[joorge]

There’s a thread around here detailing how I came to build this particular sub. I got lot’s of help from MikeP and from reading the threads.

I have size constraints and this box (2.77 ft.) is the largest that will fit where it has to go. The $300 budget explains most of the rest. The mix is 50/50 HT/music. I wanted something that was not straining to play at 75dB with room for a 30 dB pop from special effects.

It was going to be a 20Hz tune until I noticed a discrepancy in the T/S numbers between Dayton and PE. Now, it's closer to 22Hz.

Dayton Spec PE Spec

Le: 3.17 Hz 2.5
Fs: 22.2 Hz 25
Vas: 2.61 cu. ft. 2.27
Qms: 6.12 7.03

PE checked it out and said their specs are correct. Apparently Dayton has not updated in some time. A friend is building the box and all the parts were cut to size based on Dayton specs. I had to just live with the result.

I managed to have the port length adjusted, but not the area. It could get chuffy at high SPLs and low Hz. I don’t think it will make much difference in normal use.

The photo should explain the box construction. I’m using a folded, square port and a Dayton 240W plate amp.

 

[Owen Bartley]

Looks like you're off to a good start George. Nice looking bracing too. I'd be interested in the details on that port, can't wait to see how you build it in.

 

[joorge]

Thank you. The port is just a square made out of MDF. It has a common wall with the left side and bottom of the box. It makes a 90* turn upward about 3" from the rear of the box and uses the left side of the box as a common wall.

The ends will be "flared" slightly with a round over bit. Surprisingly, it didn't affect volume much compared to a round port with a 90*.

If there was enough room to use a round port with nice flares, I would have done so. This seems to be a decent solution compared to increasing box size. Here is a sketch of the 4 pieces necessary to make the port. Ignore the dimensions as they are not accurate.

 

[Owen Bartley]

Sounds like a good plan to me. Any way to round over that inside corner where it does the 90*? That shouldn't be too hard, but finding something like... "reverse" quarter round for the outside of the bend would be interesting too.

 

[joorge]

I have seen pictures where those techniques were used. I just rounded over each end. For this design and intended use, it didn't seem necessary. When producing 105dB, airspeed is only about 17 m/sec.

 

[joorge]

Gluing the Port.

 

[Owen Bartley]

Looks good George. So you rounded over the opening in the box then?

 

[joorge]

No rounding yet. Will do as much of each end of the port as possible.

Just want to restate that I am not doing this work. A friend is doing it for me. I use first person descriptions cuz it's easier.

 

[jmuir]

George, the blocks in the port kind of defeat its purpose. :whistling: :rofl:

Jokes aside, your friend is doing a great job!

 

[joorge]

The blocks are optional plugs for sealed box use. They are easily removable with a 4" hole cutter on a 12" extension.:bigsmile:

 

[joorge]

Gluing it up. The right side is not glued - just being clamped in position to keep things square. The right side will be removed and the braces installed when the glue dries.

 

[joorge]

It's all glued up. Bracing used up 3.8L. Looks like a lot more.

 

[Owen Bartley]

George, that's a lot of bracing! No worries about that sub being solid... nice work. Looks like you have a lot of filling to do next!

 

[joorge]

No filling for me! My friend is doing it. Seems like the longer I leave it, the more he does. Maybe I'll get a nice paint job if I wait long enough. :jump:

I discovered 2 things about the bracing. There is a lot more of it than I realized from making the sketches. The difference between all of that bracing and no bracing at all results in less than 1Hz increase in tuning.

 

[joorge]

I finally got the box!! The UPS monkey tried his best to damage it, but was defeated by superior packaging. I'll have to do some minor filling and sanding.

I installed the H-nuts with a dab of glue and used the woofer and mounting bolts to clamps it and keep the nuts square to the bolts while drying.

Here is a pic of the glue drying. Also one of a cheap PE 15" grill I'm thinking about using.

 

[Mike P.]

Looks like it time for a test run!

 

[joorge]

Almost! The weather is too good for painting to mess around. Temp 72, humidity 50%, hardly any wind. I put the foam in this morning and should have the primer finished today. May have the paint finished tomorrow. Then I'll test.

 

[Owen Bartley]

Good man... resist the temptation! How many of us have hooked up a new unfinished sub "for testing" and still been looking at an MDF eyesore 6 months later?

 

[joorge]

Been there, done that. I am gaining ground on the WAF thing and don't want to give up any attaboys.

 

[headknocker]

The sub and enclosure look great! It actually looks too good for that grill.:bigsmile: IMO, that grill looks out of place on such well-crafted project.