Acoustic Fields - Room treatment advice

[Chris]

I stumbled upon this video. Looks interesting. If you follow the links provided, you can sign up for a newsletter and free ebooks on room treatment issues.

I'm sure TomP will weigh in with his thoughts.

[speakertom]

A lot of good basic info but leaves a lot out. The best thing I can offer is to use someone who has lots of experience treating rooms. He does but I used Anthony Grimani of Sonitus USA who has done over 1,500 rooms. They also have a room calculator where you can put in the dimensions of the room and get suggested treatments and placements. Multiple types of treatments are needed for different problems. They will help mitigate room modes especially above the room's Schroeder Frequency.

www.grimanisystems.com/dt_team/anthony-grimani/

www.sonitususa.com/product/home-cinema-acoustic-systems

For lower frequencies there are two problems. The first is inherent room modes where you will get peaks and dips at different parts of the room at different frequencies. It is entirely due to the room and those modes exist even if there are no speakers. The second is Speaker Boundary Interface problems that are modes that occur due to the position of the speakers with respect to the room surfaces. Remember, whenever you take some action to deal with SBI problems, moving the speakers can alleviate a problem at one frequency and listening position, but will introduce problems at others. Some peaks at the listening position can be reduced electronically, but dips cannot be successfully treated that way. That is because if you add more power at the dip frequency to get more output from the speakers, the same increase in output goes to the offending surfaces and cancels the direct sound. It is especially problematic if the dip is high Q. The only way to successfully deal with low frequency dips is to use distributed subs.

Preventing leakage of sound to other rooms is a very complicated problem. I once went to a house owned by Earl Geddes where he built a home theater in the basement.

www.gedlee.com/Papers/papers.aspx

He used every method available including staggered stud walls, lots of insulation in the walls, mufflers in the HVAC ducts, etc. It was very effective but also very expensive. In my room, the walls that face the rest of the house use Homasote 440 which does an admirable if not perfect job. www.homasote.com/products/440-soundbarrier It can be an add on to existing rooms without tearing down walls.

The HVAC system just happened to work out because the house has two heat pumps and air handlers with the one for the audio room having no connection to the system feeding the major part of the house. Sound coming through ducts can be a big problem.

Tom