jared
Junior Member
Posts: 57
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Post by jared on Sept 5, 2020 16:41:41 GMT
Thank you Rock, Pasim and Hexspa. Appreciate your assitance!
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jared
Junior Member
Posts: 57
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Post by jared on Sept 13, 2020 20:24:28 GMT
So just a quick update.... I had an apparent “acoustician” come to my studio and he hung panels on my entire ceiling with 15mm fiberglass panels (very thin) over the entire ceiling with a 20cm gap between the panels and the roof.
This made absolutely no difference to the 120hz peak in the room. Did I just get cheated? From reading your previous responses in hindsight it appears I need very thick panels all over the ceiling...? Or am I missing something? Could it be that the 120hz peak is coming from somewhere else and this guy was legit?
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Post by rock on Sept 13, 2020 21:28:47 GMT
15mm is in the neighborhood of the drop-in ceiling panels used in offices for speech. They do very little for lower frequencies. If you had 100mm panels with a gap of 100mm you'd be a lot closer to what you need.
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jared
Junior Member
Posts: 57
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Post by jared on Sept 14, 2020 6:43:24 GMT
makes sense. thanks rock.
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Deleted
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Post by Deleted on Sept 14, 2020 10:58:37 GMT
What?? 15mm and how porous material? This sounds like a joke... What kind of "acoustician" is that..? Did you tell your problems and how he didn't hear immediately when he walked into your room... Meh.
Wish I could help you in person, but unfortunately not possible.
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Post by Hexspa on Sept 14, 2020 14:46:25 GMT
4" minimum for music and ideally 8" of rigid. You can also do 2' thick of fluffy. You can determine the dimension(s) contributing to the 120Hz peak by finding the wavelength/dimension relationship. pages.mtu.edu/~suits/notefreqs.htmlIf your dimension is 0.5x (half), 1x (same), or 2x the wavelength then you're going to have a buildup. Even moreso if more than one dimension is lined up. If you don't have around 20% of your surface area covered with at least 4" thick rigid, you're going to have problems no matter what.
Sorry about your 'acoustician' experience. Maybe he's a 'street acoustician' now but used to be a 'street pharmacist'. Avoid.
Again, a 6dB peak is not a huge deal and can probably be flattened with a little EQ. Just make sure to take measurements in a reasonable radius so your dip doesn't exacerbate a nearby listening point. I remember saying that the 100Hz ringing is more of an issue. You find ringing dimensions the same way as peaks. 100Hz is a little low so try to use plenty of 4" coverage and preferably thicker.
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jared
Junior Member
Posts: 57
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Post by jared on Sept 16, 2020 7:35:35 GMT
Thanks guys. It looks like i am going to be doing some DIY. I think a well intentioned guy but unfortunately as I said - TIA - this is Africa. We do not have access to professional assistance in the jungle. All of your advise has been invaluable. thank you to all of you.
I am going to be filling the entire ceiling with 5cm of 65kg/m3 (flow resistivity of 27000 pa.s.m2) of rockwool with a 13cm air gap.
I am also going to be moving each individual acoustic panel (5cm of 65kg/m3) 10cm away from the walls. I have 15 of these panels all over the room.
I have attached the "Porous Absorber Calculations".
I hope this will suffice! Would appreciate your thoughts on this if you think this is going to work.
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jared
Junior Member
Posts: 57
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Post by jared on Sept 16, 2020 7:36:30 GMT
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Post by Hexspa on Sept 16, 2020 14:07:41 GMT
5cm is about 2". Try to do at least 10cm with a 20cm gap. The thicker the panel, the lower in frequency to which it works. Ideally, you'll use 20cm. The only downside is cost.
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jared
Junior Member
Posts: 57
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Post by jared on Sept 16, 2020 14:39:55 GMT
Thanks Hexpa. Much appreciated. The reason I am using 5cm instead of 10cm is that the Porous Absorber Calculator shows not much of a difference between 5cm and 10cm as: If I use 5cm, I will have a bigger air gap of 13cm. If I use 10cm, I will have a smaller air gap of 8cm. Please let me know your thoughts based on this.
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jared
Junior Member
Posts: 57
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Post by jared on Sept 16, 2020 14:42:07 GMT
i only have 18cm between the new ceiling tiles I have put in and the top of the concrete ceiling. Will this treatment suffice? Or am I wasting my time? The alternative would be to spend more cash and reduce the height of the current ceiling tiles. I would be prepared to do this if its going to make a massive difference. thank you!
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jared
Junior Member
Posts: 57
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Post by jared on Sept 16, 2020 14:43:28 GMT
My main issue is 100-200hz
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Deleted
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Post by Deleted on Sept 16, 2020 14:54:13 GMT
Well, in theory that 5cm and bigger gap will work better around that low mid area. If those are your only options now. I'd go with 5cm and bigger gap. Have to trust that calculator.
Did I link you that calculator at some point, or did you found out yourself? Atleast I thought about linking that couple times, too lazy to go thru this thread.
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jared
Junior Member
Posts: 57
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Post by jared on Sept 16, 2020 15:00:54 GMT
Thanks Pasim. Makes sense. Yes - you did post the calculator in a previous post. It's a game changer. I've also been watching this guy on youtube who uses it quite a bit: www.youtube.com/watch?v=Ogpx-B7VoBsall the best
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Deleted
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Post by Deleted on Sept 16, 2020 19:02:36 GMT
Yes, I've heard some pro acousticians use that calculator as well. They might have better bought softwares too, but that's quite good still.
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