Dial In Your Speakers … Dial Out Your Room
What I’m about to suggest I have tried on a couple of occasions and have had mixed results overall, but have had fantastic results with 2-way dynamic monitors. Your mileage may vary, but it is worth an experiment as it may obviate the need for a lot of acoustic products on your walls (the absorptive-kind, which I mostly abhor).
As with most dynamic speakers and some other types, as well, the dispersion pattern (or polar pattern) of the loudspeaker tends to throw quite a bit of audible information at the walls that are nearest to them. This has mostly to do with the fact that, as the wavelengths of the frequencies that the speaker is reproducing get longer, they tend to wrap-around the body of the speaker and widen their dispersion. That all-important “first reflection” point can cause interference with the main (incident) wave of the audio signal as they mix together and confuse your ear/brain. The typical medication for this problem is a sound-absorbing panel placed along the side wall where that first-reflection is located.
Now, there are some timing-windows pertaining to phase distortion between the incident and the reflected signal that are sometimes referred to in order to spice up articles and make them seem erudite and expert. And while this might prove an interesting examination, along with a discussion about inter-aural time-delays, difference vs. sum levels, and a host of other issues related to the continuum between your ears, your room, and your speakers … I just want to get you to try something out, and we can talk tech turkey some other time. I’m not an expert, so I’ll skip these and try to keep the post short(ish) and to the point.
Setting up loudspeakers in a moderate to modest space usually winds up as an exercise in equilateral triangulation. You place your speakers some distance from the front wall … not so close that you lose a sense of depth, not so far that you lose proximity-loading for the bass. You’ll try and place them as far from the side walls as possible, but that isn’t usually very far because who among us lives in a mausoleum? My room seems to be average based on an informal survey I took some years ago: 15′ x 25′ with 8′ high ceilings. Your room may be bigger or smaller, but probably not terribly much bigger or smaller. If your room is smaller, this technique should work even better for you. If it is larger, you probably have larger speakers …
So – getting back to our Equilateral Triangle: I originally placed my two-way monitors (Sonus Faber Extrema) about 4.5 feet from the front wall and about 3 feet from the side wall. That set them about 9 feet apart, from tweeter-to-tweeter, so I placed my listening seat so that my head would be 9 feet from each tweeter. From that point forward I tweaked the speakers forward and back (to adjust for bass) and then adjusted toe-in to balance soundstaging and imaging (Fig.1). This seems to be the traditional routine, with fits of adjustments here and there as I tried to eek out every last bit of whatever from the setup. I’m oversimplifying, but you get the idea.
The Extreme Toe-In is not an equilateral/equiangular triangle – you move the speakers forward a bit and closer to the side walls to form a right-triangle. In my case, I moved the speakers forward toward the listening chair so that they were 6 feet from the front wall, and then I moved them out toward the side walls so that they were about 20 inches from the side wall (measured at the base rear-outside-corner of the stand’s plinth) and – swinging the rear-outside corner towards the wall – angled 45 degrees toward center. This would place the rear-outside corner of the speaker stand’s plinth at ca: 9″ from the wall. The listening chair moved about a foot back to a position 15 feet from the front wall. The tweeters are about 11.5 feet apart, and about 9 feet from the listening position (Fig.2).
As it turns out, this is not a problem with frequency response as the listening position should still be within the tweeter’s full-range polar pattern (tweak for best results!). There should be no perceptible drop-off in high-frequency response – but you do have to be careful with how extremely you toe-in the speakers. As with all such tweaking, you’ve got to listen for the changes and tweak it back a little if you notice the HF rolling off a little. If you’re hearing roll-off, lean forward until you hear the HF restored. If the “stereo picture” sounds correct, move your listening seat forward. If it sounds distorted (as if the phantom-center image seems as if it is starting to rise toward the ceiling), toe the speakers back out a bit until the HF is restored at the listening position.
The degree to which your speaker will be susceptible to HF roll-off is almost entirely placed at the foot of the particular tweeter being used in the speaker, so there can’t be a concrete standard placement for every possible speaker. Your tweeter’s horizontal dispersion pattern/polar response will determine the extremity to which you can toe them in without losing the top-end.
The (Perceived) Benefits
By this extreme placement, I trade in the proximity bass-loading of the front wall for even better proximity loading against the side wall … so we’ve got a little bit better bass response from the monitors. But that wasn’t really the point of this placement, it’s just a bonus. The real benefit is what this does for soundstaging and imaging, creating a far more immersive experience and a much more invisible loudspeaker.
It performs this “trick” by dialing out some of the first-reflection issues: pointing the tweeter’s output (as well as the higher-frequency output of the mid-woofer) away from the side wall effectively removes that wall as a source of “extra” information to smear the acoustic signal. Further, those frequencies low enough to start to “wrap around” the cabinet will encounter the wall and reflect – BUT – that reflection will be so close in time to the incident signal, and low enough in frequency, that your ear/brain won’t be able to tell much of a difference between the reflection and the original.
What I’ve described here is what I’ve done in my own listening room with really fantastic results, but there’s more tweaking of positioning and toe-in that I’ve done but haven’t documented here for the sake of brevity. That means you can start where I’ve indicated, but you’re going to have to experiment in order to get excellent results. I’ve had only mixed results with 3-way speakers, dipoles, and others – it’s worth trying, but I’ve found that this tends to work extraordinarily well for 2-way dynamics.
If you try this out, remember … take down the acoustic treatment from the walls! Especially the absorbing-kind! They suck the life out of the room, out of the music, and leave you with some dull and un-involving ghost of music in its place. You’ll know it when you get it, the whole thing locks, and then you just want to play records and not even think about speakers, acoustics, etc.