Suggestions for in-wall L/C/R?

[CraigG]

Hello all! I'm looking for ideas to build some in-wall speakers for left/center/right positions in a home theater.

Things I need to consider:

Size:
I have two options here.



47.5" H x 14.5" W x 11.25" D is the largest that will fit into the existing framing. If more volume would be beneficial, it wouldn't be much trouble to knock out the short studs in the middle (not load-bearing, except for the sub!) and build a cabinet the full width of the wall, giving a maximum of 47.5" H x 25" W x 11.25" D for each speaker.

Screen:
These will be behind an AT screen.



I've seen test data indicating that this screen material attenuates the high end to the tune of 2db @ 20kHz as compared with 2kHz. The screen's frame also puts some limitations on baffle layout. The bottom of the screen frame occupies the area between 17.5" and 20" from the top of the speaker opening. If I used a TMW, MTMW, or MTMWW design, there would need to be a few inches of vertical separation between the T/M section and the W section, so that none of the drivers are situated directly behind the frame.



Amplification:
I've ordered an Emotiva XPA-3 to power the fronts, so inefficient or low-impedance designs shouldn't be a problem.

Current equipment:
Denon AVR-3806
Emotiva XPA-3 (on the way)
IB sub using 4x Dayton RS-15HF, with Behringer EP2500 amp & DSP1124P for EQ
Current speakers are 7x Klipsch KSB-3.1
Source is an HTPC sending LPCM audio from over HDMI to the receiver.

Room:
This is an oddly-shaped room, and quite small--less than 800 cubic feet. The main listening positions are about 6 feet from the screen.

Budget:
Well, that's kind of open-ended. $500 each (for drivers + crossover) is fine, but if there was a really compelling reason to double that amount, I could do it. On the other hand, if factors such as the requirement to fire though an AT screen will obscure the difference between a $250 speaker and a $500 speaker in my application, there's no sense in spending the extra cash.

Performance:
Current use of this room is 100% movies, but that could change, especially with some really spectacular speakers! I have no complaints about my current Klipsch setup, but it's an "ignorance is bliss" situation--having never heard Really Good Speakers™, I probably just don't know what I'm missing. I don't need insane SPLs; I'm just after accuracy and clarity.

Construction:
These will be hidden, so there's no need to do complex construction solely for aesthetics, but I'm not afraid of complexity if a good-sounding design requires it.

What looks promising so far:
--Khanspires--if they could be adapted to fit (no BSC, top woofer moved to the bottom, separation on the baffle between the MTM and WW, and reduced depth), they would be just about perfect, especially since it would open the door to using In-Khan-Neatos as surrounds down the road. I have no idea if these changes would require simple tweaks to the crossovers, or a complete redesign.

--In-Khan-Neatos--these would just about work as-is, but if I can go full-range with the space I have available, I'd prefer to do that.

--I'm curious about the "Coming in 2010" Modula MTWW and TMWW Xtreme in Jon's sigline, too--could either of these work? I'm in no hurry...

--3x center channels might work, too--Khancenter and some of the Modula variants in particular.

Any thoughts, guidance, recommendations, etc. would be appreciated!

[---k---]

--In-Khan-Neatos--these would just about work as-is, but if I can go full-range with the space I have available, I'd prefer to do that.

The In-Khans would probably qualify as "Full Range" at most retail outlets. The design is a 3-way design with a dedicated 7" RS180-4 woofer. The RS180-4 have surprising bass in this sealed configuration. The F3 is some where in the mid-50hz range. This easily supports a 50-60hz crossover. With room gain, you get strong bass extension.

The only way to have more full-range is to go ported. And this would be true for almost any speaker (except for 3-ways using the 10" RS drivers). And porting only extends the bass deeper, it does not increase the output. With a crossover to a sub (unless you're crossing down at 40hz), most of the benefits of porting the speakers will be lost and the results not much different than the sealed configuration.

With the subwoofers you have, I personally would build sealed - no matter what project you choose.

There a probably a lot of projects out there that could be made to work. I would focus on projects specifically designed to be in-wall. You might still need a little adjustments to get the tweeter level right if they weren't designed to be behind a screen.

Off the top of my head, I would say the In-Khans and Zaph's ZA MTM in-wall kit are your best bets.

[CraigG]

OK, you sold me. I was almost ready to pull the trigger on parts for a set of 7 In-Khan-Neatos, when another thought occurred to me--how about using three KhanCenters for the fronts? Any reason not to do this? This would allow me to get the tweeters as high as possible, keep all the drivers in a smaller space vertically, and I wouldn't have the downward lobe of the In-Khans. The only disadvantage I see is that I would need to rebuild my "stub" wall under the IB sub manifold, but that's not a big deal.

I see that the KhanCenters can be built less deep than the original, but by how much? Can I go down to 12" total depth? If so, would I want to build them taller (keeping the drivers in the same places relative to each other) to make up the volume?

Thanks!

[---k---]

You can probably do three khancenters. Should work.

Yeah, the khancenters can be built shallower. If you're going to increase the height to keep the volume the same, I wouldn't worry about the depth. You can probably go as shallow as 7 - 8" deep. Maybe build it as deep as the mid chamber, and then make sure you have enough space top and bottom so the woofer chamber is shared.

[cjd]

What you probably want is the in-walls I use behind my screen...

WMTW with 2 RS180-4, RS150, and Seas27TDFC...

[Mazeroth]

Room:
This is an oddly-shaped room, and quite small--less than 800 cubic feet. The main listening positions are about 6 feet from the screen.

6 feet. Surely you're kidding, right?

[CraigG]

What you probably want is the in-walls I use behind my screen...

WMTW with 2 RS180-4, RS150, and Seas27TDFC...

Hmmm...I'm intrigued, but I'm having trouble finding any info about them. Do you have a link? How would you say they compare to the KhanCenters?

From what I've read, the KhanCenters should work reasonably well in-wall, but something designed as a "real" in-wall could be a plus. And if you're using them behind a screen, I assume you've compensated for that as well. I have no concept of the magnitude of the differences here, though--I don't know if we're talking about a difference like putting a pillow over the speakers, or a difference like moving your head an inch.

One other thing--I'm almost certain I'm going with a set of In-Khans for the surrounds. With a different tweeter, are these going to be as well matched to the In-Khans as the KhanCenters?

Thanks!

[CraigG]

6 feet. Surely you're kidding, right?

Negative, Ghostrider. I just measured it--the distance from my ear to the screen is 71". Not ideal, but it makes for an immersive movie experience! :T

[cjd]

No info out there on them really. They're not entirely perfectly flat response, and tailored to the Seymour screen also.

[CraigG]

No info out there on them really. They're not entirely perfectly flat response, and tailored to the Seymour screen also.

OK, so it sounds like to pursue these, I would need to ask you for things like a baffle layout, crossover schematic, BOM, etc., which you probably haven't worked up for public consumption yet. There are a couple of reasons I don't really want to do that:

1. I love that there are experts like you here who are so willing to share their time and expertise, but I'm new here, and I don't want to be the charity-case guy who asks for a bunch of free custom work without giving anything back. I can help support the site by using the referral link for PE, and I plan to do a build thread with lots of pics, but in the interest of full disclosure, I really don't anticipate "evolving" to the point where I'll be contributing my own designs or anything like that.

2. If you were interested in giving me some help on something specific to my application, I think what I would *really* want instead is an in-wall, no-BSC version of your RS WMTW crossover, ideally with a bit of compensation for the AT screen baked in. However, I don't even know the level of effort I'd be asking for here--I don't know if this is something you could throw together in 15 minutes based on simulations, or if it would involve many hours of work, shipping a test enclosure for measurements, etc.

So, what do you think? Do you have any interest in working up a modified RS WMTW, or should I stick with trying to find the closest existing design to do what I need?

Either way, thank you!

[cjd]

2. If you were interested in giving me some help on something specific to my application, I think what I would *really* want instead is an in-wall, no-BSC version of your RS WMTW crossover, ideally with a bit of compensation for the AT screen baked in. However, I don't even know the level of effort I'd be asking for here--I don't know if this is something you could throw together in 15 minutes based on simulations, or if it would involve many hours of work, shipping a test enclosure for measurements, etc.

The in-walls (WMTW) I use in my HT and am speaking of here HAVE baked in response to work with the AT screen (mine is Seymour AV) as well as a slight extra nudge in the range needed to make speech more easily understood at lower output levels. They get a little harsh if you really crank it up, but they're really quite nice at low (70dB) levels. They were built and measured in-situ. So full in-wall, behind the screen.

I just have to pull the data together for sharing - it's all somewhere.

By crank it up I mean >110dB@2M

[---k---]

What you probably want is the in-walls I use behind my screen...

WMTW with 2 RS180-4, RS150, and Seas27TDFC...

I agree, but you're always tight lipped about them, because they aren't perfect. I think they sound good enough, especially when compared to most of the stuff out there or converting box designs to in-wall. I think you worry to much about people being happy.

[CraigG]

Sorry I wasn't clear in my rambling--I was referring to the bigger WTMWs mentioned in the KhanCenter thread, using RS225/RS150/RS28A. I'm thinking I have the room for them height-wise, so why not go bigger?

Is matching the Seas tweeter in the front with the RS28A in the In-Khan surrounds a concern?

I do like to crank it up for action/sci-fi, so I'm a little unsure about the harshness. I don't know what a given dB level sounds like without measuring, so I'm not sure whether this would be a concern for me.

[CraigG]

Also, I've had another thought (I know--I'm all over the place--sorry about that). The consequence of putting the big WTMWs in-wall is that they'll be bass-heavy, right? I'm wondering if my receiver's Audyssey room EQ wouldn't smooth that right out, while leaving me with speakers I could still use out-of-wall if I ever have to move, or decide to reconfigure the room again. After all, the Klipsch speakers I'm using in-wall now weren't designed for it, and I really have no complaints. Worst case, if they sound awful, I'll just have to get over my aversion to post-install tweaking and make some adjustments. Is my logic sound here, or am I asking for trouble?

EDIT: To answer my own question, I've decided this wouldn't make any sense. The width of the space I have available means that I couldn't fit the big WMTWs between studs--they would have to be an integral part of the wall, supporting the IB manifold (and even then, I'd have to fudge the width a tiny bit). They wouldn't be re-usable out of the wall, so even the small benefit of future flexibility wouldn't be there to offset the disadvantage of adapting these to in-wall use.

[CraigG]

Well, now I'm committed--I just ordered parts for 3x KhanCenters, and 4x In-Khan-Neatos. :E

[---k---]

Cool... Looking forward to hearing how it turns out.