How to build a dedicated home theatre

[Prof]

Firstly to clarify, "a dedicated home theatre" means that the room you will be using will only be used for watching movies and perhaps some TV..

A home theatre can range in price from approximately $5000 - $500,000 and more !! Some American home theatres cost over 1 million dollars !!

This tutorial will describe how to build the lower end of the range..

Firstly you will need to find a suitable room..The bigger the better, but it must have four walls and a door..Open rooms connecting other rooms will not be suitable..

The other aspect of a suitable room is whether you need the theatre room acoustically removed from the rest of the house..

This requires an additional construction to the room to isolate it from the other rooms..

I will include briefly what needs to be done, but for the most part I will proceed on the basis that this will not be needed..

There are a variety of building materials that are used to construct rooms in a house..Timber or steel framing with plasterboard walls, or brick or concrete block walls..

Each of them have their own acoustic values..

The stages of the building process...

1. Selecting the room..

2. Acoustically isolating the room..

3. Selecting the wall and ceiling paint or fabric coverings..

4. Choosing the type of floor coverings..

5. Setting up the front of room for screen and speakers..

6. D.I.Y the screen or purchasing a commercially made screen..

7. Adding acoustic panels on the side walls..

8. Adding acoustic panels in the front corners..

9. Adding acoustic panels to the rear of the room..

10. Selecting the front speakers..

11. Selecting the surround speakers..

12. Selecting the subwoofer..

13. Choosing the lighting..

14..Selecting Amplifier/ receiver..and ancillary equipment

15. Selecting Blu-ray player..

16. Programming the whole system..

So as you can see there is a lot to building a dedicated home theatre..But the end result is a very satisfying movie experience.. 

More to follow..

[Prof]

FINISHING OFF FRONT OF THE ROOM..

With the screen in place it's obvious that there's empty gaps top and bottom and at each end..

These need to be covered to finish off the front of room..

Before doing that, in my own theatre I added a shelf across the uprights at the back..This shelf holds the amplifier for the subwoofer and the light controller..

With the covering being an open weave black cloth ( as can be seen in the photos ) the IR sensor unit for the lighting can be controlled by a remote through the fabric..

The covering top and bottom is made with a simple framework and covered with black polyester fabric..This material has an open weave and is stretchable in both directions..

The covered framing is attached to the uprights using Velcro cloth..This makes it very easy to remove the panel to gain access to the equipment on the shelf..

For the side open areas, I've just add some curtaining..The gap between the end of the screen and the wall was very minimal..

If your gap is more..I don't advise building any cabinets to fill that gap as some people do..

It introduces another acoustic environment being an open face cabinet...

[Prof]

Apologies for the delay..I've had all sorts of computer problems..and my wireless remote extender that's used to control all the theatre equipment failed and finding a suitable similar unit became a real headache..I went through two other units (both of those failed) before the one I have now..So far so good!!..

SIDE WALL ACOUSTIC PANELS..

The next stage of our theatre build is making / buying acoustic panels..

To buy acoustic panels can become quite expensive and as they are quite easy to make yourself..that's what I would recommend..

If you have any handyman skills then they will be very easy to make..

You will need four identical panels for the sidewalls..Where they are to be installed on the walls I will describe later..

To make a panel you just make a frame out of 70 x 35 pine approx. 450mm. x 600mm..They can be larger if you have very high ceilings..

The frame is made with the timber on edge..i.e. the depth of the frame is the 70mm. dimension..This will give you enough depth to fit the 50mm. thick acoustic material..

The front of the panel is covered with black polyester fabric..This is an open weave material which stretches in both directions making it easy to have the fabric stretched tightly..

The filling is a piece of semi rigid acoustic fibreglass 50mm. thick called Ultratel..The glass wool is yellow in colour and comes in sheets 1200mm x 2400mm.

You just cut the material to fit snugly inside the frame and then pushed up against the front covering..The  reason for doing this is to provide a space between the wall and the Ultratel  material..This helps to improve the acoustic control of the bass sound field..

A further improvement can be had if you space the whole panel 50mm. away from the  wall..

You will need to make four identical panels..Two to be fitted on each side wall..

The position on the walls will be decided by two methods..but firstly the panels can't be positioned until you have the front speakers in place..This will determine the height for the panels on the wall..

The first step is to place a small mirror on the wall at a height where you will be able to see the reflection of a speaker..

You will need to have someone slide the mirror along the wall while you sit in your centre seat..When you see the reflection have them make a mark above the mirror..This is your first reflection point..

The second reflection point is found in the same way..Have your helper slide the mirror along the wall..after the first reflection point until you see a speaker in the mirror again..Mark that position..

Repeat the same process on the other wall..

Next with your front speakers in their positions measure the height from the floor to the centre of the bass speaker..This will be the centre of each acoustic panel when fitted to the wall..

So now you have your first and second reflection points where to fit the panels..

The easiest way to mount them..and considering they will be fairly heavy..I would suggest using French cleats..as described earlier...

[EricL]

Hi @Prof

Would ordinary Earthwool 90 x 580 x 1160mm 9.4m² R2.5 HD Insulation SoundShield Wall Batt - 14 Pack work for those sidewall panels? It has an R rating of 2.5 which is rated for in-home domestic noise? 

Eric

[Prof]

Hi EricL,

Those Earthwools and pink batts are too low in kg/m3..The Ultratel is 48kg/m3 which is a lot higher than the other types..

The other types are also quite flexible whereas the Ultratel is like a solid sheet..

 

[Prof]

THE SCREEN.

As mentioned previously the screen will be an acoustically transparent screen for this theatre..

The type of screen is CinemaScope screen with a ratio of 2.40:1..and for this exercise we'll say it is going to be a 100" screen..

If you were to buy an Australian commercially built screen of that size it will cost you approx. $1700.00.!! and going up to a 130" screen it would cost approx. $2700.00

If you were to build it yourself..using a US made screen material ( the same as the commercially made screen ) and built a frame..it would cost approx. $500.00..

The screen is fixed to those two uprights..

A piece of timber 90 x 19 is fixed across the uprights at the height the screen will be mounted..

The simplest way of doing this is to fix half of a French cleat to the back of the screen and the other half to the cross beam..

This allows the screen to hang freely and gives the screen the ability to slide on the French cleat..making it easy to centre it...

The height of mounting the screen will be determined by your seating position..

When seated your eyes should be level with screen a little less than a third of the way up from the bottom..

This positioning will give you some image interaction for your viewing experience..

[EricL]

Hi @Prof

What's your opinion on the eBay home theatre screens? Some of them had good reviews, but you know I've always had a little voice of doubt at the back of my mind about the quality. Is there a budget option for home theatre screens that is passable quality-wise? What about older style pulldown screens? I currently have an old spring-loaded pull-down Screen Technics about 100". It's starting to show its age but it's better than my white painted wall.

Eric

[Prof]

Hi Eric,

Actually I've never looked at the screens on eBay..so I just had a look to see what's on there and I was surprised at how good the prices are..

Mind you these are just an open weave type screen and I question what they say the gain is and what the screen material is made from..

My screen which is a matte white.. perforated solid one piece vinyl material is rated at 1.2 gain..by the manufacturer..

Because it's a solid vinyl very little light is transmitted through the screen..The more light transmitted, the lower the gain..

The material that I believe they are using is called Spandex..The reason that it has a separate black backing is to reduce the transmissibility of light through the Spandex..

Spandex as you probably know is a stretchable material, which when stretched opens up the weave..which again requires a black backing..

If you have a projector with a high lumen output, then these screens would be quite suitable..

Most of the newer pull down screens are a solid matte white vinyl ( similar to my Centre Stage XD screen except no perforations. ) and show a nice image..

My only concern with them is that if they don't have any side  bracing..they can curl..

[Prof]

FRONT WALL ACOUSTICS..

The front corners of this wall are the areas that need the most acoustic treatment..

Acoustic control known as "Bass traps" are what will be fitted to the corners..

These bass traps are made in two different ways..

1..A similar design as the side wall panels, only these panels will have up to 100mm thick fibreglass wool and be a larger size panel 1500 x 600..

   These panels will be fitted across the front corners..

2..These will have triangular cut fibre glass panels which will lay on the floor and be fitted into the corner..Then the individual cut  panels will be stacked on top of each other right up to the ceiling..

The panels will be 600mm. wide at the base with the angled sides to form the triangle 400mm. long.

This type of bass trap will be most effective in large rooms..

They will also need some sort of framing to hold all the pieces together..

The next stage of the acoustics is the front wall itself..

The space between the two bass traps will be covered with sheets of Ultratel, floor to ceiling..

The sheets only need to be 25mm. thick..for adequate acoustic control..

[Prof]

REAR WALL ACOUSTICS..

This wall needs only minimal treatment and is pretty much the same for small or large rooms..

First requirement is a panel design similar to the side wall panels that fits across the back wall and is approx.three quarters the width of your seating area..

If you have 3 seats wide across the back wall..then the panel will be approx.1800mm wide x 600mm. high..with a thickness of 50mm.

It will be positioned centred across the wall and midway the height of the wall..

It is advisable to also include corner bass traps ..These can be of the panel type that fit across the corners..

With all these acoustic treatments the room should have no standing waves or unwanted resonances and provide a smooth sound field..

[MitchellMc]

Another great instalment @Prof! I'll be looking forward to the next one.

Mitchell