HTM Speaker Kits

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

  1. I treat the bottom of the waveguide as the acoustic center. Yes there are some directional cues coming from the woofer but most are provided by the tweeter.
    Mike Whittingham likes this.
  2. Thanks Matt, much appreciated
  3. Good question. How many rows of seating do you have? If it's one, and the speakers are aimed right at that row, I'm not sure what advantage there could be by fitting them upside down, so I'd just fit them the usual way (waveguide higher).

    But if they're not pointing directly at your row, then it could depend on whether they're aiming short of your row, or past it - and if you have multiple rows, then that too could affect your choice. I believe Matt suggests that when getting away from they're +/- 20 ish degrees sweetspot, then above that (ie, higher than that when waveguide on top) is better than lower.
  4. Does anyone know the Qts of the HT-12 12 woofer and HTM-12 woofer?
  5. How much effort would it take to add a Celestion CDX1-1731 to an HT or HTM speaker? I'm assuming some changes to the crossover.
  6. Hello Matt/Erich,
    I just purchased the htm12 x 3. I am planning on redesigning the box to be more WAF friendly. Will the overhang around the front of the speaker affect the sound greatly?

    Thank you,
    Screen Shot 2021-09-02 at 11.14.29 PM.png
  7. No that should not cause too many issues.
  8. Nice!
  9. Hey Matt, I have at my disposal a polyurethane foam mattress topper that is 0.5"-1.75" thick (varies due to ridges), and extra loft Poly-Fil at a nearby store.

    For the HT-8, I didn't see a specific damping method outlined in this thread. Which of the above would be your suggestion, or should I consider something else?
  10. You should be fine the line with walls with the mattress topper and if you want add the poly-fil in the top portion of the cabinet behind the waveguide.
    Dalton likes this.
  11. Hey Matt,
    I have 3 htm 12s being shipped to me. I watch this youtube review on htm 12.

    The reviewer mentioned a 200-300hz resonant/boomy due to standing waves - "audible and annoying" as he described the sound. Will varying the cabinet stuffing remedy this as recommended by the reviewer?

    I do feel the review was mostly positive however for people who are not in the industry or versed in the technical terms - this can stir people else where. For me, other great reviews here, avsforum, etc. outweighs a single review.

    With that said, the review will get traction when researching for this speaker due to people's preference to watch rather than read reviews. Would you mind addressing this issue here as anyone who is inclined to buy the htm 12 will definitely come across that review video.

    Thank you sir,
  12. #362 Skoonky, Sep 7, 2021
    Last edited: Sep 7, 2021
    I'm not sure most of us would even hear that annoying sound. The tool he is using will not be used by 99.999% of people. I ask him to review the Titans, but he said it most likely wouldn't happen. Not sure the Titans would review much better than he mentioned in the HTM 12 review.
  13. The reviewer said that it is "absolutely audible" and the way he was explaining seem to be from listening without the measuring tools. As I mentioned, It is one review but can definitely spread the wrong impression because it is in Youtube.

    A good example are the Volts speakers. Erich mentioned that they were great sellers until one bad review from a Youtuber.

    I'm just curious what Matt's comments would be as he was not there - I wish he was similar to the 1099 speaker review.
  14. #364 Matt Grant, Sep 8, 2021
    Last edited: Sep 8, 2021
    Here were my findings on the AVS thread for the review which is where most of the discussions took place:

    Basically the woofer has a resonance of the surround that causes the dip in the 400-500hz range and then a peak between 250-350hz. The hump in output there in combination with some ringing would be resonance he is hearing. It can be completely fixed using some form cord or paracord inserted in the grove of the surround as I posted there, though I don't have any spare drivers myself to attempt gluing it in permanently.

    Now the I did notice I used more damping in my cabinet then the speaker cabinet in his review. I do wonder if that may have helped reduced the audibility in my testing. You can certainly add more damping to the cabinet, even a light fill would even be fine. There will be some reduction in bass output near the port tuning but if used with subwoofers and crossed around 80hz it makes little difference.

    The other fact is that when using the speaker with room EQ (these are mainly intended to be used with such in a home theater) the response hump in that range should be flattened out which will further reduce the audibility of the said resonance.

    The resonance in the cabinet he tested may be clearly audible for someone with a trained ear specifically listening for any artifacts in the sound of a speaker, and I won't deny that it is there as I have confirmed it in my testing. Though when the speakers are setup in a full system as intended with some EQ and not just critically listening to a mono speaker I do question how noticeable or objectionable it may be to the average listener.

    The Volts are always a good example of a split between how the speaker looks on paper and how it actually sounds when used as intended. When looking at the frequency response of the Volts they can look downright terrible, in fact I was apprehensive in continuing the original design because the response data from the coaxial looked so poor compared to what I was used to working with. But when I listened to it the first time I noted that it didn't sound nearly as bad as the graphs would lead you to believe. Yes the volts are not the best speakers ever made but nearly everyone who has built them has positive reactions even when moving from speakers that on paper or according to the response graphs should sound better. This leads me to believe there are performance metrics (largely suspect they are dynamics and output related) that are not being fully tested or quantified yet are often responsible for swaying our subjective impressions of speakers nearly as much as the response linearity and dispersion.

    Amir's review of the JBL SRX835P comes to mind as well. At first he bashed the speaker based on the measurements alone but then actually listened to it and with some EQ to fix the irregularities in the response and it was an instant reversal.
  15. Separate post for this but there are a couple minor mods to the crossovers I will be posting shortly based on Erin's data to address to slight bump I am seeing around 800-1000 Hz and a fix for the sharp dip around 4 kHz.
    Mike Whittingham likes this.
  16. Hi Matt,

    Since Erich sold all the assembled crossover for the HTM12 and with all the proposed fixes, will we see a v3 version soon?
    Skoonky likes this.
  17. #367 Rich, Sep 15, 2021
    Last edited: Sep 15, 2021
    Hey Matt/Erich,
    I just got my HTM 12 x 3. I would like to stuff the boxes with blue jean insulation however I don't see any place locally that sells them in individual packages. Can rockwool safe n sound be a good alternative? Or can I just buy wallmart pillows and stuff two per htm 12 box? Thank you!Screen Shot 2021-09-15 at 10.30.29 AM.png

    I just read that some people react to the Rockwool so that takes it out of the options. I just realized htm12s are not stuffed but lined so that takes out the pillows as well. ANY OTHER OPTIONS?
  18. Yea, seems like denim ultratouch insulation may have been discontinued and I couldn't find an alternative when I was looking the other day? Probably best to use the walmart foam mattress topper to line the walls since it's a ported box. I'm not sure how big of a concern it is, but probably best to not use rockwool in a ported enclosure so fibers aren't blown out of the ports.
  19. #369 Matt Grant, Sep 18, 2021
    Last edited: Sep 18, 2021
    Yeah foam and polyfil are going to be the easiest to find. Though fiberglass works just as well as the denim and if you are worried about the fiber blowing out of the ports you can use a thin fabric stapled over the it to contain the fibers.

    If using the foam you may want to double it up if it's less then 1" thick, also filling the top section of the enclosure behind the waveguide with polyfil will also help.
  20. I recently finished up a new larger motorized speaker turntable I've been planning/building for a while:

    So now I'm finally slowly getting around to taking clean measurements of the HT series speakers for posting here.

    At the moment I've just done the spins on the HT-12 which will be posted below, distortion measurements for that one at various output levels to follow soon.

    I'll have these linked on the first post so that they don't get buried.
    mattcc22 likes this.
  21. #371 Matt Grant, Sep 18, 2021
    Last edited: Sep 22, 2021
    HT-12 Measurements:

    Measurements taken outdoors at 2.83v/2m 4pi, measurements gated so resolution below 200hz is poor. I'll try to add a ground plane measurement soon to accurately depict bottom end response.

    Power & DI graph has been scaled up 6dB to approximate 2.83v/1M output.
    HT-12 Measurements Power+DI.png

    Horizontal off axis:
    HT-12 Measurements Directivity (hor).png

    Horizontal Normalized:
    HT-12 Measurements Directivity (hor) Norm.png

    Horizontal Polar Sonogram (contour lines at every 3dB):
    HT-12 Measurements Directivity (hor) Sono.png

    Vertical above axis:
    HT-12 Measurements Directivity (ver, pos front).png

    Vertical below axis:
    HT-12 Measurements Directivity (ver, neg front).png

    Distortion @ 80, 90 & 100dB / 1m:
    HT-12 Distortion 80dB.png
    HT-12 Distortion 90dB.png
    HT-12 Distortion 100dB.png
    Mike Whittingham and EarlK like this.
  22. #372 Matt Grant, Sep 18, 2021
    Last edited: Oct 3, 2021
    HT-10 Measurements:

    HT-10 Power+DI.png

    Horizontal Off axis:
    HT-10 Directivity (hor).png
    Horizontal off axis (normalized):
    HT-10 Directivity (hor) Norm.png
    Horizontal polar (normalized):
    HT-10 Directivity (hor) Polar.png
    Vertical above axis:
    HT-10 Directivity (ver, pos front).png
    Vertical below axis:
    HT-10 Directivity (ver, neg front).png

    HT-10 Harmonic Distortion 80dB.png

    HT-10 Harmonic Distortion 90dB.png

    HT-10 Harmonic Distortion 100dB.png
  23. #373 Matt Grant, Sep 18, 2021
    Last edited: Oct 3, 2021
    HT-8 Measurements:

    HT-8 Power+DI.png

    Horizontal Off Axis:
    HT-8 Directivity (hor).png

    Horizontal Off Axis (Normalized):
    HT-8 Directivity (hor) Norm.png

    Horizontal Polar (normalized):
    HT-8 Directivity (hor) Polar.png

    Vertical Above Axis:
    HT-8 Directivity (ver, pos front).png

    Vertical Below Axis:
    HT-8 Directivity (ver, neg front).png

    HT-8 Harmonic Distortion 80dB.png

    HT-8 Harmonic Distortion 90dB.png

    HT-8 Harmonic Distortion 100dB.png
  24. HT-6 Measurements...
  25. HT-88 Measurements...
    This speaker isn't done but I'm reserving the post anyway.

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