OJ's DIYSG HTM-12 Build

Discussion in 'DIY Speakers' started by OJ Bartley, Jun 13, 2017.

  1. OJ Bartley

    OJ Bartley Member
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    OK, I'll keep Joro company in here, as long as he promises not to be too hard on my craftsmanship. ;)

    With our basement renovation finally making some progress, and the design of the theatre taking shape, it was finally time to decide what speakers to use in the new space. Since I will be putting them behind the AT screen, I knew I wanted three identical speakers up front. I have been planning this project for so long that I've had a lot of different speakers in mind over the years (yes, years)... NatP, Modula MTM, Dayton RS-P WWMTM, Mini Statement... I liked aspects of all of those (and many other) options, but none of them really firmly established themselves as a clear, definitive choice. At least until I discovered DIY Sound Group.

    Reading about the SEOS speakers, I knew that this was going to be it. The question was "what flavour of SEOS?" I started out thinking the Fusion 6 would be the one, then moved on to basically consider nearly every model in the Fusion and Cinema lines. Some were easy to eliminate due to their large size. Then I learned that the larger SEOS horns were generally more desirable, and started to focus on that, which led me to the 88 Special. This speaker was shallow, wall mountable, praised for its clarity and output, and it used the big SEOS-15 waveguide. It seemed perfect, and I was just waiting until we got closer to starting the full project before ordering. And then I was pointed to the HTM line, which made me start all over again.

    The things that I was looking for in the front stage were: first and foremost, clear and clean dialogue, good output to match a pair of 18" subs, and a depth that would fit behind a shallow 1' false wall in the screen area. The reviews of the 88 Special suggested that it was fantastic for dialogue, and speaking with Erich about my goals and needs reassured me that they would shine in my setup. Once I had checked out the HTM line a bit, which wasn't easy because they were so new that there was barely any information out on them, I became convinced that they might be a little bit better than the 88 Special, and Erich assured me that I would be happy either way. In the end I decided that I have room for the HTM-12, so I'd go for the big woofer and SEOS-15 to make sure I didn't leave any performance on the table. Once @eng-399 got his review of his HTM-10 build up online, I was 100% convinced that I was making the right choice. If the 10s impressed him that much, the 12s must be spectacular.

    It took a little while, but I have finished all 3 speakers. I haven't given them a PROPER listening test yet, but based on a test session in my normal setup with just 1 replacing my usual centre channel, and casually listening to some tunes in stereo in the basement, they sound very good. Here's a brief summary of the build.

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  2. chrapladm

    chrapladm Moderator
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    Very nice so far. Dual 12's should be enough for dynamics I hope. :greengrin:
     
  3. OJ Bartley

    OJ Bartley Member
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    And here is the second half of the build. I wanted to finish them in something like flat black, since they will be behind the screen. I'm a big fan of "mistint" paint, and so when I stopped in at a Sherwin Williams store and found a can of "blacktop" in a flat finish for $10/gallon, I thought I'd hit the jackpot. It turns out that blacktop is a little greener than I'd ideally like, but since they will be hidden I don't mind so much. They are dark and flat, and will do the job just fine.

    HTM-12 030.jpg

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    I don't think this is actually necessary, but I had a bunch of Dynamat on hand, and figured I'd put a strip on the back of each of the waveguides to help damp any vibration or resonance. They are very thick, and very well made, so I doubt I've gained much but I think I was maybe able to tell a TINY difference with a knock test.

    HTM-12 044.jpg

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    And a few pics of my very very basic initial testing. I will say that in place of my usual Paradigm CC-370 there was a dramatic increase in volume and clarity for the centre channel. That's one of the main goals behind this project, so it made me very happy.
    HTM-12 047.jpg

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  4. OJ Bartley

    OJ Bartley Member
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    Yep... I think these will be enough in the tiny little room they're going into. :redgrin:

    When i was listening in the basement I had them hooked up to my old Denon rated for 70wpc and they had NO trouble getting loud. Whatever AVR I end up with for the theatre will likely be 120wpc+, so they'll have the potential to send people running from the room. :hush:
     
  5. Jororaitchev

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    I do not know what to say, maybe my age / I'm 57 years old /? I have a metaphor I think it is mine I don't know will you understand its meaning but I will try:
    There comes a moment when the low frequencies become high and the high ones are not heard.
    Joro
     
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  6. Tonto

    Tonto Active Member

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    Very nice work Owen, those should be perfect!
     
  7. Todd Anderson

    Todd Anderson News Editor / Reviewer/ Senior Admin
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    Owen - those look pretty killer. And you have a budding audiophile helping out! :T

    What's the frequency response?
     
  8. Leonard Caillouet

    Leonard Caillouet Technical Guru
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    Great write up and it looks like you are on track to accomplish what you are after. I like the way you take us through your decision process.

    And while things like that little bit of damping on the wave guides may not make a difference, that kind of attention to detail in total might. When you go above and beyond at every step you just might hit the one that does make a difference. Even if none of it does, at least you have the confidence in knowing that you did everything you can to tweak your build. That in itself is of value.
     
  9. OJ Bartley

    OJ Bartley Member
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    Thanks Todd. They're going to be hidden, so I went with a basic finish, but I still think they came out pretty decent. If they were to be out on display, I think I would have tried my hand at using some of the amazing looking WilsonArt laminate.

    The HTM-12 is an 8 ohm speaker, sensitivity is 97dB 2.83v/1m (very high, so they don't need much power at all), rated for 10 - 500w input power, and they have a stated frequency response of 55Hz - 20kHz. They won't be bass monsters if used in a pure stereo setup, but that was never their intention. They were designed for theatre setups where they would blend in with subwoofers, crossed over probably from 60 - 100Hz or so. They should deliver a good amount of midbass, being tuned to around 45Hz if I remember correctly.

    And yes, I try to involve my 2 little "helpers" in some aspect of all my projects, so later on I can tell them they helped to build the theatre.

    Thanks Leonard! I am very optimistic about how my front stage will sound with these properly set up.

    This hobby really is about the little things, isn't it? You're right, all the details add up, and when you start with a high quality product like these, any little tweaks may be incremental... but they add a little bit of uniqueness to a project, which is another big aspect of DIY. :)
     
  10. tesseract

    tesseract Senior Admin
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    I would like to, but have yet to hear any DIY Sound Group builds, although I have followed development of SEOS since the beginning (clear back to the Zilch Econowave days) and have heard SEOS used in an AudioKinesis design.

    Nice build, Owen, thanks for sharing.
     
  11. Negatron

    Negatron Active Member

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    Looks great, and I bet they will sound great too...have you thought about making your surrounds the same as your front 3?
     
  12. OJ Bartley

    OJ Bartley Member
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    Wow, it sounds like we really need to get you an audition with some of these!

    Thanks Negatron, I'm looking forward to the day when I can fully "turn them loose". lol. I think my wife and i might take a staycation day with the boys still in daycare and blast a few movies with them in a temp setup once I get the subs built.

    I wish I had a room large enough to use a full matching set all around, but I'll be shoehorning the Volt-6 in for surround and Atmos duty as it is. If I had more space, I'd definitely have considered the HTM-6 for surrounds (well I would have if they were out at the time) but I think I'll still be very happy with the Volts.
     

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