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Silent Screamer

Sound Proofing...When do you have enough?

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On 19/01/2019 at 2:24 PM, Silent Screamer said:

Apparently and expanding room helps with standing waves.

It does not work as well as human nature would predict it might.

 

For an example.    let's say you have a room which gets wider as you go from front to back.   It's 4m wide at the front, and 5m wide at the back.

 

If you look at the primary width mode, it is 43Hz where the room is 4m wide... and 34Hz where the room is 5m wide.    There isn't a lot of difference.

 

At higher frequencies the reflections from the side walls will be different (due to the angle) ..... but this doesn't necessarily mean better.... and there are other ways to modify those reflections (eg. by moving the speaker and/or the listener)

 

 

It is the same with "golden ratio" room dimensions.

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4 hours ago, Peter the Greek said:

100%

Definitely.   The basic reason is that the distances between things matter a lot(!!) more than what angle the surfaces are.

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3 minutes ago, davewantsmoore said:

It does not work as well as human nature would predict it might.

 

For an example.    let's say you have a room which gets wider as you go from front to back.   It's 4m wide at the front, and 5m wide at the back.

 

If you look at the primary width mode, it is 43Hz where the room is 4m wide... and 34Hz where the room is 5m wide.    There isn't a lot of difference.

 

At higher frequencies the reflections from the side walls will be different (due to the angle) ..... but this doesn't necessarily mean better.... and there are other ways to modify those reflections (eg. by moving the speaker and/or the listener)

 

 

It is the same with "golden ratio" room dimensions.

I have seen similar written before that while a lot of it is good in theory, the real world application often doesn't meet expectations. I guess it comes down to do the best you can without increasing the cost so dramatically that it outweighs any benefit you might get from it.

 

If option allows common sense dictates that you don't build a perfect cube room because it has the worst possible room modes. Sometimes we might be dealing with less than ideal but it is what we have to work with. Fortunately having a clean slate to work with I do have options, but I need to be mindful of the cost to any benefit to be gained.

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On 19/01/2019 at 11:25 PM, Silent Screamer said:

Sweet! http://cardas.com/room_setup_golden_trapagon.php finally I can do it semi properly.

What they say is true

Quote

The Golden Cuboid (Diagram H) is the best "rectangular" shape for a listening room.

.... what they don't tell you is how close in performance many(!) room dimensions are.

 

 

They make it sound like as you zero in on the golden dimensions that the performance improvements will come...... when in reality it is as you move away from the very problematic dimensions the performance improvements will come .... and as you go close and closer to "golden dimensions" the performance improvements will slow/stop.

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1 minute ago, davewantsmoore said:

What they say is true

.... what they don't tell you is how close in performance many(!) room dimensions are.

 

 

They make it sound like as you zero in on the golden dimensions that the performance improvements will come...... when in reality it is as you move away from the very problematic dimensions the performance improvements will come .... and as you go close and closer to "golden dimensions" the performance improvements will slow/stop.

I have actually seen quite a number of alternate ratios listed on the web, some for listening, some for movies, even ones claiming to be for THX.

In what why do you consider them problematic? Aren't they called the golden ratio because they are mathematically the perfect ratio?

 

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5 minutes ago, Silent Screamer said:

If option allows common sense dictates that you don't build a perfect cube room because it has the worst possible room modes.

Yes... understanding the "golden ratio" idea is good because it tells you what not to build.

 

Build a oblong room, with reasonably unrelated dimensions .... and don't be temped to sit too far back (lots of space behind you is good).... room width needs, really starts to depend on how close you plan to sit to the speakers, and what the directivity of the speaker is  (ie. does it fire sound over a wide-ish windows like most speaker, or is it more narrow, like a horn, or open baffle)

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2 minutes ago, Silent Screamer said:

I have actually seen quite a number of alternate ratios listed on the web, some for listening, some for movies, even ones claiming to be for THX.

In what why do you consider them problematic? Aren't they called the golden ratio because they are mathematically the perfect ratio?

 

"Problematic" dimensions are kinda the opposite of the golden ration.   eg. a cube ... or integer dimensions (for example) 4m wide, 4m high (or 2m high), and 8m deep) .... etc.

 

On the other end of the spectrum ..... moving a wall 10cm, so it corresponds closer to the "golden dimensions" will make zero practical difference.

4 minutes ago, Silent Screamer said:

some for movies, even ones claiming to be for THX

This is nonsense.  Sounds is sound.

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10 minutes ago, davewantsmoore said:

"Problematic" dimensions are kinda the opposite of the golden ration.   eg. a cube ... or integer dimensions (for example) 4m wide, 4m high (or 2m high), and 8m deep) .... etc.

 

On the other end of the spectrum ..... moving a wall 10cm, so it corresponds closer to the "golden dimensions" will make zero practical difference.

This is nonsense.  Sounds is sound.

Ahh ok I miss understood your previous post, I thought you were saying that the golden ratio was problematic, but what you really said was there is more benefit to be had from moving away from the really bad ratios (like a square room) than there is gain to be had from going from close to golden ratio to spot on it.

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Had this page open and just spotted that they recommend different ratios based on the volume of the room which is interesting... I guess that could have a bearing on it if they are factoring in things like sound decay. https://www.salford.ac.uk/research/sirc/research-groups/acoustics/architecture-and-building-acoustics/room-sizing-for-studios

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2 hours ago, davewantsmoore said:

It does not work as well as human nature would predict it might.

 

For an example.    let's say you have a room which gets wider as you go from front to back.   It's 4m wide at the front, and 5m wide at the back.

 

If you look at the primary width mode, it is 43Hz where the room is 4m wide... and 34Hz where the room is 5m wide.    There isn't a lot of difference.

 

At higher frequencies the reflections from the side walls will be different (due to the angle) ..... but this doesn't necessarily mean better.... and there are other ways to modify those reflections (eg. by moving the speaker and/or the listener)

 

 

It is the same with "golden ratio" room dimensions.

Just looking at my SketchUp drawing and I think the trade off is probably not worth it. If you loss a meter of width at the front that is half a meter each speaker could be further off the wall or better placed.

 

When you want a big screen (which I do) you don't want the speakers blocking the picture, so all and all it probably isn't worth sloping the walls (maybe still do the roof) for a tiny gain in room modes which will probably need fixing in other ways anyway.

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