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Author Topic: How to approach early reflections?  (Read 1941 times)

jetbase

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How to approach early reflections?
« on: November 27, 2006, 11:39:49 pm »

I'm nearing completion of basic construction of my control room. So far the only acoustic treatment I've done is to build bass traps on the roof similar the the DIY designs on Ethan Winer's website ( http://www.ethanwiner.com/basstrap.html ). Here's a picture looking towards the front of the room:

index.php/fa/3787/0/

In my previous control rooms I treated early reflections by having someone run a mirror along the walls while I sat in the listening position. Where I saw the monitors in the mirror is where I placed some absorbative material, like 50mm (2") Tontine Acoustisorb (     http://www.tontinefibres.com.au/Data-Sheets/Acoustisorb/Acou stisorb-2-Data-Sheet.asp ). I also had thick velvet curtains drawn across the front wall. I'm just wondering, since now I'm trying to do things a bit better (but still DIY), is this still a valid approach for treating early reflections, or does it make the room dull in the process? I have quite a bit of 703 left over & thought of sticking it directly to the walls & covering it with fabric. An alternative I thought of would be to build something similar to Ethan's Mid/High frequency absorbers and placing them horizontally at ear level on both side walls. What do you think of these ideas?

The other thing I was thinking about doing (since reading posts on this forum) was to make porous bass traps for the front 2 corners of the room, probably 8' high & 2' wide made from 100mm (4") thick Tontine Acoustisorb & maybe hang some glasswool batts behind it. I could line the walls behind with 703 if that would further help. My thinking behind this was 1. more bass traps, & 2. it would help with symmetry of the room (you can see in the photo it is not quite symmetrical).

Any thoughts, comments or advice would be greatly appreciated.

Room dimensions are approx. 5.26m x 3.67m x 3.3m

Thanks,
Glenn
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Glenn Santry
http://www.myspace.com/glennsantry

Ethan Winer

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Re: How to approach early reflections?
« Reply #1 on: November 28, 2006, 03:29:59 pm »

Glenn,

> or does it make the room dull in the process? <

It depends on how you define "dull." I tend to prefer rooms more on the dead side, so short of lining every surface with absorption you're not likely to do harm using liberal amounts of absorption. As I see it, small room ambience is generally poor sounding ambience.

> make porous bass traps for the front 2 corners of the room <

Sure. You can never have to much corner bass trapping. Likewise for the corners where the walls meet the ceiling and floor.

--Ethan

jetbase

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Re: How to approach early reflections?
« Reply #2 on: November 29, 2006, 05:14:46 pm »

Hi Ethan, thanks for your reply. I'm not defining dull as dead. I am talking about deadening the room in a way that doesn't just lop off all the highs. Maybe I'm worried about nothing & it really is a case of try and see + bass traps, bass traps, bass traps! Do you think it would be better to put an airspace behind the absorption (703)?

Thanks,
Glenn
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sleep is not an option

jwhynot: "There's a difference between thinking or acting dogmatically and drawing from experience."


Glenn Santry
http://www.myspace.com/glennsantry

Ethan Winer

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Re: How to approach early reflections?
« Reply #3 on: November 30, 2006, 01:40:56 pm »

Glenn,

> I am talking about deadening the room in a way that doesn't just lop off all the highs. <

This is an excellent point that is often overlooked. The goal is always for broadband absorption rather than absorption that affects only higher frequencies. This is the problem with so many amateur rooms - they're covered with "thin" absorption like 1 or 2 inch foam or 703 or - worse - carpet. So the room is too dead yet boomy at the same time.

> a case of try and see + bass traps, bass traps, bass traps! <

Yes, as far as I'm concerned it's not possible to have too much bass trapping. You can never make any small room perfectly flat anyway, so the best you can do is add as many traps as you can manage. The more you add, the closer you get to a flat response with no ringing.

> Do you think it would be better to put an airspace behind the absorption (703)? <

When straddling corners that's not needed, but it is useful for panels mounted flat on a wall. In that case the ideal air gap is equal to the panel thickness.

--Ethan
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