[JLM]

OP,

Skew speakers, go non-symetrical while aiming for the golden ratio and maximizing space in the room design.  Be creative.  Proper room design should be your first priority, then treatments, and finally EQ.

usp1,

The ancient Greeks invented the golden ratio (5 x to deal with all the hard/stone walls in their most impressive buildings (temples).  The math can demonstrate that this ratio minimizes the multiples of length to width of echos, so they don't reinforce each other even at evenly divided (multiples in frequency because as frequency increases the length of sound waves reduce).

[Hipper]

'8' then ')' equals .

Ratio 5 x 8

[usp1]

Slap echo isn't going to be solved by a room ratio.  That's just a matter of addressing large, flat, hard, parallel surfaces.  This can be done with absorption or diffusion.

What good room ratios so is to help spread room modes farther apart and distribute them more evenly through the spectrum so they don't pile up and reinforce each other making them more difficult to address - especially in the lower frequencies.

ALL rooms, regardless of the ratios will have modes and modal problems.  Some are just less bad than others.

Bryan

Thanks Bryan. I understand that different ratios will have different problems. What I was more interested in knowing was why the golden ratio has any significance for sound. Is there anything specific about this ratio that somehow reduces the modal problems. Or is it through experience and "golden ear" listening that people have decided that this is a good ratio.

[RCduck7]

Before i start anyone individual replying, here are some pics of the place i can work with...

The back of the room where i will be sitting about 4 feet from the wall...
(The 2 closets will be gone of coursse, and the white stuff you see everywhere from the ground up to the ceiling is isolation to safe energy at winter and keep it cool on summers)



The front of the room where i will be planning to place the speakers...



One side of the room, the other side will have the same measurements except it will not have the window opening you are seeing there...



A close up picture of the isolation... The surface doesn't feel very soft but becausse of the bubbles you see it might counter first reflections a bit.





I have been thinking of the possibility to place the speakers in the length of the room but then i would have one side of the speaker at a 90 degree wall and the other on a sloping ceiling. I guess the sound wouldn't be very even then.
Besides a friend of mine was very happy when he placed it's speakers at the wide side of the room instead of in the length. As you can see the sloping ceiling goes all the way up and i'm not planning to have a flat roof there, this to maximise the space and reduce up and downwards reflections.

[JLM]

Hipper/usp1,

How'd that happen?   


RCduck7,

I'd put the speakers along the brick wall, provide short knee (vertical) walls on the right and opposite sides, build a taller knee wall (at least 4 feet tall) on the left side (switch right/left if you like).  This would provide maximum soundstage depth, breakup the boring symmetry and sonic reflections, and provide wall space for furnishings.

Seriously, don't leave insulation exposed (it can off gas or crumble or decay with long term expsure to light).  None of those options are healthy.

I like the overall space and the exposed framing (great place to mount lights/etc.).

[rofo]

what a fantastic space, your imagination is infinite, maintain the angles, add a little fuzz and it will sound great.

[usp1]

Just a quick update on my research on room dimension. I looked at several research studies on line and none of the studies mentions the golden ratio. The golden ratio seems to have been popularized by Cardas. I am not sure if there is any scientific evidence supporting the use of this ratio. One of the more recent studies http://www.acoustics.salford.ac.uk/acoustics_info/room_sizing/?content=best

suggests the following room ratios as being best over a range of room sizes. Notice that the golden ratio is not one of the suggested ratios!

1.00   2.16   2.96
1.00   2.16   2.97
1.00   2.16   2.98
1.00   2.17   2.96
1.00   2.17   2.97
1.00   2.17   2.98
1.00   2.17   2.99
1.00   2.18   2.97
1.00   2.18   2.98
1.00   2.18   2.99
1.00   2.00   3.00
1.00   2.19   2.99
1.00   2.00   3.00
1.00   2.19   3.01
1.00   2.19   3.02
1.00   2.20   3.01
1.00   2.20   3.02
1.00   2.20   3.03
1.00   2.21   3.02
1.00   2.21   3.03
1.00   2.22   3.03
1.00   2.22   3.04

(The above can be viewed as Length, Width and Height in any order)

To the OP, sorry if I am derailing the thread. You seem to have a wonderful opportunity to structure a good room and I look forward to your buid thread with lots of pic!

[brj]

I am not sure if there is any scientific evidence supporting the use of this [golden] ratio.

I mentioned that link more to highlight the fact that angled walls and ceilings can be potentially beneficial, rather than to dwell on the golden ratio itself.

(Never having had the luxury of building a listening room from scratch, I have yet to research specific ratios.)

[Big Red Machine]

You have an automatic non-parallel wall situation so this should work very well.  I would put your speakers on the narrowest wall and allow you to sit back with enough room behind you.  Symmetry can help and symmetry can hurt.  I would think you could easily manage the sloping wall off one side of a speaker with a false wall or hard-faced trap, if needed.

It's pretty easy to see how the bass will build up in those deep triangular sections along the floor, so plan for some serious trapping.

How is the roof ventilated?  Is there airflow on the other side of this sprayed material?

[Hipper]

That room looks like a good oportunity for you.

Because it looks unpredictable to me, I'd be tempted to just bung the gear in there as you planned, listening position somewhere by the brick wall, play something and walk round the room to hear where it sounds best. Move speakers and chair around until something sounds decent.

There will be problems which you should of course try to identify and solve as they arise, starting with any bass difficulties.

Trying to anticipate and solve the problems before playing anything may see you wasting your time and money.

The unknowns would be how the bass (roughly 300Hz and below behaves). You should be able to have some idea of the how the higher frequencies react by knowing the dispersion pattern of your mid and high drivers. I understand now that it is a good thing to get side wall first reflections, and you may get these.

[RCduck7]

The insulation for health is a worry. I should brush it off good with a mask on my face and see if after some time there will still be coming some of the stuff down. If so, i should finish the room with wooden plates. I have been walking around the room, and yes i should experiment with placing the speakers along the brick wall or in the length of the room before finishing the place. But when i would place the speakers along the brick wall i would be sitting in the area where the angled ceiling will be over my head. That is a worry. It is a certainty though that i should make short knee vertical walls where the angled ceiling starts. This project isn't for this year anymore though. Next year there should be also a new (better) floor if everything goes to plan. Also insulation in the floor to fill up these hollow spaces to not make the room sound boomy. It is not a concrete floor you see. It's also worth mentioning that music in stereo will come first place but the room will also be for home cinema use, 5 channel and maybe 7 channel if i would feel the need to do that. The room is not small at 17'x24', and that measurements are when i have short knee verticall walls in the angles. But the angled walls make the space gradually smaller starting at about 3 feet.

[RCduck7]

You have an automatic non-parallel wall situation so this should work very well.  I would put your speakers on the narrowest wall and allow you to sit back with enough room behind you.  Symmetry can help and symmetry can hurt.  I would think you could easily manage the sloping wall off one side of a speaker with a false wall or hard-faced trap, if needed.

It's pretty easy to see how the bass will build up in those deep triangular sections along the floor, so plan for some serious trapping.

How is the roof ventilated?  Is there airflow on the other side of this sprayed material?

Those deep triangular sections along the floor will be behind a wall of at least 3 feet high, maybe higher depending on which side. Not sure how thick the walls should be. But behind these walls there will be here and there stuff stored. Even with the short knee walls i should still put traps in the corners of the room.

I'm certainly considering placing my speakers on the narrow side. I had the chance some time ago to be playing music in a bigger attic then this with an even higher angled ceiling as an experiment. And it striked me how beautiful voices were prensented in the middle of the room a bit higher then i was sitting but as if the person was singing in front of me on a stage. It sounded so good, even my wife said so. I think it was possibly due to the extremely high ceiling in this attic but the room was also pretty wide. Maybe a combination of both, i don't know.

The room i'm planning for my future listening has no ventilation but i could create air circulation by opening the window in the attic and at the same time opening the door to the attic which goes to a room where i could also open a window. I'd propaly would do this on a daily base when i'm not in the room playing music. But maybe a bit unpractical and i might look further then this.

[RCduck7]

Here are some pics of the work i have been doing lately...

Carpet is removed, floor is out to file up the space between the beams.
Not very much to do with the acoustics topic i suppose...










When the floor is ready i can start experimenting with placing the speakers for the best possible sound and to know where i should put the walls to make the room in the attic.

[RCduck7]

The insulation in the floor is now complete. When i previously stomped my feet to the floor wihthout the insulation there was a hollow sound and the room resonates. When i stomp my feet now with the insulation in place the sound is less hollow but i still get the room (or parts of it) to resonate. Still, the rather stiff laminate floor of 0.3" thick has yet to be placed. Hopefully that will make up a lot. Any tips regarding this before the laminat will be placed??

My dad has finished the beams for making a wall. The wall will also have 2.4" insulation. As we placed the beams it turns out the room is going to be 16' by 18'. I worry if this is still to close to being a bad square room. It is still not to late to make the room 14' or 15' by 18'. Or do i worry to much and would 16' by 18' be just nice for the acoustics?? I plan to place basstraps in the corners either way.

[bpape]

It's a tradeoff.  16x18 isn't bad, 15x18 is better. All of that said, as long as you have flexibility in setup, positioning, and treatment, I'd take the wider space.

Bryan

[jriggy]

A few things I have learned from the acoustics engineer/designer that i am working with for my angled wall/ceiling attic space, is to not finish the knee walls with drywall at all. Finish them with acoustic fabric! They can be made to look like a wall until you go up and touch it... Then you can line the space with bass trapping, taking care of a lot of issues from the angles. As well as any worry of exactly what room width is optimal.

Also, you may want to consider a second layer of flooring.

[bpape]

If you want the room that dead from that much absorption, it can certainly help some things. The other option is spot treatment with diffusion mixed with targeted absorption where required.

Bryan

[jriggy]

Absolutely. And I am no expert like Bryan is. Just a novice at all this really... But just to clarify, I didnt mean to fill the entire space with absorption.  "where needed" are key words but the false walls in a space like your may work.

[RCduck7]

Absolutely. And I am no expert like Bryan is. Just a novice at all this really... But just to clarify, I didnt mean to fill the entire space with absorption.  "where needed" are key words but the false walls in a space like your may work.

I think it will work very well judging that i had to try out a similar attic and even a taller space like this. Only low frequencies have to be in control, this IS an issue from my experience in a space like this. This is where the walls come in to resolve this issue, or part of it. The other part that plays a big role is the floor. I need to have mass and some form of decoupling as it is not a concrete floor. Who knows this might turn out very well, fingers crossed. I have been shopping and this is what i'm going to do.

Placing an underfloor for the laminate of 7mm (reduces up to 15db) + some sort of foam (2mm) before the laminate goes in place to have some form of decoupling and further reduce the room to resonate. I would also make sure he plaster walls don't make contact with the floor.

As i told the 16' by 18' measuremets of the room was a worry but people like bpape told not to worry to much if treatments were taken afterwards. Still i have come to the idea to make benefit of the 18 feet long wall to make shelves to storage CD's and DVD's. This would take almost a feet away, making the room closer to 15' by 18'.

The following is coming between the floor and the laminate...











And the 2.4" thick insulation for the walls...

[BobRex]

Not to crush either your enthusiasm or project, but:
1) How big are your floor joists?  They look on the small side to me.  Also, check with your local codes.  I was under the impression that notching joists is a no-no.

2) I see at least 2 electrical junction boxes that will be buried under the floor.  Unless they can be accessed from underneath (doubt it), you are in violation of the electrical code.

You might want to check these out before you get too far in the construction.