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

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post #1 of 15 Old 12-06-15, 06:06 AM Thread Starter
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Peter
 
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Is this a horrible RT-60

Hi,

I've finally achieved a satisfactory FR (thread here and here) with my mains + subwoofer; however, with concrete walls and wooden floors there is a lot of reverb and I'm thinking this is why the sound isn't *that* good at all...

My first RT-60 is shown below, and I'm wondering, is this horrible? I've read that it should ideally be within 300-500 ms...



Topt = Green
T30 = Purple

I'm looking into room treatment now in order to lower the reverb, but I'd like your thoughts on the initial results with no treatment

Room dimensions are:
Depth: 12.96 ft
Length: 25.85 ft
Height: 8.23 ft

See layout below

Last edited by Takechan; 12-06-15 at 01:14 PM.
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post #2 of 15 Old 12-06-15, 11:37 AM
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Re: Is this a horrible RT-60

What are the room dimensions? Decay time curve is dependent on the volume of the space.

Also, RT60 really isn't valid in small room acoustics. It's more for larger venues. You certainly wouldn't want things to be 30-50ms. Think, more like 300ms.

I am serious... and don't call me Shirley.

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post #3 of 15 Old 12-06-15, 01:05 PM Thread Starter
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Re: Is this a horrible RT-60

bpape,

Hi, thanks for the reply. Here are my room dimensions:



I forgot at zero on each interval, so yes, I mean within 300 - 500 ms.

On the right side of the living room there are large windows, but they are covered with a curtain, so hopefully they've taken the worst reflections...

Best regards,

Peter
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post #4 of 15 Old 12-06-15, 05:14 PM
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Re: Is this a horrible RT-60

Curtains are high frequency absorbing only. It would be better if there was something thicker at the side wall reflection zones to better address any SBIR and not unbalance the absorption curve. For this application and that size of room, I would be looking to be no more than 400ms in the bottom and probably around 250 in the upper end.

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post #5 of 15 Old 12-07-15, 01:36 AM Thread Starter
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Re: Is this a horrible RT-60

Wow, 400 ms and 250 ms is a far cry from where my measurements put me at the moment

Would my first are of interest be the tridhedral corner or the point of first reflection?


Reference

I've heard that bass traps are the best way to start out seeing as they also do broadband absorption. Would you agree?
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post #6 of 15 Old 12-07-15, 07:18 AM
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Re: Is this a horrible RT-60

Bass control is the first thing I would tackle as it covers the broadest range of frequencies. Bringing down the bass decay time also helps 'unmask' low level information like imaging cues, micro-dynamics, and low level harmonics.

Tri corners are certainly nice to do though I would not concentrate all my efforts there. Certainly not at the expense of dealing with non-modal bass issues, SBIR, and early reflections.

IMO the best course of action is a moderate amount of bass control, reflections, and any modal/non-modal bass issues. Then you can look at the other things like limited range bass control and diffusion to help with flutter echo - usually up higher in the room.

Whatever you do, don't get sucked into the trap of foam. Can't tell you how many rooms I redo weekly when people have spent a lot of money on foam and realize it just doesn't work very well.

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post #7 of 15 Old 12-07-15, 08:05 AM Thread Starter
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Re: Is this a horrible RT-60

Perfect, I'll start with the tri corners then.

So I take it this is a nogo?

http://www.advancedacoustics-uk.com/..._bass_trap_3ft
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post #8 of 15 Old 12-07-15, 11:36 AM
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Re: Is this a horrible RT-60

.5 at 100Hz is not what I call a good bass trap - sorry. I would highly recommend staying away from any foam based product. Fiberglass or mineral wool cores yield MUCH better performance.

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post #9 of 15 Old 12-07-15, 03:39 PM Thread Starter
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Re: Is this a horrible RT-60

Ok thanks! I guess that sounds a lot like a DIY project.

Unless you're willing to spend some big $$$ (which I'm not really at the moment...)

I'll supply some new readings once I've added some acoustic treatment to the corners
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post #10 of 15 Old 01-20-16, 02:46 PM Thread Starter
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Re: Is this a horrible RT-60

Hi,

I've treated my ceiling around the 1st reflection point with absorbing "tiles" 3x3 and put an acoustic picture on my rear wall now

The RT60 (T30) has improve around 0.1 ms, but the audible improvement is surprising!

Since my listening room is rather small I've been told not to use RT60, but rather look at ETC. However, I've tried to search the web on how to read it to no avail... Can someone help? I've included measurements (L,C,R) before and after my room treatment (here).

ETC (center position no treatment)


ETC (center position with sound treatment)


I'd love some opinions
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