Guy’s

I am in need of some help. I am making a custom sub box for my 04 Z. I have no problem getting the internal volume required for a single Boston 10” G2. The problem is my box design will not allow a 3” port 10” long. Can I use two 3” ports @ 5” long each? This is the same volume but does the port length affect the tune??? Can someone with software help me out?

Thanks in advance for the help

Monty

 

2 3" ports is not the same. Is it possible for you to bend the port inside the enclosure? It does not have to be straight.

 

Hi,
Thanks for the fast reply. I may be able to put an elbow on it. I will have to check it out. If I can't what are my options??? Can I use a 4" pipe and if so how long does it need to be? The guys at Boston have not returned my email. This has got me at a stand still.

Monty

 

I wish I could answer that but my software is not on this computer. I bet you can find something for fre on the net. Try doing a search for "port calculator" or "port dimensions". I will look to see if I find something.

 

Check this.

http://mobile.jlaudio.com/support_pages.php?page_id=165

 

hey randy, how about a flexi port? are those any good?

 

Well I was not expecting a longer port lenght for a multi-port design. If I can't fit an elbow on the 3" port then I will give up and do a sealed box. Either way Boston has recommended internal volume for both types. I could always use the second 10 I have and do 2 10's in a sealed box.

BTW whats a flexi tube????

 

it's a port tube that allows you to bend it around (think coil) so you can easily get the desired port length. ive never built a ported box so i dont know how well they work, they could work great for you though

 

I will look into it.

 

you can probably find them cheaper, but:
http://68.208.124.66/dealer/items.as...atus=0&Tp=&Bc=

 

They work very well. I have used them several times and I like to epoxy the port in place so it does not vibrate free...I do that with PVC also.

 

There is a lot of box and port info and calculators at the12volt.com . Brian steels page.

 

WinISD is great software to help with port design. You might want to look into trying a slotted port.

Look for winisd alpha, its free.

 

WinISD is a great program. I use it quite often.

To recap the tuning question: a 3" port that is 10" long could be replaced with other size ports... depending on the application.

Port size can be funny... go too small (diameter... or area in all cases) and you can get 'port noise' due to too much air velocity from the port. Go too large, and you lose the reenforcement that the port gives you.

A port with a smaller area (2" port for example) will require a shorter length, whereas a larger port (4" port for example) will require a longer length to tune your box to the same frequency.

That being said, you can replace a 3" round port with a square or rectangular port, so long as the port area is the same. In other words, a 3" port (pi*r^2... 3.14*1.5"^2 = 7.065" total area) can be replaced with a port that is 2.65" x 2.65" square and 10" long. It could also be a 3.53" x 2" rectangle that is 10" long.

If you want, you can build the port as part of the box, and fold the port along the sides of the box. Just make sure that the port is open to the box and not too close to any one side. (The sides of the box would become part of the port... makes it kinda unpredictable in tuning. Might not be a problem in a car environment.)

If you have the info on the driver, we could help come up with a design for ya. Hope this helps.

Mark