Finishing MDF Speaker Enclosure

[Jerry Solomon]

I'm planning to build powered subwoofer using 3/4" MDF for the cabinet. I think the enclosure will be a cube approximately 24" L/W/H. I'd like to have it looking suitable for the den as LOML will be less than enthusiastic about anything that looks a little too (shall we say) primative. Any suggestions on ways to make the exterior of an MDF box look a little more like furniture?

[Jim Becker]

Subs are usually placed out of the way so unless you need it to serve some purpose other than shaking the room...black comes to mind.

MDF finishes nicely as long as you prep any exposed edges well. I usually hit said edges with some lightweight drywall spackle, sand, apply another coat of the compound, sand, prime with two coats on those edges and then paint. This provides a really nice smooth surface. Your sub should be similar to some sculpture display boxes I built for a friend of LOML's and the technique I described worked out great. (Many museums build stuff this way these days.

Of course, you can always veneer it if you want that look!

[John Miliunas]

24" square? Holy smokers, Jerry! Whad...You gonna' have a 15" sub-woof in there?

Anyhow, once you have an adequate superstructure for the speaker (and I believe 3/4" mdf should do just fine), I would simply laminate and flush trim the exposed sides & top. What material you use for that would primarily be guided by the decor in the room you intend to use it in. For a cube, I've always personally been kind of partial to shiny jet black Formica*. For whatever reason, it seems to accentuate any object put on top, for instance, a nicely turned bowl or a neat lamp, ect... I guess it has that "art gallery" flair to it. Or, you can choose to laminate it to match or contrast with the general scheme of the room. If you do go with some laminate, the most important thing is to get 100% adhesion or you're bound to get "buzzing" when the sub is doing its "thumpity, thump, thump"! :cool:

[JayStPeter]

My theory is hide it in plain sight.
This is one of my first projects. It is a cherry veneered MDF box with solid cherry top and base.

[Mark Hulette]

Wow, Jay

I'da never known! Pretty cool and I just love cherry. Did you use a vacuum press? If so, pretty courageous as an early project.

Nice work.

[JayStPeter]

Mark,
No vaccum press. I just used contact cement and a "j" roller. It's paper backed veneer.

Jay

[Richard Allen]

Hi Jerry

Laminating with the wood of your choice can also turn a sore thumb into a show piece. Adding a little trim in the right places, like making one side appear to have a raised panel door or a gallery rail around the top can change a sore thumb into something that doesn't have to be hidden.

A cube is not a very attractive shape, worse, that shape is a bad speaker inclosure. A cube will provide a peak volume for a specific frequency and an attenuated volume at other frequencies.

The golden ratio is a good place to start for a speaker inclosure that delivers an even reinforcement over a broad range of low frequencies.

The golden ratio is also a good place to start for an attractive shape.

1.618 is the golden ratio.

There are other things to consider in a speaker inclosure beside shape. Interior volume, dampening material, port size, shape and length (if using a ported design). Different speakers have different requirements for the volume of the enclosure.

You can easily make the interior shape different from the exterior shape so it is possible to have a rectangle within a cube.

Good luck with your project.

[Jerry Solomon]

Thanks to all for sharing your ideas. Jay, your veneered cabinet is beautiful and my wife "approved" that finish as soon as she saw it. Being retired, I have plenty of time to think of projects and a friend proposed one to me recently. He has a sub in his car with 2 x 12" drivers. He wants to build something for his house and proposes to give me one of the drivers if I will help him with the woodworking. He has a sub design program that we recently used to build an enclosure for his fiancee's car. I currently have a 10 year old Paradigm PS-1000 sub. If the new design sounds better than the Paradigm, I'll keep it we'll build a second for his house.

I'll post a followup report later. Thanks again to everyone.

[Jim Becker]

He has a sub in his car with 2 x 12" drivers. He wants to build something for his house and proposes to give me one of the drivers if I will help him with the woodworking. He has a sub design program that we recently used to build an enclosure for his fiancee's car. I currently have a 10 year old Paradigm PS-1000 sub. If the new design sounds better than the Paradigm, I'll keep it we'll build a second for his house.

Geepers...I can only imagine how that will sound given the much smaller unit that came with our Sony "dream system" home theater setup can shake our entire great room during a movie at only half volume! The bigger driver must really rumble when appropriate to do so... :eek:

[Scott Greaves]

Hi Guys!

I like the idea of building your own sub-woofer. I would really like to do that. So, Jerry, Richard and Jay, how do I, a person who has never built a speaker, go about building a sub-woofer? Heck, it doesn't even need to be powered, as I have a powered sub out on my receiver! Are there places with plans? Suggestions on the driver? TIA

Scott.

[JayStPeter]

Scott,
I would suggest surfing over to adireaudio.com. They sell drivers and povide reference designs and box design software to "tweak" the designs. Once you prove to yourself that you can duplicate their results, you can find lots of "subbox" design programs/spreadsheets on the web. Adire also sells amps, but you can also try partsexpress.com for amps and drivers. The box design programs will allow you to put in the driver parameters so you can see what size box will give you the response your looking for.
The sub shown above was budget driven. It is a $15 driver with a $99 amp. Its output is very similar to my 12" Infinity, although the Infinity is a much much smaller cube. Because of the cheap driver, I had to build a large enclosure, 2 ft^3 to be exact. It was built to be part of a sub-sat system. It accomplished its goal of being wife friendly and sounding better than boze.
I plan to replace my Infinity in the living room with an end table built around the Adire Tempest driver using the Adire alignment. I will put some fake frame/panel look and possibly a fake drawer front on it. Believe it or not, this budget 8" sub made me realize how poor sounding the infinity is.
Here is a pic of one of the sats that go with this. I used a 3" adire driver and a small tweeter. Overall $55 worth of drivers and $10 worth of crossover. They were made from some scrap 1/2" MDF and covered with the same veneer as the sub. I made it a little bigger than I had to so it would integrate better with the sub. I designed the box to give the 3" space to respond down to around 110Hz. I believe the front panel is around 4x9".

Jay

[Scott Greaves]

Thanks Jay! I will check them out!

Scott.

[Hal Flynt]

I built my sub from out of 3/4" MDF except for the front baffle. For the baffle I sandwiched 2 @ 1/2" pieces with yellow glue and cut the outside one to the outside deimensions of the woofer and the inside to the inside demensions of the mounting flange (it's a 1 inch thick baffle with a 1/2 inch rabbet basically.)

I uses some dewaxed shellac to seal it, then 2 coats of black latex and 2 coats of the water based semi gloss poly. It sits kinda outa SWMBO sight and not very noticable.

[Boyd Gathwright]

Nice job

Boyd;)


My theory is hide it in plain sight.
This is one of my first projects. It is a cherry veneered MDF box with solid cherry top and base.