Building some HT-10s

Discussion in 'General Topics' started by dubwoofer, Oct 11, 2020.

  1. #1 dubwoofer, Oct 11, 2020
    Last edited: Oct 11, 2020
    I've purchased a set of HT-10's for the L+R positions in our small 5.1 home theater to compliment an 88 Special I built several years back. They will take the place of my Forte II's, which are fantastic speakers in their own right but they never blended well with the 88 and are better suited for stereo use.

    The well-packed kits arrived over the weekend and as of this posting I've assembled the crossovers and glued up both cabinets. All the panels were straight and everything fit together just fine. The only issue I encountered was the vertical brace protruded a tiny bit past the top/bottom pieces and had to be trimmed (I used a sharp chisel to shave it flush to the edge).

    On the crossovers I opted to shorten the leads of the inductors for a cleaner look. To expose the bare copper I scraped the enamel coating off with scissors and finished with sandpaper...there were no problems soldering to them. I also decided to omit the screw terminals and will be soldering the driver hookup wire directly to the board. I highly recommend getting the optional circuit board with these kits.

    Question: I have a couple sheets of 1" sonic barrier from PE and a few lbs of acousta-stuf on-hand. Should I both line the enclosure and loosely fill it with stuf?

    Attached Files:

  2. You can certainly use both the sonic barrier and the acousta-stuf, just try and line the walls with the stuf rather then just loosely pack it in. You at least want a sizeable gap or space behind the woofer itself with a clear path to the ports. The upper portion behind the waveguide can be loosely filled up.

    You can use the volt enclosures here as an example for stuffing with poly:
    Volt Coaxial Speaker Kits
  3. Stuffing and lining are two different things with different purposes.

    With ported cabinets the goal is to line the cabinet, not stuff. Think about a bare room that rings when you clap your hands. Add absorbing materials and that goes away. The same thing is happening inside a speaker cabinet and just like adding acoustic treatments to that room, you are also trying to kill resonances within the cabinet.

    An unlined speaker cabinet will resonate at the frequencies and harmonics of the quarter wave length of the internal dimensions of the cabinet. If you measure the output response of frequency sweeps in an unlined cabinet you should see peaks at those frequencies.

    Stuffing is filling in the cabinet space of a sealed speaker. How much is stuffed in there will change the response curve of the speaker. In particular subwoofers will become "boomy" and show a large output spike in a limited range. If you want a smoother response instead of one note bass (nod yes) then stuff that cabinet. The denser it's packed the more the output curve will smoothly drop off as the frequency goes lower, as opposed to spiking hard and then dropping like a rock. There is a happy medium for a more flat response and an accepted standard, though people's tastes vary to some degree on what they consider ideal. When people talk about preferring a subwoofer having a more laid back or smoother response then they're the types who want their sealed subs stuffed more.

    As with all things speaker design stuffing a sealed cabinet it's a trade-off.

    But the HT-10 is ported so just line it and move on. I'm a fan of recycled cotton/denim. The BondedLogic stuff that Home Depot carries online is pretty darned good, very easy to work with, and sticks nicely with help from a hot glue gun. Unfortunately they're out right now which kinda makes sense. People aren't buying clothes like they used to, so there's less denim waste to recycle.

    Maybe chop a U-Haul moving blanket? I'm talking about the ones that look like they're made of recycled denim (heh heh). They not particularly thick so it will have to be folded over.

    It might seem a bit unorthodox, but then again people cram pillows info subwoofers. Like the whole pillow, intact, it just goes straight in.
  4. Thanks for the input. I chose to use what I had on hand and lined the cabinets with the sonic barrier foam, and then added about 1/4 lbs of acoustastuf in the space behind the waveguides. If anyone is wondering, one 18x24 sheet of foam is enough to line 90% of each enclosure.

    Whelp, I completed the speakers over the past few days and forgot to take more progress pics along the way (d'oh!). I think they turned out great. Listening impressions to come...IMG_20201015_124505[1].jpg
    LADPT and Matt Grant like this.
  5. You should be fine, the sonic barrier stuff is open cell.

    More importantly how do they sound? Be sure to drive them to excess and have them do whatever you ask of them, because you can :D
  6. #6 dubwoofer, Oct 17, 2020 at 6:43 PM
    Last edited: Oct 17, 2020 at 7:37 PM
    Funny you say that, as I started with an outdoor test-drive. I set the speakers up with a dac and a Marantz 75 wpc amp (the biggest I had that was readily available) and kicked them off with Dire Straits: Brothers in Arms. Fortunately our neighbors are few and very far between so I could give them as much juice as my gear could deliver without the cops showing up. Soon the family gathered around with camping chairs and we enjoyed cocktails while we listened to Getz/Gilberto and watched the sun set over the valley.

    We had nothing but good remarks for them. Powerful, dynamic, focused, and great top-end detail...and vocals sound very lifelike! We also noted if we ever had an outdoor gathering (ya know, if we ever beat this covid thing) we would totally use these for PA speakers.

    IMG_20201015_163135[1].jpg IMG_20200612_203714.jpg

    Yesterday I moved the the HT-10s into our theater room. The room poses a small challenge for speaker placement since the Dolby-recommended L&R position coincides with the 1/4 width subwoofer location I've been using. After a little experimentation I found simply stacking them on the subs works well and puts the throat of the waveguide only a couple inches above seated ear level. With the HT's connected to my Anthem MRX 310 I proceeded with a calibration session in ARC Genesis, with a maximum EQ frequency of 1khz. I still haven't gotten around to playing a film through them but I listened to more music. Again, no complaints: The HT's deliver great sonics over a large listening area, just as advertised. :cool:
    IMG_20201017_121309.jpg IMG_20201017_121349.jpg

    Movie test to follow...
    EndersShadow likes this.
  7. Don't touch anything, it looks like a proper setup. I just want to point out a misconception that I had wrong as well, and that's assuming the tweeter is what you line up on.

    Generally voices are around 1000 hz so the rule of thumb is whatever driver is responsible for this frequency is what should go at ear level. The HT-10s cross at 1600 hz therefore if you were to sit 4 feet away by yourself then the woofer is what you should consider lining up on. If you're going to have two rows then line the woofers up over the front row's heads.

    If you're sitting back a bit, which it looks like you are, then this is all basically moot anyway and dropping them on top of the subs is perfectly valid and practical. Any difference you'll ever hear from elevating them is going to be related to not having them sitting on a flat surface creating baffle diffraction, but they're already correctly pushed forward to the edge of the subs.

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