No particular tones sticking out, no particular timbre. And it's even more useful as you move around, giving you a good idea of what the dispersion pattern is like.
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Why evaluating the sound of a single speaker is essential
- Thread starter Floyd Toole
- Start date
Vuki
Senior Member
Acoustic measurement and then correlate the results with your room’s dimensions using an online room mode calculator.
Keith
Keith
Audionaut
Major Contributor
Give me some time, I'll think about it.
No, that was just a few little hints on how you can get a feel for the changes.
For example, in the first Step, by leveling a coaxial driver in the frequency response to +- 1db exactly at 1m and then taking the position of the microphone. Ideally in free field, if circumstances allow and the environment is quiet enough.
DSJR
Master Contributor
If you have a known good-measuring reference to compare the 'sound' of pink noise to, it helps a good bit in an admittedly general sense.
When they're in the hundreds or thousands of Hertz, it's a safe assumption that the speaker is doing that.
tmtomh
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To those folks who seem unpersuaded by the scientific explanations and the listener-preference/sensitivity test results, I’ll offer an anecdotal (or “common sense”) observation, for what it’s worth:
It never occurred to me to evaluate a speaker in mono (using just one instead of a stereo pair), until I joined ASR - and I still have never personally listened to just one speaker in my setup.
But, to @Floyd Toole ‘s point in the first post, I have repeatedly - and quite easily, without even consciously thinking about it - noticed that my current speakers are by far the most balanced, pleasant, and for lack of a better term convincing sounding speakers I’ve ever owned, when it comes to hard-panned sounds.
Don’t get me wrong - they’re the best sounding (to me) speakers I’ve ever owned in all respects. But within that, they’re also the only speakers I’ve ever owned where I don’t perceive a fall-off in their sound quality from center-panned to hard-panned sounds. My previous speakers were quite enjoyable, but they were quite obviously worse sounding when most or all of the sound was coming from one speaker.
I think this is a very easy thing to detect, and you don’t need to unplug a speaker to do it.
It never occurred to me to evaluate a speaker in mono (using just one instead of a stereo pair), until I joined ASR - and I still have never personally listened to just one speaker in my setup.
But, to @Floyd Toole ‘s point in the first post, I have repeatedly - and quite easily, without even consciously thinking about it - noticed that my current speakers are by far the most balanced, pleasant, and for lack of a better term convincing sounding speakers I’ve ever owned, when it comes to hard-panned sounds.
Don’t get me wrong - they’re the best sounding (to me) speakers I’ve ever owned in all respects. But within that, they’re also the only speakers I’ve ever owned where I don’t perceive a fall-off in their sound quality from center-panned to hard-panned sounds. My previous speakers were quite enjoyable, but they were quite obviously worse sounding when most or all of the sound was coming from one speaker.
I think this is a very easy thing to detect, and you don’t need to unplug a speaker to do it.
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Vuki
Senior Member
Then expect a visit from the Easter Bunny and Santa Claus, all at once.
The room controls the response below Schroeder at least as much as the speaker does, but those modes are easy to spot when moving around a bit. That's one of the reasons people use DBA or Waveforming.
For some time now, I have compared speakers under review close-up, in mono, side-by-side with pink noise as well as music tracks. While this quite divorced from normal listening conditions, no other listening test makes the differences between the two speakers more distinct. It provides me with specific issues to which I will attend when listening to the stereo pairs from my listening seat.
Some quick editorial points for this thread that I hope may be useful for those participating here...
source. In stereo all sound images between the loudspeakers are phantoms, created from identical
sounds radiated by each loudspeaker – double-mono - with inter-channel amplitude or time
differences to provide location cues for image position. Each ear receives two versions of the
same sound separated by a delay and modified by head diffraction. The only exceptions are the
hard-panned sounds emerging from the left and right of the soundstage; these are monophonic
components and are timbrally and spatially distinctive. So stereo listening is a hybrid
experience, partly mono but mostly double-mono with the inherent corruptions.”
Like many, have heard some euphoric experiences from stereo speakers. Since stereo seems to mainly be an interesting illusion, can see how some will insist it is some holy grail. From my perspective, despite progress in recent decades, seems we can still look forward to even more realistic reproduction in the future.
Finally, have seen a lot of interesting and potentially valuable dialog here from members. Though without the sort of research and evidence provided by Dr. Toole, not clear whether much of it is just nice convincing words or something more. Look forward to seeing more good research.
- The thread title was entirely my creation (though Dr. Toole did not object). After decades of evaluating speakers in stereo, after reading his research, it became clear to me why stereo speaker evaluation did not produce satisfying results. Previously, had only thought it was room/room treatment that caused the apparent contradictions I had experienced.
- Please read the opening post and the attachment.
- A notable (dare I say enlightening) quote from the attachment...
source. In stereo all sound images between the loudspeakers are phantoms, created from identical
sounds radiated by each loudspeaker – double-mono - with inter-channel amplitude or time
differences to provide location cues for image position. Each ear receives two versions of the
same sound separated by a delay and modified by head diffraction. The only exceptions are the
hard-panned sounds emerging from the left and right of the soundstage; these are monophonic
components and are timbrally and spatially distinctive. So stereo listening is a hybrid
experience, partly mono but mostly double-mono with the inherent corruptions.”
Like many, have heard some euphoric experiences from stereo speakers. Since stereo seems to mainly be an interesting illusion, can see how some will insist it is some holy grail. From my perspective, despite progress in recent decades, seems we can still look forward to even more realistic reproduction in the future.
Finally, have seen a lot of interesting and potentially valuable dialog here from members. Though without the sort of research and evidence provided by Dr. Toole, not clear whether much of it is just nice convincing words or something more. Look forward to seeing more good research.
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tmtomh
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Makes sense - and I have had a watered-down version of this same experience, courtesy of some of Erin's recent reviews: he plays pink noise, and then plays pink noise run through EQ that simulates the speaker' anechoic Klippel response. It comes via compressed YouTube audio of course, but the difference is always quite obvious.
Jaxx1138
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This statement is not completely accurate for a subjective evaluation of a loudspeaker. but would be true for an evaluation of a stereo recording. it looks as though you believe that these two things are the same. The stereo effects are not the loudspeaker, they are the recording. The linearity, directivity and any non-linearities are the loudspeaker itself. The psychoacoustic effects are created from using two loudspeakers and a stereo recording. The evaluation of those effects are not an evaluation of the loudspeaker but of the stereo effects. It is not an opinion, it is in fact a part of the physics of acoustics and our current recording process.
Here is what AI says;
The attribute of "spaciousness" is not solely a product of a single loudspeaker unit. While a well-designed single speaker can contribute to a sense of scale, true "spaciousness" in audio is a complex psychoacoustic phenomenon influenced by a multitude of factors, most of which go beyond the individual speaker itself.
Here's a breakdown of what contributes to spaciousness:
Factors Beyond a Single Loudspeaker Unit:
- Multiple Speakers and Stereo/Surround Sound:
- Stereo (Two Speakers): This is the most fundamental way to create a sense of space. By presenting different signals to the left and right ears, stereo playback utilizes interaural time differences (ITD) and interaural level differences (ILD) to create a "soundstage" where sounds appear to originate from various points between, behind, and sometimes even beyond the speakers. This illusion of width and depth is impossible with a single speaker.
- Surround Sound (Multiple Speakers):Systems like 5.1, 7.1, or Dolby Atmos use multiple speakers positioned around the listener to create an even more immersive and encompassing sense of space, placing sounds precisely in a 3D field.
- Room Acoustics:This is arguably the most significant factor after the number of speakers.
- Early Reflections: Reflections that arrive at the listener's ears shortly after the direct sound (typically 5 to 80 milliseconds) are crucial for spaciousness. They provide cues about the size and boundaries of the listening environment.
- Reverberation: The decay of sound in a room as reflections bounce around. Proper reverberation (not excessive echo) contributes to the sense of a large, natural acoustic space.
- Absorption, Diffusion, and Reflection: The materials and geometry of the room (walls, ceiling, floor, furniture) determine how sound waves are absorbed, diffused (scattered), or reflected. A well-treated room helps manage these reflections to enhance spaciousness rather than create muddiness.
- Room Size and Shape: Larger rooms generally have longer reverberation times and different modal characteristics, which can naturally contribute to a sense of spaciousness compared to a small, heavily damped room.
- Early Reflections: Reflections that arrive at the listener's ears shortly after the direct sound (typically 5 to 80 milliseconds) are crucial for spaciousness. They provide cues about the size and boundaries of the listening environment.
- Recording and Mixing Techniques:
- Reverb and Delay Effects: Audio engineers intentionally add artificial reverberation and delay effects during mixing to create a sense of space around instruments or vocals. This can make an instrument sound "farther away" or "in a larger room."
- Microphone Techniques: Using spaced microphone arrays during recording (as opposed to coincident mics) can capture more natural spatial cues and contribute to a wider, more spacious soundstage upon playback.
- Panning: Manipulating the left/right balance of sounds in a mix contributes to soundstage width.
- Direct vs. Reverberant Sound Ratio:The balance between the direct sound from the source and the reflected sound (reverberation) is a key cue for perceived distance and spaciousness.
- Reverb and Delay Effects: Audio engineers intentionally add artificial reverberation and delay effects during mixing to create a sense of space around instruments or vocals. This can make an instrument sound "farther away" or "in a larger room."
- Speaker Placement: Even with multiple speakers, their positioning within the room critically affects spaciousness.
- Distance from Walls: Placing speakers too close to walls can cause excessive bass and muddy reflections, collapsing the soundstage.
- Distance Between Speakers and Listener: Optimizing the "sweet spot" (often an equilateral triangle between the speakers and listener) helps establish a stable and wide soundstage.
- Toe-in: Angling the speakers slightly inward can affect the width and focus of the soundstage.
- Distance from Walls: Placing speakers too close to walls can cause excessive bass and muddy reflections, collapsing the soundstage.
How a Single Loudspeaker Can Contribute (but not solely create)
While a single speaker cannot create a true stereo soundstage, certain design attributes can contribute to a sense of spaciousness or openness:- Wide Dispersion: A speaker that disperses sound widely (i.e., its sound doesn't beam too narrowly) can energize the room more evenly, potentially creating a less "localized" or more "room-filling" sound. This is especially true for omnidirectional or bipolar speaker designs.
- Low Frequencies: Well-defined and deep bass can contribute to a sensation of scale and "room filling" even from a single speaker.
- Absence of Cabinet Resonances/Coloration: A speaker with a very "clean" and uncolored sound, free from internal resonances, can allow the recorded spatial cues to be heard more clearly, even if those cues are limited.
- Driver Design and Integration: A well-designed speaker with seamlessly integrated drivers (e.g., a good crossover network, point-source designs like coaxial drivers) can present a more coherent sound that avoids drawing attention to the speaker itself, allowing the listener to perceive any subtle spatial cues present in the recording.
Vuki
Senior Member
Exactly - great for detecting differences between loudspeakers, but not for evaluating sound quality.
Of course. Please note that I do this at a distance of <1m with no illusion that it represents how the speaker sounds under normal listening conditions. It is a tool that informs the rest of the evaluations.
watchnerd
Grand Contributor
I'm curious what this progress will mean for the massive back catalog of 20th century music recorded in stereo.
I haven't found, for example, SACD multichannel remastering/remixes of classic mid century jazz to be to my liking vs the originals.
May be a challenge but have to admit that when I started this hobby (playing vinyl) that I did not imagine that most of my music would fit on a thumbnail-size memory card either...
If our old recordings are not as pleasing on a future playback system, would expect some support to play them in some suitable fashion. If I can extract vocals from music today, seems logical to be able to extract most of the individual instruments and remix them into some more pleasing presentation in the future. After all, if stereo is mainly a pleasing illusion, replacing it with another seems acceptable.
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watchnerd
Grand Contributor
I don't know if I'd find it better. It depends on how radical the difference is.
With jazz LPs, in particular, the order of songs to fit the LP, the mixing, etc, were part of the art.
I can listen to it now, in its original (ish) mono or stereo form, with some thoughts that I'm not hearing something too many standard deviations removed from the original intent.
[We don't usually try to change the dialog in Shakespeare plays from Elizabethan to current modern English, either]
New content, on the other hand, would be a different matter entirely.
Agree there may be some aspects that may be lost, but better the key aspects retained than losing it entirely...
I can be happy with really good. Seeking perfect is often extreme masochism in my experience.
Not that I have read every statement he has made on the subject, but my understanding is that Dr. Toole has said the speaker that "wins" sound quality in mono always wins sound quality in stereo, but I do not recall him saying that the speaker that "wins" spatial quality in mono always wins spatial quality in stereo. And the way he uses the two terms, spatial quality is not a subset of sound quality.
Somebody please correct me if I am mistaken.
(I first recognized and began using single-speaker evaluations as more revealing of sound quality differences back in the mid-80's, as an enthusiastic amateur.)
Excellent point!
As one who designs speakers for stereo, taking placement and toe-in and reflection path lengths into account, I am not convinced that a mono evaluation of one of my speakers placed far from the side walls, and not on or near the designed-for listening axis, will be a reliable predictor of either its sound quality or its spatial quality in stereo. My designs use time-intensity trading, wherein the speaker axes criss-cross in front of the listening area, and I don't think that can be evaluated in mono:
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