HTM Speaker Kits

Is there any meassurements on the "optional HF padding" ?
Or how much does it dampen?

 

I'm very intrigued by the HTM-12 and the concept behind DIY Sound Group in general. I've been into home theater and audiophile sound systems for many years now. I'm in the process of building my first dedicated theater right now and want something that will produce reference level sound in my 4000 cubic foot theater. I've been looking at some very expensive sound systems from companies like M&K, Klipsch, and RBH. I produce video and mix sound for a living on very high-end JBL and Genelec monitors. I'm accustomed to pristine sound. I've always been under the impression that if I put a professional, PA style driver and compression tweeter in the home environment, I'm not going to get "the right sound." Yes, they use 12" and 15" mid drivers and compression tweeter with wave-guide horns in commercial theaters, but the audience is sitting 40-50 feet from those speakers. What happens when I put a HTM-12 behind my AT projection screen in my home theater and then sit 12-19 feet from the LCR's? I'm surprised to hear that it's not fatiguing or harsh. Aren't these drivers designed to be harsh so that they sound natural at 40' and fill a huge room with natural sound. I'm not trying to debunk. Like I said, I'm very intrigued and I want them to work because I love the price and idea of building my own speakers. But I'm skeptical and looking for understanding and explanations.

 

Follow up question to my last... how does the HTM-12 compare to something like the NEXUS? I'm just trying to wrap my head around commercial style theater monitors in the home environment vs traditional HiFi.

Thanks in advance!

 

I am ready to order 3 HTM-12s... When might the pre-built crossovers be available? These are what I am waiting for. I don't mind soldering, but have more money than time this winter... SUCKS! But I can glue and assemble in the wee hours...

 

It's small, about 1-1.5dB but since it pulls everything above 1.5khz down by that much it makes a noticeable difference.

These speakers are designed and voiced specifically for use in home theaters. While the drivers used come from the pro sound world they are very high quality and the crossover design (often the most important and influential aspect of design) tames them for home usage providing smooth natural reproduction while not giving up the impressive dynamic capability of the drivers used. Many people have switched from more conventional Hi-Fi speaker designs to these kits after hearing them.

One of the main advantages of these designs over a more conventional dome/cone speaker is the pattern control from the use of the SEOS constant directivity waveguide and the smooth transition of the horizontal pattern control of that waveguide to that of the woofer at the crossover point. The SEOS shape was designed to provide ideal pattern control and it's smooth contours result in low diffraction and none of the honk or constricted sound that badly designed horns can have. The constant directivity aspect means more of the sound is directed towards the seats and also provides uniform sound side to side across the listening area while allowing less sound out towards the side walls, floor and ceiling thus reducing amplitude of the reflections off those surfaces which in turn improves sound clarity and intelligibility of dialog. Another benefit of the constant directivity design over more conventional designs is as you you move off axis on a constant directivity design the frequency response remains fairly consistent, this means any sound that does end up reflecting off the side walls of a room tonally matches that of the direct sound, thus acting more like true source of a sound rather then a speaker reproducing it.

The other big advantage these designs have over hi-fi designs is their sensitivity and power handling. Often you see hi-fi speakers list their sensitivity or efficiency in the mid 80's, some more efficient designs in the upper 80's. Many of the DIYSG designs are in the mid to upper 90's roughly 10dB higher then most of the conventional designs. Now for every 3dB increase in sensitivity it requires half the input power to reach a specified output level, a 10dB increase in sensitivity is a 10 fold reduction in required input power. This means both the speaker and amplifier are having to work much less to reach a desired volume level, increasing both headroom and dynamics. On top of that the voice coil size and power handling of the pro sound drivers is often much higher then that of more conventional hi-fi drivers which leads to less heating of the voice coils and results in lower power compression further increasing dynamic capability. Many hi-fi designs will not even approach reference level output without severe compression of dynamics either from the speaker itself or from lack of amplifier power which results in higher distortion and listening fatigue. Often when switching to these speakers people will sometimes notice how they can now listen at higher volume levels without experiencing that listening fatigue.

 

The Nexus Tower is designed as a full range speaker, no need for subwoofers for music playback. All the high efficiency SEOS kits do need subwoofer to augment the low end even for music playback unless you build a custom cabinet on some of the larger designs. Now the Nexus does have a more open sound to it while the HTM-12 is more direct, as such the Nexus might be preferred for music while the HTM-12 could be preferred for movies or reference level playback which the nexus would struggle with.

 

If I wanted to run with theAVR set to mains and center full range plus send their signal to the lfe channel and use a minidsp to integrate 3 subs into my system using the Geddes approach would it be feasible to add an appropriate highpass to these speakers to roll off the very bottom and protect the driver from over excursion? No idea how to design said highpass and would it have effects on rest of the crossover?

 

If these will be powered by the AVR a highpass should not be necessary as the drivers will be safe from over excursion damage at AVR power levels. At worst you get some distortion if low frequency content below 40hz is at high enough level to drive the woofer past xmax but again excursion should remain within safe limits of the driver.

If they will be powered by an amp with much more then 100-120w then it would be advisable to use a high pass around 45-50hz which would require separate minidsp's one fore subs and one for the main speakers.

 

I was thinking about doing it passively in the existing crossover if possible. Was assuming the parts for doing that would be cheaper than another minidsp. And the goal being making it a complete non issue whether receiver and distortion issue or separate amp and over excursion issue.

Will likely be a Pioneer 1130 or something similar driving them.

 

A 40-50hz passive high pass for a ported speaker is very difficult do. Passive crossovers that low in frequency require very large values which are expensive and you also have to compensate for the impedance peaks at the low end which also require very large values. It's just not an easy or cheap solution and often the losses at those low frequencies can be pretty big.

It might be easier to run the speakers sealed or plug one of the ports which will lower tuning to around 30-35hz and cone excursion will remain within xmax down to below 30hz with AVR power.

 

Thanks, that answers the part where I was ignorant. I understand what a crossover does, I don't understand at an electrical level how it's implemented. I'll be modifying the enclosure quite a bit so I can get it closer to a side wall while toed in properly since my theater room is just under 11' wide. I'll cut some mdf plugs and make it appear like the baffle never had port holes, unless Eric can get 3 baffles cut without the port holes.

Trying to mesh these two statements. I've always had difficulty understanding why a speaker that is accurate to the input signal and very capable would be said to be great for home theater but might not be preferred for music. Is that because for a lot of music listening people expect a certain amount of coloring of the sound? What about music in movies? How does the Fusion 12 or 15 compare with this type of comparison?

 

Would there be any consideration to corner loading these (as opposed to putting them in a baffle wall)? I'm going to make my screen wall as dead as I can, but the side walls will stay pretty live.

 

Corner loading these might make them too bass heavy, you are going from 2pi to 1pi which can give an additional 6dB of output at the low frequencies. Might be correctable with EQ in which case you will gain a lot of extra headroom in the bass but I have not tried it myself so I can't say what the results will be.

 

I won't have a baffle wall but they will be enclosed in a shelf that is up against the front wall with the pj screen above it. On each side is an opening approximately 3-4 feet wide. (a door on the left that I'll keep open and a hallway on the right) and beyond that 1st reflections will be attenuated by absorbing room treatments. Do you think in my case they won't have as much mid bass? They'll be about 6"off the ground and tilted back a little so theyll be aimed at ear level. I'm geuessing a 80hz crossover will be most effective. What do you think Matt?

 

It's hard to tell, do you have speakers in those locations now? If so do they lack mid bass? Chances are if it's a bad location for mid bass reproduction from one speaker it will be the same with another.

Based on you description the proximity to the floor will help reinforce the low end though I expect the shelf sits out away from the wall above a bit, there is a chance you will get a cancelation at a frequency where the depth of the cabinet is equal to a 1/4 wavelength. For a 16" deep cabinet that would be about 210hz, for 20" it's 170hz. So you can see how common distances speakers are placed from a wall will put that notch right in the middle of the mid bass range. Just divide 3375 by the distance to the wall in inches and you can figure roughly what frequency you will have a cancelation.

If you have a mic some quick measurements with any speaker should tell you how well they will perform at those locations in the real world. Just look for any large dips in the response in the 60-300hz range, if it's free of any large depressions in that range you should be good.

 

Thank you Matt. It's 10" deep so 337Hz might have a dip. I might be OK . The speakers I have now are just simple MB Quart monitors so they just don't compare to the HTM-12. I have four Infinity 1262's and four sealed 2sqft flat packs for nearfield subs I have yet to put together and I already have a quad 18" IB sub (done) so between the subs and 3 HTM-12s I should be in good shape .

 

Any ETA for the HTM-8 kits?

 

Still don't have a sample for the woofer that will be used in the HTM-8, it will likely end up being a totally custom driver from Eminence.

Good news is that the HTM-6 design in pretty much finished so it should not be long for that design.

 

Sweet! That is good news. Looking for some 6 or 8 to accompany my HTM-12

 

Here is photo showing HTM-12, HTM-10 and HTM-6:

 

Nice, thanks Matt. What's the size of the HTM-6 and is there any info regarding potential size for the HTM-8 enclosure? Trying to figure out if I should go with these as surrounds and Volts for Atmos / DTS:X.

 

The HTM-6 is 13.5"h x 10"wide x 7" deep.

I don't really know what the dimensions of the HTM-8 will end up being. My guess is somewhere around 11.5-12.5" wide 16-17" high and 8" deep.

 

Thanks again, ballpark figures for now is fine.

 

Any chance we can get a version of the flat pack designed for in-wall use? It would be great if it was a couple inches thinner and you can go a full 15-15.5" wide and any height so that it fits between 16" on-center studs. Height doesn't matter at all in a purpose-built theater setting.

If no flat pack will be available for this purpose would it be possible to build our own boxes as long as the total volume is the same?

 

Also what's the dispersion like for using an HTM-6 for Atmos? Should I switch to a Volt 6? Current plan is:
- 3 x HTM-12 for LCR
- 4 x HTM-6 for surrounds
- 4 x HTM-6 or Volt-6 for Atmos

Either build my own shallow boxes and make them all in-wall or figure out some other way to mount them (baffle wall + pillars or something)