The single most important and effective set-up tweak is proper loudspeaker placement. Before you upgrade components or spend money on your system, be sure that your speakers are delivering all the performance they are capable of.
Correct speaker placement not only improves the overall sound, but specific placement techniques allow you to dial-in and optimize particular aspects of the presentation. Just through speaker placement you can fine-tune the system’s tonal balance, the quantity and quality of bass, soundstage width and depth, midrange clarity, articulation, and image focus. In this month’s Tip, we’ll just consider how to create a large soundstage with precise image focus within that stage.
Before adjusting your speakers’ positions, remove their spikes (if they have been installed) and place four furniture sliders beneath each speaker, one in each corner. This will make it much easier to move the speaker on carpet or on floors with hard surfaces, such as tile or wood. When you’ve found the best positions for the speakers, remove the sliders and re-install the spikes.
Let’s start with the fundamental relationship between the listener and a pair of speakers. The speakers and listener should form a triangle. It’s vital that the listener sit exactly between the two loudspeakers, and at the same distance from each. This listening position—equidistant from the speakers and slightly farther from each speaker than the speakers are from each other—is called the “sweet spot.”
Setting the distance between the speakers is a trade-off between having a wide soundstage and a strong center, or phantom, image. The farther apart the loudspeakers (assuming the same listening position), the wider the soundstage. As the speakers are moved farther apart, however, the center image weakens, and can even disappear. If the speakers are too close together, the soundstage narrows. Speakers placed the optimal distance apart will produce both a strong center image and a wide soundstage. There will likely be a position where the center image snaps into focus, appearing as a stable and almost tangible presence exactly between the speakers. A musical selection with a singer and sparse accompaniment is ideal for setting loudspeaker spacing and ensuring a strong center image.
With the speakers fairly close together, listen for a tightly focused image precisely between the two speakers. Move the speakers a little farther apart and listen again. Repeat this move/listen procedure until you start to hear the central image become larger, more diffuse, and less focused, indicating that you’ve gone slightly beyond the maximum distance your speakers should be from each other for a given listening position.
The amount of speaker toe-in also influences this trade-off between soundstage width and image focus. Toe-in is pointing a loudspeaker inward toward the listener rather than aiming it straight ahead. No toe-in produces a larger, more billowy, less precise soundstage. Instruments are less clearly delineated spatially, but the overall sound is bigger and more spacious. Toeing-in the speakers can reduce the apparent size of the soundstage, but allows more precise image definition. When toed-in, many loudspeakers provide a more focused and sharply delineated soundstage. Images are more clearly defined, compact, and tight, rather than diffuse and lacking a specific spatial position.
Toe-in will also change the tonal balance; specifically the sound will be brighter with toe-in. And keep in mind that some speakers are designed for flattest frequency response with no toe-in. These speakers should be positioned according to the manufacturer’s guidance, with no toe-in.
Identical toe-in for both speakers is essential to great soundstaging. That’s because a speaker’s frequency response changes with toe-in, and imaging is dependent on the identical response from each speaker. Achieving identical toe-in can be accomplished by measuring the distance from the front wall to both rear corners of one speaker; these distances will differ according to the degree of toe-in. Repeat this procedure on the other speaker, adjusting its toe-in so that the distances match those of the first speaker.
The most accurate way to assure identical toe-in of both speakers is a free app called Loudspeaker Angle, available at the Apple app store. You place your iPhone on a speaker that’s facing forward (no toe-in), then toe-in the speaker, and the app tells you amount of toe-in in degrees.
Adjusting the distance between the speakers, and the degree of toe-in, allows you to fine-tune your system’s soundstage for the best balance of spaciousness and imaging precision.
Excerpted and adapted from The Complete Guide to High-End Audio (fifth edition). Copyright © 1994–2016 by Robert Harley. hifibooks.com. To order call (800) 841-4741.