THX Ultra2 Install Advice

[BigBundyTime]

All,

I added a comment yesterday to another member's similar post; however I thought I would add some additional questions and comments on a new post.

I am in the process of finishing my basement and am considering incorporating some of the components of the THX Ultra2 system into the project.

The main room is aproximatley 14' x 50', which will incorporate a HT area, pool table and full bar.

I am probably going to go with a 65" DLP projection TV. The lights will frequently be on when the TV is on, so a projector is probably not an option. I am a little leary of the burn in factor on Plasmas and LCDs are just not big enough for me yet.

My goal is to come up with a clean custom install that will blend well with the athstetics of our home. One thought that came to mind was a to have custom cabinets built along the wall that would accomodate the speakers and also hold the TV (see attached).

I am looking for advice on how best to accomplish this idea.

One of my biggest concerns is that the location of the subs would create too much resonance through the cabinets. I have a storage room to the left of the setup where I could have them sitting on a concrete floor and firing through grills built into the walls.

I am open to any suggestions. Thanks

[BigBundyTime]

Here is the design idea:

[RichardP]

The THX Ultra II subs are made for exactly your situation, where they can be installed in custom cabinets (nice plans, btw). A front firing driver, a front port, and outboard amp means everything is coming out of the front, and no need to access the rear once installed. The sub enclosure is rock solid, so there should be no resonance in the wall cabinetry. With such an extensive built-in project, it may be worth spending a little $ to get at least a "consult" from a local custom installation specialist (if you can't get any further specifics from anyone here). You may also be able to get more tech/installation info from Klipsch customer support.

[DrWho]

What kind of budget are you working with for the cabinet layout?

If at all possible, I would try to angle the wings on the side of the TV towards the listening position. This will reduce early reflections off the side-walls while also providing a better on-axis response and a wider sweet spot. Attached is a crude drawing to give you an idea of what I'm talking about.

As far as mounting the speakers - you're going to want to take special considerations to prevent resonances from blurring the sound. The speaker cabinets are going to vibrate slightly and excite the cabinet in which they're sitting. Ideally you'll want acoustic foam surround the speakers, but not touching. And if it all possible it would be beneficial to have the speakers resting on a platform that is isolated from the rest of the cabinet - basically this could be a shelf mounted to the studs in the wall behind the speaker, or a stand that goes straight to the floor without touching the cabinet. I assume you're going to have a scrim in front of the speakers anyway?

Do you plan on putting your equipment on the shelves surrounding the speakers? You might find the lights on all the electronics to be a bit disturbing - especially if you'll be turning off all the lights for a movie.

[BigBundyTime]

The first quote for TV cabinet was aprox. $3,500 installed (unfinished). If the cabinets were deep enough, I intended to have them angled in, but not as much as your suggestion.

I planned to build an equipment rack into the closet that goes under the stairs to the left to keep the equipment accesible. That is what that little box was actually intended to be. I am looking for some suggestions on the best way to accomplish that too. I have looked into a couple of network racks that may suffice.

I was concerned about resonance in the cabinet too, especially from the subs if they were actually sitting on a shelf attached to the cabinet. Once I got closer to making a decision, I was going to have the contrtactor leave the bottoms out of the cabinets along the bottom, so they can sit right on the concrete floor. I could prorbably have them leave the backs off behing the L&R too to mount to the wall. Do you think there would be that much resonance from those too?

Thanks for the input.

[DrWho]

The goal with angling the speakers is to have their face perpendicular to a line drawn between the speakers and the center listening position. You also want to make sure their nominal dispersion covers all of the listening positions and keeps as much sound off the walls.

Resonance is absolutely a concern with the mains - in fact, you could argue moreso than the subs due to the wavelengths of their passbands. If you go with the flat front on the side cabinet wings and angle the speakers on the shelf, then be sure to leave room for acoustical foam for above and below the speaker. The sound doesn't come straight out, but rather spreads out rather quickly (at 90x40 or whatever their nominal dispersion is, and it's going to be wider as you go down in frequency). You don't want to let standing waves build up between the top and bottom (and the sides for that matter). The further front the front the speakers are, the bigger a concern this will be.

As far as aesthetics, it can be done to be visually acceptable. I need to run here in a bit, but I can provide some pictures later this week or probably next week if you're interested. The Ultra2 speakers are very fine sounding and I'd hate for your implementation to reduce that quality. But if you're not worried that much, then I might suggest going with the Reference lineup and saving a few bucks (blasphemy I know).

[BigBundyTime]

I would appreciate taking a look at some pics if you have them. Thanks

[TheSoundBroker]

I'd propose an alternative. Instead of doing a large custom cabinet...do a screen wall up front. You have a large storage unit to the left of the front where an equipment cabinet could be recessed in. Then up front you could put a screen wall with an Acoustic screen, the THX Ultra 2 L/C/R (at the proper height) and the subs. Everything would be hidden, super clean clean and this would cost you far less (no custom cabinet) and give you not only a far larger screen, but better sound and dialogue localization. With an SMX acoustic Screen (1.2 gain) and a projector like the Panasonic PT-AX100U, even with the room lights up, the image will still be more than usable and if you want anybody to see the image from the bar area, a 65" set simply won't cut it. If you dimmed the room lights even 25%, which is perfectly fine to still see, your contrast will be okay. And when it is time to really watch a movie...no comparison. With a room that size, it is unquestionably the way I'd go. I'd also seriously re-think your seating layout. Putting people along the side wall is definitely not the way to go.

[mas]

Just a couple of ad hoc comments and observations (as this is not intended to be a systematic detailed analysis)...(or... isn't it easy to find problems!? [])

First, a decision must be made as to whether you desire a critically tuned listening room, or a casual room where aethetics supplant acoustics. Simply saying one wants 'both' is not a reasonable balance, simply because priorities must be established.

If this is intended to be a 'critically' tuned listening room, the observation regarding the seating along the wall is quite valid. While fine for a casual room, it is not optimal for a critial listening room.

I will also offer an additional suggestion that will not be a popular one. Mounting the speakers in cabinetry has many problems. Ideally you would want to mount the speakers on acoustically isolated pedestals anchored to a solid slab floor (ideally a foundation). Likewise their placement within cabinets is going to cause all sorts of very interesting tuned resonances. I know that my suggestion may not be a reasonable solution in most residential environments. The screen wall that was mentioned is also a good idea, but I rather get the impression that room aesthetics are the primary consideration...so priorities need to be established and choices need to be made... []

Most significantly, you are going to have a heck of a time with the stairway alcove! Not only will it really skew the imaging due to the lack of symmetry regarding early reflections Lr, as well as create some really nasty focused specular reflections, but it will act as a coupled space. As a coupled space it will also serve to significantly reinforce tuned LF resonance modes within the room. In other words, left untreated, this 'feature' is a real problem! But appropriately treated, if also offers some very interesting possibilities!

This alcove is a significant feature effecting the room response in the room. In addition, the angled wall opposite the base of the stairway is a 'hard' reflective surface that is going to create a very 'interesting' problem (my wry sarcastic wit is in overdrive here!), even with loads of absorption!! (read: [][:'(] ) This structure - the alcove and the wall - is going to wreak havoc with the room response and listening quality. I would seriously consider some sort of hideaway partition (even a sliding pocket door) that can be pulled shut, thus creating a flat wall surface here. This is actually not difficult to do. With a low mass wall partition you will still need to address the resonant qualities of the partitioned space, but the early reflections within the listening space will be much easier to address. But this is not as bad as it sounds, as while you will still be able to treat the early order reflections off the surface, but incorporating phase gratings as mentioned below, you can put that space to a positve use and create a sense of controlled 'space' to the room. So you can turn a lemon into lemonade!

This space - even combined with the storage room space adjacent to the alcove - offers an option whereby the volume can be used to add to the diffuse field. By adjusting the surface of a pocket door (sliding door) and using an intelligently applied phase grating you can take advantage and utilize this space to add to the ambient sense of space in a positive manner. To get a sense of what I am talking about, visit the Auralex site where Russ Berger's pArt Science Space Couplers are featured. By utilizing similar phase gratings you can effectively do exactly what Russ has been doing for many years in the very high end pocket studios. By using measurements in conjuction with appropriate surface treatment, this could be tuned to create both a diffuse wall surface as well as adding a semi-reverberant ambiance creating a sense of 'largeness' to the room. But I would stress doing this should be done in conjuction with measurements in order to tune the response appropriately as you will need to balance the early reflections along with the 'loss' of energy into the coupled space. But all of this (all of the room treatments) could be done for less than you had budgeted just for your front wall cabinetry! And I am not suggesting diminished aethetics, lest one mistakenly think that I am suggesting converting this space into some sort of techno-garage! But, I can understand that it is perhaps difficult to imagine and to envision with such a cursory description.

Mike's previously suggested recommendation for angled corner placement of the speakers is also a good suggestion.

Also, mounting equipment in the closet space as previously mentioned is a reasonable idea as well. (Of course if you would choose to employ a pocket door stored along the storage room wall shared with the listening room, this option would of course need to be modified.)

Regardless of what path you choose, you are going to want to measure the room's modal response and surgically treat it with traps! Forget even playing with the mode calculators - You have a long rectangular room with the added 'attractive nuisance' of a significant coupled space. This combination of large parallel surfaces combined with acoustically significant room irregularities will render the mode calculators as little more than diversionary computer games! Just cut to the chase and measure the real response and treat the modes with corner traps (at the vertical and horizontal surface intersections) or tube traps if you do not object to their rather futuristic presence and remeasure to fine tune and optimize the response.

Aditionally, one other issue that you are going to experience and you will need to address with the long rectangular space is that of flutter echo. If I ever get around to having a bit more time to dedicate to the Architectural Small Room Acoustics thread we will mention this phenomena as well as potential solutions. And I will be trying to do begin this within the next week or so.

But once you have decided just what your priority assessment is between acoustics and casual flow & aesthetics, it will then be possible to make a few more decisions regarding room layout and topology based upon this decision. From there, your priorities will determine just how much further you will want to proceed with regards to absorption and diffusion.

I hope that I haven't scared you! That is not my intent! There are solutions...and your preferences will also impose constraints as well. But your room offers a combination of real issues along with some rather fascinating potential to turn those liabilities into real assets! So please do not be disheartened!

I have rambled a bit (allot!) and I also realize that it is not my place to tell you what to do or how you should orient your home or your lifestyle! [][] But you do have some real options if you decide they are worth pursuing! []

[BigBundyTime]

Thanks for the advice. I am pretty much set on going the rear projection TV route and thus will require the custom cabinets. I am going to build the equipment into the wall where you are suggesting with a MidAtlantic rack, which should be a pretty good location.

I am also going to have a an LCD TV built in behind the bar, so that will help for additional viewing possabilities. Really this would only be used if we had company for a sporting event party or for myslef if I wanted to pace the room while one of my teams was playing.

I realize that the furniture configuration is not ideal, but we already own it, so we will use it for awhile. It is generally just going to be my wife and I watching movies, so I am hoping the two seats in the middle of this configuration put us in the general correct seating perspective.

[DrWho]

Oh crap, I never got back to you on the shelf design...I couldn't find any of the pics of existing installs either.

Basically, what you do is have a 2,3" frame that extends in towards the opening of the shelf. Then the remaining 1,2" between the top of the shelf and the top of the frame is filled with acoustic foam. You do this on all four sides of the speaker (especially the top and bottom). This works to decouple the speaker from the shelf it's sitting on, while dampening cabinet vibrations that go off in all the other directions. You'll probably want a layer of foam on the wall behind the speaker too. You'll want to use the denser pitch black foam - not the lighter grey open cell less dense stuff. You also want the height of that shelf to be such that when the speaker is resting on the foam, that it's barely not touching the foam above it. This raises the frequency of the standing waves that will build up, making the foam more effective. The nice thing about using the dark dense foam stuff is that visually it's unobtrusive.

Just make sure the cabients are very rigid so that you're not conducting mechanical vibration throughout the entire entertainment center. Let me know if you have any more questions - I might be able to sketch something up.