My New Theater

[bkeeler10]

The thing I'm working on right now is a good set of speaker mounts. My four surround sound speakers will be wall-mounted, and my four overhead will be ceiling mounted.

I'm trying to find a mount that doesn't require drilling any holes into speaker cabinets, but which are also aimable and adjustable enough to accommodate various sizes of speakers. Something that could clamp onto the speaker from the sides and front would be ideal. My not entirely exhaustive search has not turned up anything like this. If I had the ability I would design and build something myself, but I'm not that good. Anyone run into anything like this?

 

[Matthew J Poes]

https://www.wayfair.com/home/hd0/si...nRkrWJR_bncHtUHW9H8Q4cmqMi-R4-i4aAujDEALw_wcB

Like this?

 

[bkeeler10]

Yeah, I do like those and I think they'd be great for the ear-level surrounds. Good find.

Perhaps the trickier bit will be the overheads. My intent was to lay something like this: https://www.revelspeakers.com/productdetail/~/product/m16.html or even this: https://www.chanemusiccinema.com/A2.4 on it's side to keep it as close to the ceiling as possible. Finding something that can accommodate a speaker that wide might be challenging.

 

[Matthew J Poes]

Yeah, I do like those and I think they'd be great for the ear-level surrounds. Good find.

Perhaps the trickier bit will be the overheads. My intent was to lay something like this: https://www.revelspeakers.com/productdetail/~/product/m16.html or even this: https://www.chanemusiccinema.com/A2.4 on it's side to keep it as close to the ceiling as possible. Finding something that can accommodate a speaker that wide might be challenging.

Personally I wouldn’t feel comfortable mounting that kind of speaker over my head without using something very secure. I’m not sure I would trust those clamp mounts.

I wonder if you could work with the factory mounts to make the S16 surface mount work on the ceiling. Might be a way to use the existing mount to rig up something more secure. Unfortunately there may not be a safe way to temporarily mount overhead speakers like this.

Maybe you could have a clamp mount made specifically for overhead use that protrudes around the front of the speaker to secure it in place? If you do that, I would consider some kind of safer chane just in case. I can’t help but envision them shaking lose and crashing down on unsuspecting victims below.

 

[bkeeler10]

I wonder if you could work with the factory mounts to make the S16 surface mount work on the ceiling. Might be a way to use the existing mount to rig up something more secure. Unfortunately there may not be a safe way to temporarily mount overhead speakers like this.

I thought about the S16, but I got looking at the frequency response, and its low end roll off (down 3 dB at 70 Hz) is such that it may not mesh well with a crossover below 100 Hz or so.

Maybe you could have a clamp mount made specifically for overhead use that protrudes around the front of the speaker to secure it in place?

This is precisely what I had in mind. I figured it would have to capture the speaker all the way around the front baffle, the sides and the bottom in order to work securely. I was hoping someone out there makes something like this, but I suspect if that's what I want to do it will have to be custom-made.

 

[Matthew J Poes]

I thought about the S16, but I got looking at the frequency response, and its low end roll off (down 3 dB at 70 Hz) is such that it may not mesh well with a crossover below 100 Hz or so.



This is precisely what I had in mind. I figured it would have to capture the speaker all the way around the front baffle, the sides and the bottom in order to work securely. I was hoping someone out there makes something like this, but I suspect if that's what I want to do it will have to be custom-made.

I vaguely recall seeing a commercial vandal proof speaker mount once that may have done this. I don’t know if it’s still made. I wonder if a specialty company like SnapAV has such a thing.

 

[bkeeler10]

All right, latest update. I have ordered speakers (Revel Concerta2 - 3 F36 and 4 M16). They should be here on Monday. I will be using the pair of Chane A1.4 I have for overhead, and probably order another pair to fill out the 7.1.4 system.

I have also ordered the AVR - a NAD T758 v3, which is supposed to be here Tuesday. I already have an Outlaw Model 7125 amp which will run the front three and top four speakers, and the AVR amp will run the side and rear surrounds.

I need to terminate all my speaker cables with bananas, which hopefully I will find time to do this Saturday. I also still need to order acoustic treatments but trying to get settled on that - still a bit indecisive. See the picture for my latest thoughts. Sorry about the wild colors - it was the quickest way to make it easy to see what's going on. It's all GIK Acoustics. Basically, I have the following:

1. Soffit Traps on the front wall corners (some or all range limited)
2. Monster Traps on the front wall behind the speakers, on the ceiling forward of the MLP, and on the back wall (all range limited).
3. 4A Alpha diffusors/traps on the side walls (these can be forward facing for a diffusive surface at higher frequencies, or backward facing for broadband absorption)
4. Gridfusors (not shown in picture) for diffusion on ceiling and walls behind the MLP.

I have intentionally left the floor area clear to allow maximum flexibility in subwoofer placement.

 

[Todd Anderson]

First off: congrats on all that new gear you have incoming. Great choices, I think. I've heard great things about the Revels you ordered. And we know the receiver is good :-)

Looks like you've got the GIK order headed in a good direction. I have the 4A diffusor/traps on my side walls. Definitely gave a kick in the spaciousness department. I think they're a good choice!

 

[bkeeler10]

First off: congrats on all that new gear you have incoming. Great choices, I think. I've heard great things about the Revels you ordered. And we know the receiver is good :-)

Looks like you've got the GIK order headed in a good direction. I have the 4A diffusor/traps on my side walls. Definitely gave a kick in the spaciousness department. I think they're a good choice!

Thanks Todd. It is pretty exciting to be getting equipment in. I'm looking forward to hearing the Revels and playing with Dirac. And after considering what Matt had to say about treating first reflection points, I decided a device like the 4A would allow some flexibility and experimentation to see what works best for me on the side walls. Tell you what though - acoustic treatments ain't cheap. I'll be spending more with GIK than with any other single vendor. But it's that important IMO. Gear is more glamorous, but you can spend all sorts of money on gear and get a mediocre result in a poor room. So I think it's a good long term investment.

 

[bkeeler10]

Revels are in the house! Well, in the garage anyway. NAD will be here tomorrow. I'll post more pictures later this week.

 

[JStewart]

Looking forward to your first impressions of those Revels. Just found and read the white paper on them. Got to give Harman props for the solid science behind the products. Looks like a great choice. Congrats. Hope you really like 'em.

 

[bkeeler10]

Yeah I'm excited to hear them. I've never heard a Revel, but the quality of R&D done by Harman on them is reassuring and makes them a rather safe bet. At the very least, they will be competent. I'm expecting more than that though

 

[Todd Anderson]

Gotta love the pallet delivery! That's exciting... I'm sure you're going to enjoy those speakers.

 

[bkeeler10]

NAD's in the house! And a pair of F36. Got them hooked up, plopped down on the floor with no particular care for placement, and sat to listen for 15 minutes. Not a fair shake at all, but I couldn't help myself!

I'm really torn at the moment about acoustic treatments. I filled up my cart at GIK earlier today, and the sticker shock set in. I had been thinking about building broadband absorbers but was hoping to buy everything prebuilt. Now I'm reconsidering. Problem is, it's easy to build a broadband absorber, but a bit more complicated to build one that works like their "Flexrange" versions work, or especially diffusion products (which I never considered attempting).

Now I gotta stop messing around and terminate some more speaker wire.

 

[Todd Anderson]

Have you thought about going the DIY using GIK's frames and supplies?

https://www.gikacoustics.com/product-category/diy-acoustic-panel-bass-traps-supplies/

You could buy your own fabrics and get creative without having to build frames, etc.

 

[bkeeler10]

Well, after agonizing endlessly over what to do about acoustic treatments, I finally pulled the trigger and placed an order with GIK today. I whittled things down significantly to get to a reasonable price, which was still more money than I would have liked and also possibly less treatment than would be ideal (hence the agonizing). Here's the list:

1. Soffit Traps, range limited (3 - for the front wall/ceiling corner)
a. I was originally planning on 6 of these, so this saved a ton!
2. 244 bass traps, range limited (8 - 4 on front wall, 3 on ceiling in front of MLP, 1 on back wall)
a. I really wanted the Monster Trap for all this, but I saved significant coin with the 244 and perhaps I will space them 2-3 inches off the boundary to get some of that extra low end absorption back.
3. Alpha 4A (4 - 2 per side wall at first reflection points between front 3 speakers and MLP)
a. I ordered these reversible (back side finished) so they can be a combination of diffusive and absorptive as intended, or they can be turned around and be broadband absorbers.
4. Gridfusors (8 - for back wall, and ceiling and side walls behind MLP).

I seriously considered going DIY, and I think I will still be doing a little bit of that. The things I bought from GIK are the things that would be harder to DIY, such as diffusion or range-limited absorption. Broadband absorption is much easier, and I think the plan at this point is to install what I've ordered, measure, and decide where to go from there. I suspect reverberation will be a little higher than ideal for theater, and if it is broadband absorption will be the answer. I guess we shall see. It is hard to model this in the program I normally use because GIK doesn't provide absorption coefficients for most of their products (just the thinner panels). Instead, they provide sabins of absorption per unit.

Along those same lines, the other thing I've been agonizing over has been how to mount my surround side and surround back speakers. I had an epiphany last night about this. What if I built a floor-to-ceiling framed pillar with a cut-out the size of the speaker in the proper place. I could fill the rest of the pillar as needed with compressed fiberglass and wrap it in fabric. The pillar would probably be 12-15 inches square, so could provide whatever extra mid-high frequency absorption might be required, and also help out a bit with bass absorption.

 

[Matthew J Poes]

Well, after agonizing endlessly over what to do about acoustic treatments, I finally pulled the trigger and placed an order with GIK today. I whittled things down significantly to get to a reasonable price, which was still more money than I would have liked and also possibly less treatment than would be ideal (hence the agonizing). Here's the list:

1. Soffit Traps, range limited (3 - for the front wall/ceiling corner)
a. I was originally planning on 6 of these, so this saved a ton!
2. 244 bass traps, range limited (8 - 4 on front wall, 3 on ceiling in front of MLP, 1 on back wall)
a. I really wanted the Monster Trap for all this, but I saved significant coin with the 244 and perhaps I will space them 2-3 inches off the boundary to get some of that extra low end absorption back.
3. Alpha 4A (4 - 2 per side wall at first reflection points between front 3 speakers and MLP)
a. I ordered these reversible (back side finished) so they can be a combination of diffusive and absorptive as intended, or they can be turned around and be broadband absorbers.
4. Gridfusors (8 - for back wall, and ceiling and side walls behind MLP).

I seriously considered going DIY, and I think I will still be doing a little bit of that. The things I bought from GIK are the things that would be harder to DIY, such as diffusion or range-limited absorption. Broadband absorption is much easier, and I think the plan at this point is to install what I've ordered, measure, and decide where to go from there. I suspect reverberation will be a little higher than ideal for theater, and if it is broadband absorption will be the answer. I guess we shall see. It is hard to model this in the program I normally use because GIK doesn't provide absorption coefficients for most of their products (just the thinner panels). Instead, they provide sabins of absorption per unit.

Along those same lines, the other thing I've been agonizing over has been how to mount my surround side and surround back speakers. I had an epiphany last night about this. What if I built a floor-to-ceiling framed pillar with a cut-out the size of the speaker in the proper place. I could fill the rest of the pillar as needed with compressed fiberglass and wrap it in fabric. The pillar would probably be 12-15 inches square, so could provide whatever extra mid-high frequency absorption might be required, and also help out a bit with bass absorption.

All sounds good to me.

This is probably too much agonizing in my part, but you may want to consider making the pillar as acoustical small as possible. If you wrap it in fabric, you may want to consider constructing it of half inch dowels to reduce diffraction effects.

When I built my front wall I used 2x4’s and Geddes gave me a hard time about diffraction problems I probably introduced. I wrote that off given the way I placed the speakers. Recent measurements I’ve taken suggests I do have diffraction problems. I now wish I had listened to him and made the wall acoustically smaller to avoid these effects. It didn’t need to be this strong.

The acoustic treatments sound good to me. You can always add more.

If you want to make your own range limited treatment, try building a panel as normal and then covering it with a membrane. I use sticky carpet paint protection film. I bought a huge roll for under $30 dollars. You can also use latex or vinyl if you prefer, but it costs a lot more. You can always build a bunch of panels, put the membrane on and temporarily install them in the room and take measurements with and without the membrane. That can tell you what they are doing and help you tune the membrane (by adding more layers of need be).

 

[bkeeler10]

This is probably too much agonizing in my part, but you may want to consider making the pillar as acoustical small as possible. If you wrap it in fabric, you may want to consider constructing it of half inch dowels to reduce diffraction effects.

You're talking about rounding off the edges, I presume. It's a good point I hadn't considered.

If you want to make your own range limited treatment, try building a panel as normal and then covering it with a membrane. I use sticky carpet paint protection film. I bought a huge roll for under $30 dollars. You can also use latex or vinyl if you prefer, but it costs a lot more. You can always build a bunch of panels, put the membrane on and temporarily install them in the room and take measurements with and without the membrane. That can tell you what they are doing and help you tune the membrane (by adding more layers of need be).

So AIUI, the membrane performs two functions. The first is to reflect higher frequencies, which effect generally increases as frequency goes up. The second is to vibrate sympathetically at certain lower frequencies, thereby increasing low end absorption. I kind of thought that the membrane would have to be tensioned to accomplish this second function, and that of course the amount of tension would determine at what frequencies it would vibrate sympathetically. You're suggesting it has more to do with the mass of the membrane. So does the membrane sit limp against the fiberglass? If so, it's much easier to build than I anticipated.

 

[bkeeler10]

I did a quick Dirac calibration on the NAD with a pair of F36 and a pair of subs. I could only listen for a few minutes to the result before other things pulled me away. Wow, it's good to hear calibrated sound again! It's been over a year since I took down my former Audyssey Pro calibrated system, and it has been sorely missed!

 

[Matthew J Poes]

You're talking about rounding off the edges, I presume. It's a good point I hadn't considered.



So AIUI, the membrane performs two functions. The first is to reflect higher frequencies, which effect generally increases as frequency goes up. The second is to vibrate sympathetically at certain lower frequencies, thereby increasing low end absorption. I kind of thought that the membrane would have to be tensioned to accomplish this second function, and that of course the amount of tension would determine at what frequencies it would vibrate sympathetically. You're suggesting it has more to do with the mass of the membrane. So does the membrane sit limp against the fiberglass? If so, it's much easier to build than I anticipated.

I had similar thoughts about the tension of the membrane, but I recently received a bunch of test data on different panel setups that let me build knowledge based on past research. Adding a membrane always increases the LF absorption, with its mass and flexibility impacting where the bulk of the increase is. A very thin membrane largely increases absorption between 100 and 500hz. A heavier membrane shifts it down and lowers the bandwidth. Where it might provide decent boosting over 4-5 octaves at higher midbass frequencies, it may only produce 1/2 of an octave of boost at the lowest frequencies. The tension impacts the resonant frequency of the membrane, but otherwise doesn't seem to make a big difference. Even the box being sealed or not is not as important as people make it out to be. It changes the response, but it isn't a necessity. Leaks certainly don't seem to make a difference.

One thing I figured out from a lot of modeling and a review of a lot of these past tests is that the frame and backer boards rigidity do impact the absorption. They create a second resonant frequency and thus a double hump in the absorption curve. If you have knowledge of this you can use this, but if not, it can be a problem. It even shows up in broadband absorbers. It's caused by the rear panel acting like a panel absorber (and since its near the wall, its at the point of maximum pressure and thus maximum efficiency). My broadband panels are built without any rear panel, just a few cross-braces to avoid the problem. With those panels that need to have a solid back, I have tried different things but still get the resonance. My suggestion is to use two 1/4" panels adhered together with a damping glue (like green glue, but I used an M polymer adhesive when I tried the idea). I would then add trianguler fillets to brace the panel. This seems to stop the resonance and makes the panel more predictable (but of course, adds a bunch of work). You can also ignore it and hope for the best, when I attempted in room measurements, I didn't actually see a big difference. I mostly saw the difference in my simulations and in direct measurements on the panel (like with accellerometers or with the mic right up on the panel).

 

[Matthew J Poes]

NAD's in the house! And a pair of F36. Got them hooked up, plopped down on the floor with no particular care for placement, and sat to listen for 15 minutes. Not a fair shake at all, but I couldn't help myself!

I'm really torn at the moment about acoustic treatments. I filled up my cart at GIK earlier today, and the sticker shock set in. I had been thinking about building broadband absorbers but was hoping to buy everything prebuilt. Now I'm reconsidering. Problem is, it's easy to build a broadband absorber, but a bit more complicated to build one that works like their "Flexrange" versions work, or especially diffusion products (which I never considered attempting).

Now I gotta stop messing around and terminate some more speaker wire.

I'll be shocked if you don't love the Revel's. They are a really great speaker at a good price, given the performance and finish. I've heard Revel's a number of times, including in my own space, and always loved them. The old Ultima Salon's remain a reference for me. I heard the PerformaBE's at AXPONA and the room sounded so good it was almost boringly so. James Larson and I walked into that room expecting great sound and that's what we heard. There was a handful of rooms that we had more private time with, and while not my favorite experience, it was in the top 3. The Revel, TAD's, and Salk's were by far my favorite sounding speakers at AXPONA. TAD and Salk were a surprise, Revel was not.

 

[AudiocRaver]

The sound proofing part if this is especially interesting to me. I pretty much concluded that sound proof + not outrageously expensive is just not going to happen in my space.

Dirac Live: Like Sonnie and others, I cannot imagine trying to live without it.

 

[Matthew J Poes]

The sound proofing part if this is especially interesting to me. I pretty much concluded that sound proof + not outrageously expensive is just not going to happen in my space.

Dirac Live: Like Sonnie and others, I cannot imagine trying to live without it.

I spent a fortune on soundproofing. Like many, I wasn’t very disciplined in the moment and kept buying stuff without considering the grand cost. I had 4 five gallon buckets of green glue, a mix of 5/8” and 3/4” drywall, hat channel, various types of isolation clips, insulation, etc. it all added up quick.

If you want modest sound isolation and do the work yourself or have a cheap contractor, their are half measures that work. Resilient channel works well as long as you don’t short circuit it at all. Two layers of 1/2” is still better than one layer for sound isolation. If you use hat channel and two layers of 1/2” drywall and you are very careful to avoid short circuits you should get a decent improvement in isolation.

 

[bkeeler10]

The sound proofing part if this is especially interesting to me. I pretty much concluded that sound proof + not outrageously expensive is just not going to happen in my space.

Yes, doing sound isolation really well is expensive, both in cost and space and especially if you are interested in controlling the bottom few octaves. However, great improvements over standard building construction can be made with some simple and inexpensive changes, especially at frequencies above 125 Hz or so. Check out the attached pictures, which show STC values and also transmission loss (in dB) at various frequencies. One is standard construction (wood studs @ 16" on-center, 1/2" gypsum on each side). The second replaces the wood studs @ 16" on-center with light gauge metal studs @ 24" on-center and adds 3" of fiberglass in the cavity. Just those changes, which cost very little, make a huge difference everywhere 125 Hz and above.

The third adds mass by replacing 1/2" gypsum with two layers of 5/8" gypsum and is another huge step forward at 125 Hz and above, but notice that there is very little benefit in the 63 Hz band. If you really want to isolate low frequency, you have to mechanically isolate the inside of the room from the outside of the room, including walls, floor and ceiling (also called room-within-a-room). That's where it gets expensive and starts to chew up a lot of space.

Point being, if you're starting with new construction it is easy and inexpensive to make vast improvements over standard construction. Unless you're in a theater and interested in bass . . .

 

[Matthew J Poes]

Well Increasing the wall thickness can help. If you go with a staggered stud or double stud it makes a difference in the bass. If you simply go with a thicker wall by replacing the 4” studs with readily available 6” studs, that pushes the resonant dip lower. That should incur no increase in cost. You lose a few inches of floor space.

My biggest partition is 14” thick and it’s resonant frequency dip sits really low because the hollow of the wall is so large. I’m also seeing a lot more transmission loss in-situ than is supposed to be true for this wall type based on their lab tests (they didn’t test a 14” wall). I’m still working on overcoming room noise issues but I managed to accurately capture below 80hz. I’m seeing about 30dB of TL at 30hz. That sits well within modal regions so I’m still working to be sure that’s not an anomaly. As you likely know @bkeeler10 thst is unusually large TL for such low frequencies.