John Sayers' Recording Studio Design Forum Archive

Hi all!

Let's say my room (after insulation) will have the following dimentions:
Length = 499.0 cm
Width = 472.0 cm
Height = 400.0 cm

I add those measures in a room mode calculator...

How do I interpret those result?
Which frequency should I targer for treatment? (I plan to build some limp mass bass absorbers)

http://imageshack.com/a/img921/3488/9JlWxy.png

Thanks in advance

Hi. Please read the forum rules for posting (click here). You seem to be missing several things!

How do I interpret those result?

I'd suggest the book: "Master Handbook of Acoustics" by F. Alton Everest. It has an entire section on room ratios, and also points out that they aren't that important anyway.

Which frequency should I targer for treatment? (I plan to build some limp mass bass absorbers)

none of them. You cannot get rid of modes. You can only damp them. And trying to hit all of those individually with limp mass traps would be both impossible and also a very bad idea even if you could do it.

You seem to be fundamentally misunderstanding what room modes and room ratios are all about. Everest's book should help you with that.


- Stuart -

Hi Soundman2020,

Thank you for taking the time to answer me.

I just updated my profile, sorry for that

I'm trying to do a Sketchup plan of the room, I was wondering if I could anticipate some problematic frequencies to know at least what should be the deeper limp mass bass absorber.

Maybe I should just wait to buid the room and then take some measures at the listening point...

Just yesterday I wrote a long post about room ratios and modes, on another thread. Here's the link, so I don't have to repeat it all here!

http://www.johnlsayers.com/phpBB2/viewt ... 35#p139772

I'm trying to do a Sketchup plan of the room, I was wondering if I could anticipate some problematic frequencies to know at least what should be the deeper limp mass bass absorber

The most problematic frequency in most rooms is the one associated with the fundamental mode on the length axis, and it's harmonics. The second most problematic issue (which will NOT be at a specific frequency, but will vary with location in the room), is the SBIR effect associated with the rear wall. They are sometimes at similar frequencies, which is an even bigger problem.

to know at least what should be the deeper limp mass bass absorber

Why do you insist on using limp mass absorbers? How do you know you would even need one of those? Do you even have enough space to build one large enough to deal with a very low frequency problem? How would you tune it? How would you check the tuning, and adjust it if needed?

Have you ever designed, built, tested, and adjust limp mass traps before? It's not as easy as it looks. In the rooms I design, I only use them as a last resort, when all other treatment has already been completed and there is still a specific issue. I NEVER use them as the first choice of treatment. And I'm not even convinced that you would need one.... What makes you think you have no choice here, and will have to have a limp mass device? Why do you think that simpler, cheaper, and more effective treatment options won't work in your room?


- Stuart -