The Stonewater Cinema Build Thread - Page 7

I completely agree that the Denon was a landmark piece. Even used these things are still fetching $5000 - $6000 from what I have seen which is out of my budget. I should have been more specific with model numbers in my previous post, but on my current shortlist was the Marantz AV8801, the Denon AVR-4520CI, the Integra DHC-80.3 and the Emotiva XMC-1 (when released). I'd love to consider the Denon AVP-A1HDCI, the Theta Casablanca, the Anthem D2v or any of the other truly high-end preamps available but they are just not in the budget since all of that money will most-likely be heading into QSC equipment.

I love the sound of Classe equipment and that SSP-800 is a beast, but not having any surround decoding or streaming capabilities is a killer for me with this piece. I know you can bypass this issue with an external Bluray or other device that can do the processing, but I will be settling into a streaming system for all media content (at full resolution I might add!!) and my preference is for decoding in the preamp vs. through a lower-cost streaming client which could cut the Classe off "at the knees", acoustically speaking. Even a Dune HD Max doesn't have the processing capabilities of the Classe at the level of the Classe and that is really the best quality streaming client I am aware of.

I may be in Portland. The 3.5 hour drive to Bend may be a little beyond my schedule this time around, but I will let you know if things change via PM.

I recall reading Kevin Voeck's (Harman) white paper on the optimal number and placement of subwoofers in a home theater to get the smoothest bass response. If I remember correctly, the optimal number was four with placement at the midpoint of each wall. And like you suggested above, having two subwoofers placed at the midpoints of the front and back walls is recommended. Procella has their own white paper which recommends that you use two subwoofers in a baffle wall, with the left sub located between the left and center speakers and the right sub located between the right and center speakers. A handful of the professional builds I have seen using Procella setups supplement bass at strategic spots in the room with additional subwoofers either from Procella, Triad (low profile) or Velodyne (low profile).

As it stands now I have planned four Fi Car (gulp!) Audio IB-318 subwoofer drivers driven by 4000 to 6000 watts of amplification either from Crown or Behringer.using the same wiring topology found in Crutchfield's wiring schematic below:



As of now (i.e. design stage) one pair will function as a left sub and the other pair will function as a right sub - both of which will be located in a front baffle wall with a sealed IB chamber immediately behind. There is ongoing discussion about the number and location of any potential balancing subwoofers going into my room with the most-likely location being the midpoint of the back wall. Here I will have to use some sort of conventional subwoofer as there is no room for an IB baffle chamber anywhere but on the front wall. I'll keep you and everyone else posted on this as the plans develop. One other point FWIW....the subwoofers are configured in two separate arrays facing the room and not the back-to-back manifold designs you may see here on the forum from time to time.

Thanks again for all of your input!
Edited by TMcG - 1/3/13 at 8:28am

FYI - For those of you following this thread and would like to read Harman's white paper that NicksHitachi and I are referring to, the pdf can be found HERE.

My door would get in the way for the left rear of the room and the decorative columns would get in the way at the front the way I have it designed. Due to design constraints I am pretty much set with the two subwoofer arrays as per the Procella white paper although I have always been keen to try four subs at the midpoints to see how good it can sound.

But regarding your point on bracing the structure...in an ideal world what would you recommend? I was going to go with 3/4" plywood (maybe even T&G) as a first layer of sheathing to provide some structure to the baffle chamber followed by 3 layers of 5/8" drywall with Green Glue in between. All layers would be directly connected to the plywood sheathing with the appropriate length screw. I was then going to structurally bond the back side of the baffle wall to the (real) front wall with a bunch of Unistrut for bracing at 3 feet intervals. The front of the baffle wall would receive one layer of 3/4" MDF and then two layers of 5/8" drywall with Green Glue between all the layers.

Building two manifolds would force me to build cabinets to house these woofers and increase the depth of the IB chamber by another foot or so to accommodate these manifold boxes. As I am already cramped for proper viewing distances, especially from the front row, every bit of distance to the screen counts.

I pulled up a few YouTube videos of that Maelstrom 21 subwoofer you have....no wonder you were having problems with your projector vibrating!!! All I saw was guys cracking windshields, stuff falling off walls, animals running in fear for their lives and a few PhDs from NASA talking about how these subs have altered Earth's orbital path around the Sun. I'm thinking you probably have to alert your local law enforcement and SWAT teams before watching any Michael Bay movie. That thing is a monster!

EDIT: Fixed link to Harman White Paper
Edited by TMcG - 1/3/13 at 11:08am

Sorry, I was a victim of multi-tasking when I wrote that...I meant to say 3-D and streaming. But even then I see now that there is an update for this unit with HDMI 1.4 so it still boils down to streaming. Either way, this phenomenal piece is way out of my budget, even second-hand.

If I were to list my other "nice to haves" in a preamp (aside from good sound quality, HDMI 1.4 and streaming capability) it would be integrated AirPlay, HD Radio, IP Control (RS-232 is my control minimum), 4k pass-through (or upscaling) enabled and an integrated USB port (preferably 3.0, but 2.0 minimum).

The Marantz is at the top of my list, pending reviews and release of the final specifications of the Emotiva piece. But like you said, I will not be purchasing anything until I am beyond ready to make connections. I've learned the "early purchase" lesson the hard way like many others here on the Forum.


Along those lines, one thing I failed to mention before is that I am VERY hesitant to make a significant investment in three pieces of equipment - the Preamp/processor, the projector and the Bluray player - because the pace at which newer technologies for these product categories are moving it will be some time before a technological "plateau" is reached. So these are the parts of my system that I predict I will "turn and burn" as the needs arise. All others - The speakers, screen (and material), the NAS, power amplifiers, QSC DSP (upgradeable), etc. are all items I don't mind making more of a long-term investment. as the technologies are well-established and relatively unchanging as far as I can predict.

Thanks Nick. I hesitate to say this is only scratching the surface of a lot of the planning I have done for this theater. I just hope the execution goes along without any problems because of the planning and working out problems while they are still on paper (or in the ether here on this Forum ).

And thank you as well for the driver manifold sketch. I understand what you mean, but turning the woofers in any direction but facing straight out (toward the room) or straight in means that I will have to build a supporting manifold "box" (cabinet). Given the width of these woofers, the amount of "meat" in wood you have to put around these woofers for secure mounting, and having the drivers deeply imbedded in the chamber to get past the baffle wall framing (since they are side firing at this point) not to mention the 1.5" minimum thickness of the box....all of this adds up to almost 30 inches in depth I would have to give up where as I sit just over 18" right now according to my CAD from Dennis. So that's the extra foot of viewing throw distance I was talking about that I would lose.

If the only reason to do a manifold is to limit potential vibration, then I will do the array and glue, screw and brace the living crap out of the baffle wall and chamber. That's the reality of my short theater depth with two rows of seating and the gargantuan screen I lucked out in finding. If I had a 120" width screen I would have a bit more breathing distance on viewing angles, but this 140" width really puts the squeeze on my room dimensions. I just couldn't pass up the steal of a deal I got for a curved and motorized CIH screen frame, but that's another story.

Regarding the positioning of these woofers...Dennis has them more shaded toward (i.e. under, but not centered) the left and right speakers and not centered between the center channel and their respective main L/R channel. I may very well end up with just the four woofers at the front of the room and nothing further, but that's still being worked out at this point.

Thanks for your input and clarification Sanjay. I hadn't looked at that paper in a very long time. Thanks as well for the link to the updated paper - I can't wait to read it later tonight.

Regarding positioning....I am a bit (i.e. 100%) limited on where I can place my subwoofers in this room. Between structural supports, foundation concrete and other mechanical systems there is literally not a single spot in the entire room except for the front wall where I can locate my subwoofers unless I was to artificially narrow the room to "build in" the subs or have them sitting out in the open - neither of which are options I prefer. It is my sincere hope that getting the placement right in the baffle wall with the QSC DSP will give me the clean, smooth bass response I seek for the entire room and not just certain seats within the room. This is the primary reason I hired Dennis and his team, because you just can't beat an experienced professional with all the advanced resources available to acoustically dial in the room. The room has the greatest impact on final sound quality, so getting things right now should make calibration easier down the road. So far there has been no red flags in the front wall IB setup from Dennis' perspective.

But to your point, if my room wasn't landlocked I would definitely explore all subwoofer placement options. As it stands now, I am basically making my own pair of DIY Procella P18 subwoofers which has dual 18" drivers. Dennis has used two of these subs for rooms far larger than mine with award-winning results. Hopefully I can mimic most of their performance with my IB setup. If the P18s weren't $10,000 each, I would consider them but I don't have that kind of scratch, especially with our first child coming in April.

Thanks for subscribing SM2K! I may have said this at some point but yours and Moggies builds were my own personal inspirations for going with IB subwoofers and a FOSI star ceiling. You also introduced me to 3-Form and their synthetic panels which I greatly appreciated. I am a bit sidelined at the moment with an injured foot (above posts), but look forward to having you chime in throughout the build with your experience and opinion.

Ever hear of the "Law of diminishing returns"? Or even the "Law of the diminishing bank account"!!!