65 replies to this topic

[Bsaac]

Hi guys

I'm after yet more advice/information

The dimensions of my impending theatre room have been changed by the architect in order to fit the other requirements we have for our extension

What this has meant is that the room is going to be narrower at 3.6m wide and in order to maintain the screen size I want I'm thinking of putting the speakers behind the screen to save the space I would need to have the left and right speakers on the side of the screen

So I have some questions regarding acoustically transparent screens:

Do they have any negative affect in the sound from the speakers behind it?

I haven't been able to find much information on the cost, are the generally much more expensive than standard screen? (I was planning on getting a Oz Theatre screen)

[oztheatre]

Nothing negative about it from all reports from AT screens we've done. smx use the same material so for more detailed info I'd suggest the smx screen thread over at the AVS forum?

The upside is your soundstage will be very accurate in that the vocals coming from the actors mouths will sound like it's coming from their mouths rather than under the screen if using a solid white screen. Just be sure to make the screen wall and behind the screen dark, matte black if possible.

My next showrooms will feature a 150 AT scope with the new Krix extreme home theatre speakers behind it. I'm looking forward to that!

[bbar]

Agree with Rich. I have been to a number of AT setups and the audio is excellent and as Rich says the soundstage for film is often improved,

[Elill]

The only "negative" is a 3db which EQ fixes in all of 2 seconds.

Massive, massive positives regarding soundstage, especially a properly positioned center channel (and you dont need a horizontal center so you can match the LCR's).

From what I understand, the cool thing about the OzTS material is that you can pretty much put the speakers directly behind it i.e. you dont need to leave ~300mm

[Bsaac]

Thanks for the comments guys

I hadn't thought about how much space was required between the screen and the speaker, OzTheatre could you give us an idea of what you recommend when using your screens?

[SDL]

Probably worth going on the Stewart film screen website and reading the white paper on AT screens. Talks about the various pros and cons of different types and also discusses the sound issues. Lots of generalisations and people making statements that are not truly representative. I have an AT screen and it is probably one of the best purchases I have made.

[Elill]

SDL - holy crap nice screen, did you source that locally? it'd cost almost as much as the rest of your gear combined - is it masked?

[oztheatre]

Here's the paper here http://www.stewartfi...residential.pdf

Not sure what 'woven' AT material they tested against, but it measures 0.76 for gain... It's not something I've encountered in obtaining samples from around the traps.. Have never seen anything that low... They dont name the material so it's a little biased imo. Could have been anything.. Fair comment?

Personally I think needle hole vinyl AT screen materials are yesterdays technology.. Woven is where it's at these days and most manufacturers today are using woven materials.

I was told they were developing their own woven AT material?

Here's the SMX audio testing results vs a perf vinyl screen.. perhaps this is also biased? http://www.smxscreen...asurements.html
Seems to contradict the stewart testing.. So who's telling the fibs? I have no idea.

[bbar]

, As they say Rich, there are small lies, big LIES, and statistics...

[SDL]

Not suggesting that the white paper is  covering or even trying to cover every screen in detail.  It more explains the advantages of an AT screen and some of the misinformation. As for woven v microperf it just depends on whether you are in the Screen Research camp or Stewart camp really nothing to do with old technology as both technologies are being adapted and winning awards still for their work.

[SDL]

Elill, thanks yes the screen IMO looks brilliant but I am biased I had to pay t for it. Was sourced locally but obviously built in the US and imported. I don't have masking as my room is fully light controlled and has Matt black ceiling and black surrounds and black panels around the screen so when the lights are out very little can be seen other than the projected area

Edited by SDL, 06 June 2012 - 02:47 PM.

[mr-happy-pants]

SDL's screen (and whole HT) does look awesome.

I am incorporating some of the design aspects into my HT design.

[oztheatre]

SDL, on 06 June 2012 - 02:41 PM, said:

Not suggesting that the white paper is  covering or even trying to cover every screen in detail.  It more explains the advantages of an AT screen and some of the misinformation. As for woven v microperf it just depends on whether you are in the Screen Research camp or Stewart camp really nothing to do with old technology as both technologies are being adapted and winning awards still for their work.

I agree but if the article was solely about the benefits of going AT to start with, they should not have needed to run their 'comparison' against an unknown woven material (perhaps the worst one they could find?) The article is good, but it also attempts to place woven screens in a poor light.

There isn't too much you can do with a needle hole vinyl apart from the making the holes different sizes and distances apart.. It is old tech and that is evidenced by 80% of screen manufacturers who have moved away from using such materials. Not saying they don't do the job either, just that woven is where most are right now.

[Bsaac]

Thanks for the replies and the information links

Before I get to exited about going down this path I'd better find out if it is going to  be feasible budget wise, is anyone able to give me an idea of how much a 125'' or 130'' AT scope screen would cost?

[Quark]

See here - you'll need to select the AT fabric you want.

[Prior]

I can give you the RRP of the OzTS screens, but I have no idea what the street prices are;

130" acousticvision - $2384
130" acousticvision 4k - $2739

As a comparison, a NON AT screen @130" is $1799

Cheers,

Chris

[MarkTecher]

Woven screens seem to be have a little different from the perforated screens.  In the original specs from Stewart, it was suggested that you need to leave 6" or 150mm between the back of the screen and the baffle wall.  It does not seem to be the case with a weave.  I have had my AT screen set up since 2007 and there is maybe an 1" 25mm at the centre from the baffle wall.

The tricky part is the baffle wall which needs to cover the area behind the screen, allow the speakers to play through and not have large gaps for sound to escape.  I made mine from 16mm MDF and I even made it in 3 parts to allow the L and R speakers to be toed in.  Mine in covered in 25mm foam and it works a treat.  Imaging is something else.  It is smooth and the sound does not jump from speaker to speakers as it can when you place speakers in free space (AT screen, no.baffe).

Yes you do need to make the treatments behind quite dark or you risk the light from the projector lighting it up.

HF losses are inevitable however, it seems the losses from a weave are much less than those from a perf screen.  Stewart actually supplies a small equalizer to use, however they only provide one for centre and ideally, they need to offer this EQ for all three LCRs.  When I tested mine, I used a RTA to measure the response and there was nothing measurable between my AT screen and no screen.  And of course with todays modern Room EQ, any losses will be compensated for anyway.

[:)]

mr-happy-pants, on 06 June 2012 - 03:27 PM, said:

SDL's screen (and whole HT) does look awesome.

I am incorporating some of the design aspects into my HT design.

second that, its an absolute beauty !  mr hp looking forward to see what you come up with

[oztheatre]

:), on 06 June 2012 - 07:16 PM, said:

second that, its an absolute beauty !  mr hp looking forward to see what you come up with

Where's the room pics? I can't see a link?

[Owen]

Is it possible to have a woven screen with no visible screen texture?
One of the main reasons I am looking to upgrade my screen is because I can see the texture of the screen at my viewing distance of 2.8-3.0 metres.

[MarkTecher]

Yes at a cost.  The fabric used on Screen Research is extremly fine and it costs a heap.  It also marks easy too.

[SDL]

Mark my Stewart screen came with 3 equalization amps for LCR speakers however found I didn't need them with the way room equalizations works now anyway.

MarkTecher, on 06 June 2012 - 07:10 PM, said:

Woven screens seem to be have a little different from the perforated screens.  In the original specs from Stewart, it was suggested that you need to leave 6" or 150mm between the back of the screen and the baffle wall.  It does not seem to be the case with a weave.  I have had my AT screen set up since 2007 and there is maybe an 1" 25mm at the centre from the baffle wall.

The tricky part is the baffle wall which needs to cover the area behind the screen, allow the speakers to play through and not have large gaps for sound to escape.  I made mine from 16mm MDF and I even made it in 3 parts to allow the L and R speakers to be toed in.  Mine in covered in 25mm foam and it works a treat.  Imaging is something else.  It is smooth and the sound does not jump from speaker to speakers as it can when you place speakers in free space (AT screen, no.baffe).

Yes you do need to make the treatments behind quite dark or you risk the light from the projector lighting it up.

HF losses are inevitable however, it seems the losses from a weave are much less than those from a perf screen.  Stewart actually supplies a small equalizer to use, however they only provide one for centre and ideally, they need to offer this EQ for all three LCRs.  When I tested mine, I used a RTA to measure the response and there was nothing measurable between my AT screen and no screen.  And of course with todays modern Room EQ, any losses will be compensated for anyway.

[Bsaac]

MarkTecher, on 06 June 2012 - 07:10 PM, said:

Woven screens seem to be have a little different from the perforated screens.  In the original specs from Stewart, it was suggested that you need to leave 6" or 150mm between the back of the screen and the baffle wall.  It does not seem to be the case with a weave.  I have had my AT screen set up since 2007 and there is maybe an 1" 25mm at the centre from the baffle wall.

The tricky part is the baffle wall which needs to cover the area behind the screen, allow the speakers to play through and not have large gaps for sound to escape.  I made mine from 16mm MDF and I even made it in 3 parts to allow the L and R speakers to be toed in.  Mine in covered in 25mm foam and it works a treat.  Imaging is something else.  It is smooth and the sound does not jump from speaker to speakers as it can when you place speakers in free space (AT screen, no.baffe).

Yes you do need to make the treatments behind quite dark or you risk the light from the projector lighting it up.

HF losses are inevitable however, it seems the losses from a weave are much less than those from a perf screen.  Stewart actually supplies a small equalizer to use, however they only provide one for centre and ideally, they need to offer this EQ for all three LCRs.  When I tested mine, I used a RTA to measure the response and there was nothing measurable between my AT screen and no screen.  And of course with todays modern Room EQ, any losses will be compensated for anyway.

Ah baffle?

I was just planning to have the speakers free standing behind the screen with the centre speaker raised to the tweeter level of the left and right speakers, is this not going to work?

Thanks for the prices Prior!

[oztheatre]

Bsaac, on 06 June 2012 - 09:27 PM, said:

Ah baffle?

I was just planning to have the speakers free standing behind the screen with the centre speaker raised to the tweeter level of the left and right speakers, is this not going to work?

Thanks for the prices Prior!

Well you don't 'need' to do this but it would be beneficial for the reasons THX state here; http://www.thx.com/p...nd-baffle-wall/

There's a cool story about full wall baffles from the 1980's. George Lucas tried to sue Scott Krix of Krix Loudspeakers for using a full wall baffle. Lucas claimed he was the first.. Scott Krix proved he'd done it years before and beat George Lucas in court. Thanks to Tom Tolley from Krix that cool story : )

[oztheatre]

MarkTecher, on 06 June 2012 - 07:10 PM, said:

Woven screens seem to be have a little different from the perforated screens.  In the original specs from Stewart, it was suggested that you need to leave 6" or 150mm between the back of the screen and the baffle wall.  It does not seem to be the case with a weave.  I have had my AT screen set up since 2007 and there is maybe an 1" 25mm at the centre from the baffle wall.

The tricky part is the baffle wall which needs to cover the area behind the screen, allow the speakers to play through and not have large gaps for sound to escape.  I made mine from 16mm MDF and I even made it in 3 parts to allow the L and R speakers to be toed in.  Mine in covered in 25mm foam and it works a treat.  Imaging is something else.  It is smooth and the sound does not jump from speaker to speakers as it can when you place speakers in free space (AT screen, no.baffe).

Yes you do need to make the treatments behind quite dark or you risk the light from the projector lighting it up.

HF losses are inevitable however, it seems the losses from a weave are much less than those from a perf screen.  Stewart actually supplies a small equalizer to use, however they only provide one for centre and ideally, they need to offer this EQ for all three LCRs.  When I tested mine, I used a RTA to measure the response and there was nothing measurable between my AT screen and no screen.  And of course with todays modern Room EQ, any losses will be compensated for anyway.

So ideally then, people should be using a baffle with free standing speakers also? An AT screen with a screen wall baffle is going to sound better than a non AT screen with no baffle. I gather we're talking about absorption and diffusion treatments to act in a similar way to a baffle with an AT screen?

What about energy lost at the rear of the speakers? or is this a non issue?

Edited by oztheatre, 06 June 2012 - 10:29 PM.