New room acoustics plans

[scott_01]

I've just bought a house. It's a turn of the century, stone built semi detached property. The living room is going to be the 'audio room' and will have to be livable in too.

However, the significant other is surprisingly happy for me to acoustically treat it (within reason). We are stripping the whole thing down to the joists anyway, so I have the opportunity to do some reasonably serious stuff.

I've looked briefly at Rives Audio, but their level 2 service which includes construction plans is $2800 and a bit too much for me to spend.

I've had good experiences with absorption and bass trapping in my present room but I'd like to take this a step further.

The current speakers are Harbeth SHL5 although I plan to augment with 2 x DIY subs to deliver a full range system in the long run.

I've made some Cara sketches of what I would like to do and would be grateful for comments. I have the facility to measure the room, but that isn't much use at the moment becuase it's just bare stone and brick.

Speakers and listening position - Top View

This is the room from above, the alcove to the rear is the old halway that we've knocked through to increase the size of the living room. The stairs are blue and to the rear, front door is to the right of stairs.

3D view from rear hallway towards fire place

This view shows what you see if you come in the front door and look right. I'd like to put some big shelves up either side of the fire place.

Proposed treatment front

Bass trapping is shown in yellow, diffusion by that black grid thing.


The ceiling

I'd like to build a diffusion array into the ceiling

Looking rearwards from listening pos

Looking towards the rear I could bass trap all underneath the stairs and would look to some absorbtion in the corners of the cut-away wall. The space above the stairs (in light blue dots) is of course open to the 1st floor.

Assumptions

1. I'm DIY competent and can make these things
2. I want to mess around a bit and am prepared to get it wrong a couple of times.
3. I have the tools to measure the reaction of the room to individual treatments.
4. I know I can't get true full range in this room

Questions

1. Does this rough plan make sense?
2. Will the large opening above the stairs and the one through to the rear left make any big difference to the effectiveness of these treatments?
3. At what freq should I be looking at bringing in the diffusion arrays?

 

[bottleneck]

Nice one Scott.

Have you modelled the expected finish in Cara? (early days but just wondered)

Are you going to build the actual diffusors and bass traps into the plasterwork and therefore actually 'hide' them from view? - I have always wanted to do this. Invisible room treatment!

A few questions...

In Cara - have you moved the armchair to a different location to see the results? Is it there to help with the adjoining space of the stairs at the back of the room?

NB
I think this work of yours deserves a 'blow by blow' photographic journal in the DIY section of the forum


Another thing - In hifi, I often am able to get noises from the TV in particular through the hifi... of course coming through the mains.

I'm not one to mess extensively with mains personally, it's a small thing in my book. However, given a 'back to joists' construction I would personally run a few seperate spurs in, to prevent noise from other household appliances coming through. I should think the cost would be minimal, given what you have planned anyway..

Just some thoughts.

Enjoy the move and the build

NB
I am moving next month also, it's a real tumult of emotions, isn't it?

 

[MattC]

Hi Scott,

our house is also turn of the century, and stone built and semi-detached, our living/listening room is very very similar to yours. We also have the stairs going up in exactly the same place, as the hallway has been knocked into the living room - curious as to why you left the short pieces of the original hall walls protruding into the room - was this to take a supporting RSJ?

we've got builtin bookshelves/cupboards in the alcoves either side of the fireplace, and have the bookshelves well loaded up with books, which definitely helps the sound.

the other thing if that I prefer the sound in my room with the speakers on the long, lefthand wall in your first diagram, and the main sofa on the (but not tight to) the long righthand wall, and the second sofa (not yet arrived!) will have it's back to the stairs.

I too put a dedicated spur in whilst we had it in pieces, and think it contributes in good way overall - definitely worth doing if you can.


all the best
Matt

 

[drummerjohn]

Sound traps are best put in corners ie wall to ceiling, wall to wall. So the ones on the ceiling move against the wall so they join at a 45 degree angle.

The sound traps on flat surfaces are more effective kept away from the wall slightly ie 50mm if absorbstion is on both sides of the sound trap.

As you have indicated in your drawing diffusion or a sound trap on the side walls just ahead of the speakers is good.

 

[scott_01]

Thanks for the pointers guys. In no particular order:

Are you going to build the actual diffusors and bass traps into the plasterwork and therefore actually 'hide' them from view?

I'm not going to do this as I want it to be reversible if we decide to sell. The Bass trapping will have the same wood fronts as the shelving units. The diffusion arrays will have to be uncovered I think. I'll build in the ceiling ones and stick on the side ones.

Have you modeled the expected finish in Cara?

Not yet, I will do though. As I'm planning to mess around with some Helmholtz resonators I might have to adopt a 'measure and see what happens' approach.


curious as to why you left the short pieces of the original hall walls protruding into the room - was this to take a supporting RSJ?

Yes, we haven't had this done yet, so I was planning on worst case scenario with a fair bit of protrusion.

I too put a dedicated spur in whilst we had it in pieces, and think it contributes in good way overall - definitely worth doing if you can.

I'll be doing this too (well, an electrician will be). I've just this second laughed at R Andrews latest comic but am wondering about Balanced Power, is there any point in this? I won't be paying 3 grand for his effort though.

Sound traps are best put in corners ie wall to ceiling, wall to wall. So the ones on the ceiling move against the wall so they join at a 45 degree angle.

Thanks john, I've completed the treatment in my current place like that, got some covers made and hung sheets of wickes high density insulation, in the corners and it made a noticeable difference, even with the already extensive absorption I have.