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Author Topic: Resonance problem?  (Read 4558 times)

andrebrito

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Re: Resonance problem?
« Reply #15 on: March 03, 2009, 03:11:39 pm »

I also dislike rooms with gypsum they sound horrible ! boinggg !
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franman

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Re: Resonance problem?
« Reply #16 on: March 03, 2009, 08:59:10 pm »

Bill_Urick wrote on Tue, 03 March 2009 07:15

Thomas Jouanjean wrote on Tue, 03 March 2009 03:04

I think the 703 in the ceiling is too dense. It has a too high surface impedance, which is reflecting mids.



Being, at this point, heavily invested in 703, this is not something I wanted to hear.

What material do you recommend instead?

We'll try your suggestion and let you know.

Thanks so much!





Guys,
I can't help but butt in here. Thomas, please trust me the OC703 is a staple of all of our studio designs. It's surface impedance has never been a problem. We use it as the first surface in many treatments and sometimes even the more dense 705. Even at a relatively low angle of incidence, the 703 (at 3lbs/ CF) isn't a problem with mid frequency reflections. It would certainly not be the cause of flutter issues at the frequency in question.

There may be a resonance, or you may be hearing (previously) masked flutter at a specific frequency as this area of the room is now well damped. Could it be coming from another area in the overall space??

I don't pretend to have the answer, and to tell you the truth I would never try to diagnose this without an 'in person' visit, but I felt I needed to chime in on the OC703 issue.. Bill, don't get too worried about the 703 being the problem...

FM
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Thomas Jouanjean

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Re: Resonance problem?
« Reply #17 on: March 04, 2009, 03:01:18 am »

franman wrote on Tue, 03 March 2009 19:59

Thomas, please trust me the OC703 is a staple of all of our studio designs. It's surface impedance has never been a problem.


I was still very surprised by the product everytime I saw it. The ones I saw used in U.S. studios always had a rigid waffled crust like thin layer on, which I noticed reflected lots of energy. Hence my immediate reaction to Bill's problem...

The rockwool of equivalent density here doesn't have that attribute at all, much smoother surface (We don't have such type of densities in fiberglass here, so I can only compare it to rockwool).

Anyway, you are used to that product and I'm not, so I absolutely take your word for it Smile

(Note to self: go harass a 703 provider in the US next time around)
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Thomas Jouanjean
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Ethan Winer

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Re: Resonance problem?
« Reply #18 on: March 04, 2009, 02:06:49 pm »

franman wrote on Tue, 03 March 2009 20:59

Even at a relatively low angle of incidence, the 703 (at 3lbs/ CF) isn't a problem with mid frequency reflections. It would certainly not be the cause of flutter issues at the frequency in question.


I'm glad you said that first. Laughing

The measurement shown in the graph below was taken in my living room, and shows the change in response with and without 1-inch thick 703 covering a wood "wall" placed nearby. The angle was about 45 degrees, so clearly 703 works well even at an angle.

--Ethan

http://www.realtraps.com/rfz-response.gif

Thomas Jouanjean

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Re: Resonance problem?
« Reply #19 on: March 04, 2009, 03:42:48 pm »

Ethan Winer wrote on Wed, 04 March 2009 13:06

The measurement shown in the graph below was taken in my living room, and shows the change in response with and without 1-inch thick 703 covering a wood "wall" placed nearby. The angle was about 45 degrees, so clearly 703 works well even at an angle.


Thanks for the graph Ethan!

My problem was not a question of incidence though, but of surface impedance which I remember from my US projects to be too high for my tastes (hence I used something else of about similar density, but with a different surface: rockwool).

I did notice though that the core of it had a nice density, which I assumed would make it quite efficient in the lower frequency range.

But then again, this is not a product I am used to as we don't have it in Europe, so I am, as expected, cautious Smile

I will soon have another chance to try it and maybe work with it on a new project on your side of the pond, which will be interesting!

Anyway, back on topic: Bill, any news? Did you try anything?  



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Thomas Jouanjean
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Bill_Urick

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Re: Resonance problem?
« Reply #20 on: March 04, 2009, 07:48:38 pm »

So far, we're planning on not recording any more handclaps, or anything that has a "D" in it.

Edit-No, but seriously...

Not sure, rug on the floor, perhaps some additional non-703 stuff on the ceiling.

I'm feeling reassured re the 703, but there's already a lot of it and it's not killing the ring.

I'm believing it's something about the flooring or just a room resonance.

Could it still be a reflection floor to ceiling? The rug over 703 did kill it.

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Ethan Winer

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Re: Resonance problem?
« Reply #21 on: March 05, 2009, 05:04:19 pm »

Thomas Jouanjean wrote on Wed, 04 March 2009 15:42

My problem was not a question of incidence though, but of surface impedance


It always seemed to me that the very best mid/high frequency absorber would be fluffy fiberglass. Or a layer of fluffy fiberglass in front of rigid fiberglass, with the fluffy part at least two inches thick. But I never tested that so I'm just guessing. And my test of rigid fiberglass above shows it's fine anyway, even at an angle.

--Ethan

Bill_Urick

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Re: Resonance problem?
« Reply #22 on: March 12, 2009, 05:48:45 am »

Update, FWIW:

Thinking and reading around on this forum, came to the conclusion that trying to make a room this small very live is a mistake.

So far, a rug with a pad underneath is helping a lot.
Next step is to replace some of the slats with absorption, so that we don't have any slat diffusers directly opposite each other.

Letya nough...
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rankus

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Re: Resonance problem?
« Reply #23 on: March 13, 2009, 02:52:26 pm »

Bill_Urick wrote on Thu, 12 March 2009 02:48

Update, FWIW:

Thinking and reading around on this forum, came to the conclusion that trying to make a room this small very live is a mistake.



As someone with a small room I can agree.  I started out as live as possible and kept adding until it got to approx 30% absorbing coverage. Which is where it stayed for the last few years. IE:  Broadband traps, clouds, carpet... Then I leave the door open with a mic down the hall for a livelier sound... works decently


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