Room dimensions for new build

[Rakalel]

We are building a new home and I’m able to get a media room. I see there are a few golden rules or measurements and using one I came up with 6.9x5.4x2.6 using one of the formulas and was going to make it 7x5x2.6.

 

 Anybody else think this is a good start or what would you choose based on a 2.6m high ceiling?

[Assisi]

In terms of aesthetics and what is pleasing to our eye and brain, the golden ratio or phi is 1.618.  So the numbers should be 8mts X 5mts.  How that fits with a ceiling of 2.6mts and the treatment of  sound I do not know.  I have read that it could be W/H which in this case gives 3.125mts as the height.  So overall a bit longer and higher than you plan.

John

[Lochawe]

What exactly will you be setting up in this "media room"?

 

7m x 5m is decent size but if there is any way you can increase ceiling height it will be well worth it.

 

My current room is 5.8m x 4.3m x 3.4m high which works well but I only have a 2 channel audio system.

 

There is enough acoustic room treatment advice online to keep you busy researching for the next 10 years...

 

Good luck,

 

Chris

 

 

[Rakalel]

I’m mainly interested in stereo and will probably end up with a 2.2 channel system. It will handle the tv as well but that’s secondary for me. 

Would it be best speakers along the long or short wall? I’m still trying to figure out layouts but I figure with 5m as my short side I can still be 1m from the wall for speakers, three metres between them so 3m back allowing 1m between the seats and back wall.

[awayward]

Probably a little over the top for what you want, but check out Paul McGowen from PS Audio room build videos on YouTube, might give you some ideas.

Edited October 30, 2019 by awayward

[wen]

on a 2.6 ceiling height, 4.16 wide by 6.6 long using 1  x  1.6  x  2.56 being classed as the golden ratio, but , there are quite a few ratio's.

the design of our house was more open plan, we put doors where we felt we needed privacy, the front lounge now has double sliding doors, we also put a door in the corridor to close off the back half of the house, put acoustic insulation in the wall of the lounge and master bedroom, i can now listen to music late into the night/morning without any complaints

[Pim]

Have a look here:

 

https://www.jhbrandt.net

 

I'm not sure how I got it from them, download or email, but they can provide you with a spread sheet that will show you exactly what size room does what. It's very comprehensive and a bit complicated.

[andyr]

On 30/10/2019 at 3:53 PM, Rakalel said:

We are building a new home and I’m able to get a media room. I see there are a few golden rules or measurements and using one I came up with 6.9x5.4x2.6 using one of the formulas and was going to make it 7x5x2.6.

 

 Anybody else think this is a good start or what would you choose based on a 2.6m high ceiling?

 

If you want to PM me your email address, I will send you a room-mode spreadsheet (which originated from THX).  I used it for the dimensions of my current 'listening' room and it has worked out very well.  (You enter your chosen dimensions and see what this does to room modes; the instructions tell you how to get the best room mode combo.)

 

(When Paul Spencer was measuring my room to set up the 2 subs he provided, he said that it was a very "well-behaved" room, bass-wise.  )

 

Andy

 

PS: my ceiling is 2.7m.

 

Edited November 5, 2019 by andyr

[Pim]

2 minutes ago, andyr said:

 

If you want to PM me your email address, I will send you a room-mode spreadsheet (which originated from THX).  I used it for the dimensions of my current 'listening' room and it has worked out very well.  (You enter your chosen dimensions and see what this does to room modes; the instructions tell you how to get the best room mode combo.)

 

(When Paul Spencer was measuring my room to set up the 2 subs he provided, he said that it was a very "well-behaved" room, bass-wise.  )

 

Andy

 

PS: my ceiling is 2.7m.

 

I wonder whether that's the same spread sheet. If not, it would be interesting to compare.

[almikel]

from an acoustics perspective, build the biggest room you can and avoid even multiples with dimensions (height isn't width/2, or width isn't half the length etc) - I especially wouldn't reduce a room dimension to align with a golden ratio - they do avoid even multiples, but aren't that "golden" beyond that from an acoustics perspective.

 

For audio you want the biggest space you can manage while avoiding even multiples as that will intensify specific room modes.

 

Aesthetically golden ratios work - that's a different discussion.

 

Every room will have it's own issues to manage acoustically - including rooms with "golden ratio" dimensions.

I'd prefer a larger room with even multiples over a smaller room with golden ratios.

 

cheers

Mike 

[almikel]

On 30/10/2019 at 2:53 PM, Rakalel said:

We are building a new home and I’m able to get a media room.

There are a few more things you should be considering with a new build for a "media room":

• additional isolation/soundproofing from the rest of the house - this adds to construction costs, but isolation/soundproofing can't be added afterwards - if you think it would be great to be able to crank movies/music late at night without annoying other house occupants or neighbours then you need to address better isolation during construction.
  
  Normal gyprock/stud room construction leaks low bass like a sieve - actually good for the "in room" sound, but terrible for others in the house and neighbours.
  I would recommend reading https://www.soundproofingcompany.com/soundproofing-101
  
  For any new build of a media room I would recommend whisper clips, 2 layers of Gyprock with Greenglue, and fluffy insulation behind...or at a minimum another layer of Gyprock with Greenglue
  https://www.soundproofingcompany.com/soundproofing-walls
• The above only considers walls - but there's plenty of info on ceilings/floors on the same site
• It's important to note that soundproofing/isolation typically works against good "in room" sound - especially in the bass end...a concrete bunker has great isolation but dreadful bass - the bass bounces around and rings forever, compared to a tent in an open field, where the bass passes through and doesn't get reflected within the room - your room will sit somewhere between these two extremes - and the approaches recommended will provide good isolation and good bass absorption within the room
• Run a dedicated power circuit to the room - think about where your gear will be and provide sufficient power outlets and a few more (6 x double GPOs at least), then put additional double GPOs around the room (minimum 2 per wall)
• Consider RCA interconnects in the walls to run subs, and speaker cable interconnects to run surrounds
• Consider ethernet cabling to smart TV/Apple TV etc - sure WiFi works, but copper is better

cheers

Mike

[Rakalel]

Thanks for the detailed reply, unfortunately the media room looks like a no go now. The reason being is I’m trying to build with hempcrete which is a bit more expensive so I had to make the house a bit smaller. I still have to get body corp approval to use that though but I’m semi confident. If I have to go back to normal materials the media room is affordable again.

 

Currently I’ve got 10x5m for the media/kitchen with a 2m wide hallway beside that. I’ll have a 5m wall separating them at the start so at least I’ve got a uniform U shape so first reflections are equal. The last five meters work out to being 7m wide and the hallway extending a few metres past the kitchen. 

With just the wife and I we are going to also soundproof the main bedroom a bit so that might mitigate the open media room. The walls will be thicker than standard and I’ll be using the lime binder keeping the walls breathable which from my limited understanding of the top search result means it will deal with the lower frequencies better than regular concrete. I’m hoping that will be the roof insulation as well as its thermal properties are meant to be amazing which will come in handy for closing up the house in the tropics to up the volume.

 

I was going to try have an Ethernet cable with most power points but I’m not sure about the rca sockets in a wall.

[almikel]

On 17/11/2019 at 1:29 AM, Rakalel said:

I’m trying to build with hempcrete

I'd never heard of it before your post - it looks an interesting product on a quick 5 min look...

 

Good for you for trying something different...the pictures make the finished product look a bit like hay bale construction (at least in the depth of the walls) - thermal insulation at least should be fantastic!

 

Do you use hempcrete for internal walls also?

I would imagine they have very good isolation/soundproofing properties, and possibly good bass absorption also.

 

On 17/11/2019 at 1:29 AM, Rakalel said:

With just the wife and I we are going to also soundproof the main bedroom a bit so that might mitigate the open media room

Just remember soundproofing can really only be done during construction - you can't easily add it after the fact.

If you used hempcrete for the internal walls, which should isolate well, you would only need to consider flanking paths. If you have a slab floor, the flanking paths will be primarily the ceiling and doors, but also HVAC vents etc.

 

Use the Soundproofing site for reference on isolating the ceiling 

Soundproofing A Ceiling | Soundproofing Co.

WWW.SOUNDPROOFINGCOMPANY.COM

---

Complete solutions for soundproofing ceilings - commercial and residential. Recommended for home theaters, recording studios and neighbor noise.

 

On 17/11/2019 at 1:29 AM, Rakalel said:

but I’m not sure about the rca sockets in a wall.

It just makes things neater - especially if it turns out the best place for subs is at the back of the room and the gear is at the front...but I wouldn't bother trying to run them through hempcrete walls unless really keen, or it's being sprayed, and it's easy to run some conduit in a cable for Ron (lateR on)

 

Good luck with the build.

 

Mike

[Southerly]

Rakalel,

you will not regret using this hempcrete, much the same properties as aircrete. You say that using it is more expensive than 'normal' materials? maybe if your doing a self build but if your using tradesmen surely not. Normal materials mean lots more operations, especially where insulation is concerned. 

 

What width of block will you use for the internal walls? I ask because I intend to use 15cm.  This means that using the half bond makes installing electric cables and boxes very easy - the perp on one course of blocks is chased for the wire and a long drill bit takes care of the block above. Cut out the boxes 50/50 on the beds of two blocks on a bench and wash with a Unibond 5-1 mix, this will toughen the area and make life easier. So, you install the cabling at the same time as building the walls.

 

You do not need to use a hard plaster finish, skim any defects, then size the walls and use 1200 grade lining paper. I know it's more expensive but batten out the floor and notch where nec. and you can run your wiring along the floor and finish with t & G floorboards, stain them/varnish them any way you like. You'll havr a much quieter home than using tiles and especially the music will sound a lot better.

[Guest DrSK]

Beyond what others have said the key thing is making sure your doors and trafficable areas are located so they don't get in the way of the space you need behind and beside speakers and for cabling. Same for having enough space between the listening chair and the rear wall. 

 

All rooms will have issues which can be tuned by speaker and listening position placement. Just don't make the mistake of badly distributed absorption or dimensions that are multiples with the worst case being a square. Better to start with a bare room and add treatment where you need for tuning.

 

Larger rooms are generally good but delays from reflections become noticeable in lengths of around 5 to 7m and above. Need to ideally resolve with diffusion. PS Audio's test room shows how to do diffusion well. 

 

In a 4.5m by 7m room set up long ways rear wall reflections are audible without treatment as a delay with seating 1/3 from speakers to front wall, low frequency works well but side walls are close and speaker spacing is limited (I find about 3m is best for my system but to tight long ways). Set up width ways the now side wall reflections without treatment are noticeable as image ghosting (previously when long ways the delay times were too short to do this) without treatment and speaker position from the front wall and seat position from the rear wall are more critical to manage low frequency. I always avoid seating in the middle of a dimension (other than my other living space where a first order mode perfectly balances up some small bookshelves at the bottom end in the frequency domain at least).

 

With the limitations by existing doors, trafficable areas etc, spacing between speakers my room works best set up width ways. Meant many hours of rewiring. 

Edited December 11, 2019 by DrSK

[davewantsmoore]

On 16/11/2019 at 7:16 PM, almikel said:

from an....

This post.

 

 

Speaker and listener placement within the room, will makes a much much much bigger difference than the precise room dimensions, as long as they are not any combination of dimensions which conspire to create a particularly uneven distribution of modes.

 

Make sure there is plenty (!!!!) of space behind the listeners .... the more the better.....  and that if using typical "wide" coverage pattern hifi speakers, that you can get them a decent distance from side walls.

[Guest DrSK]

31 minutes ago, davewantsmoore said:

Make sure there is plenty (!!!!) of space behind the listeners .... the more the better.....  and that if using typical "wide" coverage pattern hifi speakers, that you can get them a decent distance from side walls.

This is the trade off that surprised me given a few other limitations. And after much trial and error caused me to rotate my room. The improved side wall and speaker spacing for me gave me better overall results than when I had massive rear wall distances (4m etc). Got the low frequency sorted well enough with less rear wall distance (1.4m or so) with very careful placement 15cm at a time shifts of couch to rear wall and seperate speaker to front wall adjustment to smooth out the low frequency. Think perhaps the lower directivity of the low end output means the dips weren't as bad as I'd expected.

 

And the direct and rear wall reflected path differences are such that all the imaging from direct arrival is clear. Only gets audibly stuffed front to rear when I get closer to the rear wall when the reflection creates the feeling of standing in a room mode. 

 

Dave, can you provide an recommendations for practical diffusers? How much over what theoretical range makes a useful difference? Easy to have a good feel for absorption but diffusers are not so commonly found or measured. My RTs are not bad. Easy to model and predict I'd benefit in my room, but really thinking I need to just build some stuff to get a subjective feel. In a position where more absorption in the right place improves imaging but deaden the room too. 

Edited December 11, 2019 by DrSK

[almikel]

A bit off topic for this thread, so apologies to the OP...

On 11/12/2019 at 10:38 PM, DrSK said:

can you provide an recommendations for practical diffusers?

QRDude is an amazing free tool to help design 1D and 2D Quadratic Residue Diffusers (QRDs).

https://www.subwoofer-builder.com/qrdude.htm

 

User Guide here: https://www.subwoofer-builder.com/qrdude-user-guide.htm

You can set a lower design frequency (how low you want diffusion to go), and it will calculate depth , or you can set the maximum depth and it will tell you how low diffusion goes.

 

Just in case you're not familiar with QRDs

This is a 1D QRD - diffuses in 1 dimension

 

This is 2D QRD - diffuses in 2 dimensions

 

This is a 2D Skyline QRD - it doesn't have the walls between the wells

 

QRDude does everything you need for designing QRD diffusers for whatever frequency you want...of course the depth gets large if you want to diffuse low - but you can muck with the parameters, and QRDude will tell you where you only get scattering and where diffusion starts to help you make decisions on compromises before making sawdust...

 

Keep in mind that Cox and D'Antonio (the gurus of diffusion) recommend a listening position at least 3 wavelengths away (at the lowest frequency diffused) from the QRD diffuser in order for the diffuse field to be generated - closer than this and you might hear artifacts from the diffuser...and the lower you diffuse the more gap required...always compromises.

 

A simpler type of diffuser is the Binary Amplitude Diffusers (BAD panels) - these don't provide as much diffusion as QRDs - but because they don't provide as much diffusion as QRDs, you could likely sit closer without hearing artifacts.

 

BAD panels are a reflective mask in a random pattern over absorption.

A 1D BAD panel is simply different width slats/gaps over absorption - very easy to DIY

 

a 2D BAD panel mask that would be mounted over absorption

 

Similar to QRDs, a 1D BAD panel diffuses in 1 dimension, and a 2D BAD diffuses in 2 dimensions.

 

I've never found design criteria for the lower and upper limits of diffusion for BAD panels - but IMHO they're ideal for the scenario where you've added too much absorption into the room and want to reflect higher frequencies and want to add diffusion at the same time.

I tried to pull together some info on BAD panels in this thread - but I didn't get very far

 

@hochopeper wrote some code ages ago to calculate the hole placings for 2D BAD panels in whatever size required. Thread here 

 

 

For 1D BAD panels, you can use any random sequence to derive the slat/gap sequence - flipping a coin would work or use a random MLS sequence like in this thread

https://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/395773-diy-binary-amplitude-diffuser-anyone.html

You would use the sequence by choosing the minimum slat/gap width at (say) 20mm. Every 1 (or head on a coin toss) means slat, every 0 (or tail on a coin toss) means gap. Three 1's in a row means a slat 60mm wide, four 0's in a row means a gap 80mm wide etc.

 

cheers

Mike

 

Edited December 13, 2019 by almikel
clarification

[davewantsmoore]

On 11/12/2019 at 11:38 PM, DrSK said:

Dave, can you provide an recommendations for practical diffusers? How much over what theoretical range makes a useful difference?

It's a really complicated question.

 

Many things sold as, or considered as, diffusers, really do nothing much of the sort.

 

One big issues is the frequency range you want to cover.   The diffuser will get very large (deep) as the frequency goes down .... and the seating distances for most diffusers are quite substantial (you need to sit a long way away from them) ..... otherwise they just act as funky reflectors.

[Guest DrSK]

1 hour ago, davewantsmoore said:

Many things sold as, or considered as, diffusers, really do nothing much of the sort.

Thanks Dave, that's the conclusion I'd come to looking at some on the market. 

 

Digging into some of Mike's links and various papers above. Ranging from Cox and D'Antonio etc, various publications including on BEM modelling of performance which looks interesting and robust. Haven't touched BEM since 2003, seems like a few good packages out there. 

[davewantsmoore]

7 hours ago, DrSK said:

Thanks Dave, that's the conclusion I'd come to looking at some on the market. 

 

Digging into some of Mike's links and various papers above. Ranging from Cox and D'Antonio etc, various publications including on BEM modelling of performance which looks interesting and robust. Haven't touched BEM since 2003, seems like a few good packages out there. 

To keep it simple you can have a tinker with qrdude.

 

Notice the minimum seating distance.