HTM Speaker Kits

Is the denim better, or is foam just as good? It's the R6.7 denim that seems to be sold out everywhere. I can find R13, but I don't know if that's a problem (for HT-8s.) It says R6.7 is 1.6" thick and R13 is 3.5" thick.

So, which is the best option:
1) Wait until R6.7 denim comes back in stock. (No idea when, though.)
2) Go with R13 denim now.
3) Go with 1.5" thick acoustic foam now.

 

Yeah the R6.7 is just about perfect for the HT-8's and HT-10. One roll is enough for two of those enclosures.

R13 is a little too thick for the HT-8/10 but it can be used in the HT-12 or HTM-12.

1.5" acoustic foam would be a better choice if you can't get the denim right now.

 

I was wondering if this was an acceptable amount of 1.5in acoustic foam for an HTM-12. Should add additional polyfill on top of this? The box is glued up, but everything else is just placed inside for mock-up.

 

That looks decent as you've largely covered the parallel surfaces, which is the goal. Hang them together and see how they sound. If you're unsure then you can always remove the SEOS and woofer after the fact to adjust things.

I wouldn't add any poly-fill.

 

Any word on what's going on with the HT speaker line up? These haven't been in stock for a long time now. Are these still being made at all?

 

The HT10/HT12 have been in stock a few times in the past month. They are all still being put together from what I can tell. It just seems different parts are out of stock for different models at different times. Erich has started a thread where he gives updates on availability. Keep an eye on this thread.

http://www.hificircuit.com/community/threads/speaker-kit-inventory.5745/page-2

 

Does the shape/structure of the foam matter in this case? I can't seem to find any denim insulation available either but I'm seeing wedge foam, pyramid foam, grid style, etc. Didn't know if one would perform better for this application.

 

The shape doesn't really matter but because the foam isn't uniform thickness (unlike the denim batts) you will want to use at least 1.5". Though 1" should be ok on the HT-8 and possibly the HT-10 if you cover all the walls well. It also depends on the brand, sometimes they cheap out and you don't actually get the full marked thickness.

PE has some 1" on sale

 

Roger! Just wanted to be sure. Makes sense about the thickness. I may grab 2" foam for my HTM12/HT12's just to be safe.

Was hoping to just use the denim as it seems easy to work with but no one has any in stock.

 

I have a stock alert from Home Depot that it's finally available again.

https://www.homedepot.com/p/UltraTo...ll-16-in-x-48-in-6-Pack-60306-16482/202710055

 

I have 3 htm-8 that I'm using as my front LCR. I was listening to some music the other day, loud but not crazy loud and noticed some breakup that seemed to be coming form one of the compression drivers. I came here to try and find the part number to replace one.

I see the htm's are being phased out and the ht's are being sold instead. I couldn't remember if the htm 12s had the same compression driver or not as the 8s

 

In regard to the HTM-12, is a single layer of the R6.7 denim enough, or should I be trying to double up with some spray adhesive?

 

Have you tried swapping the waveguide/compression driver with another speaker to see if the issue follows the driver? If there are cold solder joints or a loose connection to the crossover it can create a similar sound to a driver going bad.

 

One layer is probably good on the sides/top/bottom but you could double up the back if you wanted.

 

I will check that out and see, thanks for that tip. If it is the driver do you know the part number?

Edit: I guess if I pull one out I'll have the part number hahaha

 

It used the DNA-325.

 

Matt, any chance you can describe the transfer function of the hd pad? I think some of us might be interested in recreating the pad via dsp, out of curiosity, if nothing else. At least I do

I think it would also be cool for you to tell us a bit more about the tech in the HTM-12's new drivers. Like the benefits of the shorting ring in the new woofer, etc. I bring this up because as I'm trawling through Erich's old 640+ page SEOS thread on AVSForum, features like the shorting ring were brought up as highly sought-after, something that took the speaker build into the premium performance realm.

 

Here's a model of the placement I'm planning for my theater. I'm going to do this with sealed enclosures. The room is 11' 1.5" wide. Not modelled yet are dual 18" subs that will take up all the space under the screen and act as a stand for the speakers, the screen and the masking system. The whole thing will be covered with fabric such that all you'll be able to see is the screen. The screen will be a dual layer of black then white milliskin spandex. The left and right channel will get a dual layer of black milliskin spandex. The rest will be a black felt of some other less expensive fabric than the spandex. I'll be making the front wall as dead as possible (behind the screen and the top and front of the sub enclosures will be covered in insulation and polyfill batting). I'll have a 2" thick rigid rockwool sound treatment on the wall immediately next to each left and right channel. The speakers are toed in at a 37.5 degree angle which puts the left speaker on axis pointed at the right front row seat and the right speaker pointed at the left front row seat.

https://a360.co/39YEkzp

My question is this has the compression drivers at 48" above the ground which should be just slightly above ear level from the first row of seats. However the center channel's 12" driver will just barely be above the bottom of the screen, and when I'm watching a 2.35:1 movie the adjustable bottom mask I have planned will be moved up and end up partially covering the 12" driver.

Would I be better off raising the speakers so the compression drivers are even higher above ear level until the center channels 12" will clear the bottom mask or mounting the speakers upside down so the 12" is above the compression driver and it is at ear level?

 

Human vocals center around 1000 Hz, which in the case of the HTM-12 means it's coming out of the woofer, not the compression driver. If you're going to be pedantic about it then that's what's ideal. That said, with how far away the seating is it's not going to matter as speaker placement is about what apparent angle the sound is coming from as opposed to absolutes.

If it were my room I'd consider lowering the screen so it fits under that soffit on the right side of the room and widen it to the full width. Then it would be possible to place LCR all behind the spandex screen and you can get them all at the same height for more seamless panning and all dialog is anchored on the screen. You might want to move the seating forward a bit as the angles will be a little different, but that's not necessarily a bad thing.

 

Are you suggesting I move the speakers in a little bit from the wall, but keep them toed in, but behind the screen? Or move them in a bit and have them facing straight forward behind the screen?

The issue with making the screen that big and fitting it under the HVAC bulkhead is the bottom of the screen will then be low enough that the first row of seats will cut off the bottom of the screen for the second row of seats. Especially since the masking system I have planned will require 4-6" around the screen to house the masking rollers and hardware to move them.

From your 1000hz comment rather than considering center of the waveguide as what should be at ear level, I should consider center of the wave guide and 12" driver combined what should be close to ear level, in which case they would end up high enough that clearing the bottom of the screen won't be an issue. No matter which way I end up deciding to go, all 3 at the same height was a given.

 

All three behind the screen, toed in. It will cost a couple inches of depth versus all three flat against the wall but it's a good trade.

It sounds like you are currently planning for a 16:9 screen and then masking for 2.39:1. You could instead put in a 2.39:1 screen and then mask down and lens memory zoom for 16:9 content. If your primary use is movies then this might be the better screen ratio compromise and also be a way to deal with the height problem. It depends on which you use more or want to be more impactful.

Between the two in opting for 2.39:1. We've of course got 16:9 in the living room for casual watching. It used to be that action movies were generally 2.39:1, but more and more non-action movies are that ratio. Streaming shows are starting to be that ratio as well. Honestly, I think once 8K TVs runs its course or fizzles out the TV manufacturers will make 2.39:1 the next gimmick.

 

I'm actually planning a just over 2:1 screen. Masking system will be 4 way motorized. Raspberry Pi running custom python app controlled via bluetooth and Harmony remote. GRBL CNC control board running 3 stepper motors with 24V power off brakes. Side masks will be linked and mapped to X axis. Top and bottom will be to Y and Z.

Full height on academy flat and full width on cinemascope. Called a constant area and makes the visual impact of both equal.

 

Constant area sounds like a novel compromise.

 

Matt, I just stumbled across this post and since I’m building custom cabs for my HT8 surrounds, I’m considering increasing box volume for extended bass response (I would keep the waveguide in the box).

How much would increase box volume by to achieve the response you mentioned in the thread?

Are t/s parameters available for the HT8 woofer so it can be modeled in Winisd?

Thanks!

 

The HT-8 uses the Celestion TF0818 so you can use that to model the enclosure volume.