HTM Speaker Kits

This is the official thread for the HTM (Home Theater Monitor) and HT (Home Theater) series of speaker kits.

2020 Update:
The HTM-6, HTM-8 and HTM-10 have been replaced with the HT series which offers much of the same performance for a lower cost. Many of the same details in this thread apply to the HT series of kits.

HT Series Measurements here.

HT-8 full measurements.
HT-10 full measurements
HT-12 full measurements

If you have a question about a certain aspect of your HTM or HT series speaker build feel free ask them here.

This line of speakers was designed for high quality truthful audio reproduction across a wide dynamic range and are ideally suited for home theater or small screening room use. All designs in this series are voiced matched allowing seamless integration of LCR and surrounds. These speakers have been designed and tested to work well in both normal or baffle wall installations.

Achievable distance for reference level playback (105dB) at the listening position for the HTM/HT series speakers.
HTM-6, 7-9' on AVR power, 12-15' with max rated amplifier power.
HTM-8, 9-12' on AVR power, 18-22' with max rated amplifier power.
HTM-10, 10-15' on AVR power, 20-25' with max rated amplifier power.
HTM-12, 11-16' on AVR power, 25-30' with max rated amplifier power.

HTM-8, HTM-10, HTM-12:


On axis frequency response HTM-12 (original):
New measurement taken March 2022, 2m outdoor, 14ms gate, 1/48th octave smoothing blended to diffraction adjusted near-field response below 250hz.

HTM-12 Off axis Response (original):

Polar HTM-12 (original) (measurements gated and accuracy below 600hz is not great)::







On axis frequency response HTM-10:

Polar HTM-10 (measurements gated and accuracy below 1000hz is not great):


On axis HTM-6 (outdoors 4pi 2m gated):

Polar for the HTM-6, note due to a small 1dB hotspot off axis at 6-10k it pulls the apparent -6dB point in by 1dB, in reality the waveguide -6dB point is closer to 45 degrees not between 30-45 as shown:




Crossovers on new PCBs
Some of the more recent assembled crossovers use the new PCB's, these have both positive and negative connections at the same terminal block rather then separate like the milled boards in the photos above. The HF pad now works by connecting a wire between the two positions on that terminal block.

New PCB v1.2 (components rearranged slightly to make things more compact):

 

More info...

Damping info, (for HTM-6 see post #4)
I had used R13 Ultra touch recycled denim insulation in my HTM-10 and HTM-12 boxes covering the entire back on both the HTM-10 and HTM-12 with some small pieces on the sides and top of the HTM-12.

Other damping materials can be used but should be of roughly equal thickness 1.5-3" and similarly placed. Generally for thicker material I will cover a little less of the box or cover more of the internal walls with thinner material.

The Ultratouch R6.7 rolls also work great for all four HTM models, iirc one roll is just enough for two HTM-10 enclosures.

HTM-10:



HTM-12:



Port Length:
HTM-12 - 3" (tuning ~45hz) *On new 2020 design use ports at full length without cutting.
HTM-10 - 3" (tuning ~50hz)
HTM-8 - 1.5" (tuning ~70hz)
HTM-6 - 2.25" (tuning ~75hz)


Adding inside flares to the HTM-12 ports.
This is a totally optional modification you can do to the flared ports used on the HTM-12. Most people will not notice any real world benefit from doing this but if you have the tools and scrap MDF or plywood it's pretty much free and only takes a few minutes

I cut some 3.5" discs out of scrap 3/4" MDF, any type of wood can be used here but it should be at least as thick as the round over size that will be used on the end. Note that you will have to cut the port down equal to the thickness of wood added so it ends up the same length, for the 3/4" MDF I was using I took 3/4" off the plastic port length.

You can see I used an adjustable hole saw for this part.


Next I drilled a hole in the disc making it a ring, the hole is sized to be just less then the inside port diameter so that it can be flush trimmed to fit later. The hole saw I used for this part was 2.5".


I did some quick flush trimming of the outside edge just to clean up the edge left from the cheap adjustable hole saw I used at the beginning.


I then glued the rings onto the ports, I used hot glue as it is quick and plenty strong enough for this task.


Once the glue was cool I used the flush trim bit on the inside to get a nice smooth transition from the port to the MDF ring.


Finally I added the round over to the MDF, I believe I used a 5/8" round over but only at about 80% depth.

I don't have a photo of it but I did paint the flares black as well.

 

Thanks.

Gross internal volume (not subtracting for bracing or drivers):
~1.8 cuft for the HTM-12
~1 cuft for the HTM-10
~0.375 cuft for the HTM-6.

External dimensions of the stock enclosure built from 3/4" material with included 1" thick baffle should be:
18" wide x 25" high x 9.75" deep for the HTM-12
15" wide x 19.5" high x 9.25" deep for the HTM-10
Note the HTM-10 is listed as 9" deep, this may be correct as we might have shaved a 1/4" off the depth of the flat pack, Erich would have to confirm. Either one of those depths would work fine if you plan on building your own box.

HTM-6 using 3/4" material for baffle and 1/2" for the box:
13.5" high x 10" wide x 7" deep

HTM-6 damping info, could not add to second post as it made character count for the post too large:
This one does not need as thick of damping material, I used two strips of about 1.5" thick poly batting material placed along the sides/back behind the waveguide and behind the woofer. The bottom 2" of the enclosure does not have any material.

 

Was working on getting those off my laptop, added the on axis, still need to process the off axis files.

Some other HTM photos added here since I ran out of room on the first post,
HTM-12, HTM-10, HTM-6 (unpainted sorry)


HTM-8:


HTM-12, HTM-10:


HTM-12 Poster:

 

Added that info to the first post.

 

There will be pre-assembled crossovers offered soon.

The kits will come with a single 1" thick baffle which does not need the inner baffle layer. Since my boxes are prototypes we cut everything from some 3/4" on hand and a single 3/4" baffle was not thick enough to flush mount the woofers while leaving enough for a screw to really grab which is why you see it doubled up. The 1" thick baffle solves that problem.

 

The inside flares likely won't be an option, I have a bunch of port samples here that do have inside flares but none are the correct size/length for these designs. It's not likely you'll ever have an issue with the stock ports unless you play bass heavy music without a high pass on them or run sine waves at high levels (which is what I was doing).

The HTM-6 could likely be used as an atmos speaker if you have only one row of seating, high ceilings or you will place them at a lower angle to which the difference in angle in the vertical axis of the speaker remain small between rows (<30 degrees) . The Volt-6 is better if the differences in angles to the speaker between seating positions will be greater then 30 degrees.

I should mention that the HTM-6 has yet to be designed, currently working on the enclosure sizing and baffle layout. It will likely end up close to double the enclosure volume of the Volt-6.

The volts should still blend well if used with the HTM series speakers.

 

Thanks,

The HTM-10's might give you a little more chest thump over the Fusion-8's as I did design them with a little bit of a midbass bump but your issue could also very well be a Room/placement or integration/EQ issue causing a dip or cancelation in the frequency range that gives you that impact feeling.

 

I have not directly compared the HTM-12 to the 1099, that said the HTM-12's sound is similar to the Fusion-15 so I would look to the comparisons of the Fusion-15 and 1099. But being that you already have the 1299 center I would go for the 1099's as they are likely to be voiced and sound more like the 1299 then the HTM-12 would.

The HTM series was meant as a stand alone line where someone can use the larger HTM-10/12 for LCR and the 6/8 for surrounds (when they become available) knowing that all the designs are voice matched and work well together. There is nothing to keep someone from using the same speaker for LCR and their surrounds, some would say that is the ideal setup for seamless sound.

The cabinet design of the HTM line was designed to be geared more for home theater use where the wider but shallow shape allows easier placement behind AT screens where space is limited but there is nothing keeping them for working well for music playback other then the need for a subwoofer to help fill in the bottom end.

The Cinema series was started to help fill the need for designs where a matching horizontal center channel was needed and to accomplish that without sacrificing horizontal coverage in the midrange. A three way design was the way to accomplish that so the mids and waveguide could be rotated on the baffle for vertical or horizontal use. Eventually the 88-special (which sort of accomplishes the same thing without extra woofers) and Cinema-8/10 got grouped in there as well though the Cinema-8 is just the Fusion-8 MTM, while the Cinema-10 is more like a Fusion-10 MTM but uses the larger DNA-360.

I'd say for the best matching of LCR and surrounds to stick with speakers in the same line as they will likely sound the most similar but you will likely have good results no matter which speakers you end up choosing.

Thanks, I used the same process as the Flex-12's subs which you may or may not have seen on AVS a while back.
3 - 4 coats of sealer primer (Zinsser FastPrime 2) light sanding between coats then two - three coats of flat black (Conco 9500) no sanding between coats, all just rolled on with 6" fine foam roller ). I can usually apply the primer on 5 sides of a box at once and if I have a fan going and am doing more then one box when I am finished with the initial coat I can go back and hit them again in order as the primer will be dry to the touch allowing me to get two coats on the boxes without waiting.

Link to Flex-12 page:
http://www.avsforum.com/forum/401-d...able-subwoofer-mid-bass-using-mbm-12-kit.html

 

Might be a little while, going to be working on getting a custom neodymium motor 8" driver made for it but have yet to get any samples. The HTM-6 might be done sooner, just need to figure out baffle layout and find some ports to use and then it's on to crossover design.