View Single Post
Old 12th August 2019
  #16
Lives for gear
 

As Bert, Johann, JayPee, dinococcus, and Boggy have all pointed out, quite correctly, there's a simple system for setting up the speakers and listening position in rooms, based on the principles of acoustics and simple geometry, plus actual measurement with REW. There are very good reasons for their recommendations and comments, which are totally right.

With the speakers against the front wall, you force the initial SBIR dip up to a higher frequency, in the bottom end of the mid range, where it is not so objectionable and can be treated. If you have the speakers away from the front wall, then that first SBIR dip occurs down lower, in the low end. The further you move the speakers from the wall, the lower the frequency is, and that's a problem: it will be very much more noticeable, and very much harder to treat, acoustically. Using a single sub to "fix" SBIR brings in a bunch of other problems. If you have lots of money to play with, then setting up two (or four.. or more) subs in a plane wave bass array can be quiet effective at dealing with several low-end issues at once. But that's not so easy to do... and it is expensive, since you need multiple subs.

On the other hand, the "floor bounce" is very different, and not so much of an issue to start with! It might look ugly on your REW graphs, but it isn't usually noticeable, for several reasons: first, your brain expects it, and "tunes it out", second, it's usually a very narrow dip, and third there's no "ringing" involved. All of those make it sort of "invisible". Some folks from Genelec did a survey of many dozens of high-end control rooms a few years back, and the floor bounce issue is clearly evident in pretty much all of them. It's a fact of life: there will be a floor bounce in your room, and treating it is somewhere between "really really hard" and "impossible". So don't sweat the floor bounce. SBIR is a real issue. Modal ringing is a real issue. Symmetry is a real issue. Decay times are real issues. The floor bounce is "real" too, but not worth worrying about too much.

About your desk: It can be an issue yes, which is why you'll often see recommendations to make the desk as small as you can, and as "open" as you can, in the sense of not having lots of large, solid surfaces that could cause reflections or other issues. Some people even tilt the desk surface slightly. Most set the desktop level as low as possible, to minimize the effects of the desk. With careful planning and design, you can have a desk that does not cause major issues.

- Stuart -