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Jester_Fu

Death of Sound - Room Accoustics

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I'm toying with the idea of re-arranging the studio again. Yes, i know... it's far less work to move things about than make tracks  :eatadick:

Anyway... i was thinking about some recent conversations and posts i've seen on various sites about room treatment and the 'default' position most people seem to have that "you need to sound proof a room and need to take reflections off walls". I.e. it seems to me a lot of people think that making a room dead is the solution to all your studio worries...

And this got me thinking. The great studio spaces of the world are renowned for having a particular sound. That is, they're not dead - they have anomolies of relfection and standing waves and all sorts of fun things that make a room sound a particular way. If people are willing to invest so much money in making a room not dead, why does the domain of the home/project studio seem to lead everyone to making the room dead?

Yeah, in your monitoring space, you need to have a failry true sound. True does not equal dead, IMO. The other thing a dead room needs is more sound (hence bigger speakers and more energy) to achieve the same volume as a correctly tuned but 'live' sounding room. So, why oh why do hobbiests and modern producers insist on taking thins away? Why is the default position to damp and remove energy rather than diffuse problem frequencies?

My not so humble opinion is that a room should sound good. That doesn't mean dead and it doesn't mean flat. The room needs to have a pleasing and workable frequency response that, just like monitors, you learn the sound of.

Why do you think this is, fellow punks?

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Someone over on the SOS forum ran a thread detailing their step-by-step conversion of regular room to a rockwool cave with every surface covered almost a metre deep. Can't find the exact thread, but it's somewhere in these 64 pages: http://www.soundonsound.com/forum/postlist.php?Cat=&Board=DESIGN

Now I don't know what gave him the idea it'd be a good idea as there's not a pro studio facility I know of in the world that's gone down that path (aside from anechoic chambers, which ain't studio control rooms anyway).

As for dead rooms, I'm not sure people regularly insist on making a room totally dead, let alone strive to achieve it. People love to suggest the 'just install a few bass traps around the place' though. Is that what you're referring to?

Personally, the number one area of concern has been room modes around the 80Hz thru 150Hz region. Consisting of both dead zones and boomy drones, it's these standing waves that require treatment over anything else. My current place is reasonably OK, helped no doubt by a dense futon sofa bed in the room with me. At my place in Sydney, the peak at precisely 132 Hz proved a nightmare to hear definition between kicks and basslines (it all was a blurred mush) requiring headphones to make any critical judgements.

My next concern is comb filtering in the mid-upper range via early reflections off adjacent walls, so I just ensure my monitors aren't pushed up against side walls and are toed in. I also now have a mattress up on its end against the wall between my monitors (seemed like a good place to store it, and does seem to draw my attention to what's coming from the monitors themselves).

But for everything else, I leave it alone as it all just seems to fall into place, the signature of the room if you will. Certainly nothing else will inflict such serious mayhem on the sound to influence any critically misguided mix or sound design decisions.

And I'm a believer (and it's often said by others) that striving for a dead room is likely to do more harm than good, with the mid and upper frequencies being wiped out first, leaving the far more dangerous bass energy to wreak havoc in what's left of the room. And it's this phenomenon that makes that SOS studio rockwool makeover such a hysterical waste of time (though to his credit, there were minimal bass issues due to extensive depth of rockwool used - making the capacity of the room significantly smaller in the process). I so wish I could remember what the thread title was so I could search for it.

So yeah, what's this thread about again, oh yeah, agree with you totally on this one.

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^The Diffusers work great... i just can't build them and the mate who's meant to finish making them for me hasn't had time. Bastard. I also made some larger 'cylindrical' type diffusers and tried those. They worked well, but my construction looked like shite... so i'm re-making them. It's a focus for me over the next couple of weeks, so i'll post pics of the cylindrical styled ones when done. The pyramids might take a bit longer...

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The totally dead room is a throwback to the 1960's when soffit-mounted speakers became the rage and there was an argument that totally dead rooms allowed the speakers to be the only point of reference and therefore the mix would be 'true'. Problem was engineers were getting prematurely fatigued from the lack of natural room reinforcement. try being in an anechoic chamber for more than a few minutes and your brain starts to hurt  :'(

The 70's saw the live-end-dead-end (LEDE) room become the rage and its theory wasn't too bad - deaden the space around the speakers but leave the back of the room diffuse. This prevents early reflections from the front wall comb-filtering with the direct sound of the speakers, and prevents listener fatigue by permitting natural ambience behind the head. Worked a treat for ages, but the problem is the sweet spot is small and only in the exact centre of the speakers.

More modern rooms employ the early-sound-scattering design (ESS) which flips the LEDE backwards so the diffusion is on the front wall behind the speakers. This apparently permits a wider sweet spot, and the diffusion prevents comb filtering with the direct speaker sound. The downside is they are expensive to build - but they do sound awesome.

The interesting thing all round is that with each decade, control rooms have been getting more ambient, not less. The prevailing theory is that a control room should be a 'controlled' version of a normal living room in a house. It should have similar ambient properties, but with treatments to even out the spectrum and prevent resonant bumps and dips in the room.

My vote for small home studios is actually the LEDE design, or at least a rough version of it. For a small square room, deadening the area behind and to the side of the speakers makes them sound tighter and throw forwards with more focus. The live area at the back of the room can be diffused with bookshelves, tube traps, whatever.

The worst thing I see in home studio pics is the speakers backing onto a flat plasterboard wall  :bang: This is about as bad as it gets IMO, and yet the most common thing of all. Then people realise what a horrible mistake they are making and go to the other extreme of killing all life out of the room entirely. They would be much better with a mix of some absorption and some diffusion.

At least kill the flat hard walls - they are evil.

Finally, if the room is too dead, you create mixes that are too dry. In a dead room, you'll hear the reverb send start to work its magic at really low levels and so you dial in very little reverb. Then you play the mix in a normal room of the house and the room ambience masks your reverb. If the control room has similar ambience to a normal room, then you'll mix in the right amount of reverb from the start  :)

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:) -20 marks for not answering the question!

:eatadick:

So what you're saying, Dr Rhythm, is that the concept of a dead room is a throwback from the 60's. In this age of techmonologomy and intramahyperwebs, why is it i still seem to see so many threads and have conversations with people who seem to default to trying to make the room dead? Is it simply because there are more absorption panel manufacturers than diffuser manufacturers... or is there a surplus of Wiki worthy bad information o nthe web??

I mean, i can think of lots of neat ways to get diffusion that don't cost much. So why is it that absorption and rockwool seem to remain gospel?

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The model frequencies that you generally need to worry about are below 300Hz…So most of the problem frequencies are located too low in the frequency spectrum to diffuse efficiently.  This is simply due of the  nature of their long wavelenths.  For example, in order to diffuse a 100hz modal problem, the longest depth of a quadratic diffuser (with a prime seed of 13) would have to be aprroximately 1.6 meters.   Therefore, absorption is much more practical especially as far as smaller spaces are concerned.  A panel absorber for 100Hz would not need to be as deep as a diffuser for 100Hz.  Plus, diffusion is generally much more effective at higher frequencies :)

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:) -20 marks for not answering the question!

:eatadick:

So what you're saying, Dr Rhythm, is that the concept of a dead room is a throwback from the 60's. In this age of techmonologomy and intramahyperwebs, why is it i still seem to see so many threads and have conversations with people who seem to default to trying to make the room dead? Is it simply because there are more absorption panel manufacturers than diffuser manufacturers... or is there a surplus of Wiki worthy bad information o nthe web??

I mean, i can think of lots of neat ways to get diffusion that don't cost much. So why is it that absorption and rockwool seem to remain gospel?

He he you're right, I just read 'dead room' and got excited...  :P

I think M-9 is onto something, it's easier to trap low end than diffuse it. But this principle hasn't aged, it's more what we have done with mids and highs - and yes it's amazing that people still believe killing them with sonex and rockwool is the way to go.

Some theories...

- once people start to look at acoustics seriously they see the maths and their eyes glaze over, they look towards quick and easy answers and are often happy to go with 'established' theories they've heard from the bass player in their band or uncle Patrick who worked in radio for 40 years where booths are almost anechoic - even if said theories are total rubbish (I still hear that eggshells work as good as sonex  :- ). Seriously, I recently saw a garage lined with eggshells stuffed with tissue as a solution to loud noise for band practice  ;D

- Sonex looks 'professional' - no studio is complete without walls of dotty foam, innit? It's what all the cool pics in SOS have, innit?

- Absorption is easier, cheaper, faster - blankets, doonas, mattresses - hey it's why they call us "bedroom producers" innit?

- Absorption as an acoustic principle is more intuitive for noobs to understand than diffusion. Go with what you know...

- For some reason, 'isolation' and 'control' are seen as one and the same. People often confuse acoustic treatment with soundproofing.

- For many homes, soundproofing is a higher priority. Unfortunately a mattress won't do much against 100dB of 80Hz...

Do I pass my resubmit sir? :P

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Yar... you do alright.

M-9... i don't agreee that you need to entirely diffuse the frequency. I also don't agree that nodal problems are most common below 300Hz.

Certaijnly effective diffuser design is either more complicate or involes a higher level of 'hit and miss'/experimentation if you don't want to do the math. I just thought it was interesting the default response to response is alway absorb.

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M-9... i don't agreee that you need to entirely diffuse the frequency. I also don't agree that nodal problems are most common below 300Hz.

Jester I did not say they were the most common-put your glasses on!!! 8) I said below 300Hz is where modal problems are going to cause the most problems—because of their inherent nature of being harder to treat than the higher frequencies!!!!! 

Certainly the default to only treat with absorption is perilous, especially when its not correctly applied in many cases-as  rb stated….  Then you are only serving to exaggerate problems in the room … all the blankets, doonas, egg shells, egg cartons in the world are not going to fix the low modal issues-(or perhaps if you had very very large quantities they would help with their sheer mass ;)) but all they will really serve to do is deaden the reverb time of your highs-which in most cases will prob just make the room sound like crap… ;)

I don't think that designing an effective diffuser would be any harder than implementing effective absorption....

perhaps its just that people are listening to good old uncle patrick when they really should be getting their facts from a more reliable source

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well... Fair enough. I misunderstood what you'd said. Still reads a tad ambiguous to me, but I get your point and agree.

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The model frequencies that you generally need to worry about are below 300Hz…So most of the problem frequencies are located too low in the frequency spectrum to diffuse efficiently. 

Sorry dude, in English, what you've just said there is that most of the problem frequencies are below 300Hz... which translates to "the most common problem frequencies are below 300Hz". It might not be what you meant... but it's what you said.

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(I still hear that eggshells work as good as sonex  ). Seriously, I recently saw a garage lined with eggshells stuffed with tissue as a solution to loud noise for band practice 

this made me happy!! i love my eggshell carton walls. now if only i could get velcro on the ceiling.......also the comment about soundproffing being confused has acoustic treatment....if only you could see some of the rooms a scam artist around here pulled off... everyroom he did is dead....room inside a room and both outer and inner walls lined with foam....just foam...brown foam.

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Isn't their something dangerous about eggshell walls? I vaguely remember some warning about them in my VET Music Production course..

Not sure, maybe I'm going crazy.

Sometimes I record vocals in my bathroom or kitchen though because i like the acoustics better than in my room.

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