4 sweet sacks of Rockwool

Hello fellows! Just received my 4 huge sacks of Rockwool Rock-Batts Super. The question is, may i just leave those sacks in four corners without unpacking? How effective would it be? Also, will plastic bag reflect notable spectrum of frequencies? thanke ===zee

Stacking them sacks in the corner will do; it's like a suppachunk basstrap. And yes, the wrapping will reflect mid/high. But it should not be a big problem, too much mid/high absorbing will dull your room and leave low/high freq range unbalanced (too much bass). Tho I'd wrap some cloth around it (burlap for examp) which "looks" better.

Zee - you need the rockwool in more places than just the corners. You should line the wall directly behind your listening spot and you may need some to be used in a cloud above your listening spot. cheers john

thanks for the notes, Ro & John! i am using a different material for the upper range of frequencies, a certain ISOVER/ECHOPHON TECNO. i'd fancy an advice where exactly should i place those TECNO sheets though but first i need to sort out the layout:) cheers, ===zee

Hi again! So, here's an approximate layout of my upcoming workspace (apologies for the metric ruler :wink:) Room dimensions: width 3 m (~9.8 ft) / depth 4.3 m (~14.1 ft) / height 2.8 m (~9.2 ft) ++ asymmetrically placed 1.47 m (~4.8 ft) wide and 2.05 m (~6.7 ft) high "doors" covered with fabric. R is for sack of Rockwool Rock Batts Super (each holds 6 rolled 100 mm (~4 in) sheets sized 0.6 x 1 m (~2 x 3.3 ft), see my first post for absorption characteristics), M is for nearfield monitors Mackie HR824, and then there's a table and a chair as indicated. I've tried to draw everything in a proper scale however I'm not exactly sure on the speakers/listening spot placement. A side of the "listening triangle" is going to be somewhere between 1-1.5 m (~3.3-4.9 ft).. Got lost while calculating notorious roommmodes :oops: Anyway, besides Rockwool stuff, I've got 18 sheets of 50 mm (~2 in) Echophon Tecno TAL-H, each sized 0.6 x 1.2 m (~2 x 4 ft). Where should I place those? And just as important: how? Glued to the walls/ceiling? Spaced away from walls? Any advice on placing desk/chair/monitors is most welcome as well:) t h a n k y o u ===zee

errr, did i miss something? :cry: I've very little time, money and patience left for this: I'm a musician at first, and even if sound clarity is of utter importance to me, I can't wait much longer or else I'll ruin the whole project artistically. Therefore I decided to finish it as simple as possible. Now I've found out some of the answers myself, still I am in a bad need for help. Just to remind, I've got 4 sacks of Rockwool Rock Batts Super and 18 sheets of Ecophon Tecno. The Batts are destined for corners and I've decided to place Tecno panels as described on RealTraps site (except for the Rockwool replacing the corner traps):

However, there is a problem with providing the air gap behind the panels. The walls are gypsum and I have no clue where the metal framing is hidden, therefore I've decided to use glue for attaching the panels. How much do I lose if the panels will be placed directly on the wall? I may try to come up with an air gap solution but at the moment I have nothing on my hands. Also, one side of the Tecno panels is covered with glass tissue or aluminium laminate, is it generally recommended to use the covered side as surface? Finally, is it ok to paint those panels with "water dispersion" color? really hoping for your assistance 8) ~~~zee

Losing the airgap will reduce the effectiveness of the panels at the low end. Typically, this is usually around an octave or so, if you space the panels out from the wall they will absorb to a lower frequency. I don't know the technical details, and there is some disagreement as to how this works, but most agree that pulling the panels out from the wall approximately equal to the panel thickness is the optimum. As far as painting the panels, as long as the paint you choose does not seal the panel cloth (ie, make air no longer pass through it) you should be OK. It may change a bit on the high end, if the paint causes sound to reflect some.

jwl wrote:

but most agree that pulling the panels out from the wall approximately equal to the panel thickness is the optimum.

I don't, And no acoustics book I know about does. In fact the further away the better (within reason). If you have 50 mm panels (as z99 states above), it's better to make the total thickness as large as practical. An 150 mm cavity will be significant better than a 50 mm cavity. Hence Z99 see how you can hang them, and what's still feasable for you based on the idea the further the better. The total thickness (cavity + board) is a more defining factor than this ratio. That's where standard "mineral wool tile" suspended ceilings are based on. This are relative thin tiles on large cavities often in a ratio 1:10 or even less. Just call whatever mineral wool tiles producer telling their suspended ceilings are acoustically best mounted with a 50/50 %, 1:1 ratio and see how they will respond. The reasoning JWL refers to is based on a plane wave at straight incidence for a very thin absorptive material. A related picture of Everest (used on certain faqs) is used in his book to explain some basics, not to substanciate this 50/50 % relationship. This same topic comes up over and over, mainly caused by one "Acoustics FAQ". That FAQ shows the picture meant by Everest to show physical principles, not real live circumstances. And the picture on the next page meant by Everest to show how these principles translate in a real live measurement is not shown on that FAQ. Hence Everest himself, nowhere in that book, of which a picture is used out of the context it's intended for, confirms, or even sideways refers to a 50/50 % relationship as an optimum for practical use. "Most agree" here means: "follow what that FAQ and its Author states about it." And I pitty to agree with the notion "Most", which shows the magnitude of the problem. At least when related to studio groups. EDITED: I just checked Everest now to see what he himselfs states about the effect of a cavity behind absorption material: The following is to be found at pages 191-192 of The Master Handbook of Acoustics: Analyse the above and one can only conclude that the picture used on that FAQ is used to substanciate something NEVER meant by Everest as such. Therefore is used out of context, just to substanciate a private assumption. NOTHING in Everest confirms this 1:1 ratio These stylized pictures and simple text refer to a continueing increase (within limits not defined here and rather complicated). They represent what Everest himself has to tell about the effect of increasing the cavity. Everest not only not confirms this 1:1 ratio but via this picture contradicts it.

Thanks for clearing that up, Eric. I misused the word "optimum" in my original post; what I was thinking is closer to "represents a good compromise between performance and saving room space." In other words, in my mind the 50/50 arrangement is a good rule of thumb, a starting point when placing acoustic treatments. But certainly your post clears up those details. As I said in my post, I was aware that there is some disagreement about it. ;-)

jwl wrote:

I misused the word "optimum" in my original post ... I was aware that there is some disagreement about it. ;-)

No, you were right the first time. :) "Optimum" is indeed the right word for the reasons I explain in my FAQ. Apparently Eric agrees too because Eric's pal Scott Foster recently posted the quote below at the Sound on Sound forum. --Ethan

The rule of thumb I have been quoting from Eric Desart for years [Eric has been studying this stuff since dinosaurs roamed the streets of Antwerp - both in the lab and in building world class soundstages and control rooms] is "gap the panel off the wall at more or less the panel thickness" for max bang-for-the-buck. This advice has worked well in thousands of applications.

Ethan Winer wrote:

No, you were right the first time. :) "Optimum" is indeed the right word for the reasons I explain in my FAQ. Apparently Eric agrees too because Eric's pal Scott Foster recently posted the quote below at the Sound on Sound forum.

If I enter personally official measurements here in the forum which don't suite you, you discuss the validity with everything you can. If somebody, NOT ME, makes an obvious mistake in a forum, you think is usable for your purpose, you shut your mouth and take it as granted. Hence hearsay, even when OBVIOUSLY wrong to ANYONE, become facts to you when usable, better abusable. The forum even removed ANY reference to me from that post you refer (hence your related quote even doesn't exist anymore). That whole thing had NOTHING to do with me or what I ever told. And that it wasn't correct was very obvious when your employee got wild about it, causing that thread to be removed completely, edited, the post of your employee removed and then the thread restored. He could have simply and gently stated: Scott that isn't true, that's not what Eric sais. And Scott should have had no other choise than withdrawing that reference to me. I ALWAYS say the same about such stuff, since what I say is NOT an opinion, but a description of physical phenomena. I did NOT give an opinion here. And this is how you abuse such information: http://forums.musicplayer.com/ubbthread ... ost1725656 And how a new chain of misinformation starts. (I made a copy of that thread) Further I deny you the right to quote me as you did in that thread, without the link to the original message, so that people can find my words in context and the context of the thread. And this relates to legal use of Copyright which also applies to messages entered in forums. That guy asks an honest question, clearly in discussion with someone who seemingly knows what he's talking about. I will not express my feelings about what you did in that thread. That should be clear to anyone.

Eric, > If somebody, NOT ME, makes an obvious mistake in a forum < In that case, please invite Scott Foster to post in this thread that he was wrong for saying that. Scott Foster should also explain what he did mean if the quote above does not reflect his opinion. > Further I deny you the right to quote me as you did in that thread, without the link to the original message, so that people can find my words in context and the context of the thread. And this relates to legal use of Copyright which also applies to messages entered in forums. < But it's okay for you to outright steal pages from my personal site, and take copyrighted data from my company's site and twist it to suit your own agenda? :roll: --Ethan

Ethan Winer wrote:

But it's okay for you to outright steal pages from my personal site, and take copyrighted data from my company's site and twist it to suit your own agenda? :roll:

If you have an issue with Scott arange that with Scott, which you could have done in the related thread itself, in a normal manner. He certainly will kindly answer your questions after you referred to him as "one of the acoustic "wise guys" (in the Mafia sense)" in the referred thread. Maybe you didn't notice but I'm called Eric ...., not Scott And I don't steal nothing, never, nowhere, and unlike you are very aware about Copyright and "Fair Use". And I stop this here, since once more you want to divert the topic from the content, making me the bad guy and you the sweet victim. I'm out. Your intevention wasn't needed and only meant to provoke, I explained my point gave the necessary references to Everest etc.

Eric_Desart wrote:

Your intevention wasn't needed and only meant to provoke

No, this nonsense from you was meant to provoke:

This same topic comes up over and over, mainly caused by one "Acoustics FAQ".

Eric, in case you haven't heard, the "acoustics war" is over. Give it up, okay? And please have a happy Easter.

I may be overreacting here, but I'm going to lock this thread before things get out of hand (if they're not already). Ethan, I recommend not even mentioning Eric's name or referencing his findings. The passive-agressive thing, whether intended or accidental, needs to stop. Eric, don't take Ethan's bait, whether real or imagined. zee (z99), I'm sorry you had to be in the middle of this and I'm sorry to shut down the thread. Please feel free to start a new one if you have any open items you'd like to discuss.