Is this a horrible RT-60 - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #11 of 15 Old 01-20-16, 06:56 PM
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Re: Is this a horrible RT-60

Here is a good goal.

no reflections higher than -15db for the first 5ms... from 5ms-10ms you want no higher than -18 and from 10-20 you want no higher than -20 and 20-40ms you want to be around -24db.

anything beyond 40ms adds ambience/space but you should be down to -30db around 80ms. This has been my learning in recent studies and practice. I've spent some time chasing reflections and it makes a difference.

If your couch is all the way up against the wall like that you need some 2 or 4" absorption panels. You have a ton of reflections in the first 5ms and this means behind your head... and floor... and that side wall.

Something that would really help is some simple 2" 2x4 panels from GIK that would be placed to the far left at intervals around every 4' or so would really help bring down some later reflections but your critical spots are very close. meaning they are first and close second wave from teh back right corner. absorption isn't the end all fix but your setup could benefit from it.

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post #12 of 15 Old 01-20-16, 07:19 PM
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Re: Is this a horrible RT-60

Here is your left channel... the red line would be your goal. Your MOST critical area is 0-5ms. Really you want this closer to 20 but I feel you can get away with it around -15db.

You can see the absorb vs. no treatment it did improve slightly but the acoustic tiles doesn't seem to have helped much. You need some 2" thick panels to improve this.
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post #13 of 15 Old 01-21-16, 02:45 PM Thread Starter
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Re: Is this a horrible RT-60

Hi Tally,

Thanks a ton for taking a look at my .mdat file and providing the graphs above It certainly makes more sense now. The left side is not improved that much, but looking at the right side it's much better when looking at the before/after ETC. However, it's not near the ranges you recommend (unfortunately!).

Two questions:

1) If the direct sound is 0 ms, what are negative ms then?

2) How did you overlay my before and after ETC ?
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post #14 of 15 Old 01-21-16, 02:50 PM
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Re: Is this a horrible RT-60

Quote:
Takechan wrote: View Post
Hi Tally,

Thanks a ton for taking a look at my .mdat file and providing the graphs above It certainly makes more sense now. The left side is not improved that much, but looking at the right side it's much better when looking at the before/after ETC. However, it's not near the ranges you recommend (unfortunately!).

Two questions:

1) If the direct sound is 0 ms, what are negative ms then?

2) How did you overlay my before and after ETC ?
1.
Quote:
The portion of the response before the initial peak at time=0 is actually due to the system's distortion - looking closely, there are scaled down, horizontally compressed copies of the main impulse response there - each of those copies is due to a distortion harmonic, first the 2nd harmonic, then the third, then the fourth etc. as time gets more negative. The initial peak and its subsequent decay after time=0 is the system's response without the distortion
2. Top buttons... says overlay then click impulse and then select the tests you want to use.

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post #15 of 15 Old 03-01-16, 11:52 AM
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Hello

The measurement clearly shows the reflections from the right wall and the back wall.

I would recommend
1. A smaller listening triangle (make it also equilateral)
2. moving more into the room with the triangle. Especially move away from the back wall.

That will help you to delay the arrival time ofthe reflections by more than 5 ms.
The additional distance also reduces the level of the reflections. You can get another -3 dB at least - for free.

Just make an experiment and set up a small listening triangle on the middle of the room. The length of each side not more than 2-2,5 meters (about 6,5 to 8 feet).

Listen to the difference. ;-)

Cheers
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