Ported Subwoofer Build Projects

**bluejay** · **01-07-09, 06:59 AM**

Quote:

I don't see that term "EBS" used too often.

I am pretty new to subwoofers, all of Home Theater in fact. EBS and LLT are equally new to me as well. I did not know what either meant 2 weeks ago. I did notice that two of the tuning choices inside WinISD are described as EBS 3db or 6db.

After reading the LLT description a couple of times I came to the conclusion that my chosen design was not aiming low enough to meet LLT criteria.
This has a lot to do with my budget on this project. I was up in the air for a long time choosing drivers. For an extra $100 or so I could have procured a driver more suited to LLT, something lending itself to flatter response below 18 Hz.

So for now I will enjoy all I can with an extended bass shelf design using the MJ-18m. If the cash crunch ever lets up around here I can easily upgrade to an IXL-18.2.2. I think that is a better subwoofer for a large and low tuned box, based on playing around in WinISD for only about 1 week.

**ISLAND1000** · **01-07-09, 10:31 AM**

Your project is gonna produce some prodigious bottom end. The box will probably need more braces. I built a similar sized ported box using an 18" Pro driver and began with 2x4 braces spanning the center of each panel. It wasn't enough bracing. The panels would vibrate at higher dbls at certain frequencies and it was perceptible. At lower volumes it wasn't. Try yours and see.
The IXL 18 2.2 IS an excellent driver. Others have used it and rave about it.

**tcarcio** · **01-07-09, 11:17 AM**

Build looks great, Have you decided on a finish?

**bluejay** · **01-07-09, 12:49 PM**

Quote:

Build looks great, Have you decided on a finish?

Yes, I picked out a green paint yesterday. I am trying for an environmentally friendly sub.

The next pictures are before and after I siliconed the port tubes in. I also squeezed a bit of no nails adhesive into a few gaps to see if that product will stand up to subwoofery. I have heard good things about it from my cabinet maker friend.

http://www.hometheatershack.com/forums/attachments/ported-subwoofer-build-projects/11435d1231353775-ported-ebs-build-pics-img_4138.jpg
http://www.hometheatershack.com/forums/attachments/ported-subwoofer-build-projects/11436d1231353775-ported-ebs-build-pics-img_4139.jpg

**ISLAND1000** · **01-07-09, 01:06 PM**

I just love lookin down the throat of that sub and seein all the innards and stuff. Great photography.

**bluejay** · **01-08-09, 07:27 AM**

Quote:

The box will probably need more braces. I built a similar sized ported box using an 18" Pro driver and began with 2x4 braces spanning the center of each panel. It wasn't enough bracing.

Now that I look at it some more, I am hoping the actual tubes and their mounts are going to aid in this problem.

Quote:

I just love lookin down the throat of that sub and seein all the innards and stuff.

Me too. If something loosens up in there, I will definitely hear a rattle or buzz of some sort. That being said, my cabinet maker friend swears by the strength of glue over mechanical fasteners so I have to give his theory a try. I used his shop and he gave me a hand when 4 hands sped up the process.

**Mike P.** · **01-08-09, 07:45 AM**

Looks like it's time to install the sub and fire it up.

**Quake25** · **01-08-09, 07:48 AM**

Looking good so far! Have you decided on a batting and/or fill? I am still considering these materials myself.

Just ordered my Driver and Sub...I'm right behind you!

**bluejay** · **01-08-09, 08:35 AM**

Quote:

Have you decided on a batting and/or fill? I am still considering these materials myself.

I am semi allergic to pink fiberglass insulation, so definitely none of that. I don't want to have light fasteners like staples, detaching inside and gumming up the magnet. The inside will be hollow as you see it.

I just do not think I will be that hard to please. I need a sub do dump off the low frequencies present in home theater, so my other speakers don't over excur. Plus the music these days contains tons of low frequency tones, boom boom boom. My regular speakers make tympany sound like tympany, cello sound like cello, and guitar sound like guitar. I expect the sub to make boom boom boom sound like boom boom boom.

I am not trying to oversimplify the subject or make light of the technical details. I just think I am not that hard to please and batting won't help make it better to me.

**ISLAND1000** · **01-08-09, 10:15 AM**

Quote:

bluejay wrote:

I am not trying to oversimplify the subject or make light of the technical details. I just think I am not that hard to please and batting won't help make it better to me.

There are some technical considerations regarding acoustics and physics using batting. But since your box and driver combination wasn't an attempt to use a smaller box than optimum for your driver and desired frequency response then the only reason you need batting is to reduce internal reflection. There is even a debate over whether ANY batting is needed. But since egg crate foam is easy to obtain and it's cheap and it's easy to install, I say cover the inside with some foam. It makes a "box" seem a little bit more complicated for those that "don't know anything" and need to be impressed with your sonic accumen.

Advertisement