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Listening Room

Murrayp

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#1
Hi all,
I'm sort of new here though I know many of you from the requisite 20 years on audio forums ;o)
I've had bit of a search here but I haven't spotted a thread on listening room dimensions. Googling this readily shows many opinions and approaches. The general recommendation seems to be to keep the room cuboid so that at least the standing waves are predictable, and then adjust dimensions to avoid reinforcement in the three dimensions (keep the dimensions away from integer multiples of each other). Audio professionals have simple ratios that have proven good over time. The golden ratio is often used and seems to give a good spread of frequencies. The more I looked the more it seems, so long as bad dimensions are not chosen, there are many possible room sizes that work pretty much as well as each other. But bigger is better.... On the other hand it is just me listening and I don't really want to disappear into a giant cave, so there's a driver not to be too big too.

I'm building a new house and have reasonable freedom to choose the listening room size. I'm expecting something around 2.7m high with the golden ratio, 4.4 wide and 7.1 long (about 9' x 14.4' x 23.3'). If worthwhile it could be 3.0m (10') or even higher with the relative increased width and lengths.

It will have concrete floor (probably wooden surface), and concrete ceiling (again of course some finish). The walls can be concrete, concrete block or timber and drywall.

If it was a virtue I could slope the ceilings and walls...... The speaker end is likely to be a glass wall (again to avoid the man cave effect) and I plan to mount it with a slope to reflect sound to the ceiling probably.

My speakers tend to be largish (currently Tad R1s, but have used B&W801ds, JBL Everest, and Sony SS-AR1 too. I'm more of a near field listener than far field. Subs can be applied as required more or less.

I have dabbled in room correction (Tact, Lygndorf, Room Perfect, etc, etc), though I generally prefer not to use it currently.

So, any ideas, recommendations? I guess the obvious one is go find a good acoustic company and work with them....

Btw - disclosure - I'm an electronics engineer......sad but true....which is why I'm here I guess ;o)

Thanks

Murray
 

Purité Audio

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#2
Murray sounds a wonderful oppurtunity do you have space to build a room within a room ,mastering studio style ?
Keith
 

Murrayp

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#3
Hi Keith,
Oops, I missed the Lansche you supplied to me on my list of speakers over the years :eek:)
Yes, I could do room within a room, but really I doubt I need that. The house is in the country so I'm not bothering anyone nor is there much noise to bother me, so probably I don't need to go that far. Thanks M
 

Purité Audio

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#4
Murray I wouldn't be too disappointed about the LANSCHE speakers, re the room I wasn't thinking about sound proofing as much as absorbing bass, you could place rock wool or similar completely around the room, floors and ceiling too, low bass is always the major problem in domestic reproduction.
Keith
 

Murrayp

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#5
Ok - I see. Keith. Yes, bass transmission is a problem in our current house. In our new house the listening room on the lower level is well isolated to living spaces on the upper and offset level by a concrete roof/floor - I hope. Actually a bigger bass problem is my 12 year old son who seems to be picking up on audio and already has made his own 15" sub in his bedroom......;)
M
 

Purité Audio

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#6
Murray It is not the transmission of bass into other parts of the house that I am primarily concerned with although 6 feet of rock wool on every surface will help, it is the sound quality if you can build a room that absorbs low bass you will enjoy much much higher sound quality without having to employ passive or active correction within the room.
Low bass is very difficult to tame but a room within a room with rockwool under the floor above the ceiling behind the walls would really help, many pro audio rooms are built this way, you could too as you are building from scratch.
Keith
 

Murrayp

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ah, ok - got it this time Keith. So it would be hard to manage the bass in a room surrounded by solid concrete.....
I will have concrete above and below, so having wooden walls designed for absorption will help.
In reality I'll most likely work with an audio engineering firm and no doubt they will know all this stuff. Still, it will help me to understand what they are up to, and/or answer their inevitable questions or needs.
Thanks
Murray
 

Purité Audio

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#8
The more solid the construction the more bass will be reflected back into the room, it is the fundamental standing waves that can be an issue, they cause the BRRRRRRRRRR sound you often hear in systems which are capable of low bass.
Keith
 

dallasjustice

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#9
The bigger the better. You don't want a square room. Concrete walls or floor is the least desirable construction. If concrete is the only option, you may want to hire an acoustician to design some false walls inside the room. If all walls are concrete, it will be very difficult to use DSP to overcome all the bass problems.

If I were you, I'd hire an acoustician to design the room before you start building. It will save you a lot of money and heartache in the long run.
 

amirm

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#10
Welcome to the forum and good first post!

Build a room to your comfort. The magic ratios and such have a key assumption that is never true, i.e. they assume you put your speaker in one corner of the room and you sit in the opposite corner. Dr. Toole shows this vey well in his book:

upload_2017-5-28_9-28-1.png


Further complicating matters is that acoustic dimensions (i.e. what the "sound waves see") is not the same as physical dimensions. If you have any walls other than concrete, they move and push out the actual dimensions of the room beyond what is physically visible.

So while I would not make the dimensions a perfect cube, any other is as good as any prescribed one.

As Dallas said, make it as large as you can as that pushes your bass problems to lower frequencies.
 

amirm

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#11
It will have concrete floor (probably wooden surface), and concrete ceiling (again of course some finish). The walls can be concrete, concrete block or timber and drywall.
As Keith mentioned, try to make them as limp as you can. You can go with concrete but then put flexible drywall in front of it.

For floor, if you go with wood, then you need to put a thick/shag carpet on it to absorb floor reflections.
 

Murrayp

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#12
Thanks Dallas and Amir,
OK, I sort of came to this conclusion after spending a few hours on the net too. I've been a bit lazy really - yes I have Floyd's book - above is Fig 13.6, right?
But I haven't read it - time I did I guess. Yes, I've employed a firm of acoustical engineers - as Dallas says I'm sure it will be cheaper and waaay less frustrating in the end. They've had one run at it already, and have given quite a detailed design - including the construction of the various absorbers and dispersion elements. They haven't suggested anything like traps, but have got the rear wall (as well as portions - below 1m - of the side walls) lined with quite deep absorbers to help with bass. Noted re concrete walls - if I end up with them (structural engineers might dictate this) I'll run a false wall inside.

Many thanks.

btw I've introduced a friend Pater here - he's another ee and has spent much time developing his own active speakers - has strong signal processing knowledge. And a very healthy disdain for audio bs (to the extent of embarrassing me twice with ABX tests when I claimed to be able to tell one cable from another.... He also relates a story of expectation bias - spent a full day once hearing step by step improvements all day in his work on his computer audio - only to realise at the end that nothing was compiling ........ nothing had changed all day, but that wasn't what he heard!!! With any luck Pater might contribute.
 
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Thomas savage

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#13
Thanks Dallas and Amir,
OK, I sort of came to this conclusion after spending a few hours on the net too. I've been a bit lazy really - yes I have Floyd's book - above is Fig 13.6 right :eek:)
But I haven't read it - time I did I guess. Yes, I've employed a firm of acoustical engineers - as Dallas says I'm sure it will be cheaper and waaay less frustrating in the end. They've had one run at it already, and have given quite a detailed design - including the construction of the various absorbers and dispersion elements. They haven't suggested anything like traps, but have got the rear wall (as well as portions - below 1m - of the side walls) lined with quite deep absorbers to help with bass. Noted re concrete walls - if I end up with them (structural engineers might dictate this) I'll run a false wall inside.

Many thanks.

btw I've introduced a friend Pater here - he's another ee and has spent much time developing his own active speakers - has strong signal processing knowledge. And a very healthy disdain for audio bs (to th extent of embarrassing me twice with ABX tests when I claimed to be able to tell one cable from another.... He also relates a story of expectation bias - spent a full day once hearing step by step improvements all day in his work on his computer audio - only to realise a the end that nothing was compiling ........ nothing had changed all day, but that wasn't what he heard!!! With any luck Pater might contribute.
Great to hear, please post some pictures throughout the construction. It will be great to see the various stages of construction and on the Audio side see the special methods used.
 

amirm

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#14
Thanks Dallas and Amir,
OK, I sort of came to this conclusion after spending a few hours on the net too. I've been a bit lazy really - yes I have Floyd's book - above is Fig 13.6, right?
But I haven't read it - time I did I guess. Yes, I've employed a firm of acoustical engineers - as Dallas says I'm sure it will be cheaper and waaay less frustrating in the end. They've had one run at it already, and have given quite a detailed design - including the construction of the various absorbers and dispersion elements. They haven't suggested anything like traps, but have got the rear wall (as well as portions - below 1m - of the side walls) lined with quite deep absorbers to help with bass. Noted re concrete walls - if I end up with them (structural engineers might dictate this) I'll run a false wall inside.
That's good. Feel free to run their recommendations by us and we can opine -- validly or not :D -- whether they are doing some good or not.
 
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