A New Atmos Media Room

[Ian Mackenzie]

I everyone,

I’ve been busy of late on a home audio project.

I’ve put this in the general audio forum as l bought most of the additional equipment after l sold off what l no longer needed. The alternative was thinking about it for 20 years….Lol.

What started out as a home renovation has morphed into a multi purpose media room for home theatre, hifi sound reproduction and a studio for webinars and podcasts.

About twelve months ago l decided to obtain a recommendation on acoustic room treatments while involved in the home renovations.

I became interested in home theatre and Atmos music recordings. After a long gestation of thoughts l started to procure equipment including a JBL Synthesis 16 channel processor, powered JBL LRS 308 monitors and JBL 2P Control monitors. The front and centre channels are M2 clones. I was a bit concerned the LSR 308 wouldn’t cut it subjectively. In this application it works very well.

Progress
The bass traps are almost ready.
I am currently installing the balanced signal cables in the ceiling which is a challenge.

Once to ceiling to re painted a timber equipment rack will be fabricated for the audio components.

Still a fair way from completion. I’m certainly not the first to consider a JBL M2 based multi channel system. With the M2 components on hand it made sense.

Why the JBL SDP 58 processor?

In the end it offered more than any other processor with the features l needed. My own view is that Atmos music will at some point become more than binaural (headphone). The difference over a stereo mix is a game changer when done right on some recordings. (IMHO. Note. I am prone to excessive exaggeration and changing my mind frequently…Lol). I bought this processor much cheaper than the RRP. How? Don’t ask.

The sound.
Based on my initial listening without Dirac EQ l’m impressed. It’s more than multiple channels with Dolby’s latest processing. The sound is alive in a natural way that draws your attention to the content. Not the equipment. Harman Luxury Group have offered technical support if required. (Piece of mind).

I sort out the least costly way to do this. But even after hocking off everything l didn’t need (excluding the grandmother) it does add up. That said l think the project will open up opportunities to explore new media formats and AV experiences. Yes l will still enjoy two channel analogue with JBL legacy monitors.

Thanks to Mr Widget and Rob H for their kind input.

The bottom image is for illustration purposes only. The actual room is about 19.5 ft x 18 ft.

Acoustic Treatments
The end result will be corner and ceiling bespoke bass traps, acoustic panels on walls, ceiling and acoustic curtains in a furnished room.
The products l used are in the following links
Acoustic curtains that really work. But they are not cheap.
https://materialised.com.au/product-...heer-acoustic/

https://csrmartini.com.au/our-produc...co-quiet-panel

https://csrmartini.com.au/our-products/martini-absorb

Equipment
Samsung 65” Edge Flat Screen
Amplifiers
Yamaha P7000S

https://www.crutchfield.com/S-OXECMI...ha-P7000S.html

Parasound A23+

https://www.parasound.com/a23+.php

Dual 12 inch CSS Audio subs with twin passive radiators cover the LF.
The claimed Xmax is 28mm.
Amplification yet to be determined.

https://www.css-audio.com/online-sto...fer-p110031759

One pair for surround sides
https://jblpro.com/products/308p-mkii
Three pair for Atmos overhead
https://jblpro.com/en/product_families/control-2p
Processor
https://www.jblsynthesis.com/product...cs/SDP58-.html
Fronts and centre M2 clones

Loudspeaker Format 7.2.6

I used Audio Visions online Ai Atmos theatre designer and other references for the locations of the bed layer and the overhead layer.

The primary listening and viewing position is about 2.7m from the TV screen.
Riser 15cm (portable for the 2nd row)

Loudspeaker locations
The fronts are 2.7 metres apart
Immersion 29.5 degrees (average with a 65” screen)
The main side surrounds are 2.8 m from the front of the TV screen.
The surround rears are 5.8 m from the front of the TV scream & 3.4 metres apart.

The front, middle and rear Atmos overhead loudspeakers are 1.73 m, 2.93 m and 4.12 m respectively from the front of the TV scream with an 8 ft (2.4 m) ceiling. The distance between the L&R Atmos loudspeakers is 2 m. Each Atmos overhead loudspeaker has a swivel mount to angle the tweeter precisely at the listening position.


I used a 70/30 percent Ai acoustic optimisation of the primary front row and the second row seats to set the surround and Atmos loudspeaker angles. Using six Atmos overhead loudspeaker made the optimisation possible with two rows. It will be interesting to experience how it works out.

[Mr. Widget]

That should be a kick-ass surround system. Are you considering video upgrades?


Widget

[Ian Mackenzie]

That should be a kick-ass surround system. Are you considering video upgrades?


Widget

I was actually looking at that this morning……

Any recommendations..?

[Robh3606]

Looking forward to seeing how it all works out! Bet it's going to be a great room when finished. Really like that rack!

Rob

[Mr. Widget]

I was actually looking at that this morning……

Any recommendations..?

I think Sony has the best video processing across the board. Pick the appropriate technology, then choose the size based on aesthetics and budget.
I'm a fan of projectors if it is a dedicated room. If it is a mixed use room or if light control is a problem you are best off with a direct view technology. OLED is great, but so are the higher end LED backlit TVs.

LG make great panels, but their processing isn't as good as Sony's. Samsung tends to make TVs that are the video version of the old smily face EQ curve. They can be dialed down, but are more difficult to make look natural. Also their handling of motion artifacts is not quite as good as Sony's.


Widget

[Mr. Widget]

Really like that rack!

For some reason, that just sounds wrong.


Widget

[Ian Mackenzie]

Hi Widget.

Thanks for the insights.

I have sheers & block out curtains so either way is possible.

A mid level projector with a powered screen would be less imposing than an 85 inch TV and just that bit more immersive. Block buster movies and lots of blue ray and dvd rock concerts will be the main program. We do stream as well.

So l am wondering if a projector would be easier on the eye to watch with that type of viewing content?

[Mr. Widget]

If you go with a projector, look at the new laser projectors from Sony and JVC. They are both stunningly good compared to what was available just a couple of years ago. The JVCs offer slightly better blacks, but are a bit trickier to dial in.

My screen is a 16:9 aspect ratio that is 96" wide... roughly 110" diagonal. By today's standards that is a very small screen, but at closer viewing distances it looks pretty darned good.


Widget

[Ian Mackenzie]

Here is a measurement with REW from the listening position with one 4345.

The divisions are 5 db and l have included a time domain to see the room modal resonances. It’s actually not too bad. But some of these time domain issues with be reduced with the room treatments.

There are bespoke bass traps mentioned above using high density absorption placed in the wall and ceiling junctions. Wall surface absorption is placed at first reflection locations including the ceiling. The crossover from the wall treatment to the bass traps occurs at 250 hertz. A large rug will be placed on the floor in front of the loudspeakers.

The raw materials for the acoustic treatments cost about $2,700. I’ve done most of the installation myself. Bass traps on this scale would be expensive if purchased as a finished product. The curtains across the windows and glass door were made to order at around $5,500 but absolutely necessary. They have completely changed the room acoustics.

Michael Phillips is the acoustic consultant. Michael is a practicing acoustician and he also lectures at Sydney University.

https://www.mpacoustics.com.au/our-team

One of the benefits of using REW is that it has psycho acoustic windowing of measurement to give the user a better idea of the subjective problems.

I do have Dirac at my disposal to moderate some if the response issues.

Subjectively just one 4345 was impressive.

To be continued.

[mwaldron]

Ian,

I am endeavoring on a similar project, I saw a post of yours that spoke to a design philosophy that I have latched on to, muscial recording will / are becoming multi-dimensional:

"But the trend is moving towards multi monitor 7.2.4 mid field systems for recording Atmos sound tracks and Atmos music recordings. Large monitors are simply not practical for multi channel bed layer 7.1 formats."

I am trying to create a stereoish-centric 5.1.4 system that meets the ATMOS specification for the recording / mixing room which only speaks to a 5.1.4 system. With all of the smoke and mirrors in the "Home Theater" hype, I always understood that the 7.xxx systems were formatted for multiple rows of seating. I am in the position to be selfish and only need to satisfy a singular listening position. In your opinion is my logic flawed for basing my system architecture / design from the mixing studio specification, i.e. this is the mix that the recording engineer heard whilst mixing music / soundtrack?

Thank you,
Mark

[Ian Mackenzie]

To answer your question l used this design tool FWlW.

https://www.audioadvice.com/videos-r...er-design-tool

This tool allows 100% to 60% focus on the primary listening position with one up to a number of rows. I am no expert the subject of Atmos.

In the contrast a home studio Atmos recording DAW is set up for a single listening position and is relatively compact. Dolby have a design tool for that.

Larger commercial recording studios have hybrid stereo- Atmos mixing control rooms.
The more successful contractor engineers work from home with a dedicated environment.

I’m still in the implementation phase working on the fixing and finishing bass traps. The overhead Atmos speakers are ready for final installation. Then the wall and ceiling treatments. I’m looking forward to building the M2 fronts and the subs. It’s quite a project but it’s fun!

The thing is l should be able to get some reasonably clean loudspeaker measurements in this space and use it as reference for in room measurements of different loudspeaker systems including the 2,3 & 4 way JBL systems.

I also plan to use the space as a test and learn Lab for some other activities including loudspeaker system modifications, upgrades, new designs and reviews.