@recluse wrote: “I for one would be very interested in Duke from AudioKinesis discussing soundstage in a large *and small* room.”
Imo the main problem in small rooms, as far as soundstaging goes, is the quick arrival times for the reflections, especially the first ones, because the path lengths are so short. These impose a “small room signature” on top of every recording.
The general background principle is this: Early reflections are generally detrimental, and late reflections are generally desirable. In this context, “late” would be about 10 milliseconds after the first-arrival sound. Sound travels a little over 1 foot per millisecond.
Before we go on, if you really want to get the best out of your room, engage a professional like Jeff Hedback of Hedback Designed Acoustics. Jeff is an award-winning acoustician who is still affordable. My room treatment suggestions that follow don’t begin to hold a candle to what he can do. After evaluation he can tell you exactly what kind of treatment, in what amount, and in what place, and can tell you how to do it yourself inexpensively. The smaller the room, the greater the room for improvement.
Imo there is an argument for locating the speakers close to the listening position in a small room. If we are sitting within about 4 feet of the speakers, this is what’s called a “nearfield setup”. The speakers are close enough that their first-arrival sound is significantly louder than the detrimental early reflections, which helps us to hear "more of the recording" and "less of the room".
Even with a nearfield setup, ime there is an argument for using speakers that minimize early reflections, and to treat those early reflections, ideally with diffusion but in some situations we’ll have to resort to absorption. Too much absorption can "suck the life out of the sound", so we don't want to overdo it.
The way to find the first reflection zones is this: Sit in the sweet spot and have a friend place a mirror against the floor or wall in the area of the reflection, and move it around. When you can see the reflection of the speaker’s drivers in the mirror, in particular the tweeter, that’s a first reflection zone.
The set-up I described to gene3x in my post above minimizes early sidewall reflections because the left-hand speaker’s first significant sidewall reflection will be off the right-hand side wall, and vice-versa. This is desirable because when the reflection arrives at the opposite ear from the first-arrival sound, it is generally beneficial, unless the room is very small. The narrow-pattern/cross-firing setup will give a wider listening area even in a small room. Not sure you can realistically do “nearfield setup” and “wide listening area” at the same time... but I haven’t tried it.
The floor and ceiling bounces are harder to address. A fairly narrow radiation pattern in the vertical plane helps to minimize them. A couple of small thick throw rugs on the floor in the left and right floor-bounce zones (in between those speakers and the listening area) can help. Recording studios go to the trouble of treating the ceiling bounce as well.
Not much we can do to dodge that first reflection off the wall behind the listener’s head – we’ll have to diffuse or absorb it.
There is a technique for tricking the ear/brain system into thinking the room is bigger than its physical dimensions, thus reducing “small room signature”. Disclaimer – this is something I’m commercially involved with.
First, the back-story: The ear judges the size of a room by the time delay between the first-arrival sound and the “center of gravity” of the reflections. So if we can push that “center of gravity” back somewhat, we can make it sound like the room is bigger than it really is. Fortunately all this work we’ve put into minimizing those first reflections is a good start!
But we can take it to the next level by deliberately adding more reverberant energy that arrives after a worthwhile time delay. “Worthwhile” in this context is about 10 milliseconds. The technique I use is to have a secondary array of drivers behind the main speakers, aimed up towards the ceiling. By the time the energy from those drivers has bounced off the ceiling and reached the listening area, 10 milliseconds or more have passed. The ear/brain system thinks we’re in a bigger room, so less “small room signature” is superimposed on top of the recording. We hear more of the recording and less of the room. I expect everyone to be skeptical of this claim, so let me offer some evidence:
Maggie owners have first-hand experience with this (as do owners of other dipole or bipole speakers). Maggie owners have learned the hard way that their speakers don’t sound all that good if they’re right up against the wall. So they start pulling them out from the wall, and they sound better and better. At about 5 feet out from the wall (ballpark), the soundstage is deep and a sense of immersion in the soundfield on the recording sets in. Five feet out = 10 feet round trip for the reflection path = about 10 milliseconds = a beneficial "late" reflection. At this point they are hearing “more of the recording” and “less of the room”.
So to recap, here are the general principles to keep in mind if you’re dealing with a small room:
1. If possible sit fairly close to the speakers, as that way they are louder than the reflections.
2. Minimize early reflections through speaker choice and set-up (narrow-pattern, cross-firing works well), and use diffusion or (if necessary) absorption in the early reflection zones.
3. Relatively late reflections are generally beneficial. If you have dipole speakers, get them out into the room so that the reflection path off the wall behind them is fairly long.
I have yet to build a “small-room-friendly” speaker system that brings together these and other ideas. One of these days.
Duke
