal to Qts^2.87*15*Vas so i got that to be 1.4 ft^3. Here's my first question, if i'm planning to build a box with a port as pictured below(it's the opening on the left), do i want to build my box that it has the volume of 1.4 of the hole deal, or the area that is not a port? Basically should 1.4 be the value to the blue line, to the grey line or all the way to the opening of the port.

Then Fb is the frequency that a vent needs to be tuned to. It's forumla is Fb = .42 * Fs * Qts^-.9 . Using this formula i got 24.35 Hz. Is this the same as saying that the box is "tuned to' 24.35 Hz. I herd that a good tuning frequency for a box that could be used for both sound quality and bass is 35Hz. So my question is should i go with the frequency that i got from the formula, or with 35Hz to do further calculations to make figure out port dimentions and so forth.

And another question in a box with the port like in my picture does a port end at the grey or blue line. Sorry if this is stupid but it's my first time dealing with ported boxed. Thanks alot for any input.

slickrick

iTrader: (12)

is this a pg TI sub? and where are the pix?

exardus

yes it's a ti sub, sorry i forgot to post the picture. Here it is:

http://members.***.net/exardus/box.JPG

2 Da Max

iTrader: (2)

well the ported boxes ive seen have a space where the blue line is. its supposed to be opened up at the blue line

2 Da Max

iTrader: (2)

i hope Polo doesnt mind

exardus

yeah, that was about what i was gonna do exept have only one turn on the port. So is the port area calculated from where the opening of the port to where the small piece of mdf ends? In other words, is that smaller rectangular part of the box where the port starts part of the port or part of the external valume. And what part of is is Vb?

Robert_J

It's part of the Vb, not part of the port.

Here's a design that's VERY close to what you want - link. Just make the driver opening smaller for your 10" sub.

-Robert

exardus

ok, so do i want the port to be tuned to 25Hz, or should i do it to 35Hz like alot of people do for a good mix between techno and rap. Basically does the port depend of a speaker itself or on whatever you want it ti be.

slickrick

iTrader: (12)

35 for sure with that sub.

exardus

So what's the use of this formula then? Fb = .42 * Fs * Qts^-.9 = 24.35 ? I just want to make sure that i don't blow my sub by putting it in that box. Do i need to adjust anything else besides the port like the Vb?

CBFryman

Read da siggy buddy...i design custom enclosures for donations... so they are free and a check in the mail is much appreceated. PM me or E-mail CBFryman@hotmail.com for details, include maximum dimentions, the sub name and modle, and a picture of the desired cargo area would be helpful but not needed.

exardus

Thanks CBFryman, but i think i got it down exept for the port tuning part. If you could just answer my question above i would be set. Since you probably do this alot, you must know what the Fb = .42*Fs/Qts^.9 formula is all about. Do you tune the port to this frequency or is it ok to tune it to another frequency without blowing the sub, or sacrificing some sound quality etc.

Maxima Dan

You're probably better off using some modeling program like WinISD pro to look at different alignments and how they effect cone excursion vs. frequency for any given power.

slickrick

iTrader: (12)

i have awhile ago when i wanted to port my 2 10" pg ti's...about 1.2 cuft per sub gross tuned to 35 looked good.

exardus

ok, so i've been playing around with winisd and bass box pro, so what graph do you want to be looking at to know if the sub will perform good or not. And what is the shape of it supposed to be. Like can you tell if the sub has a higher chance of blowing by looking at the graph?

CBFryman

tehe...i hate the formula....changing tuning will not blow any sub...now if you tune extremely high and play low notes the sub willl unload causing the coil to crash into the back plate if enough power is given. SQ is a personal question but for cars a good SQL box is generally tuned between the high 28's and low 30's.
Tuning the the Fs of a woofer will jsut result in a larger SPL gain over sealed than when compared to a different tuning...this is because the cone wants to travel more at the frequincy the box is tuning to restrict the driver the most.

Maxima Dan

The graph you want is typically called excursion. It's been a while since I've played with WinISD PRO (make sure you're using the pro version), but I know it will give you the info you need. The other WinISD beta doesn't.

The idea is to model the driver in the box and then specify a certian input (either voltage or power depending on the program and use P=V^2/R to convert). Increase the power until you are reaching close to XMAX on the graph.

slickrick

iTrader: (12)

also that sub can take 300-500 watts just fine in a ported box...it has good cooling capabilities. with an xmax of 17.5 it should have no problems either bottoming out on the power i recommend (unless you go for a large sealed box).