Hey guys,
It's been a while since my last post, mainly due to real life stuff, but I thought some of you may be interested in a project I've decided to undertake over the easter break; a powered subwoofer for my PC. I've been using a Sony 12" powered sub for a while, but I decided to sell the Sony, buy a new woofer and amp and build a custom enclosure from scratch.
The main parts needef for the build, MDF (medium denisty fibire-board), the woofer and amp:
The woofer I've chosen is the Response Precision 12", which are sold in Australia through Jaycar electronics. I'm not sure who the OEM is, but they're a very high quality woofer, with a kevlar composite cone, dual 3" voice coils and a massive motor structure. RRP is $249.
The amplifier is also sold through Jaycar. In this case I'm using the 350wrms monoblock, which is an old model and no longer available (their new models are a 150 and 600wrms version). Normally, the amp would be mounted in the back of the enclosure, but I've decided to build a seperate enclosure for the amp, so the woofer enclosure can be made as small as possible.
I used a free subwoofer enclosure calculator called AJSealed from AJDesigner.com, to calculate the optimal enclosue volume for the woofer, which is approximately 40 litres. I'm using 16mm MDF for the enclosure, which will have an internal volume of just over 45 litres, but once the woofer and bracing is in place, it will be very close to 40 litres.
Keeping the wood clamped firmly is extremely important. The piece of right angle aluminium was used as a guide for the circular saw.
With the sides of the enclosure cut, I test fitted the pieces to make sure everything lined up.
Cutting the hole in the baffle for the woofer is a fairly easy process with a router and a quickly made guide. I used diagonal lines to find the centre of the baffle, while a piece of sacrificial wood is used to protect the table.
The guide is bolted to the router and then screwed to the centre of the baffle and through the piece of sacrificial wood. The baffle is also screwed down in one of the corners to prevent it from moving.
The guide allows the router to swing around in a perfect arc, cutting the hole (and creating a ton of dust).
The result: A perfectly round hole that doesn't require much finishing.
Since I'm using 16mm MDF, which is slightly thinner than ideal for a subwoofer enclosure, I decided to double up on the baffle and cut one hole slightly larger than the other, allowing the woofer to sit in the recess. It's not really necessary, but it looks a little bit nicer in my opinion. The two pieces are glued, clamped and left to dry overnight.
Assembling the box. The pieces are glued and then screwed together. A set square helps to ensure the assembly goes smoothly.
The partially assembled box, with the downward facing baffle left to go.
I used a basic white sealing compound in the corners in an effort to ensure the box will be air tight. Leaks will affect the woofers performance.
That's it for now. Hopefully I'll have it finished soon and I'll update with more pics then.
Yeah, you gotta be careful not to breathe in the dust created by MDF, it'll gum up your lungs really good! Proper dust protection must be worn!
True, it is pretty noxious stuff. I've found a lot of timber places won't even cut it to size for you due to OH&S regulations, which is the reason why I'm cutting it myself.
Yeah, without proper dust collection, you shouldn't really be cutting it with power tools.
MDF is basically sawdust and glue bonded under pressure. When you cut it and blow that combination up into the air and breath it in, you can get the glue and dust re-bonding in your lungs...which is probably bad.
I hope you wore a dust mask at least.
Shit Atmo that's going to have some power - I hope that you strap yourself into your seat before you fire that baby up.
AWESOME! I could never do it though - I value all my fingers and I have a history of trying to cut them off...
Herne: Yes, I always wear some form of dust protection when working with MDF.
A few braces were put in place before mounting the baffle. I would have preferred the braces to be closer to the center of the box, but due to the depth of the woofer's basket, they had to be moved back.
The baffle was then installed, screwed and glued in place and then sealed (apologies for the poor photo)
The whole box was then sanded back to remove any raised lips where the panels joined.
I then filled all the gaps, screw recesses and any low spots with automotive body filler.
After more sanding, all surfaces of the box were nice and smooth. This shot shows the baffle partially done.
Next, I cut out a section in one side for a terminal plate.
Test fitting the plate.
With the box nearly complete, I threw on the first coat of acrylic black paint, applied with a foam roller.
After one coat, here's how it looks.
The box still needs to be sanded back and the second coat of paint applied, then the woofer, terminal plate and feet can be installed.
Sorry for the lack of updates, i finished this a few weeks ago but forgot to post the final pics.
The paint job mostly done.
The woofer, feet and terminal were then screwed in place.
The setup sounds really nice, it's got plenty of output for a 12" and has a very linear response, while still being really punchy. It's far better than any pre-built ~$1000-1500 powered HT sub I've heard, so for ~$600 and about 10 hours of work, I'm really pleased with the result.
Thanks Atmo!! Awesome work and looks sweet.
Did you make the feet or did you fine some pre-built ones somewhere?
That looks good - now you have to work on an "Atmo" logo to throw on the side.
Looks very cool. Does it sound good.
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