Help Needed. Wide & Shallow vs Long & Narrow Room Setup

[ThELiZ]

To cut a long story short, I've built a room in the garden that is kind of neither here nor there in terms of what it could have been. I was originally going to use it as a workshop, but now have decided to do the best I can and make it a home theatre.

The dimension are 4.9m x 2.9m. I am just wondering what the best setup would be. My main love is 2ch hifi, but this room will be mainly used for cinema.

Now, I can either choose to go for main speakers setup along the short wall firing down the length of the room (something I've never been able to do before, and I'm aware this is usually seen as the ideal), or I can put the mains on the long wall firing across the width. Both come with pros and cons. With the speakers firing down the length, I fear they will be far too close to the side walls, especially as I want 77inch TV. With the mains firing down the width of the room, I obviously have the seating position far too close to the rear wall, but I have a lot of space either side of the speakers... And I can potentially get a very large screen!

I will be using room correction down the road.

Any advise would be greatly appreciated.

 

[Eetu]

I would probably go for the long wall setup but add absorption panels to the rear wall.

Digital room correction will help with modal bass but you will still get harmful (very) early reflections higher up in the freq range due to close proximity to the back wall.

 

[ThELiZ]

I would probably go for the long wall setup but add absorption panels to the rear wall.

Digital room correction will help with modal bass but you will still get harmful (very) early reflections higher up in the freq range due to close proximity to the back wall.

Thanks for your comment. The only caveat I should add to that is on the rear of the long wall (behind my head to the right of the MLP) is a large window... So I can't use much absorption.

 

[Eetu]

Got it. One possible workaround would be free-standing panels.

Optimally the listening position should be further away from boundaries, the same thing with the front of the speakers. And if you can't avoid this, I would treat the closest surfaces with absorption.

With the short wall setup: If your speakers have good horizontal directivity, the side wall reflections might not be that harmful although still affected by side-wall SBIR. For example if you have the speaker (=driver centre) 50cm from the side wall, expect a dip around 170Hz. But then again you would get plenty of clearance behind the MLP.

 

[ThELiZ]

Thanks again for your help. I think, after mapping both scenarios up, the setup on the short wall will ‘probably’ work best in that room.

This setup gets me a 7.2.4 Atmos solution, which I’m hoping is worth it.

My biggest concern right now is whether with the stud insulation, resilient bars, double acoustic plasterboard… Will this block out enough sound. The room is a stand-alone one in the top of my garden, but there are neighbours around 15m away.

Please attached picture of proposed room layout. Please shout if there are any glaring problems.

 

[Eetu]

The first thing that caught my eye is that the sofa is almost exactly in the middle of the room, usually something to be avoided due to room modes. Maybe move the sofa another 40cm back, the 38% rule is a good starting point. Of course that assumes that all boundaries are of identical construction and you might be fine as it is.

As you use a sub, you can get rid of the main speakers' front wall SBIR effect by pulling them even further into the room. At 1.2m (measured from front baffle) the front wall SBIR dip is at ~70Hz where the sub has taken over.

Since you are concerned about the side walls maybe try extreme toe-in advocated by Geddes and others. Basically toe-in the speakers 45deg. That way you attenuate the energy reflected from the closest side wall and get more stable stereo image on the different seats of the sofa.

Just a couple of things to consider. Otherwise I think your plan looks good. I'm a strictly 2.x channel guy though so can't give advice on multi ch unfortunately.

Are the speaker distances off btw, 1.3m between speakers, 40cm from the side walls?

 

[ThELiZ]

Really appreciate your advice. I've made some slight changes (and realised the room is actually smaller than I said after plasterboarding - 4.7m x 2.7m) and am pretty happy with where I've finished. I've moved the sofa back a bit and changed the rear standmount speakers for in-walls. Also made some changes to distances from wall for mains. And yes, there was a typo on the distance between the speakers. Amended now.

This will be a project that is completed 'as and when' I have the funds, but I'll be sure to post how I get on.

 

[Hipper]

Distance to your screen must surely be the first consideration.

I'm no expert but it's said that a 4K screen requires 1 to 1.5 times it's screen size distance in order for you not to see the individual pixels. In your case 1.92-2.9m. In other words, it would seem best to use the short wall for the speakers and deal with any problems arising.

Or get a smaller TV!

Best speak to an expert on TV size/viewing distance before deciding (or look at it yourself to see).

 

[ThELiZ]

I have used the various calculators online to try and get the right tv distance. That is my first consideration.

If only I’d of built it 1m wider! Hindsight!