[Extended Power]

Using the port calculators...does it matter what size of sub is used?

If it's a 2 ft3 box, with a 12" sub and your tuning it to 32 Hz, it calls for say a 1.5 x 9 x 12" slot port.
Does it matter if it was a 10" sub or an 8"?
Does it matter if the port is on the same side as the sub surround?
Could the port be on the exact opposite side of the box?
Does it have to have an extension leg, or are they just to make up the port length if the box is too short?

 

[Extended Power]

Re: box size, sub size, pot size?

Title should read "port", not "pot".

 

[Extended Power]

Re: box size, sub size, pot size?

Using the port calculators...does it matter what size of sub is used?

If it's a 2 ft3 box, with a 12" sub and your tuning it to 32 Hz, it calls for say a 1.5 x 9 x 12" slot port.
Does it matter if it was a 10" sub or an 8"?
Does it matter if the port is on the same side as the sub surround?
Could the port be on the exact opposite side of the box?
Does it have to have an extension leg, or are they just to make up the port length if the box is too short?

-Of course it matters what size the sub is...a 10" sub does not move as much air as a 12" sub...

-Yes it matters which side the port is on...if placed in the wrong spot, it would cancel out the sound wave of the woofer.

-Opposite side might work...as long as the timing of the port and woofer are figured out.

-The port seems to be different for every change in Hz. And I'm not sure if the restriction of the 90* bend of a corner is even taken into consideration for the port length.


Any one see anything wrong with my own answers?

 

[cubdenno]

Re: box size, sub size, pot size?

-Of course it matters what size the sub is...a 10" sub does not move as much air as a 12" sub...

-Yes it matters which side the port is on...if placed in the wrong spot, it would cancel out the sound wave of the woofer.

-Opposite side might work...as long as the timing of the port and woofer are figured out.

-The port seems to be different for every change in Hz. And I'm not sure if the restriction of the 90* bend of a corner is even taken into consideration for the port length.


Any one see anything wrong with my own answers?

Sub size: Only thing that would change sub to sub is the enclosure volume lost from the speaker displacement. Generally an 8 is physically smaller than a ten is smaller than a twelve etc...

Port location: lots of "rules of thumb". Port location is usually not important. You just don't want to choke or affect tuning by placement.

Yes the port can be on the opposite side of the woofer.

Not sure what you mean by extension leg... A bend? like a 90 degree bend? or a 180?



For a port, you need to know desired tuning, enclosure volume and port area for the most simple of equations. What becomes important to know is subwoofer vd and power being used. the sub vd parameter is basically knowing the speakers area (sd) and xmax to determine the volume displaced by cone travel. This is the max number. Knowing the power that is going to be utilized lets a modeling program help better determine the port air speed. which becomes very important when designing a ported enclosure.

the more port area required to minimize air speed, the longer the port becomes for the same tuning.

Download WinISD and play around to help understand what goes on when you use a given sub in a specific volume on different power levels.

 

[Extended Power]

Thank you for your response.
That's why I was wondering about the size, and length of the port for different subs.

I'm using the JL12w7's, and the only volume they give under their spec's page is the volume of the sub itself. (0.14ft3)
I'm at work, and only have my iPad, so I can't seem to get the program to work..it just sits there, so I will have to work it out when I get home...unless someone already has the program and wants to crunch the numbers for me?

1 JL 12-w7 per box.
Box will be 2.2ft3 internally, with the volume of the sub taken out. (No volume for the port taken off though.)
Amp is a JL 1000/1v2
Trying to tune it for 32-33Hz.
The box will be facing the amp rack/rear wall of the truck cab, sitting between the rear bucket seats. (~6" away from the amp rack.)

JL spec's

Where one sub will sit.

 

[cubdenno]

2 subs or one?

 

[Extended Power]

2 subs or one?

One sub between the the rear seats, and another one between the front seats. (Both sets are bucket seats.)
Front one will probably be bigger yet, as it can extend forward more, and create a more "console" style box, than just "Box".

 

[Extended Power]

Here are some sketches.
I used ink in the one drawing, and it put the sub on top, instead of the port, and it just isn't right...sorry.

 

[YukonXL04]

You sir need to download Google sketch up lol...

 

[Extended Power]

Not really.
See I have what's called an imagination.
You may not be able to see it the way I do...but in the end, you will.

I don't need a 100% accurate drawing to figure out what it's going to look like when it's done.
But thank you for the suggestion....I looked it up, looks pretty good...I just don't have time to learn about another program right now.

 

[sed8ed]

It seems we are doing a very similar layout in our trucks... I finally surrendered and paid to have my center console box designed.

Build log and picture of the box rendering.
http://www.diymobileaudio.com/forum...l-gallery/172108-sed8eds-2013-f250-build.html

The sub I am using has a deeper mounting depth than yours and I have 4" of clearance below the sub for excursion. In your case, what if you were to do a design similar to two of my boxes end to end with one sub in each?

What is your maximum width between the front seats and between the rear seats? Mine is 15.25 inches, I'm just wondering if Ford kept the dimensions constant.

Keep in mind as well that the W12gti sub requires about 30-40 percent more box volume than your W7 so you would be able to shorten the rear box significantly. The trim panels I am making for the sides of the console will fit flush with the dash and the arm rest is at the original factory height. There will be 3 cup holders in the lower part of the box as well as my VHF radio.

 

[YukonXL04]

Not really.
See I have what's called an imagination.
You may not be able to see it the way I do...but in the end, you will.

I don't need a 100% accurate drawing to figure out what it's going to look like when it's done.
But thank you for the suggestion....I looked it up, looks pretty good...I just don't have time to learn about another program right now.

Oh I can easily see it the way you do. But I just find it easier to visualize it in the program. But I also suck at drawing.

Carry on.

 

[Extended Power]

It seems we are doing a very similar layout in our trucks... I finally surrendered and paid to have my center console box designed.

Build log and picture of the box rendering.
http://www.diymobileaudio.com/forum...l-gallery/172108-sed8eds-2013-f250-build.html

The sub I am using has a deeper mounting depth than yours and I have 4" of clearance below the sub for excursion. In your case, what if you were to do a design similar to two of my boxes end to end with one sub in each?

What is your maximum width between the front seats and between the rear seats? Mine is 15.25 inches, I'm just wondering if Ford kept the dimensions constant.

Keep in mind as well that the W12gti sub requires about 30-40 percent more box volume than your W7 so you would be able to shorten the rear box significantly. The trim panels I am making for the sides of the console will fit flush with the dash and the arm rest is at the original factory height. There will be 3 cup holders in the lower part of the box as well as my VHF radio.

I'm at work right now, and the pictures don't show up.
I will def look up your build tonight when I get back to camp.

Here is my build: http://www.diymobileaudio.com/forum...71891-2003-ford-f350-king-ranch-4x4-ccsb.html

 

[Extended Power]

Re: box size, sub size, pot size?

Sub size: Only thing that would change sub to sub is the enclosure volume lost from the speaker displacement. Generally an 8 is physically smaller than a ten is smaller than a twelve etc...

Port location: lots of "rules of thumb". Port location is usually not important. You just don't want to choke or affect tuning by placement.

Yes the port can be on the opposite side of the woofer.

Not sure what you mean by extension leg... A bend? like a 90 degree bend? or a 180?



For a port, you need to know desired tuning, enclosure volume and port area for the most simple of equations. What becomes important to know is subwoofer vd and power being used. the sub vd parameter is basically knowing the speakers area (sd) and xmax to determine the volume displaced by cone travel. This is the max number. Knowing the power that is going to be utilized lets a modeling program help better determine the port air speed. which becomes very important when designing a ported enclosure.

the more port area required to minimize air speed, the longer the port becomes for the same tuning.

Download WinISD and play around to help understand what goes on when you use a given sub in a specific volume on different power levels.

Thank you for the email.
I am at home now, and will try to download the program and see if I can figure a few things out.

 

[cubdenno]

Re: box size, sub size, pot size?

Thank you for the email.
I am at home now, and will try to download the program and see if I can figure a few things out.

No problem. Hope it helps at a minimum as a reference.

 

[Extended Power]

The WinISD program I downloaded only has round ports in it.
And when I plug the sub spec's in, it tunes it to 22.3Hz.

Any way to change the shape of the port from round to rectangle?

I'm probably going to use the measurements you sent me, but am curious why the port size changed from 3.5 to 2.5"

When calculating the volume of the box, do you include the port volume as part of the box volume?

 

[cubdenno]

PM'd

 

[cubdenno]

The WinISD program I downloaded only has round ports in it.
And when I plug the sub spec's in, it tunes it to 22.3Hz.

Any way to change the shape of the port from round to rectangle? Yes. Clik on the round symbol to make it square.

I'm probably going to use the measurements you sent me, but am curious why the port size changed from 3.5 to 2.5" To lower the tuning frequency for the given port length. it was about 40-43 hertz.

When calculating the volume of the box, do you include the port volume as part of the box volume?

Nope.

Answers in red.

 

[Extended Power]

If I wanted to tune a box from say 40Hz down to 32-35Hz, do you make the port bigger/longer, or smaller/shorter?

I'm guessing it would have to be bigger...to slow down the air velocity, and reduce the amount of compression the sub creates inside the enclosure.

 

[cubdenno]

If I wanted to tune a box from say 40Hz down to 32-35Hz, do you make the port bigger/longer, or smaller/shorter?

I'm guessing it would have to be bigger...to slow down the air velocity, and reduce the amount of compression the sub creates inside the enclosure.

It depends. If in the design stage it can be fairly easy.

But for a given enclosure volume (this doesn't change in theis exercise)

If port area stays the same: port length gets longer

or
Port area gets smaller with same port length.

If port area gets larger (to lower port air speed): you have to make the port longer (even to maintain the same original tune)

Examples:
2 cubic foot enclosure tuned to 40 hertz
4"ID round port
40 hertz:7.61" long
35 hertz:10.84" long
30 hertz:15.81" long
(per WinISD)


Same enclosure
3" ID Port
40 hertz:3.73" long
35 hertz:5.55" long
30 hertz:8.34" long
(per WinISD)


Going bigger:
Same enclosure
6" ID Port
40 hertz:19.32" long
35 hertz:26.58" long
30 hertz:37.76" long
(per WinISD)


Hope this helps