Why should screen always be on shorter wall?

Dobbyisfree

Well-known Member
Or go narrower but consider front wides? For me, I'm a bit dubious about that, given that they would be up-mixed for most content and not discrete.
 

Triggaaar

Distinguished Member
My understanding is that the recommended angle is 22 - 30 degrees. I can achieve 22 degrees if the speakers sit inside the screen at 2.5m apart. Or I can fit outside screen up to max 3.8m apart but then angle increases to about 33 degrees. Better to follow the Dolby guidelines or go for wider sound field?
What speakers are they? And those measurements are to the centre of the speakers, right? And is that with the speakers toed in? And do you already own the screen?
 

Praetorpwj

Active Member
They are IW MK 150 LCR and IW 85 and 95.

I already own the screen so I am having to make everything work around it which isn't ideal.
 

Praetorpwj

Active Member
Sketch of 2 options
 

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Praetorpwj

Active Member
In general due to throw distance and a couple of other practicalities I am currently veering towards option 1. In the dim and distant future when video walls are a thing I may switch to something like option 2.
 

Triggaaar

Distinguished Member
In general due to throw distance and a couple of other practicalities I am currently veering towards option 1.
What projector do you have, or are you thinking of getting?

Also, are the 4 seats because there are regularly 4 of you watching together, or will all 4 be used together only occasionally?

Either way you can have your speakers butted up to the edge of the screen.
 

Praetorpwj

Active Member
What projector do you have, or are you thinking of getting?

Also, are the 4 seats because there are regularly 4 of you watching together, or will all 4 be used together only occasionally?

Either way you can have your speakers butted up to the edge of the screen.
Still got the X7000! Not looking for a replacement for a few years yet as I will need all cash for new room, but I'm mindful of the reduced throw distances on the new JVC.

We are a family of four but will usually be two or three viewing.

If going with option 1 I am minded to toe in the speakers but since I don't want a baffle wall will probably build the front corners out at an angle as indicated.

Option 2 is obviously wider so I can position speakers flush without getting too close to side walls.
 

Praetorpwj

Active Member
I see that your projector is out of the room in both examples. Is this an existing room, and is that easy to achieve?
This is all part of a new build extension so I can design it either way (same for position of entrance door). In general option 1 is easier as it is a separate room. Option 2 is just a recess into an adjacent room so not so good for ventilation / adjusting connections etc.
 

Triggaaar

Distinguished Member
Still got the X7000! Not looking for a replacement for a few years yet as I will need all cash for new room, but I'm mindful of the reduced throw distances on the new JVC.
Ok.


We are a family of four but will usually be two or three viewing.
If it's not usually 4, then the benefit of the wides being further from the sides is lost a bit. Do you already have the seats? I chose some reasonably slim seats (still plenty of room) and a loveseat in the middle, so that those on the sides aren't too far from the centre, which benefits both audio and video.

If going with option 1 I am minded to toe in the speakers but since I don't want a baffle wall will probably build the front corners out at an angle as indicated.

Option 2 is obviously wider so I can position speakers flush without getting too close to side walls.
I'd toe in anyway, it would give a much better balance for those not in the centre.
 

Triggaaar

Distinguished Member
This is all part of a new build extension so I can design it either way (same for position of entrance door).
Ah fantastic. If you can move the door away from the corner that would allow you to put a sub there in the future, regardless of whether you go option 1 or 2. It may be that the room benefits from a sub there, or you eventually go for 4 subs. It would also allow a deeper baffle/false wall if you ever went for different speakers.

In general option 1 is easier as it is a separate room. Option 2 is just a recess into an adjacent room so not so good for ventilation / adjusting connections etc.
I'd go option 1, but option 2 also works.

Given that the room is new, will it have sound-proofing to other rooms?
 
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Praetorpwj

Active Member
Ah fantastic. If you can move the door away from the corner that would allow you to put a sub there in the future, regardless of whether you go option 1 or 2. It may be that the room benefits from a sub there, or you eventually go for 4 subs. It would also allow a deeper baffle/false wall if you ever went for different speakers.


I'd go option 1, but option 2 also works.

Given that the room is new, will it have sound-proofing to other rooms?
Thank you for feedback.

My thinking was that because this was a 5m deep room if I added a baffle wall it would increase my MLP position from 3.1m to around 3.6m and that would then create some room mode issues (0.72 rather than 0.62 of room depth). Hence I though it better to drop the subs to the rear of MLP where I can properly shift them around.

The finished dimensions of 5m x 4.2m include for a perimeter of 150mm soundproofing including for recessing of in-wall speakers.
 

Triggaaar

Distinguished Member
Thank you for feedback.
Pleasure.

My thinking was that because this was a 5m deep room if I added a baffle wall it would increase my MLP position from 3.1m to around 3.6m
Well first I wouldn't add a baffle wall to a short wall, because that would make your room even squarer - but you could have a false wall, because that wouldn't change the acoustic properties of the room. But please not I'm not suggesting you do that either, only pointing out that if the door was away from the corner just a little, then it would be a future option if you ever wanted different speakers.

Looking at your drawing, I get the feeling the screen is already a few inches off the main wall? That's all a false wall is anyway, I'm just saying you could allow a bit more than a few inches. Not another 50cm.

You're currently planning on sitting 3.1m from the screen. Sorry if I've missed it, but I don't know how much experience you have with cinema rooms - for all I know you've spent 20 years sitting 3.1m from a 2.9m wide screen, and love it. That's a nice size, relative to your seating, but quite a few people like bigger (/closer), so if you haven't already tested screen size to seating distance to death, it's possible you'll decide to sit closer.


and that would then create some room mode issues (0.72 rather than 0.62 of room depth). Hence I though it better to drop the subs to the rear of MLP where I can properly shift them around.
Subs at the rear is fine. My suggestion was only to move the door a little, which would give you more future flexibility. If moving the door causes issues outside the room, don't worry, but if it doesn't, then it's easy to do. FYI, the door to my room (in an old house) was about 5" from the wall. That wasn't going to work for me, so I went to the trouble of blocking it up from the cinema side (it's still there on the other side) and making a new door at the other end of the room, about 2 feet into the room. If you can move your door now, with zero effort or cost or compromise, it just gives you more flexible future options.


The finished dimensions of 5m x 4.2m include for a perimeter of 150mm soundproofing including for recessing of in-wall speakers.
Ah lovely. Not wanting to teach you to suck eggs here - do you need any advice on that?
 

Praetorpwj

Active Member
Pleasure.


Well first I wouldn't add a baffle wall to a short wall, because that would make your room even squarer - but you could have a false wall, because that wouldn't change the acoustic properties of the room. But please not I'm not suggesting you do that either, only pointing out that if the door was away from the corner just a little, then it would be a future option if you ever wanted different speakers.

Looking at your drawing, I get the feeling the screen is already a few inches off the main wall? That's all a false wall is anyway, I'm just saying you could allow a bit more than a few inches. Not another 50cm.

You're currently planning on sitting 3.1m from the screen. Sorry if I've missed it, but I don't know how much experience you have with cinema rooms - for all I know you've spent 20 years sitting 3.1m from a 2.9m wide screen, and love it. That's a nice size, relative to your seating, but quite a few people like bigger (/closer), so if you haven't already tested screen size to seating distance to death, it's possible you'll decide to sit closer.



Subs at the rear is fine. My suggestion was only to move the door a little, which would give you more future flexibility. If moving the door causes issues outside the room, don't worry, but if it doesn't, then it's easy to do. FYI, the door to my room (in an old house) was about 5" from the wall. That wasn't going to work for me, so I went to the trouble of blocking it up from the cinema side (it's still there on the other side) and making a new door at the other end of the room, about 2 feet into the room. If you can move your door now, with zero effort or cost or compromise, it just gives you more flexible future options.



Ah lovely. Not wanting to teach you to suck eggs here - do you need any advice on that?
Yes sorry I meant a false wall. Since I have in-wall speakers the only purpose of a false wall would be to hide subs at the front (hence the 500mm) which seems a inefficient use of space. I take point about alternate speakers though.

The door can be adjusted a little deeper about 300mm however this would rule out future installing wides if that every becomes a thing. I do intend for the door to sit flush with the wall and be covered in blackout material to minimise intrusiveness. Maybe add a curtain to draw over?

3m distance is largely due to advised minimum distance for XD fabric and I understood that 1:1 width/distance was a good ratio. I hadn't really considered a bigger screen but there is no reason why I couldn't increase to 3.3m wide from 2.9m I suppose.

For soundproofing I had assumed standard 20mm gap, 100mm stud and insulation, 18mm OSB, 12mm soundbloc. Probably need a bit more for first reflections and blackout fabric.
 

Triggaaar

Distinguished Member
Yes sorry I meant a false wall. Since I have in-wall speakers the only purpose of a false wall would be to hide subs at the front (hence the 500mm) which seems a inefficient use of space. I take point about alternate speakers though.
That's if you never change speakers. Fine if you know that's the case.


The door can be adjusted a little deeper about 300mm however this would rule out future installing wides if that every becomes a thing.
I'm installing wides, the door isn't close to being in the way.


I do intend for the door to sit flush with the wall and be covered in blackout material to minimise intrusiveness. Maybe add a curtain to draw over?
I'm covering my door black with fabric, as well as adding absorption to it.


3m distance is largely due to advised minimum distance for XD fabric
Ah - well I've been doing a lot - I mean, A LOT of research on the XD fabric, as I have the same issue. And my conclusion is, it's a non issue. I went to @Ringnut 's home to see his (thank you Jon :) and I couldn't see the weave when sat at under 3m. He also did some testing, and had to get crazy close before he could see the weave. There's a youtuber called Youthman who sits 9' from his XD, and he can't see it. If you have the world's best vision, and ever notice it, you could move back a little, but my conclusion is that it's a non-issue.

and I understood that 1:1 width/distance was a good ratio. I hadn't really considered a bigger screen but there is no reason why I couldn't increase to 3.3m wide from 2.9m I suppose.
Ok, so the only thing I've researched more than XD fabric, is screen size (ok, that's a lie, I've researched everything like the proper mad geek I am). IMO people are getting more used to large screens (times have changed, resolution has improved etc). 1:1 is really nice. Some like a lot bigger. I like a bit bigger. Only time will tell what's perfect for you, but my advice would be to avoid limiting your choices where at all possible. eg, try not to limit your size by throw distance, and consider that you might like sitting closer than 3m.


For soundproofing I had assumed standard 20mm gap, 100mm stud and insulation, 18mm OSB, 12mm soundbloc. Probably need a bit more for first reflections and blackout fabric.
So a completely isolated room inside the existing - excellent. What about the ceiling?

Depending on how effective you need the sound-proofing to be, you might also want to consider something like green glue between the osb and plasterboard.
 
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Praetorpwj

Active Member
That's if you never change speakers. Fine if you know that's the case.



I'm installing wides, the door isn't close to being in the way.



I'm covering my door black with fabric, as well as adding absorption to it.



Ah - well I've been doing a lot - I mean, A LOT of research on the XD fabric, as I have the same issue. And my conclusion is, it's a non issue. I went to @Ringnut 's home to see his (thank you Jon :) and I couldn't see the weave when sat at under 3m. He also did some testing, and had to get crazy close before he could see the weave. There's a youtuber called Youthman who sits 9' from his XD, and he can't see it. If you have the world's best vision, and ever notice it, you could move back a little, but my conclusion is that it's a non-issue.


Ok, so the only thing I've researched more than XD fabric, is screen size (ok, that's a lie, I've researched everything like the proper mad geek I am). IMO people are getting more used to large screens (times have changed, resolution has improved etc). 1:1 is really nice. Some like a lot bigger. I like a bit bigger. Only time will tell what's perfect for you, but my advice would be to avoid limiting your choices where at all possible. eg, try not to limit your size by throw distance, and consider that you might like sitting closer than 3m.



So a completely isolated room inside the existing - excellent. What about the ceiling?

Depending on how effective you need the sound-proofing to be, you might also want to consider something like green glue between the osb and plasterboard.
I can very occasionally see the fabric even at my current 11ft on a very bright scene but it certainly doesn't break the immersion. I'm think 1:1 is probably about right for me.

What I might be able to do is increase the room depth to around 5.3m and have a false wall around 500mm deep to conceal front subs and future proof for replacement LCR. If I reduce viewing distance to 2.9m then this would put me approx 0.64 for room modes which isn't bad.

There will be a soundproof layer fixed direct to roof joist (well clipped anyway) and then a false ceiling of 250 - 300mm for speakers, lights, ac etc. I want to black out front 2m ceiling, floors, walls and whole of rear wall but I don't really want a black velvet coffin; the challenge will be to create some attractive craft styles with blackout material to give it a bit of art deco style.

yes there will be green glue or that rubber stuff. I suppose realistically I need to allow around max 200mm including any treatment and fabrics.
 

Triggaaar

Distinguished Member
I can very occasionally see the fabric even at my current 11ft on a very bright scene but it certainly doesn't break the immersion.
Oh wow. Superhans is supereyes. I assume it's the weave you can see, not moire.

In that case you don't want to get too close.


What I might be able to do is increase the room depth to around 5.3m and have a false wall around 500mm deep to conceal front subs and future proof for replacement LCR.
Well you don't need to go to the trouble of building the false wall now, it would just be a shame to prevent it ever being an option, unless you had to.

If I reduce viewing distance to 2.9m then this would put me approx 0.64 for room modes which isn't bad.
There's a 4th mode 0.625 * into the room. For a room your size, that should be just above your crossover. It's not a big deal, and it's also very short, so you only have to be just behind it to avoid it. And obviously that's from your ears, not eyes (the few inches difference does actually make a difference). You can easily check the room when done, and simply make sure you're sat just behind the null. But it's worth knowing where it's likely to be before you commit to sizes, because if you're right on it, you might want to adjust your seating a little.

Note that the modes will be from the wall, not the screen fabric.

There will be a soundproof layer fixed direct to roof joist (well clipped anyway)
Again apologies if this is teaching you to suck eggs: For sound-proofing, the devil is in the detail. Make sure the inner walls and ceiling are properly joined and sealed, for both osb and plasterboard layers. It's very easy to undo a lot of expensive work.


and then a false ceiling of 250 - 300mm for speakers, lights, ac etc.
Cool, I'm doing similar.

I want to black out front 2m ceiling, floors, walls and whole of rear wall but I don't really want a black velvet coffin; the challenge will be to create some attractive craft styles with blackout material to give it a bit of art deco style.
Yeah that is a challenge. I'm going to have hidden downlights every 30 or 36", close to the walls, and try and lighten up what will otherwise be a black pit. In terms of art deco style, that's asking a lot if you're really going for blackout material.

yes there will be green glue or that rubber stuff.
Perfect.

I suppose realistically I need to allow around max 200mm including any treatment and fabrics.
If you have good control over the build, you can decide exactly what to allow. Your room is 50cm wider than mine, so you're not fighting for space like I am.

If it helps, this is what I have:
Gap to wall between 10 & 30mm, depending on whether there was skirting board on the wall
Joist of either 45mm or 70mm, depending on whether I turned it sideways to save space (insulation between studs)
36mm for osb, tecsound, plasterboard

And then where there are speakers, or the projector, I'm installing backboxes, into the structure, so that will be:
10mm gap, 36mm for osb/tec/pb = 46mm
and then the speaker (or projector)

That whole structure is isolated, and when most of the osb is on I will have to test to see if it's possible for the studs to hit the existing walls. If it is, I will have to put some rubber damping at the top of some studs, to make sure they don't clatter into the existing walls when the bass is going.
 

kenshingintoki

Distinguished Member
People probably use the shorter wall so they have the longest possible throw distance for the biggest image possible.

If you're accounting for speaker placement, false walls, gear, space for projector cooling, a longer throw is quite important.
 

Praetorpwj

Active Member
People probably use the shorter wall so they have the longest possible throw distance for the biggest image possible.

If you're accounting for speaker placement, false walls, gear, space for projector cooling, a longer throw is quite important.
Thanks for reply and I get that, I’m really interested in how it affects the acoustics side of things.

I think that if your starting out like I am you need to follow the ‘rules’ as far as possible, but having re-worked this thing many times now the rules seem quite restricting.

Hence I’m interested in basics like room shape and orientation. Conventional wisdom advises to avoid square plans for room modes but the Rob Hahn cinema on AVS Forums considered by many to be the finest private cinema in the US at least is basically square because he hates ‘shoebox’ cinemas and even with 5 seater rows wants 1m plus circulation each side.

Obviously that’s not a normal example and a fortune was spent on engineering alone but personally I really dig that concept and where the owner had the confidence to break the rules.

Anyway I have pretty much settled on a conventional orientation with screen on the shorter wall. Should the day come when throw distance isn’t a factor I’ll probably flip it round with screen on longer wall and wider seating.
 

Triggaaar

Distinguished Member
People probably use the shorter wall so they have the longest possible throw distance for the biggest image possible.

If you're accounting for speaker placement, false walls, gear, space for projector cooling, a longer throw is quite important.
It seems that people with large rooms (like in the US) still use the shorter wall too, perhaps preferring multiple rows for extra seats, rather than wider rows. There's nothing wrong with planning both ways to see which works best for each build.
 

Triggaaar

Distinguished Member
Hence I’m interested in basics like room shape and orientation. Conventional wisdom advises to avoid square plans for room modes but the Rob Hahn cinema on AVS Forums considered by many to be the finest private cinema in the US at least is basically square because he hates ‘shoebox’ cinemas and even with 5 seater rows wants 1m plus circulation each side.

Obviously that’s not a normal example and a fortune was spent on engineering alone but personally I really dig that concept and where the owner had the confidence to break the rules.
That cinema is huge, and he has more options than us on dealing with room modes, in terms of seating placement and acoustic treatment. It's a great cinema, but 'finest in the US'? That's a bit much when many won't have been seen by the masses, and for me the finest would have to have black material on the walls/ceiling.
 

Praetorpwj

Active Member
That cinema is huge, and he has more options than us on dealing with room modes, in terms of seating placement and acoustic treatment. It's a great cinema, but 'finest in the US'? That's a bit much when many won't have been seen by the masses, and for me the finest would have to have black material on the walls/ceiling.
I believe that there is a certain amount on blackout on the front 3 m and ceiling. There’s a lot of panelling as well and sconces but I think you can get away with a lot in a room that large and it’s designed as an ostentatious auditorium rather than a bat cave. Whilst I’m sure there are some mega impressive rooms elsewhere, having read the case study I’m not sure even billionaires would approach the level of care and attention in that room for the style.
 

Triggaaar

Distinguished Member
I believe that there is a certain amount on blackout on the front 3 m and ceiling.
Oh is there? I can't remember now, I haven't looked at it for ages.

Whilst I’m sure there are some mega impressive rooms elsewhere, having read the case study I’m not sure even billionaires would approach the level of care and attention in that room for the style.
Yeah true. But how many people have watched a film in his room, and some of the other great rooms? Anyway, not that it matters. It certainly looks like an amazing cinema.
 

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