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PostPosted: Fri Jun 16, 2017 4:13 am 
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edit:*my room will be treated with broadband absorption before anything.. i will be adding the 9" r30 to corners, r13 Roxul or Ecobatt for boradband around, 6" cloud, side early reflection and making sure everything is positioned in room FIRST


soon to build build my room, was going to do hanging traps but now will do R30 Pink Fiberglass in wall & ceiling corners.. And R13 for broadband.


from whats ive found online. R30's gfr is around 5000 Pa.s/m2

and 3" roxul is around 14500 ..


(rear & front wall corner absorbers will be 24" deep. rear wall entire width)


My room is 18.5' (L) x 15.5' (W) x 14.5' (H).. using room mode calculator

http://amroc.andymel.eu/?l=18.5&w=15.5& ... ue&r60=0.6

Image


i am going to treat front and back before this all but,


i wanted to know if i can choose areas to treat and target them like this:


Image


all the frequencies marked with a * are on the front wall center.. (vertically only)

Image


the cluster of frequencies in the middle there (116 - 157) are the hottest spot for this location ..


so using the acousticmodelling.com calculator i came up with these slotted panel absorbers calculations...


http://www.acousticmodelling.com/mlink. ... &v43=14500

Image




is placing the slotted absorber ive calculated in this location something reasonable?

is this a practical way to approach treatment of this area?







i'm new to this way of working.


.


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PostPosted: Mon Sep 11, 2017 10:40 am 
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Location: Santiago, Chile
Hi "Jonney", and Welcome!!! :)

Quote:
i wanted to know if i can choose areas to treat and target them like this:
Why do you only want to treat your 1.2.0 mode? That's a tangential, and probably not too much of a problem. How come you don't want to treat the other modes? I would be far more worried about your 1.0.0, 0.1.0 and 0.0.1 axials, plus probably your 2.0.0, 0.2.0, and 0.0.2. Axials are always larger and more severe then tangentials, and they are also at lower frequencies, and therefore more important, and harder to treat.

Quote:
so using the acousticmodelling.com calculator i came up with these slotted panel absorbers calculations...
Now I'm REALLY confused! If you want to treat your 1.2.0 mode, which is clearly predicted to occur at 78.7 Hz, then WHY do you want to build a device that is tuned to around 130 Hz? That doesn't make much sense...

Quote:
is placing the slotted absorber ive calculated in this location something reasonable?
Only if you have determined for certain that your 1.2.0 mode is the biggest problem that you will have in your room, and only if you tune the resonator to that specific frequency, very accurately, and only if you make it big enough to ensure that it will have a sufficiently large effect on the mode (ie. that it will damp it enough to be useful).

Quote:
is this a practical way to approach treatment of this area?
Not really, no. Helmholtz resonators are much more difficult to tune than the text books tell you about (they make it sound easy: it isn't), and since modes are very high Q, the device must be tuned precisely to that frequency in order to be useful. Plus, slot walls are not very efficient or effective at such low frequencies: they are normally used for the mid range, not for treating modes.

- Stuart -

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