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The HTiB upgrade subwoofer.

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  • The HTiB upgrade subwoofer.

    So I thought a quick build thread was in order, just in case anyone has these little guys sitting around.

    I have always wanted to build a small, passive subwoofer which would represent a significant upgrade to the small, passive subwoofers which come bundled with small "all in one home theater in a box" systems. After watching "Independence Day" on my fathers cheap little HTiB, I knew where the eventual build would go to live.

    I looked around at drivers, and heavily considered the Bravox black buyout subwoofer for this project. It has low distortion, healthy XMax, decent sensitivity and with the right alignment - very nice extension.

    However, to get to the required extension involved a footprint sacrifice I wasn't willing to commit - this had to be not much bigger than their existing unit.

    I considered the Tang Band neo subwoofers, but sticker shock set in.

    I remembered a while back, PE had a different Tang Band 5-1/4" subwoofer, shielded with a paper cone and funny dustcap. These are the W5-876 drivers, NLA from PE. They were what I wanted. I wanted to do a dual driver, I wanted a small foot print and when I found that DarrenK had measured them when he worked at PE I had my driver.

    However, being as they were NLA I could not get my hands on a pair. I didn't put up a want ad, figuring sooner or later someone would offer a pair for sale.

    Fast forward six months and Iowa DIY. Gentleman and scholar, Robert Clark had a pair for sale on the swap meet table and I snapped them up right away. Bingo.

    Anyways, the long boring history out of the way I started this a couple weekends ago and finished them up Friday afternoon.

    Front and rear baffles are 3/4" MDF, the other four walls are 5/8" particle board. The unit (without the feet) measures 7-3/8"W x 13-1/8"D x 17-1/8"H. It utilizes quite a bit of bracing.

    The port is mounted from behind the baffle and the opening was made with a 2" Forstner plus 1/2" round-over.

    Some pictures, we all love pictures.
    Internal shot showing the bracing and the way the port is mounted:

    Here is a shot in primer, the grooves along the sides are there on purpose:

    This was going to be the finish, but I decided to do them in hammered silver instead, so this ended up being a very nice base-coat for the silver hammered finish:

    The hammered finish looks like it is going to require a learning curve, but it is what it is:

    Over-all, this is one of the more "fun" builds I have done. Inexpensive and very useful. I have a passive crossover in it, more of a shaping network since I have my doubts about the HTiB receiver being able to filter out the drivers breakup adequately:

    It also incorporates a 6db high-pass to help protect from over-excursion. Anechoically, response is useful into the high 30's with the shaping network, but the HTiB will cross it over around 150-200 hz, and when I tested this with a plate amp with the crossover set at 150 Hz, it digs plenty low enough (useful into the low 30's). I threw it in the corner and it will do just fine for the parents.;)

    If a guy wanted to do this as an active subwoofer, the PE 70 watt amp would be OK, but if you buy the 50 watt from MCM (which has a far more useful form factor, measuring about 10" x 5-1/2"). Perfect for the slim subwoofers so popular today
    Don't listen to me - I have not sold any $150,000 speakers.

  • #2
    Re: The HTiB upgrade subwoofer.

    Interesting. The notion of getting deep bass from small-diameter woofers has always intrigued me. While those subs don't go super-deep, they are good candidates for alternative forms of resonant loading, like various flavors of transmission lines. I have a pair of the 4" that I'll be using in a "mass-loaded horn" design, which according to Hornresp should be able to deliver 100dB at 35 Hz while holding cone excursion within an acceptable range (where half the magnetic gap is populated with coil windings at full X, though not the conventional definition of Xmax). The application is an integrated L/C/R speaker bar for my parents.
    Best Regards,

    Rory Buszka

    Taterworks Audio

    "The work of the individual still remains the spark which moves mankind ahead, even more than teamwork." - Igor I. Sikorsky

    If it works, but you don't know why it works, then you haven't done any engineering.


    • #3
      Re: The HTiB upgrade subwoofer.

      Rory, that sounds like an interesting build as well. Pity PE doesn't carry these any longer, they are a useful driver. With their 8 ohm impedance and ability to play low enough - they are perfect for ultra-compact "bass modules" to stick under a desk, or in this case to replace the crap "subwoofer" that HTiB ship with.
      Don't listen to me - I have not sold any $150,000 speakers.


      • #4
        Re: The HTiB upgrade subwoofer.

        I have one of those drivers laying around. I would be interested in doing a horn or tapered line enclosure. If anyone has info on enclosure size and dimensions I'd like to know. Or if someone is looking for one more sub to build this dual sub project, I'd be willing to sell mine for a reasonable price.

        Good looking project, I appreciated the info on doing a passive crossover (are they called a "passover"?) : )

        Thanks for sharing.