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Stewart microperf screen - viewing distance and speaker placement advice needed.

childejc

Active Member
I have a Stewart Grayhawk microperf 100" fixed screen which I bought second hand. I thought it was a bargain but I've just done some very last minute research and am now very worried that it is not suitable for my room.

The THX recommended viewing distance ifor a 100" screen is 3m (or 10'), and this is where I intended to view from.

Unfortunately I have just discovered a Microperf White Paper which says "As an example, in a conventional theatre, with a luminance level of 12 Foot Lamberts (nominal), the studio industry standard Stewart Cinema Screen will have the perforations vanish at a viewing distance of 15 feet whereas the Stewart MicroPerf fabrics will vanish at a viewing distance of 12 feet."

If I move my viewing position back 2' to 12' I will be just 1' from my rear wall, directly below my in-ceiling rear surrounds. I can do this but it is not ideal. Does anyone have any idea how visible these microperfs will be at 10' in a dark light controlled room? Will it completely ruin the experience. My PJ is the JVC HD1 which outputs at 1080p.

My other problem is that I intended to put my Centre speaker about 7" behind the screen, taking advantage of its acoustic transparency. Again unfortunately, the same White Paper says "The speakers behind the screen need to be a minimum of 12 inches away from the rear surface for the best performance. They found that if the speakers are closer to the fabric, comb filtering can occur but when installed to specification, minimal attenuation occurs permitting truly transparent audio"

Any idea how serious this comb filtering (whatever that is) will be in my set up? Will it significantly impair the intelligibility of the dialogue?

My builder is constructing my front stud wall in 2 days, so I need to confirm the design today or tomorrow. Specifically, should I give up on the idea of putting the Centre behind the screen and instead put it below? If I do this then I will get no benefit from the screen being acoustically transparent:(

I'm beginning to think my screen was not such a bargain after all - I hope someone can reassure me on both the above 2 points.

Thanks
 

Johnny.G

Active Member
Hi Childe,
Dont get too dispondant ..... In my dedicated bat cave i use a 2.75m x 1.6m matte white microperf screen with a razor sharp Mitsubishi HC6000 pj running in low lamp mode and i cannot see the perfs after about 6 feet. My front row of seats are at about 9 feet and the back row is at 13 feet . My Tannoy IW62 TDC sides and centre are only about 2 inches back from the perf but i have an additional black acoustic material between the back of the perf and the front of the drivers. This helps with the contrast and also cuts down any screen movement at high volume levels. I compensate for the slight audio losses by boosting the mid and higher frequencies with my Onkyo 875 amp.
Not absolutely 100% , i had to make the best out of what i had got (building structure wise) but i am more than happy with the end results.

john
 

childejc

Active Member
Johnny - that is very reassuring, but I have to ask, when you say you can't see the perfs after 6', how good is your eyesight? I've read on other threads that people can see them upto 10-11'. No offence intended, but my eyesight with glasses is pretty good.

I've got to say, I am having a real panic today, as this is very last minute - my stud wall is to be built Tuesday and plasterboarded on Wednesday, so I have to make some very quick decisions. I'm even considering dumping the screen altogether.

Regarding the speaker, I am very keen to avoid losing any intelligibility of speech, so I think I will avoid the risk and stick it below the screen. Not ideal I know, and negates the benefit of the microperf screen, but this does give me the flexibility of ultimately replacing the screen material with an non perforated version if necessary. At least I did not pay a premium (I don't think) for the material as it was second hand.

thanks again
 

Johnny.G

Active Member
Hi Eric,

Good point re; the eye sight thing. Not offended at all. I use low rated glasses for viewing the screen at the distances mentioned and i can see that the BD image is razor sharpe but i cannot see the perfs. My lad who is 30 cant see them either (this is when a film is running of course).
I used to have my speakers in front on my last cinema set up which was in the lounge but her indoors wanted it back as a lounge so i had to build another room !. :eek: The microperf i use is in the attatched pic.
john.

 

childejc

Active Member
Johnny

Just to avoid any misunderstanding here, is yours a Stewart Microperf? Not a microperf from some other manufacturer, or a woven screen, as in the photo.

If so, how old is it? Mine is about 5 years old and is possibly 2 generations old now - not sure how much they have come on since then.

Thanks
 

Johnny.G

Active Member
Hi Eric,

My AT fabric was obtained from Otto at Beamax screens, this was purchased only about three or four weeks ago . Otto's site refers to it as a "Screen Research" fabric. It is a matte white finish with 0.9gain i do believe.

john
 

Johnny.G

Active Member
Further to the last ...... googling up "Screen Research" seems to refer to the "ClearPix" fabrics , the description of which is not how my fabric looks.
My microperf is a flat pvc type of fabric , just under a millimetre in thickness.

I tried all three samples of AT material as shown in the sample pic and the microperf gave the best results..... there is absolutely no moire pattening at all from the screen surface using the Mits HC6000 at 1080p.

john.
 

childejc

Active Member
Thanks Johnny - as yours is both a different manufacturer and much newer, its likely that yours has smaller holes hence why you can't see them. I will just keep my fingers crossed and hope for the best.

I've already decided to drop my intended in wall fronts and go with free standing speakers to avoid the problem and give me some more flexibility. I hope the order cancellation cost is not too high...
 

Johnny.G

Active Member
Ok Eric, good luck with the cancellation
 

Pulse1

Well-known Member
Hi Eric,


I have a Stewart Studiotek 130 1.3 gain 80inch wide microperf screen which i view 10ft from and cannot see the holes at all, I also have a Kef 23f THX speaker 8 inches behind it and no sound problems to my ears :) It's an excellent screen which i'm very happy with :D


Brian
 

childejc

Active Member
Thanks Brian.

I was too nervous about the sound issue so I have cancelled my in wall fronts and will for for freestanding speakers, so not utilising the perforations at all - a waste, but at least I did not pay full price.

I hope you are right about not seeing the perforations. However, given I have a fully light controlled room, I have been toying with getting a studiotek non perforated screen to replace my grayhawk. Once my room is finished in a few weeks I will try out the grayhawk for a few months and then see how it goes.

But thanks anyway - your experience is reassuring.
 

Pulse1

Well-known Member
I also have a Batcave :devil: All of my viewing is at 720p with both Dvd and Blu Ray from a CRT Projector, picture is awesome on this screen ;)
 
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