anybody acoustically treat their room with QRDs or sound absorbers?

[thadman]

Recently, I visited the local borders to qualm my boredom and picked up a copy of the "Masters Handbook of Acoustics by F. Alton Everest" and have been quite preoccupied with reading this bible of an acoustic book. He discusses the use of Quadratic Residue Diffusors and use of absorbent panels to control reflections/resonances, although he doesn't go into intense detail about the parameters of the concepts and how to accurately and optimally design one. I'd like to apply some of his ideas into my setting and apply some modest acoustic treatments.

I have done some research on the web (miscellaneous webpages and calculators) and made the connection between well width to upper frequency extension and well depth to lower frequency extension, but have not found a correlation between the use of a smaller/larger prime number. Do I need to diffuse >10khz (20khz) or does that diffuse itself? What is a good material and thickness to seperate the wells?

The use of 4" of Corning Owens 703 Rigid Fiberglass also seems more than reasonable (and very effective from the graphs in the Masters Handbook of Acoustics). Should I just place this on the wall? What have you guys done to make it aesthetically pleasing?

What percentage of my wall panels need to be covered with diffusors or absorbers before a noticeable and appreciable difference in sound quality is achieved?

If it matters at all, the speakers are dipole

[sploo]

I treated my room a couple of years ago. You can see the measurements here: http://spikyfish.com/acoustics/ and details of how I did it here: http://spikyfish.com/acoustics/panels.html

My room is long and thin, and really suffered from problems due to reflections from the side walls. I have since become aware of research by Dr Floyd Toole that points to not treating first reflection points.

One school of thought is that you can never have too many bass traps - as more will flatten out your low frequency response. However, you should be careful about having too many mid/high range traps, as it can make a room sound a bit dead.

IRC dipole speakers have a figure of eight polar response, so don't radiate energy sideways (someone correct me if my memory is wrong). This may result in you not needing so much side wall treatment.

I believe that diffusion is only really required for larger rooms, but I'm certainly no expert on that.

BTW Everest's book is indeed fantastic, and well worth a read.

[twitchie]

my room is low (basement), shallow and wide, so slap echoes were pretty terrible and room acoustics were pretty terrible in the beginning.

I built absorbtion panels out of 3" mineral wool in 2'x4' frames and put 7 of them at 1st reflection points. What I found afterward was all the slap echoes were gone and the system was no longer piercing my eardrums like a dentist drill.

Unfortunately, the room sounds flat and dead now, so I removed 2 of the panels and think that diffusion is the way to go next.

I've visited audio stores which use only diffusion and others which only have absorbers.

If the room is small and empty, diffusers with a little absorbtion will be best (imo) and in 'cluttered' rooms, just add some absorbers since all the 'clutter' gives you diffusion already.

The store I visited that uses diffusers solely also sells Naim gear, so the soundstage is the entire front of the room, with no particularly discernible points of source (flat-earth presentation I think it's called) - meaning soundstage is wide, but flat and imaging is nonexistent. Some people love it.

I think the effect is most like what it sounds like when your speakers are wired out of phase relative to each other. Sound comes from everywhere and nowhere at the same time (sorry, that's the best way I can describe it).