Determining Ports & Tuning

I've looked around, but need some help with this.

I would like two ports. I've decided to go with a Rectangle/Square Box design.

Sub = Shiva 12" (haven't purchased yet)

Ported Box Dim.:

Widthx4 = 35"
Depthx4 = 7"
Heightx4 = 14.5"

The problem I'm running into is that I do not know the tuning Frequency of Shiva Sub (or if it is something you determine on your own).

Also do not know what length and Diameter I need for the port? ( i know there is a calc you later here where I can plug in the number, but not sure about the Tuning Freq.).

Please let me know your comments. Thank you!

Is there anyone out there willing to help?>

https://www.adireaudio.com/Files/ShivaWhitePaper-V2.PDF

Volume calculator

Read the paper completely, as it is loaded with information on the Shiva.  It looks like a small sealed box is the favorite way to go with this sub, but if you want to use a vented enclosure that is addressed in the white paper, too.  I suggest you contact https://www.adireaudio.com/ tech support, give them your box volume and let them know you want to use two ports.  As I understand, Adire's tech support outshines most others so you might as well get the most out of it.  And you should go ahead and purchase the sub, too....that might help.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Whoa.

*You* need to do a bit of homework.


I designed a ported box with the help of the excellent tutorials on JL Audio's website. Try reading this.

Why do you want two ports?

Thanx for the info stevdart!!

I ask questions because I don't know the answers. That is what forums are for.

I do not know all that much on Ports or Port tuning *AT ALL*.

I was just hoping for some feedback on how to approach the problem at hand or suggestions.

Homework is indeed what I need. But now that I have some places to look to do the homework, I can check it out.

sedate: To answer your question, I don't "need" two ports, I just thought it would even out my box design. But since I do not know that much about ports or how to tune them, how am I supposed to know if more than port is not needed or not recommended.

What is port tuning and do you tune a port? Is it a spec from the driver that you are installing or is it a setting that you set based on personal sound?

I read the whitepapers and you are right stevdart. They recommend a sealed box for this woofer which is fine. I just heard vented boxes provide you with a better sound for techno and such since the bass response is better. I use a Sealed box for the subs I currently have and they sound great. Sealed have a tighter sound to it.

I'll do as suggested and contact Adire for some help my box design. Thanx for your help guys!

Tuning a port is focusing what frequency it will react the most efficiently at I believe. I could be mistaken. Like tuning it to 50Hz or something of that sort, so when the sub hits there, it sounds beautiful. Could be mistaken tho.

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One important thing you need for a vented enclosure is a driver (sub or mid, whatever) that is specifically designed to be used in a vented enclosure.  The Shiva has an EBP of 51 which puts it into the "sealed" catagory.  It has to do with the relationship between Fs and Qes.  Manufacturers (such as the Adire folks) design subwoofers for a variety of applications, knowing that in real life people have a wide variety of application needs.  What you hear about one type of box being better for techno, one type being better for sound quality...etc etc. is just that....chatter without substantial basis of fact.  The Shiva in a sealed enclosure built to specs and powered properly will do techno justice, you can be sure of that! 

Don't ever waste time working up the "perfect" enclosure for a Blue Light Special subwoofer, though..........it's hit or miss with the low-end junk drivers.  Usually miss.

A first-time builder should master a sealed box before he ventures into the realm of ported.  Then, following the manufacturer's specs in all regards should usually net you a fine vented box.  But to design a vented box otherwise means to invest time and study... time and study.  If you're starting with very little knowledge of all things acoustical it takes literally months and months of research and study to learn enough to successfully pull it off.  But it's fun and rewarding getting to and reaching that point.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.