When is room treatment needed - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #11 of 189 Old 12-29-10, 02:51 PM Thread Starter
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Re: When is room treatment needed

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Probably just a change in mic position. Or, could be you have smoothing set differently.

Bryan
Does this null mean I have rear wall bass problems?

How do I absorb the front wall, I wouldn't be able to put much above the screen as there is only about 5 inches from the top of it to the ceiling, I do not know how to remove the screen as it fixed and was proffesionally installed, are you just talking about surrounding the screen with something?

If my subs response is pretty good why would I need bass traps in the 4 corners, what difference would it make to the sound? Would the untrained ear notice a difference?

Thanks Again
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post #12 of 189 Old 12-29-10, 02:54 PM
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Re: When is room treatment needed

Do as much as you can on the front wall given the restrictions.

If you have a changing null based on seating position front to back, it can be helped with rear wall treatment coupled with good positioning.

For the other absorbers, remember that there is much more than just frequency response in play here. I can have perfectly flat response and excessive ringing and decay times that will muddy up sound, cause dialog intelligibility problems, cause loss of imaging cues and harmonic details, etc.

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post #13 of 189 Old 12-29-10, 03:08 PM Thread Starter
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Re: When is room treatment needed

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Do as much as you can on the front wall given the restrictions.

If you have a changing null based on seating position front to back, it can be helped with rear wall treatment coupled with good positioning.

For the other absorbers, remember that there is much more than just frequency response in play here. I can have perfectly flat response and excessive ringing and decay times that will muddy up sound, cause dialog intelligibility problems, cause loss of imaging cues and harmonic details, etc.

Bryan
Thanks Bryan

So what you are saying is the bass traps will make the sound better to the ear but not necessarily visible through REW?

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post #14 of 189 Old 12-29-10, 03:32 PM
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Re: When is room treatment needed

It will make it better in REW if you look at the decay time or waterfall windows as opposed to just the measured frequency response.

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post #15 of 189 Old 12-30-10, 01:58 AM Thread Starter
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Re: When is room treatment needed

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It will make it better in REW if you look at the decay time or waterfall windows as opposed to just the measured frequency response.

Bryan
Interesting, I wouldn't have the first idea on what to look at on those sceens

In regards to the front wall again, I saw a thread where a guy put a couple of corner shelves up and placed triangular cut slices of rockwool on top of eachother all the way up the wall. Is this the correct way of making a corner bass trap because I was under the impression that you need to leave a bit of air space between the rookwool and the corner?

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post #16 of 189 Old 12-30-10, 08:16 AM
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Re: When is room treatment needed

It's one way to do it and will work just fine.

The air gap is a common misconception. It's not the space, it's getting the leading edge of the absorber out farther from the hard boundary that helps extend performance. That said, any time you can have a solid chunk rather than a thinner chunk with an air gap (think 6" flat on a wall vs 4" with 2" of air), the solid piece will perform better. Same goes for flat panels straddling a corner vs solid triangular chunks.

Waterfalls are an easy graphical representation of how fast sound decays across the frequency spectrum. Bottom axis is frequency. Left axis is intensity (db level). Z axis (depth) shows time in milliseconds. The proper decay time varies by each room in terms of size and what you'll use the room for. Classrooms are different from churches from home theaters from listening rooms, etc.


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post #17 of 189 Old 12-30-10, 12:13 PM Thread Starter
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Re: When is room treatment needed

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bpape wrote: View Post
It's one way to do it and will work just fine.

The air gap is a common misconception. It's not the space, it's getting the leading edge of the absorber out farther from the hard boundary that helps extend performance. That said, any time you can have a solid chunk rather than a thinner chunk with an air gap (think 6" flat on a wall vs 4" with 2" of air), the solid piece will perform better. Same goes for flat panels straddling a corner vs solid triangular chunks.

Waterfalls are an easy graphical representation of how fast sound decays across the frequency spectrum. Bottom axis is frequency. Left axis is intensity (db level). Z axis (depth) shows time in milliseconds. The proper decay time varies by each room in terms of size and what you'll use the room for. Classrooms are different from churches from home theaters from listening rooms, etc.


Bryan
I understood it that the sound travels through the absorber reflects off the wall behind and then gets absorbed again?

What decay time would I be aiming for in a home cinema then? Would it be the same db level across all frequencies?

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post #18 of 189 Old 12-30-10, 12:16 PM
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Re: When is room treatment needed

True on the reflection - but - with a solid piece, it's doing the same thing but never leaving the absorbing material.

What are the room dimensions? That's part of the calculation.

The decay times will be a downward sloping curve which is somewhat flat in the middle with the low end being a bit higher and the high end being a bit shorter.

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post #19 of 189 Old 12-30-10, 12:33 PM Thread Starter
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Re: When is room treatment needed

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True on the reflection - but - with a solid piece, it's doing the same thing but never leaving the absorbing material.

What are the room dimensions? That's part of the calculation.

The decay times will be a downward sloping curve which is somewhat flat in the middle with the low end being a bit higher and the high end being a bit shorter.

Bryan
My room is 18ft 6inchesx12ft 11inches and 8.5ft high
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post #20 of 189 Old 12-30-10, 12:40 PM
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Re: When is room treatment needed

From an RT60 standpoint (really more for larger rooms but OK for reference), you'd want to be around 200ms in the midrange - maybe 250 in the lows and 160-170ms in the high end. You're really more interested in RT30 which is a bit more than 1/2 of those times but most people don't like it that dead.

Untreated, the low end is now probably closer to 1 second or a bit more.

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