HTM Speaker Kits

Discussion in 'Home Theater Speaker Kit Information' started by Matt Grant, Sep 30, 2016.

  1. I see that the HT-88 has made an appearance on the DIYsoundgroup page.

    Matt Grant, can you give us a breakdown of it's design and what potential customers should know about it? Thanks!
  2. #452 Matt Grant, Feb 21, 2023
    Last edited: Feb 21, 2023
    The HT-88 is an MTM design using a pair of 16 ohm variants of the Celestion TF0818 from the HT-8. It uses the square SEOS-77 waveguide which has a 70x70 dispersion pattern. It uses a new compression driver which is looks like a ferrite version of the CDX1-1730. This compression driver allows for a much lower crossover point without distortion becoming a problem.

    Basically this is for those of you that want a speaker with the performance of the HT line that can be used as LCR and if needed used horizontally for the center channel with only 10" of height.

    Since it is a two way MTM it has the limitations most MTM's do with more limited dispersion on it's long axis. The low crossover the new compression helps achieve (~1250Hz) does allow for approximately 30 degrees of coverage (+-15 degrees to -6dB) when the speaker is used horizontally before encountering cancellation between the woofers. This is enough for most 2-3 seat sofas or couches at 10 foot listening distance.

    Output capability of the pair of 8" woofers will be similar to the 12" in the HT-12.

    In comparison with the 88-Special which also uses the same woofers and compression driver with the SEOS-15 mounted above the pair woofers:
    The 88-special has higher efficiency (~97dB) but the bass rolls off sooner, the HT-88 is a little less efficient (~93-94dB) but with a little flatter or more full sounding bass response.

    Used as a center channel the 88-Special will give wider horizontal dispersion (~60 degrees near the crossover, about double that of the the HT-88) due to the closer woofer spacing and the larger SEOS-15 allowing for an even lower crossover point. But the 88-Special is obviously much taller with the waveguide mounted above the woofers.
    MDuyck1292 likes this.
  3. Wow, thank you for the substantial reply! Looking forward to seeing them up on the site.
  4. So I believe the HT-88 might be ideal for my "living room" theater for the LCR (using one horizontally for the center). It is unfortunately above a fireplace, so I was thinking of getting a mantle mount to bring it closer to eye level. Two quick questions:
    • Does anyone know the overall weight for one fully assembled speaker? Looking at the flatpack (22 lbs) + speaker (35 lbs), it looks like about 57 lbs.
    • I'm new to DIY speakers, so am I able to change the dimensions of the speaker as long as keep the overall volume the same? The reason I ask is because our mantle has a depth of only 8 inches, and I believe this speaker has a depth of 14 inches.
    • Does anyone know how these would do with a phantom center (100% movies, 0% music)? Only my spouse and I watch movies, so the window for listening is relatively small.
    Currently we're using two NHT C-4s (phantom center), which do a relatively good job, but I've always felt something was lacking...

    Any suggestions is highly appreciated! Although I would have loved the 1099s, it is unfortunately too expensive for us for the time being.
  5. Hi all - first post! I just ordered 3 HT-10's for my LCR - which will be more of a living room home theater than a dedicated space. That being said, I'm still going for an inconspicuous 7.2.4. Three questions:

    1. There was talk earlier in the thread about HT-6's. Is that still a possibility? Or are those dead?

    2. In my last house I had a 5.1.4 Atmos system with round flush-mount in-ceiling speakers (Klipsch). Given the new house is a living room situation, I'd like to find some in-ceiling speakers that are as inconspicuous as possible, yet timbre match well to the HT line. Suggestions?

    3. With HT-10's as the LCR, I have room for 2 subs. How do I know what size to go with? 15's?
  6. I know there was some kind of hangup on the HT-6's, I can't remember what Erich said it was, maybe no baffles/flatpacks yet.

    Some have used Volts installed IB into their ceilings, The Volt-10 works well like this, you just have to make a grill to cover the driver. One I get around to testing them I'll have a couple dozen of the original Concentric-8 drivers available, these were a large step up from the Volts in terms of quality and they also work IB (again would have to build grill and mounting solution). Otherwise for commercial products of similar design I'd recommend something like the JBL Control 226C/T 227C or 328C.

    For subs I'd say go with whatever you can fit in the space, and that doesn't exceed your buget a pair of good 15's will provide decent bass and more then most are use to especially for a living room setup. In general something like a pair of ported 15's will provide equal bass output to a pair of sealed 18's at lower cost and require less amp power to do so though it all depends on the specific drivers and enclosures used.

  7. Thanks Matt! I have some time to spare, so I'll wait and hope for HT-6's. I'll look at those JBL's for ease of install - textured ceiling, not crazy about opening it up any more than I have to. And thanks for the rec on the sub size. I was hoping dual 15's would work!
  8. One more follow up question - For a non-dedicated theater, do you think the Klipsch 5650 or 5800 would sound ok with the DIYSG bed speakers? They also have compression drivers, but don't quite reach as low as the JBL. I'm not sure what factors for Atmos speakers play into how well they interact with the main stage and surrounds.
  9. @Matt Grant
    I have a HT-8 Frankenstein modification that I'd like your opinion on. I am trying to reduce the depth of the enclosure as much as possible to reduce the amount of space the HT-8s take up on the sides of my room. Due to framing constrains I can't push the speaker into the wall which would be the easy solution. What I am considering is to remove as much depth as possible from the flat pack enclosure (this saves me from creating a four new enclosures), then making up the volume by using a piece of 3" PVC pipe, with a cap, into the top of the enclosure stuffed with polyfil. Something like this:

  10. My amps are a bit overpowered for HT-8s (400wrms), but they allow me to set RMS and peak limiting by voltage, attack, and release time.

    I see that the HT-8 specs say 250w.
    With V=sqrt(PxR), I get 44.72v.

    Any suggestions on how to configure those limiter settings for the HT-8?
  11. All the stuff I have purchased from Erich probably does not need more than 50 watts wo be painful!
    I don't know what the 1099's and Vortex-15's are rated for power-handling wise, but I have yet to turn my AVR up enough that it is distorting or clipping and I get an easy 90dB+ at my MLP. I have pushed them to 100 dB at MLP and it's just too loud. I can't imagine the output right at the speaker at that point.
  12. Yeah...I wouldn't send them that much power intentionally. It's just a protective measure, in case there's some kind of glitch. Like digital noise, or I accidentally set them to large and watch Edge of Tomorrow.

    Ideally, the speakers would be protected without affecting normal signals. I have the setting available, so I might as well enter something.

    Here are my current settings:

    RMS Threshold: sqrt(250w x 8ohms) = 44.721v
    RMS Attack: 1s
    RMS Release: 10s
    Peak: sqrt(250w x sqrt(2) x 8ohms) = 53.183v
    Peak Attack: 1ms
    Peak Release: 100ms
  13. Matt, I have three HTM-12's not yet assembled, one has the version 2.1 PCB, one has the 2.2 PCB and the third has no PCB at all. The 2.1 version came with a 20uF cap and the 2.2 the 18uF cap. Would changing to an 18uF cap match that up with the 2.2 version? Would you also have a wiring diagram for a non PCB crossover on the HTM-12? Thank you.
  14. Have you reached out to Erich to see if he has any PCBs available?
  15. DanO, did you lose one of your PCB's? Was it the 2.1 or 2.2 version?
  16. Sorry, I went and dug through the boxes again and found the other PCB. It is the 2.1 version with the 20uF cap, my question then to match these up for and LCR setup is to replace 20uF caps with 18uF and ad the resistor? Thanks again.
  17. Hey Matt!

    A couple quick questions about the 88 specials, If you got a sec.

    I'm setting up a theater in a new living room and want to bring in my 1099's for the main stage. The only problem is a fireplace/mantel/etc is involved. No possible way to use my 1099 center with out some major, and creative, renovation work. I'm looking for a diy solution that would fit my needs and match well with 4 x 1099's.

    Do you think the 88 special would be in the ball park with its nearly as high sensitivity?

    One of my biggest issues is physical size of the cab. It needs to be light enough to attach to the pull down tv mount and sized to fit between the tv and the mantel. The depth of the 88 special is spot on, but I need the height to be 10" or less. Would it be possible to cut the box in half and double the width (in order to maintain the same internal volume)? This would put the woofers in the same plane as the SEOS15 and would likely cut the width of the compression driver, but how significantly? Would increasing the box width even further (say from 42" to 57") and moving the woofers out to the ends reduce the cancelation effect of the woofers and help maintain a wider effective width for the Compression driver? Would adding 1000-1500 Cubic inches to the box volume throw things too far out of spec?

    I know this would be a pretty big modification to the design and intent of the 88 special, but it's the best option I've been able to think up so far. Next in line would be a slightly tweaked horizontal HT-88, with a box size similar to what I'd be talking above. Would either of these options work for my needs? Any better recommendations I should look at? Any advice would sure be appreciated!


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