Home Audio Sub Build

**StereoClarity** · **09-15-09, 12:17 AM**

I've been kinda migrating over here lately from one of my other forums and I thought I'd bring some of my build logs over here to help spur some ideas. I know I always like to see what other people are doing so I figured you guys might too. I built this sub initially for a friend as a wedding gift. I built him a full 5.1 system.

The motor structure on this sub is a work of art and I just couldn't hide it. This was my first application for the DIYMA R12 sub and I wanted it to be special. I think I got my wish because the final product really brings a smile to my face.

Here is what we are starting with. The DIYMA sub, a pile of hardware, solid 4ga copper and not shown is an ED LT550 plate amp and a pile of wood.

Here is my quick mock up while clamping the front baffle. Let me take a moment to explain my deign. The sub mounts to the front double baffle and is countersunk to be flush with the front. The small chamber on the left side in the picture below is for the plate amp. I didn't want to have the amp in the subs' airspace because I don't want to compromise a side of the box by cutting out the wall for the amp. Also, I wanted to let this amp breathe and cool off which posed a problem since the heatsink is on the INSIDE of the amp...retarded I know. I'll show you how I accomplished this in a bit. Lastly, the DIYMA motor structure is too beautiful too hide so I'll be using a plexiglass window on the top to allow it to be seen.

I'm all about the threaded inserts now. These things are waaaay better than T-nuts!

I wanted to use solid copper instead of wires. Why? Because it looks five million times cooler that's why! I needed to find a way to straighten the copper since it came rolled up. I decided to roll it between two sheets of MDF with all 145lbs of me (cross country runner) on top of it. It worked very well to my surprise!

So now that my copper was straight I needed to find a way to make uniform bends so I could get around the subs' motor structure. I first zip tied the copper pieces together at a few intervals so I could bend both pieces at the same time and get both of them the exact same shape. I used a can of 3M 90 spray adhesive as a guide around the magnet. It was the perfect diameter and actually stuck to the bottom of the magnet which was great since I didn't have to hold it.

Now that I had made my bends I had to test fit to see if it works....perfect fit!

**StereoClarity** · **09-15-09, 12:18 AM**

Here is the box with the top being test fitted. You can see here how big the window will be. At this point in the build stage I had to build the rest of the box around the copper so I couldn't remove it. I decided to cover it with a bag so it wouldn't get junk on it. Note the threaded inserts used here. I love these things.

Here is the rear compartment where the amp will mount. I drilled some holes in the bottom of the compartment so air could flow up through the bottom and out the top vent that I had made. Here is where I terminated the copper leads too so they could be connected to the amp.

Here is the box after some round overs and some sanding.

**StereoClarity** · **09-15-09, 12:19 AM**

After some primer and more sanding I did a coat of paint. Let me first admit that I suuuuuuuuuck at painting and I loath it. But, this time I was using some foam paint rollers that worked well. I wanted a smooth finish but yeah...that didn't happen. What did happen was actually even cooler. The rollers left a sort of texture that I ended up liking quite a bit. The second picture is with the paint dry after two coats.

After the paint had dried I connected the amp wires to the copper leads and mounted the amp. More threaded inserts were used. Check out the vent at the top. I think it came well.

I couldn't use plolyfill on this box since you could see into it. This meant that I was going to use some acoustic foam that Mir and I had ordered last summer. All walls except for the plexiglass (for obvious reasons) were lined with the foam. I used carpet tape which is my newest favorite toy. It's like duct tape that is double sided. It's strong as hell and keeps two things stuck together flush. Pretty cool stuff! It was perfect for what I wanted to do and I'm glad it was suggested to me.

Now with everything finished all I had to do was pop the sub in and seal up the glass top. I used speaker gasketing tape on the plexiglass because I refuse to build a leaky box.

Here she is all finished up!

**robertcharles123** · **09-15-09, 12:24 AM**

Quote:

ItalynStylion wrote:

Here is the box with the top being test fitted. You can see here how big the window will be. At this point in the build stage I had to build the rest of the box around the copper so I couldn't remove it. I decided to cover it with a bag so it wouldn't get junk on it. Note the threaded inserts used here. I love these things.

Here is the rear compartment where the amp will mount. I drilled some holes in the bottom of the compartment so air could flow up through the bottom and out the top vent that I had made. Here is where I terminated the copper leads too so they could be connected to the amp.

Here is the box after some round overs and some sanding.

Copper wire or tube?

**StereoClarity** · **09-15-09, 12:34 AM**

Solid core copper....stuff is TOUGH to bend uniformly!

**sub_junkie** · **09-15-09, 01:03 AM**

That look very nice...I like it.
Great work!!!

**robertcharles123** · **09-15-09, 02:08 AM**

Pretty cool. How does it perform?

**robertcharles123** · **09-15-09, 02:12 AM**

What kind of paint? It helps if you seal the mdf before you paint it. It has those end grain problems if not. Also, it takes a bunch of paint if we are not schooled painters to get furniture finish. I used about 3/4 gallon 2 part primer and about same amount of paint with hardener. Plus, the sealer which was 1/2 gallon. Lots of paint and time, but the finish is just what I wanted.

**Owen Bartley** · **09-15-09, 11:47 AM**

What a great idea for a sub. Very cool. The solid copper has such an awesome industrial look to it, and the acoustic foam pyramids look great too. Any problems with air leaking out the top? What thickness was the plexi you used? I really like the look of the back of the sub with the vent too, great job.

**StereoClarity** · **09-15-09, 05:40 PM**

Quote:

robertcharles123 wrote:

Pretty cool. How does it perform?

Very very well. It's extremely transient due to it's ultra light cone. It will bottom out if pushed two low in a HT application but for music it's just beautiful.

**StereoClarity** · **09-15-09, 05:41 PM**

Quote:

robertcharles123 wrote:

What kind of paint? It helps if you seal the mdf before you paint it. It has those end grain problems if not. Also, it takes a bunch of paint if we are not schooled painters to get furniture finish. I used about 3/4 gallon 2 part primer and about same amount of paint with hardener. Plus, the sealer which was 1/2 gallon. Lots of paint and time, but the finish is just what I wanted.

I used Latex interior paint and Killz 2 primer on it. Now I have an HPVL spray gun that I use with my air compressor. It makes painting a dream. That finish is much easier to get now and is about 10x better

**StereoClarity** · **09-15-09, 05:43 PM**

Quote:

Owen Bartley wrote:

What a great idea for a sub. Very cool. The solid copper has such an awesome industrial look to it, and the acoustic foam pyramids look great too. Any problems with air leaking out the top? What thickness was the plexi you used? I really like the look of the back of the sub with the vent too, great job.

Thanks! I used some black gasketing tape on the edges of the plexi to make sure it didn't leak. Additionally, I used some rubber washers under the bolt heads to ensure no air escaped there either. The Pleix was 1/4" but since the piece was so small it doesn't really have any flexing problems.

**Mike P.** · **09-15-09, 06:24 PM**

Nice sub! What net volume is the driver in?

**dyohn** · **09-15-09, 06:28 PM**

What's the purpose of the vent? Is it just for the amp? I don't see a vent opening inside the enclosure so it must not be a port...

**StereoClarity** · **09-15-09, 06:45 PM**

Quote:

Mike P. wrote:

Nice sub! What net volume is the driver in?

One cube sealed.

**StereoClarity** · **09-15-09, 06:46 PM**

Quote:

dyohn wrote:

What's the purpose of the vent? Is it just for the amp? I don't see a vent opening inside the enclosure so it must not be a port...

Very perceptive

Most people ask about it for the same reason. The vent in the back is for the amp. The amp is in it's own separate chamber in the rear. That particular plate amp has the heatsink on the INSIDE which is kinda a dumb design. So I've got that vent on the top to make sure it stays cool. I have some holes on the bottom of that chamber to allow the cool air to vent up from the bottom so the hot air goes out the top.

**dyohn** · **09-16-09, 11:04 AM**

Quote:

ItalynStylion wrote:

Very perceptive

Most people ask about it for the same reason. The vent in the back is for the amp. The amp is in it's own separate chamber in the rear. That particular plate amp has the heatsink on the INSIDE which is kinda a dumb design. So I've got that vent on the top to make sure it stays cool. I have some holes on the bottom of that chamber to allow the cool air to vent up from the bottom so the hot air goes out the top.

That makes sense. Good plan!

**dgilme** · **09-16-09, 11:35 AM**

You need some leds or neon in there with a dimmer switch. Something that cool needs to be visible even in a dark room. And with the dimmer you can make it match ambient lighting during movies so it isn't a distraction.

**Sonnie** · **09-16-09, 01:18 PM**

Very VERY nice build... your work is detailed and precise...

Won't the copper eventually turn dark and non-uniform in color?

Those shoes look similar to my Nike Moto6's, but I am guessing they are Asics.

**Ricci** · **09-16-09, 02:30 PM**

Nice execution. The copper wire with plexi is a neat bit of flash for a boring old subwoofer build. The amp venting is a good touch too.

How did it sound? Did the guy like the finished product?

**StereoClarity** · **09-16-09, 02:32 PM**

Quote:

Sonnie wrote:

Very VERY nice build... your work is detailed and precise...

Won't the copper eventually turn dark and non-uniform in color?

Those shoes look similar to my Nike Moto6's, but I am guessing they are Asics.

I had thought about that but wasn't really sure how I'd combat that. It's sealed in there but I still think the corrosion might persist. I suppose some light mineral oil could do the trick no?

**Sonnie** · **09-16-09, 06:18 PM**

I suppose if it were very clean, cleaned well before oiling, that it might work just fine.

Coating it with a clear rubber sealant might also work, if you can find something like that.

**ironglen** · **09-16-09, 06:48 PM**

That clearcoat stuff used in hobby/crafts might work-not spray polyurethane...it's something else-ah, clear acrylic!

**looneybomber** · **09-19-09, 11:03 PM**

I bought 4 of those R12's for an outdoor poolside subwoofer project I never did get started before the school season this year. Doing something like this would look pretty cool in the house.

Quote:

Sonnie wrote:

Coating it with a clear rubber sealant might also work, if you can find something like that.

Maybe some kind of clear fingernail polish or resin to seal it from the air?

**StereoClarity** · **09-20-09, 02:19 AM**

I think any type of sealer would have to be at least a little flexible since the leads have to move a little bit in order to "wire" up the sub. I have no real plans for treating it; maybe it will age gracefully like the Statue of Liberty.

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