In November 2019, I wrote a feature for SoundStage! Access in which I discussed a few recordings I use to evaluate loudspeakers and subwoofers. This month I write about the reference tracks with which I evaluate how well a pair of speakers can reproduce aural images of singers, instruments, and other sound-producing objects, and to create a three-dimensional soundstage on which to accurately position those images.
The soundstage is the overall sound of the entire musical event, as reproduced by the audio system and perceived by the listener -- that is, the apparent volume of space in which and on which those singers, instruments, and other sound-producing elements seem to appear. Soundstaging can also refer to the relative positions of musicians’ voices and instruments on the overall soundstage.
Imaging is the accuracy with which speakers convey the sizes and positions of the aural images of voices, instruments, and other sounds on the soundstage. Tighter imaging means smaller, more focused aural images; diffuse imaging means that the images on the soundstage are larger and not as well focused.
How a system reproduces a soundstage and the images on it are, for me, important aspects of the experience of listening to recorded music. This is one of the main reasons I prefer a pair of good, stand-mounted minimonitor speakers, which I’ve found tend to produce tighter images than do larger, floorstanding speakers. Conversely, it may also be true that, in rooms larger than mine, minimonitors can lose ground to a good pair of tower speakers in terms of overall size of soundstage.
Of course, like all other aspects of reproduced sound, soundstaging and imaging are ultimately limited by something most of us have no control over: the recording itself. If we assume a well-set-up (e.g., an equilateral triangle with good left/right symmetry), two-channel system of decent quality, the most important contributing factors to the quality of soundstaging and imaging will be the recording and mixing of the recording itself. This is why, to evaluate these attributes of speakers, I use a few carefully chosen tracks that I know very well.
Left/right balance and a dead-center phantom image
Sometimes I worry that my system’s left/right channel balance is off, which happens whenever I listen to a vocal recording unfamiliar to me, and the lead singer -- whose voice, I believe, should sound as if it’s coming from the precise center of the soundstage -- seems to be just slightly left or right of center. Obviously, the recording itself may be the problem, but I always check to hear if it’s the system, the recording, or me. If there’s a channel imbalance in the system, that may also lead to unintended imaging elsewhere in the soundstage.
Some reasons for a channel imbalance unrelated to the recording played could be: a new electronic component whose channels don’t match; a pair of speakers with unmatched outputs -- that is, one is louder than the other throughout all or part of the audioband; or I’ve got a cold, meaning some congestion in one sinus cavity and not the other, or different degrees of congestion in my two sinuses. Such congestion can affect the transmission of soundwaves from the outer through the inner ear.
Surprisingly, this scenario pops up fairly often, and, if it does, I always turn to Norah Jones’s Come Away with Me (24-bit/192kHz FLAC, Blue Note/Qobuz). From my own experience of listening to this album many times over the years, and from comments by enthusiasts on online audio forums, I’m confident that Jones’s voice was mixed dead center on the soundstage throughout the entire album. I could play any track to determine whether or not my system is accurately reproducing that mix in terms of the lateral positioning of aural images, but I usually start at the beginning, with “Don’t Know Why.” If Jones’s voice appears at dead center, then I know there’s no imbalance in the playback chain -- or my ears. If I hear an imbalance, I know I have more investigating to do.
Pinpointing multiple aural images on a soundstage
My favorite track for evaluating imaging and the accurate placement of multiple aural images in and on a three-dimensional soundstage is “Give Me One Reason,” from Tracy Chapman’s New Beginnings (16/44.1 FLAC, Elektra/Qobuz). It begins with picked guitar to left of center, then Chapman’s voice dead center. Then, about 1’ to the right and 2’ behind that guitar, the drums come in, accompanied by subtle cymbal work, then a second guitar to far right of Chapman’s voice, just inside the right speaker. All of this is then accompanied by two backing singers, the first appearing about 1’ to the right and just behind Chapman’s voice, followed by the second about 2’ to the left and about 3’ behind Chapman -- at least through my system.
When I listen to this track, I evaluate the size of each image and its position on the soundstage relative to the other images. When reproduced by a good pair of speakers in my dedicated, treated room, which is set up with very good left/right symmetry, the images on this track are tightly focused. The images created by frequencies above the bass range vary in diameter from a little under a foot (Chapman’s voice) to just a few inches (Rock Deadrick’s subtle cymbals to left of center at 1:02 in). I like “Give Me One Reason” because it’s the opposite of a congested or busy mix, which can be hard to follow when evaluating a system’s imaging: it begins with a single guitar, and voices and instruments enter one by one -- as they do, I can easily track the position of each.
Who doesn’t like it when speakers seem to project sound beyond the speaker cabinets’ outer side panels? To test a pair of speakers’ ability to do this, I play “Make a Mistake,” from Colin James’s Traveler (16/44.1 FLAC, WEA). In the chorus, when the backing singers enter, their voices typically appear at the extreme left and right of the soundstage, past the positions occupied by my speakers in my room. When I close my eyes, these voices seem to extend some 1.5’ beyond each speaker’s outer side panel. Also interesting to listen for is if a pair of speakers can perfectly anchor James’s voice dead center on the soundstage, even as the backing singers are just as firmly anchored at extreme left and right. If they can, the contrast between the positions of his voice and those of his supporting singers can be very apparent.
A track that deserves honorable mention for its ability to produce an ultrawide effect through a pair of speakers is “Vogue,” from Madonna’s The Immaculate Collection (16/44.1 FLAC, Sire/CD). This 1990 greatest-hits compilation is notable for being the very first CD encoded with QSound, an audio-processing technology developed by Canada’s QSound, Ltd., with which engineers can make aural images appear well outside the space between and occupied by a stereo pair of speakers. Just how far outside, of course, will depend on the individual audio system and the room. Roger Waters’s Amused to Death was also processed with QSound.
In my system and room, the first words Madonna sings in “Vogue” -- “What are you looking at” -- start 2.5-3’ to the right of the right speaker, at the wall, then pan left across the soundstage to conclude at the left wall. Then, at 0:52, the words “strike a pose” appear at the left wall but now 6’ in front of the plane described by the speakers’ frontmost edges -- this passage sounds as if it’s being played through a pair of side surround speakers. This same effect is repeated at 1:03, this time at the right wall. Listen to this track at home, to hear if your own system can reproduce these effects.
In my relatively small basement listening room (15’L x 12’W x 8’H), my speakers are placed along one long wall. They and my listening seat describe a 9’ equilateral triangle. This gives me good soundstage width, but leaves less than 2’ between the speakers’ rear panels and the front wall. I’ve heard many larger spaces produce deeper soundstages than my rig can in my room. For example, in the very large listening room of SoundStage! Network founder and publisher Doug Schneider, who also lives in Ottawa, there’s usually 7-8’ between the speakers’ backs and the front wall. I’ve often listened to music in Doug’s room, and each time I’m struck by the extraordinary depth achieved. And while I’m sure that there are physical acoustical phenomena that account for the difference in perceived depth between his room and mine, I feel that optics may also play a role -- seeing all that space behind the speakers might result in me imagining more depth in the recording.
Those with rooms and setups similar to mine can try this free and easy exercise. As you listen to a well-recorded track with good soundstage depth, close your eyes and imagine that your front wall is actually 6’ to 8’ behind your speakers -- in other words, try mentally expanding the size of your room. When I try this, and focus hard on the illusion I’m attempting to conjure, I swear that I begin to hear aural images placed even deeper on the soundstage than when my eyes are open and I’m not trying to imagine this.
A good album to use to test soundstage depth -- and to try with the mental exercise mentioned above -- is Blue Rodeo’s Diamond Mine (16/44.1 FLAC, WEA/Qobuz). While the album was mixed in a recording studio in New Orleans, it was recorded in an old movie theater in Toronto, the Danforth. The ambience and reverb of this large venue can be clearly heard throughout the album, and they no doubt contribute to the sense of soundstage depth that can be experienced. For example, in “House of Dreams,” behind Jim Cuddy’s voice, which is dead center and farthest forward on the stage, I can hear Cleave Anderson’s subtle drumming to the left of Cuddy and 3-4’ behind him -- just beyond my room’s front wall.
Another example of superb depth is this album’s title cut. From 1:00 to 1:15, what sounds like an organ can be heard way off in the distance, behind and to the left of Keelor’s voice at center. In my room, the organ sounds about 4’ behind Keelor, behind my front wall.
The height of a reproduced soundstage is seldom mentioned in audio reviews, but after precise imaging, it’s what I most covet. It’s also one of the reasons I like to listen at fairly high volumes: 90dB-ish, C-weighted, at my listening chair. While every dimension of a soundstage seems to increase with the volume level, height seems most affected.
Playing any track of Norah Jones’s Come Away with Me with the volume set very low -- i.e., a level at which you can still comfortably converse with the music playing -- the centered image of Jones’s voice always seems to be slightly below the midrange drivers of my Focal Sopra No1 speakers -- that is, toward the floor. But as I raise the volume, her voice rises in elevation until, at my preferred playback level, it’s typically 2.5’ above the tops of my speakers. Listening at 70-75dB vs. 90-95dB SPL, the difference between two illusions of Jones singing between my speakers is of her singing while seated, and of her singing while standing. And every time, I prefer the realism of a standing singer. What causes this auditory phenomenon I don’t exactly know, but I experience it every time I try this volume-level experiment. Try it yourself.
Of course, not all tracks offer the same degree of height information and not all speakers can produce an illusion of height as effectively as others. For example, I’ve found that speakers whose tweeters are coaxially mounted inside a midrange driver tend to project less height compared to conventional designs with tweeters mounted above the midrange.
One of my other favorite tracks for evaluating a pair of speakers’ ability to reproduce soundstage height is “What a Good Boy,” from the Barenaked Ladies’ Gordon (16/44.1 FLAC, Sire/Qobuz). Played loud in my room, this well-recorded track lets me hear lead singer Steven Page’s voice appear 3’ above the tops of my speakers.
But can aural images recorded or mixed off center also be reproduced above the tops of the speakers? I find that the farther right or left a recorded sound appears, the harder it is for a pair of speakers to reproduce it with convincing height. In “Bad Timing,” from Blue Rodeo’s Five Days in July (16/44.1 FLAC, Warner/Qobuz), lead singer Jim Cuddy is mixed about halfway between the right speaker and dead center on the soundstage. In my room and system, his voice appears about 2’ above the tops of the cabinets. A more challenging test is the chorus, in which Greg Keelor’s voice appears about 2’ behind Cuddy’s, just inside the right speaker. I like to hear if the speaker can present an aural image of Keelor’s voice at the same height as Cuddy’s, outside of the speaker cabinet. My reference Focal Sopra No1 speakers can do this.
Do any of you have suggestions for other tracks that I and readers might use to evaluate a pair of speakers’ ability to create a three-dimensional soundstage populated with convincing aural images? Drop me an e-mail -- maybe your suggestion will appear in my next list of test tracks.
. . . Diego Estan