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Tackling room resonances

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Re: Tackling room resonances

Postby Lewis Goudy » Sun Aug 18, 2019 8:32 am

I just joined SOS and have not read all the posts in this thread yet, but offer an excerpt from Davis & Petronis "Sound Systems Engineering 3E" Ch. 8 "Small Room Acoustics" This might be relevant or not--I'm a beginner.

"In small rooms, the [initial signal delay gap] is normally quite short, on the order of 1 to 5 ms. In a special design of control rooms for monitoring recording studios, a principle called "Live End Dead End,"LEDE, is used that allows ISDs of from 1o to 20 ms to be developed in rooms with dimensions as small as 2000 cu ft. Before the use of the TEF analyzer during the building of LEDE rooms, the front half of the room was made as absorptive as possible (only the diffusion and spectral frequencies are necessary) and the other half (the half to the rear of the listener) was (and still is) made as reflective and diffusive (highly important and often overlooked) as possible. It's in the reflective half that a thorough plotting of refections becomes a necessity...

The LEDE concepts are physically simple but psychoacoustically complex. The goal of an LEDE control room is to let mixing engineers, who sit at the console, hear the first reflections from the recording studio over the control room loudspeakers before they hear any from the control room the are sitting in."
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Re: Tackling room resonances

Postby blinddrew » Sun Aug 18, 2019 9:22 am

That can happen!
There appears to be a huge amount of nonsense spouted about this stuff and successfully treating a room to its absolute best requires a goid knowledge of the physics and a whole bucket of experience.
You can read books to understand the science and the theory but obviously you can only filter the relevant stuff for your environment.
Fortunately we have a secret weapon on this forum, which is the experience of a few genuine professionals, including a very highly regarded acoustician - Studio Support Gnome.
In the next couple of weeks i'll be starting my own work on treatment but before i do i shall be trawling SSG's posts as a reminder.
Plus doing a search on the various SOS articles on the subject.
I've done a lot of research already, and I have a plan, but it's definitely a case of measure twice, cut once - even conceptually. :)
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Re: Tackling room resonances

Postby Sam Spoons » Sun Aug 18, 2019 11:14 am

Here is a brief, non techie, précis of what I have learned about room treatment (and it is brief :smirk: ) I'm sure the more knowledgable will be along shortly if any of the following is just plain wrong :-

Treat the mirror points so that first reflections don't mess up the stereo image.

Fit as many, and the biggest/deepest, bass traps you can (corners are good 'cos you get a bit of 'free' depth, and don't forget there are corners between the walls and ceiling/floor, sofa's work pretty well too).

Then rule of thumb, any big expanse of wall will benefit from a broad band absorber (or diffuser, i.e. bookcase).

It won't make your living room sound like Abbey Road but it will make it sound a good bit better.
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Re: Tackling room resonances

Postby Hugh Robjohns » Sun Aug 18, 2019 11:29 am

TNGator wrote:Im officially starting to go insane regarding this stuff. :headbang: :headbang: :headbang:

I hate to say 'I told ya'... but I told ya! :lol:

Acoustics really is a black art! Of course, there's lots of perfectly sensible science involved, but applying that science is the tricky bit because every room is different. They are different sizes, different shapes and -- most importantly -- different constructions. This last part really complicates things because it's often far from obvious exactly how they are constructed, and that makes a big difference to the low end performance, in particular.

And then there's the whole measuring nightmare, as you've already found out. Interpreting what the numbers and displays mean requires a lot of experience, and it's very easy to start chasing down one avenue only to find it's a wrong turning!

But Sam is right: put as much real bass trapping in the corners as you possibly can, and treat the mirror points to improve the overall mid-range clarity and stereo imaging. And then have a good listen and see what still needs improvement or tweaking... It's never going to be anywhere close to perfect in a small room, so don't expect miracles!

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