Quote:
Originally Posted by Jeffrey Hedback  this may help you further relate these terms to your room:
- the pressure zone begins at with a frequency who's 1/2 wavelength is greater than your room's largest dimension...this doesn't mean your room can't "produce" that frequency...but that it's produced only when driven (no resonance).
- The modal zone extends up to the freq who's 1/2 wavelength is equal to your room's (speaking of length, width and height) shortest dimension...these are the issues talked about regarding bass traps and shown nicely with waterfall plots.
- above that is a little tougher to visualize...I think it's easier to begin at the higher freq's and think about a specular reflection (one who's angle of reflection is = to angle of incidence)...those are identifiable with ETC (glorious huh SAC!)...mostly predictable in a Control Room with mirror trick to identify reflections...and treated to suit with absorbers/diffusors
- the grey area is where the wavelengths do not create modal resonance but also don't "reflect" predictably...these midrange frequencies diffract (bend around) room features, can create resonant pockets with racks and surfaces, can disrupt the spatial balance of a room (how the balance of lo/mid/hi's are perceived).
So this all brings into play the room dimensions/ratios, reflection control, LF control, speaker position, listener position...the whole game! |
Hi Jeff,
You snuck that in there while I was doing math.
I totally get the modal vs specular.
It's that grey area that is baffling (ba doom ba).
Although I do have obvious problems in the 100Hz - 300Hz range, according to Davis, they are modal in nature and according to Schroeder, they are in the grey area.
BUT, the Schroeder theory doesn't really apply to my room size, so I should listen to Davis.
...or maybe it's just SBIR.