Centre speaker behind projector screen

[admin_exported]

I'm going to be building a cinema room in the attic of our new bungalow that we're renovating. It will be a projector setup, and I'm considering going for an acoustically transparent fixed screen, and building a recess in the wall behind the screen to put a centre speaker. The attic is not converted yet, so there's still plenty of scope to do pretty much what we like.

I'm wondering if there are any particular considerations for putting the centre speaker behind the screen like this. The 5.1 speakers I have now are the B&W 685 Theatre package - so the centre is the HTM62. I wouldn't rule out upgrading the speakers in the future, so does it make sense to just make a recess big enough to accommodate a larger speaker in the future?

I've never done this before, so if there is anything else that I might not be considering, please feel free to share!

Thanks.

 

[Anonymous]

That is a super cinema system. I'm no expert but logic would dictate that having the centre behind the screen is going to muffle dialogue considerably. Most people can hear the difference even without the baffle on so I think it isn't a great idea, considering that you are going to great lengths to build that cinema room.

 

[Anonymous]

You might well be right - I was just going to ask about any degradation in sound quality. However, in any of these high-end dedicated home cinemas, the speakers are often hidden - built into walls/ceiling with the centre behind an acoustically transparent screen. Also, at your local cinema, aren't the front speakers usually behind the screen? Surely they don't compromise on sound quality for the sake of aesthetics?

 

[professorhat]

That is a super cinema system. I'm no expert but logic would dictate that having the centre behind the screen is going to muffle dialogue considerably. Most people can hear the difference even without the baffle on so I think it isn't a great idea, considering that you are going to great lengths to build that cinema room.

Acoustically transparent screens are designed to allow speakers to be placed behind them without muffling the sound.

 

[Anonymous]

That is a super cinema system. I'm no expert but logic would dictate that having the centre behind the screen is going to muffle dialogue considerably. Most people can hear the difference even without the baffle on so I think it isn't a great idea, considering that you are going to great lengths to build that cinema room.

Acoustically transparent screens are designed to allow speakers to be placed behind them without muffling the sound.

Thanks professorhat. So any other considerations for building a recess in the wall behind the screen?

 

[professorhat]

Well, I've not done this myself either, but I guess the question of whether to also place the front speakers there as well is one to ask, but depends how big a screen you were going for. I'd look to include some isolation for the centre speaker from the alcove - this could just be blu-tak, or you could use something like the Auralex SpeakerDudes to do this.

Clearly getting in any wiring for the speakers without it trailing on the floor is something to consider at the same time.

 

[The_Lhc]

That is a super cinema system. I'm no expert but logic would dictate that having the centre behind the screen is going to muffle dialogue considerably. Most people can hear the difference even without the baffle on so I think it isn't a great idea, considering that you are going to great lengths to build that cinema room.

Acoustically transparent screens are designed to allow speakers to be placed behind them without muffling the sound.

Thanks professorhat. So any other considerations for building a recess in the wall behind the screen?

I'd be concerned about putting a "normal" centre speaker into a wall cavity like that, you're almost certainly to affect the sound (will possibly make the bass somewhat boomy or overblown), if you want to do that you might want to investiage in-wall speakers, which are designed for just such an application. Or perhaps the new KEF T-series would work well in that kind of setup, they're so slim you could just mount them on the wall, without having to worry about recessing them.

 

[Andrew Everard]

You might find a spot of treble lift may be needed on the centre channel when firing through an acoustically transparent screen, but the auto set-up on most receivers should detect this and adjust accordingly. Or you can just do it by ear...

 

[Anonymous]

Thanks everyone.

Andrew, what are your thoughts on using a conventional centre speaker in a wall recess behind the screen, instead of a built-in speaker in the wall? Am I likely to have any problems like The_Lhc suggested?

I could just put the speaker on show on a stand below the screen (I certainly don't find it ugly). I just thought I might get best performance with it behind the screen. Maybe it would be worth putting the three fronts behind the screen? Would this be advisable if the screen size was approx 100in?

 

[Anonymous]

Isn't the Cinema Re-Eq facility of THX systems for something like this? Or is it that film soundtracks in the cinema are recorded 'bright' to allow for the screen and the Re-Eq tones down the treble? I'm sure I read something a few years ago about this but I'm sure Andrew or someone will be better informed.

 

[Andrew Everard]

Andrew, what are your thoughts on using a conventional centre speaker in a wall recess behind the screen, instead of a built-in speaker in the wall? Am I likely to have any problems like The_Lhc suggested?

Depends on the speaker design, but yes, boom could be a problem if a conventional centre speaker was used in a recess.

I could just put the speaker on show on a stand below the screen (I certainly don't find it ugly). I just thought I might get best performance with it behind the screen. Maybe it would be worth putting the three fronts behind the screen? Would this be advisable if the screen size was approx 100in?

Yes, you could put all three speakers behind the screen, but I'd be a bit concerned that the front left and right might be a bit close together. Kind of depends how wide the room is, but I'd suggest just the centre behind the screen, and the left and right out in open air.

 

[Andrew Everard]

Isn't the Cinema Re-Eq facility of THX systems for something like this? Or is it that film soundtracks in the cinema are recorded 'bright' to allow for the screen and the Re-Eq tones down the treble? I'm sure I read something a few years ago about this but I'm sure Andrew or someone will be better informed.

Yes, the centre channel in particular in THX-certified movies is mixed 'hot' for just these reasons. The THX re-equalisation tones down the overbright treble, kicking in at around 1kHz-2kHz, and giving a gentle roll-off to a maximum of about -5dB at 20kHz.

 

[Anonymous]

Andrew, what are your thoughts on using a conventional centre speaker in a wall recess behind the screen, instead of a built-in speaker in the wall? Am I likely to have any problems like The_Lhc suggested?

Depends on the speaker design, but yes, boom could be a problem if a conventional centre speaker was used in a recess.

Any way to test beforehand whether this might be an issue? Speaker is a B&W HTM62. Might be simpler to just put it on a stand below screen. Think I will leave the left and right out in the room anyway.

 

[Andrew Everard]

Given that the speaker is rear-ported, I suspect using it in a recess will virtually guarantee boom!

 

[Anonymous]

Given that the speaker is rear-ported, I suspect using it in a recess will virtually guarantee boom!

Glad I asked!! All speakers out in the open so. Thanks for the help.

 

[professorhat]

Is there a possibility of putting the speaker on a stand at ear level (with enough space from the wall to prevent boom) and then move the screen forward so that it still sits in front of it? Just thinking, if you're going for the absolutely ideal setup, this would be it, so that centre dialogue and sound is coming directly at you from the screen.

On the other hand, having the speaker just below isn't too much of a compromise and saves you a lot of money in terms of having to buy an accoustically transparent screen (which from memory are quite a bit more expensive than standard screens).

Just voicing the thoughts I'd be having if I were implementing a cinema room

 

[Anonymous]

I definitely want to fix the screen to the wall - don't want it brought forward into the room. Think I'll be happy with the centre on a stand just below the screen.

How much can I expect to pay for a good quality fixed screen (not roll-down) of about 100in? It won't need to be acoustically transparent, obviously. The room should be totally dark when it's in use, so I guess I won't need a high gain screen either.