For those of you that have their LCRs all behind an acoustically transparent screen in a 7.x setup....what are people using?

Just moved home, but the HT was Genelec 324 based. Truly spectacular.

Seaton Catalyst here

Art

Hey Art,

Thanks for the mention, although the page & website you linked to are still very much a work in progress and not really "live" yet. http://www.hometheatershack.com/forums/images/smilies/shh.gif

No big deal, but it will move, and a lot of the text is still just filler. :o

My theater is small and I Have a SMX 120" wide 2.35:1 screen. I have REVEL M22's as my L&R and a C52 as my center, also have M22's as my rears and S30's for sides. REVEL B12's for subs.
I was going to change to F32's for my front R&L but now we are likely moving so that is on hold.

Sounds like a Rick Springfield song ;)

Time to cut off the drinks for the web-dude! Of course that's one of the 2-3 sections where completely random text was thrown in by the guy I have working on the architecture and look of the site. Most of the rest he plucked from my own forum. I do believe the above segment was written late at night, and I think Chris was entertaining himself and figuring it would better motivate me to fill it with real info. :p

Fortunately I have the site set up so I can edit all of the text and general info myself as well. http://www.av123forum.com/images/smilies/emot-ninja.gif

Happy to provide some lighter entertainment for the forum. :o

Hey Art,

Thanks for the mention, although the page & website you linked to are still very much a work in progress and not really "live" yet. http://www.hometheatershack.com/forums/images/smilies/shh.gif

No big deal, but it will move, and a lot of the text is still just filler. :o

Sorry Mark but you are too darn quiet about your stuff.

Art

Is anyone using masking on a CIH 2.35 screen with speakers behind the screen? If so...can you explain your setup please.

The Stewart Vistascope has AT masking panels.

Art

I use full range tower speakers. Mcintosh LS360s behind my retractable screen. I like the CAT stuff for in-walls. http://www.calaudiotech.com/index.php?action=viewpic&pic=elite11big

Time to cut off the drinks for the web-dude! Of course that's one of the 2-3 sections where completely random text was thrown in by the guy I have working on the architecture and look of the site. Most of the rest he plucked from my own forum. I do believe the above segment was written late at night, and I think Chris was entertaining himself and figuring it would better motivate me to fill it with real info. :p

Fortunately I have the site set up so I can edit all of the text and general info myself as well. http://www.av123forum.com/images/smilies/emot-ninja.gif

Happy to provide some lighter entertainment for the forum. :o

VERY late at night and I'm easily entertained :D

Is anyone using masking on a CIH 2.35 screen with speakers behind the screen? If so...can you explain your setup please.


Getting back on topic, Art's system is one good example of this, and I believe coldmachine had a similar setup with his Genelecs.

In most cases with a 2.35:1 screen you will have all 3 speakers behind the screen. In some very wide rooms and longer distance to the front row you may place the L & R speakers outside the screen frame, but I'd say that's the exception, especially since you have the width of the masking system to deal with as well.

With all 3 speakers behind the 2.35:1 screen, the next concern is to look at where the masking falls for each aspect ratio, and just how acoustically transparent your masking is. The early versions of the Stewart masking system made a very noticable difference in high frequency performance. Obviously Stewart payed attention, and this was changed to what is on the current models, which is much more transparent. The point is to be sure and check out the characteristics of the masking, and where it will be with respect to your speakers for each aspect ratio. For the most part you are only concerned with the tweeter location, not that of the entire speaker, and most important is having line of sight to the tweeter from the listening positions. This means you want to watch out for where any wider support bars for the masking end up with various settings. In Art's system, the masking only covers the L & R speakers in 1.33:1 aspect setting. Fortunately in most movies, especially those in 1.33 AR, the majority of information and dialoge comes from the center channel, which remains unchanged. It is possible to have some external EQ's triggered or otherwise controlled to engage separate EQ settings per the masking position with the right control system.

I went with JBL Cinema series L/R/C and dual 22" secsoround subs. I'm set up to byamp the system but not had time. I would first find out how much room you have to work with. I have a standard cinema perf screen and it sound great. No problem with masking.
regards

My speakers are behind a Stewart Vistascope as well between the 16:9 aspect and 2.35 aspect. Toed in 10 degrees approx 12- 18 inches behind the screen (SPL RUNTS - compresion driver horns).

My speakers are behind a Stewart Vistascope as well between the 16:9 aspect and 2.35 aspect. Toed in 10 degrees approx 12- 18 inches behind the screen (SPL RUNTS - compresion driver horns).

So the only time your L & R speakers are not behind the mask is when watching a Cinemascope movie?

Do you compensate for this in EQ?

Also, I thought horns did not do well behind AT screens (or is that distance-dependant?)

I went with JBL Cinema series L/R/C and dual 22" secsoround subs. I'm set up to byamp the system but not had time. I would first find out how much room you have to work with. I have a standard cinema perf screen and it sound great. No problem with masking.
regards

I bet that is a powerful theater. :D How do you like the JBLs? Did you find setting them up difficult? What other equipment are you using? I, for one, would like to see some more photos of your theater. Thanks!

Jm_etue... Stewarts new masking material is essentially acoustically transparent (like speaker grill material). The screen is 14' wide.

Gotcha!

I have three Tannoy DC12i speakers behind my curved 126" 2.35 SMX screen:

http://www.tannoy-speakers.com/products/275/small-Slide-DC12i%203Q.jpg

Those are 12" dual-concentric, horn-loaded tweeters. I have them crossed over to an SVS CS Ultra, also behind the screen, at around 40 cycles. I don't have carpet yet, so I haven't done the final EQ'ing of the sub.

Also, the sides/rears are in-wall Triad Silvers.

Kelly

Has anyone ever done serious measurements of what different 'transparent' screens do to dispersion and or THD, spectral decay or anything such as this? I get the sense that these screens are far less transparent than they are portrayed to be.

Has anyone ever done serious measurements of what different 'transparent' screens do to dispersion and or THD, spectral decay or anything such as this? I get the sense that these screens are far less transparent than they are portrayed to be.

No material is truly transparent acoustically. That's a given.

However, properly done (which means no EQ in my opinion) the impact is minimal. Top octave frequency response is about 1dB softer with the AT screen. Dispersion (how do you measure that?) differentials by ear are identical. THD I don't have any way to measure easily. Spectral decay (if you're talking about an impact on RT60) is also minimal.

If you go with speakers freestanding, ie not behind the screen, you've just given up the best locations for them. That leaves you above or below; neither of which maximizes their characteristics as there are very few speakers designed to be that far off axis and still hit their intended performance.

There is no perfect solution; so the question becomes what compromises an individual is willing to make with their system.

Has anyone ever done serious measurements of what different 'transparent' screens do to dispersion and or THD, spectral decay or anything such as this? I get the sense that these screens are far less transparent than they are portrayed to be.

No material is truly transparent acoustically. That's a given.

However, properly done (which means no EQ in my opinion) the impact is minimal. Top octave frequency response is about 1dB softer with the AT screen. Dispersion (how do you measure that?) differentials by ear are identical. THD I don't have any way to measure easily. Spectral decay (if you're talking about an impact on RT60) is also minimal.

If you go with speakers freestanding, ie not behind the screen, you've just given up the best locations for them. That leaves you above or below; neither of which maximizes their characteristics as there are very few speakers designed to be that far off axis and still hit their intended performance.

There is no perfect solution; so the question becomes what compromises an individual is willing to make with their system.

John covered most of it above.

A screen wouldn't directly impact THD beyond the relation of how it affects frequency response. The audible parts are the frequency response differences and the reflected energy that does not make it through the screen. Let's not make this much more than it is. This is the same as a grill material or acoustical fabric we might use to conceal speakers in a room. This one just has to also have desireable video qualities. Defining the relevant acoustic characteristics of a screen is not as simple as one frequency response measurement. We ideally would want to know both what is transmitted and reflected. Of course this really needs to be expanded to include different angles of incidence as happens with real use.

While I've wanted to do some more extensive testing for a while now, without someone footing the bill for my time, I mostly have anecdotal observations thus far. In simple terms, each option has different optical and acoustic limitations. In the few cases I have worked with Screen Research products, they have performed exceptionally in simple throughput of sound and subjective lack of coloration. This was a few years ago, and I haven't used any of their latest products. I have on 2 occasions seen the SMX material, but I have not had a speaker behind it which I had measured without the screen. What I heard from speakers I was familiar with leaves me very optimistic in its acoustic properties. My experience with the Stewart MicroPerf screens has been mixed. It certainly alters the sound to some degree in measurements and subjectively. I have heard that greater distance between the speaker and screen helps reduce this, which is possible. I in no way consider this a fatal flaw, but it should be acknowledged.

I have only observed the masking on the Stewart screens. The latest generations Art and Jeff(thebland) have impact sound very little when they cover the left/right speakers already behind the screen. My point above was to be concious of the masking material used and confirm just how acoustically transparent a material really is when planning.

Obviously there is a lot more to choosing a screen than the acoustic properties. I have heard very good sounding systems using quite a few different types of screens, and in the end the acoustic treatments in the room and the optimization in system setup has a far greater impact on the resultant sound.

It's one thing to be behind an AT screen...but when you add masking to the equation...that must make a big difference.

I've noticed companies like Snell and Atlantic Technology (not that I'm endorsing either mnfr's products) have treble switches to compensate for AT screens. Anyone familar with treble switches or a similar technology in speakers? Are they useful?

If any specific projector had a signature similar to how an AT screen impacts an image from a viewing range of 0-14 feet or so it would be laughed out of the mid to higher end market as nothing more than a joke.

Just to put things in perspective.

It's one thing to be behind an AT screen...but when you add masking to the equation...that must make a big difference.

I've noticed companies like Snell and Atlantic Technology (not that I'm endorsing either mnfr's products) have treble switches to compensate for AT screens. Anyone familar with treble switches or a similar technology in speakers? Are they useful?

Stewart ,and now I believe SMX, provide a high quality AT masking.

Art

hi
here I installed a 330cm scope curved screen with microperforated 1.0pvc
quality similar to Stewart SMP model.
keeps a lot more brigthness and contrast than a woven material...
no moire (DILA HD100 and ISCO)
my preference is for microperforated pvc material.

speakers behind a 15'' gunners with large horns (GKF 505) and 2 velodyne 15'' subs
there's no alternative to big horn speakers when playing with big rooms and mp screens.
this is a 4 rows HT , with a length of 9meters (27ft)