New Demo Home Cinema Room Week 2

CAD Plans & Boarding Out

Work continues on our new home cinema demo room with some quick progress this week.

The start of the week was getting the new detailed plans pinned up on the wall. These CAD plans are based on the as-built measurements of the room. They show exact locations and placement for speakers, screens, internal acoustic treatment and seating/viewing positions. The first part of day one was explaining all the components of the plans to our carpentry team.

It’s cold in the barn currently which is why we are all dressed in layers. It wont be by the time we’ve finished - Rockwool is a fantastic sound insulator and also acts as a buffer against fluctuations in temperature, by reducing air flow and heat flow.

The demo room is boarded out in OSB (oriented strand board) whilst the office partition at the back has a lower ceiling height and is boarded out internally with MDF (medium density fibreboard).

As mentioned previously to avoid resonance issues between the walls different thickness and/or materials are used each side.

Rockwool

Once the Rockwool was put in place between the studwork, we board up the external walls. We filled the void between the interior and exterior walls with around 50% Rockwool. This gives us an air gap of the same size as the rockwool for optimum performance.

Rockwool isn’t particularly nice to be working with so care must be taken to wear safety glasses, breathing apparatus , gloves and long sleeves. It’s essentially molten stone spun into a candy floss (cotton candy) type structure much like the fibre glass insulation you would see in your loft, except it’s heavier and more rigid.

An Acoustic Sandwich

Once we’ve finished boarding up the outside we are left with a kind of acoustic sandwich of materials consisting of (from left to right) OSB, Rockwool, Bitumen, MDF. This leaves us with a building that isolates a lot of noise from either side of the walls. So our cinema will be quiet(er) to the outside world, whilst inside the ambient noise from outside is reduced dramatically. This is important, the lower the floor level of ambient noise the less power the speakers need to reach a level of performance or perceived loudness. This in turn means the speakers have more dynamics and power in reserve.

Further Acoustic Treatment

Internally, at a later stage, we will use a variety of acoustic treatments to help tame the room and make it sound as good as possible. Considered design and thought into these stages can enhance and multiply the performance of all the equipment used. Lack of thought into the design will always end up costing more in equipment just to reach similar levels of performance of a well designed room. A custom home cinema will offer better pound for pound performance than a cookie-cutter, one size fits all solution.

Boarding The Roof & Ceiling

The ceiling was boarded up and the partition between the cinema itself and the workshop/office area was created. The roof boards were put in place first so that we could squeeze rockwool up against it as we were placing the ceiling boards underneath.

Bulkhead & Lasers

The Bulkhead in the cinema will feature an infinity edge so that as you look up the ceiling looks like it continue out past the bulkhead, disappearing over the horizon.

Laser measurements are used constantly to make sure everything is square, level, plumb and basically straight. Wood is a natural product and as such there are imperfections, twists and knots. Things are measured, then re-measured, then measured again - the better the fit, the better it will look and sound.

We Have Lights

Once the frame for the bulkhead was built we could start wiring in for lighting. We are using GU10 LED bulbs in a mixture of warm white (2,700 Kelvin) and colour LED fitments for accent/ambience lighting. You can see the different effects of a warmer white (on the right) to a much cooler light (on the left). The photo on the left is of the cinema room lit by work LED Spots which are around the 6,000 Kelvin range.

At this stage we also cut the holes out for our front stage and surround speakers. We will be going with a Dolby Atmos setup in a 5.2.4 configuration.

• 3 front speakers, left, centre & right with timbre matched surround speakers (rear left, rear right) the ‘5’ in 5.2.4

• 2 Subwoofers (front sub left, front sub right) the ‘2’ in 5.2.4

• 4 in-ceiling Atmos speakers (front left height, front height right, rear height left, rear height right) the ‘4’ in 5.2.4

Room Partition & Equipment Rack

On the last day of the week (Saturday - It was a long week) we worked on the partition between the cinema and the office. A mixture of OSB, MDF and Rockwool to keep it rigid and quiet. The equipment rack will be going in the divider, we are using a special dMEV trickle flow extractor fan that will be programmed for very low power use (and ultra low noise) from 1.1 watts to 4.4 watts to gently extract hot air from the equipment cabinet.

That was the end of an exhausting week, lots done and really looking forward to getting the next stage of works complete.