Subwoofer Building Project, Part 1: Sounds So Good, It Hz!

After a couple years of debating whether I needed to add more bass to my home theater system, I finally decided to go ahead and do it. It’s not that I felt my previous setup was lacking in that department; I simply wanted more, which is an unfortunate (or fortunate) effect this hobby has. Before the new addition, I was good down to around 10-12 Hz, which is quite low, although I really only reached around 95 dB in that range.

The change was mostly due to an overwhelming desire to upgrade the home theater, facetiously known as “upgraditis.” I also wanted to increase the above decibel range anywhere upwards of 120 dB. That’s enough to really shake the couch and rattle the walls with intensity, to create a genuine sense of realism during action-packed movie sequences. The added benefit of making that ultra-low bass louder is being able to feel content in the 5-7 Hz range, which can surprisingly be found on many Blu-ray titles. It’s just another step closer to bringing the cinema experience home.

The easiest option to accomplish this would of course be to buy a new subwoofer to pair with my existing HSU VTF-15H. The upgrade bug hit me hard when HSU Research released its newest model, the VTF-15H MK2. From the looks of the charts, it theoretically would have provided the decibels I was craving. Alternatively, there was Power Sound Audio, from the same team that created the awesome SVS subs, with the XS30se and the S3000i. Finally, I gave a lot of consideration to Rythmik Audio’s highly-rated FV15HP Servo beauty. Their prices are admittedly higher ($899 for the HSU, $1339 for the Rythmik and upwards of $1500 for PSA), but people shower their products with endless praise, making any of them a very tempting option.

HSU VTF-15H MK2 vs PSA S3000i
HSU VTF-15H MK2 on the left and PSA S3000i on the right

However, after further research and reading various threads at AVS Forum, I was reminded that I could gain more bass for significantly less money by going the D-I-Y route. I always knew this to be true, especially coming from the experience of building a 12″ sub about three years ago, but the big drawbacks are the time and tools required. Then again, a major plus is the satisfaction and pride of telling guests that I built the subwoofer myself, and that it works! That final tidbit is ultimately the real clincher that sealed the deal on my decision.

Stereo Integrity 18-inch SubwooferAt first, I thought I’d be content with a single 18″ subwoofer, which would cost less than half of those mentioned above. As it turns out, for about or around the same price as the VTF-15H MK2 shipped, I could build a pair of my own. I purchased two of these massive bad-boys from Stereo Integrity at $174 each and a pair of sub-kits from DIY Sound Group. The latter sells precut 4-cubic-feet boxes for $120 each that are relatively easily to assemble. To power them, I purchased a Behringer Europower EP4000 priced at $329, which would be connected to my Denon AVR-X5200W via a pair XLR-to-RCA cables ($13.50), with two speakon cables ($36.16) going to the subs. These final components were all purchased from Amazon with free shipping – an excellent bonus!

I still had to purchase a few smaller items in order to finish my new toys. I’ll talk more about those next time. As it stands, the grand total came out to $1,068.29, including shipping costs. Compared to the 15″ subwoofers from HSU and PSA, owning two DIY 18″ monsters is an incredible bargain. However, like I mentioned above, the downside to the project is the week or so of work having to construct them. But for those passionate about this hobby, the work is well worth the time and effort. It brings the satisfaction of knowing that I built an awesome addition to my home theater guaranteed to bring a smile to my face.

Next up will be a look at the build and pictures to show off my progress.

Read Part 2
Read Part 3


  1. That’s really cool. I just got a new sub myself and am loving it. Good luck with your project. Looking forward to work in progress. Do you ever visit the databass website? Those guys take their bass seriously.

    • Yeah, I’m familiar with the site — been visiting them for years and love that they graph bass content, which is something I’ve implemented into my reviews of certain Blu-rays.

      What sub did you purchase?

          • Thank you, it’s really smooth. It’s replacing a Klipsch rw-12 which I liked very much and has given me many years of enjoyment, but once in a while it makes port noise and can be distracting, so I wanted something that wouldn’t do that (at my listening levels) and so far it has succeeded.

  2. William Henley

    Wow, I thought I paid an insane amount for my sub for $350. 120dB is ridicoulusly too loud for a home – even 95 is. At the church, with a 4,000 person auditorium, 95-105 dB is what we run concerts at (and I complain is too loud), and I normally wear earplugs or headphones with a good seal if I am working the event. 120 for a sub is making me cringe just thinking about it. According to Sound levels above 85dB can cause hearing loss.

    • T.J. Kats

      It would only hit those levels for seconds of time.

      Also movies are(should be) mastered for peaks(very short peaks) of 105 to main speakers and 115 to the lfe channel.

  3. C.C. 95

    That’s a lot of cash for some rumble in bungh*le!
    The sound is supposed to make you feel the effect of the action- not make you feel like you are in it.
    I’ve been in a few car crashes, and I don’t want to hear/feel that exact sound when I am watching a movie. Methinks you are going overboard.

  4. Wow! Last thing I expected, considering the crowd and readers, was being accused of going overboard or being much too loud. Believe me, I am far from overboard, especially in this hobby. Some folks pay $3000 dollars just for one sub, like Seaton SubMersive F2, PSA T-18 or any in the JTR Speakers line, in order to reach that 120dB at the 10Hz range. However, JTR subs’ true strength is in the 20 – 30 Hz range. Things grow even crazier with DIYers building large LLTs, Martysubs, 5 or 6-foot high Sonotubes and Gjallarhorns. Hell, there are others going so far as eight and sixteen 18″ subwoofers from one small room, such as notnyt and popalock of AVS.

    This is just to show that building two subs is nowhere near overboard, but in their defense, as well as my own, you need to understand that this is not about loudness. As T.J. already pointed out, this is about achieving reference peaks, reproducing true-to-life accuracy, a sharper accurate response, and removing nulls from the listening position. This is not only concerning movies — though feeling as if being right in the middle of the action is a desired effect — but also in music, replicating the feel of listening to live orchestra and a rock concert. I’ll talk more about this in a later blog installment, but as a quick example, take the very subtle yet hauntingly responsive drumming in Dead Can Dance’s album ‘Anastasis,’ especially “Agape” and “Opium,” or listen to Craig Armstrong’s song “This Love” for some excellent understated bass that adds more depth to the rest.

    It’s not about loudness but appreciating the full range of the audio content available in music and movies.

    • William Henley

      Oh, well if its about a larger range, I am all for that. Your article came across though as being about loudness.

      I truthfully have no clue how many dB my sub will do, but I seriously doubt its 95, and I run it at about 1/3 volume in the apartment. I am house hunting now, and when I move in, I may turn it up – in my last house, I ran my sub at about half volume, and most of my friends complain I run my stuff way too loud. My sub is 10 inch, 35-200 Hz, 50 watt which is fine for a small room – I would probably go with a bigger sub if I had a theater.

      My concern is that 95 db – even in ocassional burst, is dangerous to your hearing, and 120 is just asking for hearing loss. I get that its peak – I don’t run my amp at full power – I just didn’t see the point of going from 95db to 120. But if you did it for frequency response, and don’t run the thing at full power, I am cool with that.

      • TJ Kats

        Something else to consider is that in the sub 20hz range you aren’t really talking sound so much as you are feeling. So getting the extra output in this range shouldn’t effect hearing in the same way that volume coming from the main speakers would be.

  5. I’m bookmarking this page! This might very well be what I’m looking for. I’ve been eyeballing the XTZ Cinema 3×12 sub but I could build 2 or 3 of these badboys for a fraction of the cost of the XTZ.

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