Subwoofer Building Project, Part 2: Some Assembly Required

Last month, I wrote about some recent additions to my home theater: a pair of D-I-Y 18″ subwoofers. The focus was mostly on the cost advantage of making these bad boys myself versus purchasing from an internet brand or from a brick-and-mortar retailer. Now let’s take a look at the build itself.

Before starting, and while waiting for the wood and subwoofers to arrive, we require certain equipment, small items that I’ll mention as I go along. This is stuff we need to have ready and available once the real fun begins.

There’s something oddly exciting about seeing a Fed Ex truck park outside one’s home, a feeling I’m sure we’re all familiar with, like seeing an ice-cream truck drive down your neighborhood and running out the door with all the pocket change you can muster. As an adult, of course, we try to show some restraint, holding back a Grinch-like smile while our hands form a tent and our fingers lightly tap against each other. As the delivery guy plopped two massive boxes on my porch, the thrill was quite apparent, I’m sure.

Anyhow, soon as he left, I dragged the incredibly heavy boxes into the house and immediately opened them like Christmas gifts. Naturally, the first thing I did was to place one of them on my table and took pictures of it with a Blu-ray case next to it, just to give an idea of the comparable size. Let us gaze upon the behemoth size of these beauties for a moment.

Stereo Integrity 18 inch Subwoofer

Well, after a day of admiring these shiny new drivers, the boxes showed at my doorstep the following morning. I immediately opened those suckers with the same level of eagerness. The pre-cut wood material arrived tightly packed in sturdy, foam-filled packages. Each piece was 3/4″ thick MDF board with a double thick front baffle and rabbet joints on the inside of the largest pieces, making their assembly nearly foolproof. After applying a healthy dose of Titebond II wood glue along the side, top and bottom of each panel, I held them together to dry overnight using eight trigger clamps, each measuring at least 36″ (91cm) since we’re working with a box that measures just under two feet (61cm).

Enclosures glued with trigger clamps

I did the same to the front baffle, which came in two separate pieces, except I used 24″ clamps. The only trick to doing this part was making sure that the edges matched and were even while taking into consideration how it would fit and in which in direction with the rest of the box.

Front Baffle glued with trigger clamps

The next day, after removing the trigger clamps, I had to make sure that I had an airtight, sealed box. If everything is done correctly and the joints fit tightly, there really shouldn’t be a need to do the following step. However, doing this doesn’t hurt either for those who want to be certain you have a perfectly strong enclosure. What I’m referring to is sealing the inside of the box using acrylic water-based caulk, which would ensure that there aren’t any tiny cracks or miniscule spaces from which air can escape. The reason for wanting a sealed subwoofer as opposed to a ported one is that the bass ultimately feels tighter, more responsive and less “boomy,” which is essential when listening to music. Again, caulk is not necessary, particularly when the same wood glue can be just as effective, but it won’t do the box any harm either.

It may not look pretty, but since it’s all on the inside, what does it matter what it looks like anyway?

Sealing Enclosure with caulk

Next time, we’ll drill some holes for the driver and look at the cabling, especially at the different choices available. Then we’ll line/dampen the interior with dense, egg-crate foam, as well as stuffing it with polyfill material. That will then be followed by painting, calibration and in-room measurements.

What I haven’t talked about so far are the sound benefits – what I gain in decibels and hertz as opposed to a ready-made product, especially something store bought. I’ll leave that conversation for a future entry.

Read Part 1
Read Part 3

8 comments

  1. Looking good! Did you run into any hiccups while building them, or was it all smooth sailing? What was the most difficult part of building your own sub, if at all? I know you will be writing a more in depth article about performance, but can you give a small description of how they sound. Would you ever buy another sub now that you are a do it yourselfer?

    • Thanks! I haven’t experienced any hiccups, knock on wood, unless I count having to tap the front baffle into place. But otherwise, the material from DIY Sound Group is awesome and incredibly easy to assemble, and I wasn’t thankfully met with any challenges. With everything done, both subs sound amazing and pressurize the room like no other sub I’ve ever toyed with before. When listening to music, I’m hearing and feeling bass I never noticed before, which, of course, I’m absolutely loving. After experiencing these babies, I don’t think I’m buying IB or B&M subs again. If I add another, I definitely going DIY again.

  2. Whit2001

    Hi,

    DId you purchase the 2-Ohm or 4-Ohm version of the subs? I can’t seem to find that in either of your posts so far. Thanks.

    • Sorry Whit2001, you’re totally right. I somehow forgot to mention that I purchased a pair of 2 Ohms drivers. I chose those over the 4 Ohms version for the simple reason that EuroPower EP4000 evenly divides the wattage to both drivers (2 x 2,000 watts), as oppose to 1,400 watts to each 4 Ohms. Of course, I could have done bridge mode for 4,000 watts to 4 Ohms, but I really wanted to utilize the XLR connectors in the back.

  3. E what is your primary speaker system? Each situation is of course unique, in mine I felt the main speakers are pushing out so much bass that a sub was not necessary. I eagerly await your final chapter here!

    • I use B&W speakers, which reach down to about 40Hz. However, I never use them for bass, and I personally wouldn’t recommend anyone doing so unless you tend to listen to more music than movies. But even then, a good, sealed subwoofer would be highly recommended. First, you’d be directing some of the work of producing those lower frequencies to a dedicated channel and allowing the three fronts to focus more on the mid-range and at delivering cleaner high peaks.

      Granted, most movies — or music, for that matter — don’t generally reach below 30-35Hz and on average, most action movies place more emphasis in the 40-50Hz range. Some music/movies are even intentionally filtered at around 32Hz, which includes dubstep music, because commercial theater subs are also filtered at that range. This means, yes, you could use a pair of really good towers for your listening pleasure, but there’s also the potential of the high end not coming in as cleanly or distinct because the speakers are forced to do double duty. In fact, I have my LFE crossover set at around 100Hz and the LPF set at 120Hz so that all bass content is directed to the subs.

      The reason for bigger and more subs is to even out the room response, add more of a tactile feel to the bass and hear the ultra-low frequency content in music/movies, which surprisingly happens more often than people are aware and includes lots of classical orchestra music. Of course, in the end, it’s a matter of personal taste and satisfaction. If you’re content with the amount of bass you hear from your front three channels, then that’s all that matters, but for myself, personally, I want bass directed to a dedicated channel so that I can better appreciate the full range of frequencies available in any given movie or music.

  4. whit2001

    Wanted to check back on the status of Part 3 and/or Part 4. Will we be getting final build/finish photos and listening test results/opinions? I’m very interested in the end result, both in how the build process went and your satisfaction with the outcome, sound-wise. Inquiring minds want to know?

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