Placing L&R behind microperf - AVS Forum
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post #1 of 16 Old 11-24-2001, 11:56 PM - Thread Starter
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I must mount left and right Triad Gold In-wall speakers behind, or at least partially behind, a 96" wide microperf screen. I would prefer to mount them just beyond the outside edge, but two studs in a finished load bearing wall would have to be relocated and I wish to avoid this.

I can put them as narrow as 7'-3" (tweeter to tweeter) and place them completely behind, or as wide as 8'-7" and place the tweeters just barely outside the edges of the screen border. Because the seating is 13' from the screen, I would prefer the widest setting, but I am concerned about the speakers being partly behind and partly not behind the screen. In theory, this shouldn't matter since the screen is nearly "invisible" in terms of it's effect on the sound, but... Should I be at all concerned about placing the speakers partly behind and partly not behind the screen?

BTW, the black border area is perforated isn't it?

David
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post #2 of 16 Old 11-26-2001, 12:11 PM
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Hi David.

These are my experiences:

Quote:
Originally posted by haysdb
Should I be at all concerned about placing the speakers partly behind and partly not behind the screen?
No. I have been having speakers partially behind since two years now, I dont find that at all disturbing. All of my friends agree: I have the nicest home cinema regarding to sound / picture placement even if the speakers are somewhat outside the screen.

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BTW, the black border area is perforated isn't it?
If you are talking about a Stewart Filmscreen screen; yes, the black area of the screen is also perforated. (Also notice, it is possible to specify how much black area you want around your screen when you order a new one.)

Good luck!

Marcel Risberg (Stockholm, Sweden)
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post #3 of 16 Old 11-27-2001, 05:05 PM
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You will want to make sure that you tweeter is either completely unobscured or completely behind the screen. If the tweeter is behind the screen you would ideally want to have the THX equalizers in the signal path.

Is your microperf screen fixed or retractable? You could probably get by with the tweeter partially obscured if you have a retractable screen, however the hard aluminium border of a fixed screen may not produce good results.

Given your choices you might be better the have your speakers completely behind the screen and use the THX equalizers.

I would recommend that you give test out the speaker partially obscured with a sample of a micro-perf fabric and see whether it changes the character of the sound.

Hopefully you won't notice any difference and you'll be fine whichever way you choose to go.

Regards,

Kam Fung
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post #4 of 16 Old 11-28-2001, 08:55 AM - Thread Starter
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It is a tab tensioned drop down screen but I think I am going to put them completely outside the screen. It will require cutting through two studs in a support wall:eek:, but I have that figured out.

What is this THX equalizer you refer to? Is this something provided with Stewart microperf screens, or something purchased extra? I have this screen for a year or so and did not get any equalizer that I know of. I have an Audio Control Bijou though, so it's no big deal.

David
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post #5 of 16 Old 12-04-2001, 05:19 PM
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David,

If you got a micro-perf screen I believe they usually enclose an equalizer with it for the centre speaker... It's meant to compensate for the effects of the micro-perf on your sound. I think the unit is usually included in the price you pay for micro-perf, but I'm not 100% sure. However, if someone did your installation for you with another equalizer they may not have used the one for the micro-perf.

Regards,

Kam Fung
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post #6 of 16 Old 12-05-2001, 03:48 AM
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Quote:
Originally posted by KFung


If you got a micro-perf screen I believe they usually enclose an equalizer with it for the centre speaker... It's meant to compensate for the effects of the micro-perf on your sound. I think the unit is usually included in the price you pay for micro-perf, but I'm not 100% sure. However, if someone did your installation for you with another equalizer they may not have used the one for the micro-perf.
My Stewart MicroPerf did indeed come with an equalizer for the center channel, but I never used it; it sounds great without it!

Riverside Cinemas
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post #7 of 16 Old 12-05-2001, 05:10 AM
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Buy a pair of Triad LCRs and put them on either side of the screen. They'll give better audio than the in-walls to boot!

That would be the best of both worlds if set-up allows.

Jeff

There are more than a handful of [op amps] that sound so good that most designers want to be using them as opposed to discreet transistors. Dave Reich, Theta 2009
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post #8 of 16 Old 12-05-2001, 05:24 PM - Thread Starter
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Quote:
Originally posted by thebland
Buy a pair of Triad LCRs and put them on either side of the screen. They'll give better audio than the in-walls to boot!

That would be the best of both worlds if set-up allows.

Jeff
The InWall Gold/LCR is the same speaker as the InRoom Gold/LCR, with three differences:

The InWall version is mounted in a frame that allows the entire speaker to be rotated up to 15% vertically so that the speaker can be "pointed" at the listening area.

The InWall has a more pedestrian finish since there is no need for fancy vaneers or exotic wood for the "dispersion control lens".

The crossover is slightly different to compensate for the 400Hz "bump" that you get when placing a speaker designed for stand placement against a wall.

So, in fact the InWall should yield better (or at least more accurate) sound when wall mounted than the InRoom version would sound when mounted in the same location. For this same reason, the InWall speaker would not sound as good as the InRoom when placed away from a wall. When placed where each is designed to be placed, the should sound identical. I.e if an InWall were placed in a wall on the left, and an InRoom were placed on a stand at the same height, away from the wall on the right, they should form a perfectly matched stereo pair. That's the idea anyway.

David
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post #9 of 16 Old 12-06-2001, 04:40 AM
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I disagree completely.

Your arguements sound good and there may be some support for your reasoning but in the real world, these speakers will dissappoint in the home theater application.

In walls were invented purely to provide decent sound unobtrusively or when a typical speaker can't be used for practical purposes. They are by no means a substitute or an upgrade to the typical speaker design.

In walls are colored by the way the wall is built around them. There is inherent reverberation and the entire wall acts as a baffle. If you have looked inside a well built speaker, you see that the box is reinforced and significantly braced to limit vibration and, hence, sound coloration. Moreover, you will not find until after installation that the high SPLs of a home theater may create different distortions or colorations from the speakers. Dispersion characteristics are also altered. What if a stud is loose or a piece of drywall vibrates against the other that abuts it.

A 400 mhz bump is pure gimickry on the part of the manufacturer or whoever told you that. A SPL meter and sign sweep will best discern the frequency response. No one knows how your particular room and/or wall will impact the frequency response. A parametric EQ would be a better choice to fix things.

In short, no wall is as good as a well designed and braced box.

You will have to use some sort of digital center channel delay (also a negative), since all three speakers are on the same plane, the center will be forward of the L and R speakers from the sweet spot.

This is not an ideal way to set up a home theater. Go with the Triad LCRs and then any potential problems will be averted. Use the in walls for side or rear surrounds as potential sound artifacts are not nearly as significant.

Sorry for my candor but you asked. Trying to save a 'Crap! Why didn't I really check this out?' response.

Good Luck.

Jeff

There are more than a handful of [op amps] that sound so good that most designers want to be using them as opposed to discreet transistors. Dave Reich, Theta 2009
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post #10 of 16 Old 12-06-2001, 10:51 AM
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I'm using the Atlantic Technology System 20 THX ultra speakers with the optional in-wall enclosures. I was surprised at how well this speaker system sounds and will not hesitate to recommend them to someone who must use or desires an in-wall solution.

My LR's are outside of the screen, but hearing how well the microperf allows the center channel to sound I would have no concerns with placing the LR's behind the microperf screen as well.

BTW: A pair SVS 2039CS subs helps too!
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post #11 of 16 Old 12-06-2001, 05:07 PM - Thread Starter
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Jeff,

I don't think you understand that my speakers ARE the Gold LCR's. Same enclosure, same drivers. They are an in-room speaker, mounted in a frame that allows them to be rotated to point up or down, and with a crossover optimized for their proximity to the wall. I don't believe dispersion characteristics will be effected, thanks to the "disersion control lens" on the tweeter and the fact that the entire wall the speakers will be mounted on will be covered with Johns Manville Theatre-Shield

I have no loose studs in my wall, and nothing in the wall will be
resonating. It's composed of 5/8" drywall over 1/2" drywall, glued and screwed, with 1/2" on the back, also glued and screwed.

Quote:
A 400 mhz bump is pure gimickry on the part of the manufacturer or whoever told you that.
You are saying that an in-room speaker will not exhibit a rise in the bass at 400Hz when placed in close proxomity to a wall?

Quote:
A SPL meter and sign sweep will best discern the frequency response. No one knows how your particular room and/or wall will impact the frequency response. A parametric EQ would be a better choice to fix things.
I am prepared to smooth out the frequency response with an Audio Control Bijou but I think the use of speakers designed specifically for Home Theater use (the Gold LCR in-walls are THX approved BTW), and a room designed for HT (designed by Dennis Erskine), are good starts.

Quote:
In short, no wall is as good as a well designed and braced box.

Unless the in-wall in question IS a good and well designed and braced box.

Quote:
You will have to use some sort of digital center channel delay (also a negative), since all three speakers are on the same plane, the center will be forward of the L and R speakers from the sweet spot.

You make a resonable, but wrong, assumption. My Lexicon MC-1 would deftly handle this situation, if it existed. My center channel won't quite be on the same arc as the L&R with respect to front row center (where there is no seat anyway), but it will be 6" to 8" back, and there is no seat in the front row center anyway.

Quote:
This is not an ideal way to set up a home theater. Go with the Triad LCRs and then any potential problems will be averted. Use the in walls for side or rear surrounds as potential sound artifacts are not nearly as significant.
Dennis Erskine (not to mention a lot of other "home theater professionals") needs to find a new line of work then. I'd say my theater IS pretty much an "ideal way to set up a home theater", or at least that has been my goal. I have made and will make mistakes, but I am doing the best I can, and listening to the advice of those I think know what they are talking about.

David
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post #12 of 16 Old 12-06-2001, 05:15 PM - Thread Starter
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Quote:
Originally posted by randmac
I'm using the Atlantic Technology System 20 THX ultra speakers with the optional in-wall enclosures. I was surprised at how well this speaker system sounds and will not hesitate to recommend them to someone who must use or desires an in-wall solution.

My LR's are outside of the screen, but hearing how well the microperf allows the center channel to sound I would have no concerns with placing the LR's behind the microperf screen as well.

BTW: A pair SVS 2039CS subs helps too!
Randy,

I have heard good things about Atlantic Technology speakers. People I respect speak highly of them. They were on my "short list" along with the Triads and the JBL systems.

I would be lying if I said I didn't have strong misgivings about in-wall speakers. Many things about this installation run counter to 25 years of audiophile indoctrination. Just a few of the "mistakes" I am making:

. The L&R speakers will NOT be toed in.

. The front speakers will all be mounted above ear height.

. The subs (two) will both be in corners

The proof is still a few months away, but I am confident that I am going this "the right way".

David
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post #13 of 16 Old 12-10-2001, 10:56 AM
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Dave,

I do know about these. First, my system consists of Citation THX LCRs.

I own in wall speakers. They sound great! However, not at 105 db peaks.

I am not here to denegrate your set-up. Offering advice as you asked for.

Triads are excellent speakers.

My only point is this. All things being equal, use conventional speakers.

Dennis designed my theater, too.

If in-walls are the only option for you, the advice you sought and the related arguments are moot.

SPLS imaging, etc. are the primatry reasons.

THere are many choices to make in home theater design. I am still unsure of whether to use CRt or Digital for the projector. My application makes the choice more difficult.

My point is only this. If you could go to a box sp[eaker, design the room as such. What if you want to change speakers some day? Think about it. What'll you do?

JEff

There are more than a handful of [op amps] that sound so good that most designers want to be using them as opposed to discreet transistors. Dave Reich, Theta 2009
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post #14 of 16 Old 12-10-2001, 03:41 PM - Thread Starter
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Quote:
Originally posted by thebland
Dave,

I do know about these. First, my system consists of Citation THX LCRs.

I own in wall speakers. They sound great! However, not at 105 db peaks.

I am not here to denegrate your set-up. Offering advice as you asked for.

Triads are excellent speakers.

My only point is this. All things being equal, use conventional speakers.

Dennis designed my theater, too.

If in-walls are the only option for you, the advice you sought and the related arguments are moot.

SPLS imaging, etc. are the primatry reasons.

THere are many choices to make in home theater design. I am still unsure of whether to use CRt or Digital for the projector. My application makes the choice more difficult.

My point is only this. If you could go to a box sp[eaker, design the room as such. What if you want to change speakers some day? Think about it. What'll you do?

JEff
Jeff,

The Triad Gold LCR's are relatively efficient and have decent power handling, so I see no reason why dynamic range should be limited. They are THX certified, which I would hope is some indication that they meet the criteria for this.

They ARE "box speakers".

OK, OK, you tried to be somewhat concilatory and so shall I.

The wall in which the speakers are located backs up to an "equipment closet", so I have full access to the back of the wall. I will also retain full access to the front of the wall by covering the area in front of the speakers with a removeable section of fabric wall, kinda like a very large "speaker grill". A full 3'6" wide by 4' high area is available for each speaker. I could even remove that section of wall completely, if I wanted to set a "conventional speaker" in each location. I even tried to mount the LCR's sort-a "free standing" within this opening, and surround each one by pink insulation, thinking this would be like mounting them in-room, but both Dennis and ??? at Triad specifically discouraged me from mounting them that way since they are specifically DESIGNED to be wall mounted.

If I want different speakers, I can do that. Each speaker is mounted on a 3'-6" by 4' "baffle" which can simply be unbolted from the wall and replaced. In front of the wall is a "stage". I could set conventional speakers on the stage.

A dedicated HT is composed of trade-offs. In-walls are one sort of trade-off, and yet in return I get three IDENTICAL speakers, mounted horizontally aligned, at screen center, an "optimal" configuration. With free standing speakers, the center channel is typically a horizontal version of the mains, mounted below the screen, a "non optimal" placement, especially if there is more than one row of seating.

BTW, I appreciate the opportunity to "debate" this issue. :)

David
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post #15 of 16 Old 12-15-2001, 09:52 PM
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I certainly didn't have any problems with installing in-walls behind my perf screen. My mains are on wall apogee auriga's. I used niles at-8200 in a side by side configuration. The wall enclosure was built to the tuning specs my speaker software came up with to best match the bass curve of my mains. I have test equipment that measured the thiele small parameters of both the apogee woofers and the niles woofers. I came up with from 20hz to 1800 hz on these drivers less then 1 db peaks and dips all the way. I did need to build one zobel circuit to smooth out one peak at 660 hz on the niles. In room response testing was done with my audio control SA-3050A analyzer. So through carefull planning and building the wall enclosures solid and to the correct volume for the drivers.......one can design a very workable and cosmetically pleasing design. The audiocontrol bijou further dials in the concealed centers to the rest of the system. I've been an a/v installer for seven years now, installing equiiipment such as proceed, mcintosh, anthem, lexicon and so forth.........so I'm not exactly a newbie. My real passion though has always been speaker building, so naturally inwalls can be an exciting and interesting approach for challenging dedicated theater designs. This is just my two cents worth. If nobody can understand my flow of logic, its because its 1:oo in the morning...........thanks
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post #16 of 16 Old 01-01-2002, 06:32 AM
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Quote:
Originally posted by ckaudio
I certainly didn't have any problems with installing in-walls behind my perf screen.
ckaudio:

I would like to speak with you.
Email me directly at timw@erols.com, or by personal message here if you prefer.
Thanks!

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