One of my favourite quotes is from Admiral Grace Hopper an early pioneer in computing “One accurate measurement is worth a thousand expert opinions”. Dr. Toole understood this and was indeed a pioneer in true loudspeaker research. His book is an excellent wealth of knowledge and well worth reading by all who call themselves audio enthusiasts. Keep up the great videos.
When tuning a crossover I always use one speaker and listen at both close and mid distances. This allows me to hear not only the tonal qualities of the crossover better, but also seems to bring out other anomalies such as axial lobing or directivity issues that sometimes don't show up when listening in stereo. (plus it's way easier to alter one crossover at a time and test rather than two)
You must have been an excellent teacher, Amir. From one professinal to another, I enjoy your content on an pedagogical level. This needs a like for every view, just for method and presentation
I had experienced excellence of mono testing over stereo by myself some years ago, when began my hi-fi journey. Brought 2 pairs of speakers and amps to my listening room and tried to pick up best. Shuffling them in stereo was a bit difficult physically. And surprisingly discovered, that single speaker listening was very revealing to detect difference between equipment. Now I know, that I did right)) Thank you Amir!
Amir, FYI that Harman "Single-channel Speaker Shuffler" can shuffle 8 speakers in any combination including shuffling them in stereo pairs. And is used that way too. Also it's driven by pneumatic cylinders (not hydraulic). I worked on that thing circa 2006 to make it operate properly.
You keep reminding me how little I know. But now I’m confused on a higher level. Thanks. Keep up the good work. The Hifi / “audiophile” world needs your posts.
@@AudioScienceReview keep it up! It is a relief that someone is not just talking about their feelings... still appreciate your short subjective reflections.
Once again your right. Not knowing all this myself, I occasionally build speakers and I don't have any audio instrumentation so I do everything by ear. And the only way I dial in the crossover is by listening to one speaker, obviously mono. Stereo is really intended to trick the brain so it just complicates speaker optimization. If you get it right in mono it'll be great in stereo.
Just discovered your work and ASR recently. So great! A week ago I started doing mono testing to investigate a problem I'm having with bass in my room. Mono made the comparisons so much easier. I found the culprit (bass resonances audible from a foot away on the speaker!)
Completely and totally agree Amir. The additional sound from another speaker with all of its variations in frequency response, time delays, and phase from the room added to the sound of a single speaker amounts to an interference of the sound from the speaker under test. Also the additional sound from the second speaker psychoacoustically masks to an extent the sound from the speaker under test. It all adds up to too much information. So I am not surprised that people had a much harder time distinguishing sound differences and quality in stereo versus mono. It also shows why the sound quality is less of a concern in home theater with the additional sound effects and the picture distractions. I ran a test when I worked at CBS's Technology Center in the 1980s that showed a difference in people's localization of sounds with various visual stimuli which showed how people tended to localize sounds towards the video picture when shown versus no picture. Even static images changed the localizations when presented to the subjects. It showed that the additional stimuli modified the perception of sound direction. So it is much better to limit the distractions of additional sounds and even visuals if you want to reveal the perception of the sound quality of a speaker. Then when listening in stereo or multichannel, just sit back and enjoy the music or movie knowing that you have selected the best speaker for the job based on your best ability to render a judgment of sound quality.
I first heard surround sound while recovering from an operation in hospital. I was captivated by the sound, but this was not a home theatre, it was a rest room in a hospital. It was a cheap system, yet the effect was captivating. Had I heard those speakers in mono I would have realised their limitations, but together they sounded fantastic. As I sat, immersed in the unfolding drama, I was blissfully unaware of their limitations.
@@theterriblepuddle1830 I see your point, but they weaned me off the drugs as part of the recovery process. Shame really, because I quite liked the drugs.
I still have back issues of the original Sound & Vision magazine (Canada), where they were using the NRC facilities and double blind testing and scoring for the speakers they were reviewing. The highest rating I ever saw them give to a stereo pair was the Energy Veritas 2.8 (a score of 7.9), but they had several 5.1 setups that scored higher, the highest being a Sound Dynamics THC-22 based system that was scored an 8.8. [Edit] Here's the list if you want it: S&V Issue/ NRC Fidelity/ Brand/ MSRP/ Model(s) Home Theatre 02/1997 8.8 Sound Dynamics $1,585 THC-22 main/centre; THR-BP1 surround; THS-1000 sub 09/1996 7.5 PSB $2,600 1000main, Stratus C5 centre, Ambient II surround, Subsonic II sub 08/1996 8.1 Celestion $1,999 Home Theatre in a Box 05/1996 7.1 Cerwin-Vega $2,150 HT-MDC main/centre; HT-S5 surround; HT12-PWR sub 04/1996 8.5 Polk $4,350 RT16 main, CS350-LS centre; LS f/x surround; PSW200 sub 09/1995 8.5 Axiom $700 AX1.2 main/surround; AX1.2 centre, AX120 sub 09/1995 7.2 Monitor Audio $3,197 300 Home Theatre system: 202 main, C300 centre, 302 surround; no sub 02/1995 N/A Bose $2,799 Lifestyle 12 Home Theatre 03/1994 7.1 Cerwin-Vega $1,770 HT-S6 main; HT-CTR centre; HT-S5 surround; HT-12D sub 10/1993 7.3 Paradigm $890 Titan main, CC-200 centre, Atom surround, SB-100 sub 04/1993 7.3 Energy $1,400 Home Theatre system: ESAT-2 main/surround; ECC-1 centre, ESUB-2 sub Stereo Pair 02/1997 7.4 Acoustic Profiles $999 PSL-8835 04/1996 7.6 Acoustic Profiles $799 PSL-8825 11/1995 7.8 Energy $600 Energy C-2 Connoisseur 11/1995 7.7 Paradigm $360 Mini-Mk3 11/1995 7.8 PSB $1,500 Stratus Silver 09/1995 7.2 Paradigm $450 ADP-150 dipole surround 10/1994 7.5 B&W $4,600 Matrix 802 Series 3 10/1994 7.9 Energy $7,000 Veritas v.2.8 09/1993 7.2 Harman Kardon $3,198 Harman Kardon Sixty 09/1993 7.2 Mirage $500 M-290 07/1993 7.3 Acoustic Profiles $699 PSL 66.2 07/1993 7.3 Paradigm $320 Phantom 04/1993 6.6 KEF $550 K140 04/1993 6.5 Wharfedale $439 Diamond V 02/1992 6.5 Acoustic Research $799 M4 02/1992 7.2 Audiosphere Profile $349 PSL 6.1 02/1992 7.4 Castle $3,660 Winchester 02/1992 7.1 Ethera $2,700 Vitae 02/1992 7.3 Mirage $750 M-490 For comparison, I've owned the Paradigm Phantom and Titan on this list, and both would lose to my current Kanto Yumi's + sub and my former Nuance 330's. The Phantoms were comparatively boxy sounding, and the Titans fatiguingly sibilant.
@@Daniel_Ho_Status_101 Yes, modern speakers sound better than vintage ones. Glad to see that technical progress actually results in better sound for lower cost.
@@johnwright8814 Yes, I think good sound has very much been democratized...as long as you buy a powered or active loudspeaker that's been designed around DSP. I'm not sure if passive loudspeakers really are that much better than even 20 years ago.
@@Daniel_Ho_Status_101 One thing I realised is that directivity control is more important than DSP. I look for the waveguide, which is cheaper than room treatment..
A Perfect video full of correct information! A single speaker is designed, measured and played with a mono source until the final the design is completed. At that point 2 speakers are used in stereo.
Thanks Amir! Mixing engineers often have a little speaker with a mono signal on the middle of there meterbridge; 'to check on the mid-balance' as they say. Makes a lot more sense now!
I've known many speaker designers who do their design and development work using just one speaker, sort out the sound of that one speaker, then move to two speakers.
Very interesting and much needed video Amir. Thanks! It's funny because most audiophiles that like to look at loudspeaker measurements, know that they're taken with a single loudspeaker. But then, when we want to subjectively listen to how a loudspeaker sounds, we do it in stereo; how ironic. Habits we have to change.
Indeed. People readily accept mono measurement but there is so much resistance to the same for listening tests. Our intuition definitely gets in the way.
Speakers are intended to be listened in stereo so unless you're actually developing one, mono listening brings zero benefit to you as you're never going to listen to them in mono anyway. For a speaker designer, mono listening is necessary naturally. But for a speaker shopper, mono listening does not bring any benefit in my opinion. It's the stereo imaging and the whole setup that matters in the end.
I'm currently reading Dr. Toole's book, and am on chapter 3 which covers this topic. So I watched the video. Thank you for this as it really clarifies what I've been reading.
Thank you very much for "lifting the veil" by sharing with us the beauty of using quantitative methods to analyze and compare audio equipment. So glad I found this awesome corner of the internet!
Thanks for sharing. After I've seen this, I tried it on my speakers. I played mono tracks with 1 channel and tweaked the EQ on my Schiit Loki, and I confirm that even slight changes on EQ becomes much obvious.
Found your channel yesterday, already binged all the videos haha Just a tip for Powerpoint, there is a book icon in the bottom right, which maximizes the powerpoint in the window, without going to fullscreen
I tried that last time but found an issue. I forget what it was. One of them I can fix (it fades out the mouse) but there was another reason I forget. But yes, sorry about putting you all through looking at the full output of PowerPoint. I hate it when others do it but here I am doing it. :)
@@AudioScienceReview Save the powerpoint as a PDF and open it using a PDF viewer maybe? As a Linux user I have lots of experience avoiding and working around ppt files!
Until I watched this video, I was always bothered that the movie theater in the student union at the Univ. of Az (in Tucson) only had 'only' a single, Altec Lansing "Voice of the Theater" hanging from the front center of the the theater (at least from '77-82). Maybe they were a little ahead of their time. Great job on another informative "audio mythbusting" video!
All published speaker specs are measured in mono using one speaker and one mic in a controlled environment but we quantify those numbers using two speakers and two ears in a different environment.
I've been building my owns speakers for a few years now and when test them I do an A-B comparison in mono. For me it makes it easier tell if there is any difference between the 2 speakers I'm testing. Test for comparison of different tweeters or woofers or midranges.
Thanks (yet again!) for another clear and informative presentation. I find these presentations both educational and enjoyable. Thank you for sharing your knowledge.
Totally agree, I read about this years ago from JA I always start with one speaker , also when emulating crossover design or new equipment amps etc In crossover design I run one of a pair with mod and other standard and flip from one to the other, you can usually tell very fast this way
Wow, great content. One note. The comparison to view something in B/W can not be compared with mono listening. When you change to B/W and miss the color information you'll be possible able to see _some_ kind of artefacts better. But other artefacts will be less or not visible. This will (also) depend on the type of conversion from colors to B/W (where there is not a simple / correct transformation). The correct comparison to mono listening would be to compare a 3D display (with two signals coming to the eyes) compared to looking at a single plane (2D) picture. So with visual we typically already see "mono" ;-)
conclusions? 1- don't use mono speakers while listening to the music - it will/might be horrible 2- stereo speakers might be cheaper to make them as the quality of each speaker is less relevant to the overall product 3- EQ is the worst of all algorithms 4- if the overall blind test is OK, the quality of particular speaker is less relevant - we listen to the music - we don't buy the speakers to measure them did I miss anything? OK, I might have oversimplified it a bit ;-) oh yeap: Amir, you missed one "o" on page 13 in second sentence ;-)
1 - A discrete mono signal from 3 discrete speakers is the most accurate way to listen to stereo music (left + Mono center + right) A single discrete source for each (correctly made) speaker eliminates crosstalk and gives you tight/impactful midbass without a need for EQ ( you cannot accurately restore bass at a nullpoint with an EQ - but you CAN blow your speakers) 2 - speaker quality should be paramount whether you have 1 speaker, 2 speakers, or 3 speakers 3 - An EQ only works "correctly" with discrete signals but ideally is not required in any case
And... I watched the entire video - thanks again, Amir - and I don't recall mention of the hifi audiophile interest in mono-only listening. Mono source, one speaker. Curious what might be the attraction, I experimented with this a bit. High levels of clarity and resolution, and an interesting soundfield. Wide, tall, but no depth and no discrete spacial separation. Mono sounded pretty good. Stereo brought the music into full relief.
Question: is it easier to hear the difference in MP3 and CD quality audio in mono too, if the distraction of stereo is what is making things sound pleasant? Also, point source wise, it's weird to use that phrase to describe something bad, as a point source like the Genelec at the top of the ratings is made to be point source, acoustically tri-axial, but this makes the sound halo wider.
I have not done any mono testing for lossy compression artifacts. So don't know. For a speaker to be perceived as point source, it needs to have a very narrow dispersion. Genelecs are not that.
@@AudioScienceReview Genelec refers to them as The Ones, Ultimate Point Source... They also use nearfield differently. EX: the NFS means near enough to separate the dispersion patters of different drivers, while colloquially nearfield means speakers around arm's length where the direct sound dominates. Or with point source used here it means narrow dispersion, beamy, typically negative for what people want. But with coaxial speakers, it's advertised as a good thing, since their single acoustic center point makes their off axis dispersion better vertically than comparable two or three ways. Love the videos, just wanted to clarify as some may not understand how these words are being used.
So if bad speakers sound good in stereo and you never listen to them in mono, what's your point? If I never listen to them in mono, why should I care about what they sound like in mono? If I only listen in stereo, then how they sound in stereo is the only thing that matters, right?
No. Differences in speakers in stereo is still there, just harder to hear. With experience, you may become better at hearing artifacts of the speaker even when listening in stereo. Also, content can easily be mixed to come out of one speaker more than the other. And in home theater, center speaker is always "mono." Have you seen how people drink water between samples in formal food taste tests? You don't want to say they should not do that because you don't drink water that way. Same here.
I'm wondering if mono listening puts coax concentric designs in a disadvantage, especially those with narrower dispersion like KEFs. Would be interesting to pit the LS50 Meta (objectively a really good speaker) against other speakers and see if it's possible to rise to the top in stereo blind test but plummet when mono. (Never owned a KEF speaker and prefer wide directivity speakers myself)
You gave away 1 of the cash cow concepts behind *Bowzz* :D (the other 1 being DSP corrections of improper hardware, apparently) Thx for the stellar presentation, to me it's vital knowledge, even though not working in such context. But my mind demands it ^^
Hi Amir, not to mention that in a speaker production one company should compare each unit produced to their "reference unit" or, for a lack of better definition, their "master unit". Best Regards,
Agreed. Years ago, working under one of the country's important classical recording engineers, I also learned another technique, EXCEPT on the recording side of this coin: Part of the multiple mic placement decision is to -- in rehearsal -- plug one ear and listen. It will tell you more accurately what the mic will hear. You will not be deceived by the psychoacoustic processing of your brain. It was a practice he developed in monaural recording that he carried over to multiple channels. This might be a reasonable process as a step during a listening test. But, I don't have evidence to show this as hard fact. Just take it as one listening aid. Doing it with both one and two speakers is sure to also show up a lot of listening room issues that your 'head' would disguise. I'd like to hear from trained listeners what this does for their judgment. Trolls needn't apply and are ignored.
Amir you may want to explain how to create a mono source for the testing as combining left and right channels at line level with a Y cable can cause problems and just using the left or right channel will also not be ideal. I think Audacity and other software can create mono files of stereo recordings. How do you create your mono source for testing?
When I first started speaker testing, I created mono files in my Adobe Audition. But then quickly realized that was not necessary. Much of modern music in the last few decades has similar spectrum in both channels so you can just pick one and run with it. I happen to have monoblocks for my stereo system so just leave one amplifier off.
I apologize for my ignorance. I just want some clarity or advice. Should we be testing a single speaker at a time? or pairs of speakers with a mono source? would one way be better than another?
@@AudioScienceReview Thanks, I understand a lot better after I got time to sit down and watch again. The point about combining signal to mono and out of phase information was helpful as well.
One thing you miss is how well the speakers are matched in a stereo set up ie driver frequency response and sensitivity even tolerance in crossover parts and front fabrics if you remove most of them sound better
If that is the case, and your pair varies, how is me testing that helps you? My pair could be different than yours, yes? FYI better companies perform matching to 0.5 dB in manufacturing.
@@AudioScienceReview I am not commenting on my own equipment but 0.5 db matching over all para mantas should be fine but do some measurement and listening tests with or without grilles when you have time
Amir love your stuff. Is there a way you could do some videos of teaching us who have stereos not home cinema to use REW correctly to measure our rooms and also integrating a subwoofer properly using REW measurements ? Also if you could show us step by step to find where to best put acoustic treatment Would very much appreciate it. So many acoustic treatment companies make us over treat our rooms to sell us more of their product and it would be great to figure out from someone unbiased on where there are issues in our rooms and how to properly treat them. Or could we contact you somehow to pay you per hour or however you want for private lessons on all this ? Thank you again!
Thanks for the kind words. Yes, that is on my TODO list. For now, there are a couple of text tutorials I have written on REW: www.audiosciencereview.com/forum/index.php?threads/room-measurement-tutorial-for-dummies-part-1.4/ www.audiosciencereview.com/forum/index.php?threads/room-measurement-tutorial-for-dummies-part-2.5/
@@AudioScienceReview Thanks so much Amir. Yeah I am way beyond those tutorials. Lol. I would say I am a bit above a beginner. I need to know what I am looking at more in detail etc. I am trying to use RTA in REW to better integrate my sub and I don’t know well enough how to read what I am seeing. Pardon for all that. So as the previous responder mentioned. You don’t believe in room absorption beyond the first reflections? Up to what milliseconds are early reflections? And is the reverb after 20ms? Thanks again !
That’s interesting! It pretty much like a listening to the recording in mono during editing. So, are you suggesting that one should consider to do mono audition for speaker at a shop rather than stereo as well?
electrical and mechanical differences between left and right drivers in headphones are most prominent in dynamic drivers A mono sine sweep starting at 20hz will never reach the highest frequency you can hear (if you have normal hearing) before it begins to produce a combing effect and the mono signal begins panning left to right to left to right The panning effect increases with frequency and is found in ALL headphones / meaning that you will NEVER have absolutely perfect stereo imaging at all frequencies The panning effect is far less noticeable on high quality planar magnetic headphones and start at a higher frequency than dynamic drivers Along with frequency response, transient response and distortion levels, the imaging capability of perfectly matched drivers in headphones makes a BIG difference but will never match the positional imaging realism or accuracy of correctly manufactured speakers using discrete signals in 3 speakers from properly decoded stereo information A PAIR of speakers will never sound as good as a high quality and properly decoded 3 channel speaker system Likewise, a pair of headphones can never reproduce the REALISM or imaging accuracy of a high quality and properly decoded 3 channel speaker system
I recorded some „test tracks“ in mono instead of stereo. Otherwise itˋs strange to listen to only the left or right channel. In my opinion the designation „single speaker comparison“ is apt.
I grew up across the street from the NRC in Ottawa. When I got into audio, the better salespeople would talk about the research that was done there. My first good speakers were from Paisley Research and PSB.
Dear Amir. First of all thank you for the time you take to create these very educational videos. There is something that I do not understand in what you explain or I think that it has been misunderstood with respect to what the Stereophonic system is. I really don't understand how it is possible to create a stereo image with a single loudspeaker, I really don't think it's possible, it goes against everything I know and is based on the creation of the stereo image, the works of John William Strutt, the theory of sound and how the brain captures sounds and locates a specific place direction, also the works of engineer Alan Dower Blumlein for the stereo system. And even going to work closer to the ITU itself with Recommendation ITU-R BS.775-3 I can read something that says "Spatial Quality Rating", but I want to understand that it does not refer to a stereo image. Maybe I couldn't understand what you mean, could you give me a better explanation. Thank you
And to add to that, even some studio engeniers test their mix / mastering in mono to pinpoint problems. In the end stereo (for me) is an illusion like 3d movies where for our eyes. Testing mono makes sense
How about some inputs about the review/ paper presentation... 1) how many people were involved in the listening test.. 2) duration of each listening test.. 3) were all " tested speakers " in the approx. same physical position... 4) if seperate groups listened in turns..was there random shuffling of individuals.. 5 ) was listener fatigue considered..? THANKS FOR MANY OF YOUR WONDERFUL & ENLIGHTENED VIEWS & REVIEWS.. you present here👍👍🙏🙏
On the Why Mono Comparison slide, weren't they comparing a stereo SIGNAL (i.e., front mains) with a mono signal played through the front mains? Otherwise, the test's inclusion of surrounds makes no sense.
I have a serious question wouldn't it then make sense to mono compare at least two of same model in order to test for production line consistency so you will know they have the same frequency response thus not messing up the stereo image?
Since headphones isolate each channel for each ear, I have not found this necessary. Indeed I have found headphone characterization much easier than speakers. That said, I do plan to test the idea of mono listening with headphones at some point.
I think people underestimate how satisfying mono listening can be with a great speaker. Often when I am doing testing a great speaker, I continue to listen to them in mono for a long time with much enjoyment to be had.
Brilliant! And although The Beatles Mono mixes are not a great as the final production from Steely Dan's Aja or Donald Fagan's Nightfly, I know how those mixes should sound, and evaluating Studio Monitors or HiFi speakers I will use this methodology even if I have to just crank the balance to Left Stereo or Left Mono. Thank you for sharing this solid science, Amir. I am a believer!
I have done it both ways. As long as you always use one channel, and the content is not heavily panned to one or the other, you don't need to convert to mono. I convert to mono when i have one speaker on the left, and another on the right (e.g. near-field monitors) and want to instantly switch between them. Otherwise when just listening to one speaker, it really doesn't matter. Stereo is of course more convenient because I can just play what is in my library. I just leave the other channel off in my system.
IMHO tests should help us to decide what to bring to our living rooms. It's even more important now when the dealers are disappearing and we are more and more buying stuff online. As such the tests should be as close as possible to real-life situations and "almost" nobody listens to music in mono anymore. So while I understand the methodology of testing the speakers in mono configuration, I think it gives us just a bit of an idea, how a pair would sound in our listening environments. And I'm not talking just about image and sweet spot size, but also about bass coupling and effect of the room in the stereo speaker configuration tonality. But it's just my opinion.
@Douglas Blake Like I said, you're designing a crossover, a new speaker, you need a methodology to test it, and it looks like the mono listening works in these situations. But in our listening rooms, that's about the only place where -stereo- performance matters.
@@adlervictor So you continue to believe that stereo listening is 'better' in spite of the evidence exhibited in the studies? Weird, if you were to talk about any other topic, people would think you're insane or unreasonable. But for some reason it's totally fine to have such opinions in Hi-Fi.
@@abdo-dr1tu I'm not disregarding the value of these tests. I love what Amir is doing, bringing light to the subjectivism that dominates the HiFi world. In my opinion, and I think in a free world, I can have one; this methodology can only tell part of the picture. I totally understand the limitations and the complexity of testing a pair of speakers in stereo, but in the end, it is what the vast majority of us have in our listening rooms. What we have here it the evidence to corroborate the topic. But I'm not alone with this opinion; you can see some other comments or other literature covering the speakers' different performance when evaluated as mono or a stereo pair. The book - Sound Reproduction: Loudspeakers and Rooms - by Floyd Toole - is a good example. Or maybe I'm not just a simple guy.
As I explained in the video, results of mono testing translate to stereo testing. No speaker changes ranks from mono to stereo in controlled tests as presented. Also, there is such thing as center speakers and sounds that only play out of one speaker. For me to test in stereo, it would also heaving drag in my room's design. Surely that is not applicable to your setup. Most important thing is this: you want the most reliable information you can get from a reviewer. To the extent stereo listening heavily reduces the chances of a reviewer hearing the flaws in speaker design, that is NOT the type of data you should seek.
@@AudioScienceReview Thank you for coming here to explain your point of view. Much appreciated. I'm not expecting to see from your reviews the results of a stereo setup in your living room, although even for mono testing, this effect cannot be ignored. My opinion, corroborated by the tests described in the book I've mentioned, is that a poorly rated speaker in a mono test can archive better results when evaluated in a stereo configuration (page 131). Undoubtedly, if the speaker performs well in a mono test, its performance will be equal or better when in a stereo configuration. Anyway, I don't want to make this a big discussion; it's just my opinion that the final verdict is to listen to the setup in our own listening rooms.
I see. Without knowing any science about it before, i was on correct path allready. When doing A vs B testing i connect one speaker to left channel and the other one to right channel. Then turn amp to mono or use mono recording. And i sit between speakers aimed at me from sides, relatively close to them. To hear only one speaker i tilt myself closer to it. That way i can "switch" between speakers fast and i dont forget what i heard. Works best with smaller speakers, where drivers are closer together.
That is how I test near-field monitors. I have one on the left, and another on the right. Then using my workstation software I can play one or the other channel (with content I have converted to mono).
If the improvements in mono listening is not translating to stereo listening, does it mean that the improvement is headed in the wrong direction as the ultimate goal is not mono listening? I.e. may be frequency response is not that important for stereo listening? Why not instead improve on other aspect that would matter in stereo?
Generally, As loudspeakers are minimum phase devices, when using “conventional” EQ which is also comprised of minimum phase filters, when you create the inverse of a magnitude response (level/frequency) anomaly you also, by virtue of the default nature of minimum phase behavior, create the inverse of the time domain anomaly (phase/frequency) that accompanied it. This can be observed often and with great repeatability in rooms, cars, and large outdoor or indoor venues where loudspeakers are used. It is often assumed that “because EQs also shift the phase, this must be a bad thing and negatively impact the time domain behavior of the system being EQ’d”. The reality is, When you EQ or “linearize” or “flatten” the frequency response you have also “flattened” the phase response. In other words, you have improved the time domain behavior, not made it worse. This reality is independent of the fact that a multi-way speaker system has a summed, full bandwidth response that is not in itself a minimum phase response. It is also independent of the fact that room reflections which have acoustically summed with the direct sound from the loudspeaker also can yield non-minimum phase responses. This does not change the fact that using EQ has an equally “flattening” or “corrective” effect on the time domain as it does on the frequency domain.
I do not but as I commented to another poster, I routinely continue enjoying sound from a single speaker that performs well, after I am doing reviewing it. It is remarkable what enjoyment you can have with great music and one well-engineered speaker. Mind you, I suspect stereo would be even nicer but it doesn't exclude a great experience from single speaker listening.
Not sure I agree with you Amir. I can accept testing a single speaker using equipment to measure frequency response, impedance etc. is a valuable endeavour and valid comparisons can be made listening to different single speakers. However, testing two speakers in stereo is an essential part of evaluating performance that can be expected in a home situation. Reproducing the sound stage as the engineer intended can only be done in stereo. Also the width of the sweet spot can only be determined in stereo. These are important aspects of sound reproduction. In my view, testing a single speaker in mono and not testing a stereo pair is an incomplete test of limited value. Might be a good idea to turn down the “I am always right” attitude, it is a bit grateing.
You sound like he insulted you personally or something. All he presented was what Floyd Toole and Sean Olive have proven years ago. Seems to me you didn't even watch the whole video but hurried to dash off a knee jerk reaction response. This was about comparing different speakers and how using only one will help determine which of several sounds better or worse.
@Douglas Blake yeap I agree with you, and about Geoffs words, amir said one does not invalidate the other, he just said listening to one speaker will make your job easier to determine if the speaker is good or not. About his attitude, I think he took the time to study the science, the methods, try to be as objective as possible and he has come to his conclusions and present them to you summarized, conclusions of which he is quite sure about, yet he is human. Do you not agree? Present your evidence, shut him up or just go your own way, does it really matter? I think here in the internet we tend to jump to the other throat when he/she crosses some imaginary line we have created, but in my humble and ignorant opinion, if one does not like the tone or atitude, one can just always move on.
Some speakers are built as left and right pairs with offset tweeters or side firing drivers. If testing only one speaker in mono which speaker do you choose, left or right? A speaker that tests well in mono may have serious imaging problems when used in a stereo pair. Also some speakers are designed to be listened to way off axis. Listening to only one of these speakers firing straight at the listener is of questionable value. Single speaker A May sound better than single speaker B but the opposite may be true when listening to a stereo pair. The video title statement “mono is better” is just not true.
Only now seeing this. It seems to me that the brain's limited capacity to process stimuli has a lot to do with this. Going from mono to stereo and then to multichannel means feeding the brain a lot more to process (if the eardrums can convert all the stimuli to action potentials, that is) and so people are not able to distinguish as well between speakers. IMO this is a good thing: if I'm not able to tell the difference between a good and a (little) better (costing double the price) speaker when listening in stereo or multichannel even if I am A/Bing them, then what are the chances that I would be able to tell the difference when leisurely listening to music and movies? All I have to do is not to do a terrible job choosing my equipment (which is easy having knowledge like this available).
As far as I know, the measurements are made mono - sometimes even for each speaker separately. I don't think correct measurements can be made in stereo.
next time when I go to buy speakers I will ask if I can listen to one so mono. Question: will the amplifier not break if only 1 channel is connected? That will probably be the answer of the shopkeeper, no that is not possible, the amplifier breaks down.
mono testing is nice.... but only if the recording was recorded in mono.... the decades of research you refer to is i believe from the Quad period.. when testing a stereo track nowaday and put it in mono.... you will lose half off the effects due to effects (phase crap) keepink only one channel in tact is no option either since you mis a part of the music...
Only if your content is heavily panned into one channel or the other. With modern music, I find both channels have enough of the music in them to not matter in my testing.
Logistically it is very hard for me to do that as the measurement gear doesn't accommodate a sub sitting next to a speaker. Subs also couple to the room greatly so their response anechoically is not that exciting.
Just imagine that the speaker response is flat till 20hz. Well calibrated subwoofers have great impact on the enjoyment of the speakers. Unless you have giant speakers like amir.
Amir is getting haircut but where since hairdressers are on lockdown. Amir what do think of trinnov 32, it worth throwing it in the cat litter box. As for mono how many home theaters can actually play academy mono. I can it is on my cinema processor. mono denon avc-x8500h can't do it I doubt even trinnov 32 can. Academy mono has certain frequency curve roll-off. I blind listen when I go into the THX cinema the screen may not be used with 4k laser projection all time mostly only the oled sat on the floor below the AT screen. We all used to blind listen when going to the cinema - substandard Dolby vs Dolby THX , what speakers behind the screen and how is it designed behind the screen, blind listening. When most home theatres play a mono movie on bluray 4k they play in dual mono, they forgot to switch the AVR to mono or Dolby pro-logic where the sound will come from there mismatched centre channel and it is going to sound terrible. Well nothing wrong with dual mono is there? Often I play the mono movie switch it though the five screen channels checking imaging tone on the HF horns the bass LF, and all together often for hours. which mono movies. Casablanca Coma Future World Hangar 18 Airport '75 Airport '77 Airport '79 the concorde King Kong
@@AudioScienceReview covid-haircuts are cheap even if they look botched a pair of clippers has saved me hundreds £££ no need to go to a hairdressers again.
One of my favourite quotes is from Admiral Grace Hopper an early pioneer in computing “One accurate measurement is worth a thousand expert opinions”. Dr. Toole understood this and was indeed a pioneer in true loudspeaker research. His book is an excellent wealth of knowledge and well worth reading by all who call themselves audio enthusiasts. Keep up the great videos.
Great line and well said!
When tuning a crossover I always use one speaker and listen at both close and mid distances. This allows me to hear not only the tonal qualities of the crossover better, but also seems to bring out other anomalies such as axial lobing or directivity issues that sometimes don't show up when listening in stereo. (plus it's way easier to alter one crossover at a time and test rather than two)
Thanks for chiming in Greg. I suspect this is true of just about any crossover designer.
I always design crossovers with one speaker. When things are done correctly with one speaker, two speakers in stereo will always sound amazing!
You must have been an excellent teacher, Amir. From one professinal to another, I enjoy your content on an pedagogical level. This needs a like for every view, just for method and presentation
I had experienced excellence of mono testing over stereo by myself some years ago, when began my hi-fi journey. Brought 2 pairs of speakers and amps to my listening room and tried to pick up best. Shuffling them in stereo was a bit difficult physically. And surprisingly discovered, that single speaker listening was very revealing to detect difference between equipment.
Now I know, that I did right)) Thank you Amir!
Ah, wonderful to hear about such first hand experiences!
I'm a simple guy, I see Amir on the screen I hit like.
'Complicated' people do too.
:)
@@jamesdoranto9013 steve guttenberg is simple guy that needs a haircut and shower and change of those loud t-shirts.
@@jamesdoranto9013 Simple and simpleton is completely different.
Do not confuse them.
Amir, FYI that Harman "Single-channel Speaker Shuffler" can shuffle 8 speakers in any combination including shuffling them in stereo pairs. And is used that way too. Also it's driven by pneumatic cylinders (not hydraulic). I worked on that thing circa 2006 to make it operate properly.
You keep reminding me how little I know. But now I’m confused on a higher level. Thanks. Keep up the good work. The Hifi / “audiophile” world needs your posts.
Thanks Poul. You are very kind. I wish this kind of information was more widely available but it isn't. Hopefully we can remedy it with this format.
@@AudioScienceReview keep it up! It is a relief that someone is not just talking about their feelings... still appreciate your short subjective reflections.
@@jungtarcph Speakers/reflections. I see what you did there. 😆
Once again your right. Not knowing all this myself, I occasionally build speakers and I don't have any audio instrumentation so I do everything by ear. And the only way I dial in the crossover is by listening to one speaker, obviously mono. Stereo is really intended to trick the brain so it just complicates speaker optimization. If you get it right in mono it'll be great in stereo.
Super. Great to see others chiming in who have been doing the same. Folks make it sound like I am a unicorn and only one testing in mono. :)
I didn’t realize I wanted this video until I clicked ‘play’ - great idea. This is super useful for even basic speaker shopping
Wonderful. Thanks for watching and commenting Dustin.
Thanks professor! 🙏 I appreciate this. You're helping me become a better reviewer. Excited to have you on this Sunday!
Thanks Joe. See you then!
Just discovered your work and ASR recently. So great! A week ago I started doing mono testing to investigate a problem I'm having with bass in my room. Mono made the comparisons so much easier. I found the culprit (bass resonances audible from a foot away on the speaker!)
Completely and totally agree Amir. The additional sound from another speaker with all of its variations in frequency response, time delays, and phase from the room added to the sound of a single speaker amounts to an interference of the sound from the speaker under test. Also the additional sound from the second speaker psychoacoustically masks to an extent the sound from the speaker under test. It all adds up to too much information. So I am not surprised that people had a much harder time distinguishing sound differences and quality in stereo versus mono. It also shows why the sound quality is less of a concern in home theater with the additional sound effects and the picture distractions.
I ran a test when I worked at CBS's Technology Center in the 1980s that showed a difference in people's localization of sounds with various visual stimuli which showed how people tended to localize sounds towards the video picture when shown versus no picture. Even static images changed the localizations when presented to the subjects. It showed that the additional stimuli modified the perception of sound direction.
So it is much better to limit the distractions of additional sounds and even visuals if you want to reveal the perception of the sound quality of a speaker. Then when listening in stereo or multichannel, just sit back and enjoy the music or movie knowing that you have selected the best speaker for the job based on your best ability to render a judgment of sound quality.
I first heard surround sound while recovering from an operation in hospital. I was captivated by the sound, but this was not a home theatre, it was a rest room in a hospital. It was a cheap system, yet the effect was captivating. Had I heard those speakers in mono I would have realised their limitations, but together they sounded fantastic. As I sat, immersed in the unfolding drama, I was blissfully unaware of their limitations.
@@theterriblepuddle1830 I see your point, but they weaned me off the drugs as part of the recovery process. Shame really, because I quite liked the drugs.
I still have back issues of the original Sound & Vision magazine (Canada), where they were using the NRC facilities and double blind testing and scoring for the speakers they were reviewing. The highest rating I ever saw them give to a stereo pair was the Energy Veritas 2.8 (a score of 7.9), but they had several 5.1 setups that scored higher, the highest being a Sound Dynamics THC-22 based system that was scored an 8.8.
[Edit]
Here's the list if you want it:
S&V Issue/ NRC Fidelity/ Brand/ MSRP/ Model(s)
Home Theatre
02/1997 8.8 Sound Dynamics $1,585 THC-22 main/centre; THR-BP1 surround; THS-1000 sub
09/1996 7.5 PSB $2,600 1000main, Stratus C5 centre, Ambient II surround, Subsonic II sub
08/1996 8.1 Celestion $1,999 Home Theatre in a Box
05/1996 7.1 Cerwin-Vega $2,150 HT-MDC main/centre; HT-S5 surround; HT12-PWR sub
04/1996 8.5 Polk $4,350 RT16 main, CS350-LS centre; LS f/x surround; PSW200 sub
09/1995 8.5 Axiom $700 AX1.2 main/surround; AX1.2 centre, AX120 sub
09/1995 7.2 Monitor Audio $3,197 300 Home Theatre system: 202 main, C300 centre, 302 surround; no sub
02/1995 N/A Bose $2,799 Lifestyle 12 Home Theatre
03/1994 7.1 Cerwin-Vega $1,770 HT-S6 main; HT-CTR centre; HT-S5 surround; HT-12D sub
10/1993 7.3 Paradigm $890 Titan main, CC-200 centre, Atom surround, SB-100 sub
04/1993 7.3 Energy $1,400 Home Theatre system: ESAT-2 main/surround; ECC-1 centre, ESUB-2 sub
Stereo Pair
02/1997 7.4 Acoustic Profiles $999 PSL-8835
04/1996 7.6 Acoustic Profiles $799 PSL-8825
11/1995 7.8 Energy $600 Energy C-2 Connoisseur
11/1995 7.7 Paradigm $360 Mini-Mk3
11/1995 7.8 PSB $1,500 Stratus Silver
09/1995 7.2 Paradigm $450 ADP-150 dipole surround
10/1994 7.5 B&W $4,600 Matrix 802 Series 3
10/1994 7.9 Energy $7,000 Veritas v.2.8
09/1993 7.2 Harman Kardon $3,198 Harman Kardon Sixty
09/1993 7.2 Mirage $500 M-290
07/1993 7.3 Acoustic Profiles $699 PSL 66.2
07/1993 7.3 Paradigm $320 Phantom
04/1993 6.6 KEF $550 K140
04/1993 6.5 Wharfedale $439 Diamond V
02/1992 6.5 Acoustic Research $799 M4
02/1992 7.2 Audiosphere Profile $349 PSL 6.1
02/1992 7.4 Castle $3,660 Winchester
02/1992 7.1 Ethera $2,700 Vitae
02/1992 7.3 Mirage $750 M-490
For comparison, I've owned the Paradigm Phantom and Titan on this list, and both would lose to my current Kanto Yumi's + sub and my former Nuance 330's. The Phantoms were comparatively boxy sounding, and the Titans fatiguingly sibilant.
@@Daniel_Ho_Status_101 Yes, modern speakers sound better than vintage ones. Glad to see that technical progress actually results in better sound for lower cost.
@@johnwright8814 Yes, I think good sound has very much been democratized...as long as you buy a powered or active loudspeaker that's been designed around DSP. I'm not sure if passive loudspeakers really are that much better than even 20 years ago.
@@Daniel_Ho_Status_101 One thing I realised is that directivity control is more important than DSP. I look for the waveguide, which is cheaper than room treatment..
My speaker had mono, we gave it some medication it's doing much better now.
That right there, is a funny line! :)
toooo funny!!! ( :
A Perfect video full of correct information! A single speaker is designed, measured and played with a mono source until the final the design is completed. At that point 2 speakers are used in stereo.
Very interesting, thanks for this information! You are correct, in decades of listening in stores this has never been suggested.
Thanks Amir! Mixing engineers often have a little speaker with a mono signal on the middle of there meterbridge; 'to check on the mid-balance' as they say. Makes a lot more sense now!
Ah, didn't realize that. Good to know!
Another great educational video Amir, kudos to you. Looking forward to seeing the video comparing room correction as you mentioned at 11:33 ;)
I've known many speaker designers who do their design and development work using just one speaker, sort out the sound of that one speaker, then move to two speakers.
This presentation could change the nature of speaker "reviewing." Serious reviewers will do a mono review of the speaker itself.
That's the hope. Will be interesting if they adopt what research says, or do a video saying this is all wrong because they think so!
Very interesting and much needed video Amir. Thanks! It's funny because most audiophiles that like to look at loudspeaker measurements, know that they're taken with a single loudspeaker. But then, when we want to subjectively listen to how a loudspeaker sounds, we do it in stereo; how ironic. Habits we have to change.
Indeed. People readily accept mono measurement but there is so much resistance to the same for listening tests. Our intuition definitely gets in the way.
Speakers are intended to be listened in stereo so unless you're actually developing one, mono listening brings zero benefit to you as you're never going to listen to them in mono anyway. For a speaker designer, mono listening is necessary naturally. But for a speaker shopper, mono listening does not bring any benefit in my opinion. It's the stereo imaging and the whole setup that matters in the end.
Outstanding instructional video! Paradigm shift regarding loudspeaker/monitor evaluation. Thanks, Amir!
Interesting.. Need to test my next speaker(s) in mono first in comparison to the old ones. Keep em coming Amir!
I'm currently reading Dr. Toole's book, and am on chapter 3 which covers this topic. So I watched the video. Thank you for this as it really clarifies what I've been reading.
Thank you for yet another informative and useful video! I am in the process of buying new speakers, so the timing couldn't have been better!
Wonderful.
Thank you very much for "lifting the veil" by sharing with us the beauty of using quantitative methods to analyze and compare audio equipment. So glad I found this awesome corner of the internet!
My pleasure. Thank you for kind remark. Provides the fuel for future videos. :)
Full gratitude for another masterpiece of education, keep it up Amir!
Ah, that is very kind of you Antonio. Thanks for watching and commenting.
Thank you Professor Amir!
Ah, you are very kind. :)
Thanks for sharing. After I've seen this, I tried it on my speakers. I played mono tracks with 1 channel and tweaked the EQ on my Schiit Loki, and I confirm that even slight changes on EQ becomes much obvious.
Found your channel yesterday, already binged all the videos haha
Just a tip for Powerpoint, there is a book icon in the bottom right, which maximizes the powerpoint in the window, without going to fullscreen
I tried that last time but found an issue. I forget what it was. One of them I can fix (it fades out the mouse) but there was another reason I forget. But yes, sorry about putting you all through looking at the full output of PowerPoint. I hate it when others do it but here I am doing it. :)
@@AudioScienceReview Ahh no worries, I can deal with looking at the powerpoint ui in exchange for top tier information :)
@@AudioScienceReview Save the powerpoint as a PDF and open it using a PDF viewer maybe? As a Linux user I have lots of experience avoiding and working around ppt files!
Until I watched this video, I was always bothered that the movie theater in the student union at the Univ. of Az (in Tucson) only had 'only' a single, Altec Lansing "Voice of the Theater" hanging from the front center of the the theater (at least from '77-82). Maybe they were a little ahead of their time. Great job on another informative "audio mythbusting" video!
All published speaker specs are measured in mono using one speaker and one mic in a controlled environment but we quantify those numbers using two speakers and two ears in a different environment.
As I showed in the research, stereo responses do not invalidate mono testing. They are simply harder for listeners to do.
This is actually so simple and makes so much sense. Why did I never think of this before
Totally agreed.
Thank you.
Very informative and useful information. Thanks Amir
You are an excellent teacher
Thanks John. :)
Education is everything. Thank you!
Eyes opened.
I've been building my owns speakers for a few years now and when test them I do an A-B comparison in mono. For me it makes it easier tell if there is any difference between the 2 speakers I'm testing. Test for comparison of different tweeters or woofers or midranges.
Thanks (yet again!) for another clear and informative presentation. I find these presentations both educational and enjoyable. Thank you for sharing your knowledge.
Thanks for watching and kind remarks Peter. Much appreciated.
Totally agree, I read about this years ago from JA I always start with one speaker , also when emulating crossover design or new equipment amps etc
In crossover design I run one of a pair with mod and other standard and flip from one to the other, you can usually tell very fast this way
Wow, great content. One note. The comparison to view something in B/W can not be compared with mono listening. When you change to B/W and miss the color information you'll be possible able to see _some_ kind of artefacts better. But other artefacts will be less or not visible. This will (also) depend on the type of conversion from colors to B/W (where there is not a simple / correct transformation). The correct comparison to mono listening would be to compare a 3D display (with two signals coming to the eyes) compared to looking at a single plane (2D) picture. So with visual we typically already see "mono" ;-)
Another excellent video at Audio Science Review. Thank You!
Wonderful video. Well overdue
conclusions?
1- don't use mono speakers while listening to the music - it will/might be horrible
2- stereo speakers might be cheaper to make them as the quality of each speaker is less relevant to the overall product
3- EQ is the worst of all algorithms
4- if the overall blind test is OK, the quality of particular speaker is less relevant - we listen to the music - we don't buy the speakers to measure them
did I miss anything? OK, I might have oversimplified it a bit ;-)
oh yeap: Amir, you missed one "o" on page 13 in second sentence ;-)
1 - A discrete mono signal from 3 discrete speakers is the most accurate way to listen to stereo music
(left + Mono center + right)
A single discrete source for each (correctly made) speaker eliminates crosstalk and gives you tight/impactful midbass without a need for EQ ( you cannot accurately restore bass at a nullpoint with an EQ - but you CAN blow your speakers)
2 - speaker quality should be paramount whether you have 1 speaker, 2 speakers, or 3 speakers
3 - An EQ only works "correctly" with discrete signals but ideally is not required in any case
@@bullwinklemoose7232 my comment was a joke-like ;-)
Yes! Listening in stereo saves your money because cheaper speakers sound good enough in stereo! :)
Very good review thanks
And... I watched the entire video - thanks again, Amir - and I don't recall mention of the hifi audiophile interest in mono-only listening. Mono source, one speaker. Curious what might be the attraction, I experimented with this a bit. High levels of clarity and resolution, and an interesting soundfield. Wide, tall, but no depth and no discrete spacial separation. Mono sounded pretty good. Stereo brought the music into full relief.
Question: is it easier to hear the difference in MP3 and CD quality audio in mono too, if the distraction of stereo is what is making things sound pleasant?
Also, point source wise, it's weird to use that phrase to describe something bad, as a point source like the Genelec at the top of the ratings is made to be point source, acoustically tri-axial, but this makes the sound halo wider.
I have not done any mono testing for lossy compression artifacts. So don't know. For a speaker to be perceived as point source, it needs to have a very narrow dispersion. Genelecs are not that.
@@AudioScienceReview Genelec refers to them as The Ones, Ultimate Point Source... They also use nearfield differently. EX: the NFS means near enough to separate the dispersion patters of different drivers, while colloquially nearfield means speakers around arm's length where the direct sound dominates.
Or with point source used here it means narrow dispersion, beamy, typically negative for what people want.
But with coaxial speakers, it's advertised as a good thing, since their single acoustic center point makes their off axis dispersion better vertically than comparable two or three ways.
Love the videos, just wanted to clarify as some may not understand how these words are being used.
So if bad speakers sound good in stereo and you never listen to them in mono, what's your point?
If I never listen to them in mono, why should I care about what they sound like in mono? If I only listen in stereo, then how they sound in stereo is the only thing that matters, right?
No. Differences in speakers in stereo is still there, just harder to hear. With experience, you may become better at hearing artifacts of the speaker even when listening in stereo. Also, content can easily be mixed to come out of one speaker more than the other. And in home theater, center speaker is always "mono."
Have you seen how people drink water between samples in formal food taste tests? You don't want to say they should not do that because you don't drink water that way. Same here.
If they are audible in stereo they are identifiable in stereo. If they are inaudible in stereo then they don’t matter
Where do you get mono content? are you converting stereo mixes to mono? How?
I'm wondering if mono listening puts coax concentric designs in a disadvantage, especially those with narrower dispersion like KEFs. Would be interesting to pit the LS50 Meta (objectively a really good speaker) against other speakers and see if it's possible to rise to the top in stereo blind test but plummet when mono. (Never owned a KEF speaker and prefer wide directivity speakers myself)
You gave away 1 of the cash cow concepts behind *Bowzz* :D (the other 1 being DSP corrections of improper hardware, apparently)
Thx for the stellar presentation, to me it's vital knowledge, even though not working in such context. But my mind demands it ^^
Hi Amir, not to mention that in a speaker production one company should compare each unit produced to their "reference unit" or, for a lack of better definition, their "master unit".
Best Regards,
Good point. They certainly don't do any stereo testing in the manufacturing line.
Agreed. Years ago, working under one of the country's important classical recording engineers, I also learned another technique, EXCEPT on the recording side of this coin:
Part of the multiple mic placement decision is to -- in rehearsal -- plug one ear and listen. It will tell you more accurately what the mic will hear. You will not be deceived by the psychoacoustic processing of your brain. It was a practice he developed in monaural recording that he carried over to multiple channels.
This might be a reasonable process as a step during a listening test. But, I don't have evidence to show this as hard fact. Just take it as one listening aid. Doing it with both one and two speakers is sure to also show up a lot of listening room issues that your 'head' would disguise. I'd like to hear from trained listeners what this does for their judgment. Trolls needn't apply and are ignored.
Amir you may want to explain how to create a mono source for the testing as combining left and right channels at line level with a Y cable can cause problems and just using the left or right channel will also not be ideal. I think Audacity and other software can create mono files of stereo recordings. How do you create your mono source for testing?
There's plenty of DAC and DSP which are able to mix mono rendering for both channels. RME ADI-2 DAC Amir owns is one of them.
When I first started speaker testing, I created mono files in my Adobe Audition. But then quickly realized that was not necessary. Much of modern music in the last few decades has similar spectrum in both channels so you can just pick one and run with it. I happen to have monoblocks for my stereo system so just leave one amplifier off.
I apologize for my ignorance. I just want some clarity or advice. Should we be testing a single speaker at a time? or pairs of speakers with a mono source? would one way be better than another?
Single speaker. Content can be just one channel of the music you play. Definitely NOT a pair of speakers.
@@AudioScienceReview Thanks, I understand a lot better after I got time to sit down and watch again. The point about combining signal to mono and out of phase information was helpful as well.
Hi Amir, can you please do a Room correction video, especially including time domain correction. Thanks
One thing you miss is how well the speakers are matched in a stereo set up ie driver frequency response and sensitivity even tolerance in crossover parts and front fabrics if you remove most of them sound better
If that is the case, and your pair varies, how is me testing that helps you? My pair could be different than yours, yes?
FYI better companies perform matching to 0.5 dB in manufacturing.
@@AudioScienceReview I am not commenting on my own equipment but 0.5 db matching over all para mantas should be fine but do some measurement and listening tests with or without grilles when you have time
Where does mono on two speakers fit in here? Is that a good listening test?
No. The purpose is to evaluate speakers individually.
Amir love your stuff. Is there a way you could do some videos of teaching us who have stereos not home cinema to use REW correctly to measure our rooms and also integrating a subwoofer properly using REW measurements ?
Also if you could show us step by step to find where to best put acoustic treatment
Would very much appreciate it.
So many acoustic treatment companies make us over treat our rooms to sell us more of their product and it would be great to figure out from someone unbiased on where there are issues in our rooms and how to properly treat them.
Or could we contact you somehow to pay you per hour or however you want for private lessons on all this ?
Thank you again!
Thanks for the kind words. Yes, that is on my TODO list. For now, there are a couple of text tutorials I have written on REW:
www.audiosciencereview.com/forum/index.php?threads/room-measurement-tutorial-for-dummies-part-1.4/
www.audiosciencereview.com/forum/index.php?threads/room-measurement-tutorial-for-dummies-part-2.5/
@@AudioScienceReview Thanks so much Amir. Yeah I am way beyond those tutorials. Lol. I would say I am a bit above a beginner. I need to know what I am looking at more in detail etc. I am trying to use RTA in REW to better integrate my sub and I don’t know well enough how to read what I am seeing.
Pardon for all that.
So as the previous responder mentioned. You don’t believe in room absorption beyond the first reflections? Up to what milliseconds are early reflections? And is the reverb after 20ms?
Thanks again !
@@Nightjar726 Understood. :) That is the video I plan to do. The challenge is setting it up and capturing the process using video.
@@AudioScienceReview is there any chance you would do private lessons for a fee ?
@Will who is JohnPM? Thank you
That’s interesting! It pretty much like a listening to the recording in mono during editing.
So, are you suggesting that one should consider to do mono audition for speaker at a shop rather than stereo as well?
Does this work for headphones too?
It has to work, assuming you are asking to test them in mono mode.
electrical and mechanical differences between left and right drivers in headphones are most prominent in dynamic drivers
A mono sine sweep starting at 20hz will never reach the highest frequency you can hear (if you have normal hearing) before it begins to produce a combing effect and the mono signal begins panning left to right to left to right
The panning effect increases with frequency and is found in ALL headphones / meaning that you will NEVER have absolutely perfect stereo imaging at all frequencies
The panning effect is far less noticeable on high quality planar magnetic headphones and start at a higher frequency than dynamic drivers
Along with frequency response, transient response and distortion levels, the imaging capability of perfectly matched drivers in headphones makes a BIG difference but will never match the positional imaging realism or accuracy of correctly manufactured speakers using discrete signals in 3 speakers from properly decoded stereo information
A PAIR of speakers will never sound as good as a high quality and properly decoded 3 channel speaker system
Likewise, a pair of headphones can never reproduce the REALISM or imaging accuracy of a high quality and properly decoded 3 channel speaker system
Love your "buh bye" at the end man
I recorded some „test tracks“ in mono instead of stereo. Otherwise itˋs strange to listen to only the left or right channel. In my opinion the designation „single speaker comparison“ is apt.
Makes perfect sense, as is done for sonar transducers.
Ah, good to know!
Great video!
Do you need to only use 1 speaker or can you just listen to Mono content with 2 speakers?
I grew up across the street from the NRC in Ottawa. When I got into audio, the better salespeople would talk about the research that was done there. My first good speakers were from Paisley Research and PSB.
Dear Amir. First of all thank you for the time you take to create these very educational videos.
There is something that I do not understand in what you explain or I think that it has been misunderstood with respect to what the Stereophonic system is.
I really don't understand how it is possible to create a stereo image with a single loudspeaker, I really don't think it's possible, it goes against everything I know and is based on the creation of the stereo image, the works of John William Strutt, the theory of sound and how the brain captures sounds and locates a specific place direction, also the works of engineer Alan Dower Blumlein for the stereo system. And even going to work closer to the ITU itself with Recommendation ITU-R BS.775-3
I can read something that says "Spatial Quality Rating", but I want to understand that it does not refer to a stereo image.
Maybe I couldn't understand what you mean, could you give me a better explanation.
Thank you
And to add to that, even some studio engeniers test their mix / mastering in mono to pinpoint problems. In the end stereo (for me) is an illusion like 3d movies where for our eyes. Testing mono makes sense
How about some inputs about the review/ paper presentation...
1) how many people were involved in the listening test..
2) duration of each listening test..
3) were all " tested speakers " in the approx. same physical position...
4) if seperate groups listened in turns..was there random shuffling of individuals..
5 ) was listener fatigue considered..?
THANKS FOR MANY OF YOUR WONDERFUL & ENLIGHTENED VIEWS & REVIEWS.. you present here👍👍🙏🙏
All of this is included in the papers that I referenced. AES rules don't allow me to quote too much of the papers.
On the Why Mono Comparison slide, weren't they comparing a stereo SIGNAL (i.e., front mains) with a mono signal played through the front mains? Otherwise, the test's inclusion of surrounds makes no sense.
If I understand your question, no, when testing mono, only one speaker is playing.
This why is i put you reviews above others, no one else is doing this and its frustratingly dumb.
I have a serious question
wouldn't it then make sense to mono compare at least two of same model in order to test for production line consistency so you will know they have the same frequency response thus not messing up the stereo image?
Yes
Thanks Amir!
A question: would you say one should test headphones also in Mono by switching one side off?
Since headphones isolate each channel for each ear, I have not found this necessary. Indeed I have found headphone characterization much easier than speakers. That said, I do plan to test the idea of mono listening with headphones at some point.
I've been designing a speaker, and have been enjoying listening to music in mono...
I think people underestimate how satisfying mono listening can be with a great speaker. Often when I am doing testing a great speaker, I continue to listen to them in mono for a long time with much enjoyment to be had.
Makes perfect sense to me. How can one listen to how a speaker sounds if you have two playing at the same time?
Brilliant! And although The Beatles Mono mixes are not a great as the final production from Steely Dan's Aja or Donald Fagan's Nightfly, I know how those mixes should sound, and evaluating Studio Monitors or HiFi speakers I will use this methodology even if I have to just crank the balance to Left Stereo or Left Mono. Thank you for sharing this solid science, Amir. I am a believer!
Is the music summed to mono in these listening tests?
I have done it both ways. As long as you always use one channel, and the content is not heavily panned to one or the other, you don't need to convert to mono. I convert to mono when i have one speaker on the left, and another on the right (e.g. near-field monitors) and want to instantly switch between them. Otherwise when just listening to one speaker, it really doesn't matter. Stereo is of course more convenient because I can just play what is in my library. I just leave the other channel off in my system.
IMHO tests should help us to decide what to bring to our living rooms. It's even more important now when the dealers are disappearing and we are more and more buying stuff online. As such the tests should be as close as possible to real-life situations and "almost" nobody listens to music in mono anymore. So while I understand the methodology of testing the speakers in mono configuration, I think it gives us just a bit of an idea, how a pair would sound in our listening environments. And I'm not talking just about image and sweet spot size, but also about bass coupling and effect of the room in the stereo speaker configuration tonality. But it's just my opinion.
@Douglas Blake Like I said, you're designing a crossover, a new speaker, you need a methodology to test it, and it looks like the mono listening works in these situations. But in our listening rooms, that's about the only place where -stereo- performance matters.
@@adlervictor So you continue to believe that stereo listening is 'better' in spite of the evidence exhibited in the studies?
Weird, if you were to talk about any other topic, people would think you're insane or unreasonable. But for some reason it's totally fine to have such opinions in Hi-Fi.
@@abdo-dr1tu I'm not disregarding the value of these tests. I love what Amir is doing, bringing light to the subjectivism that dominates the HiFi world. In my opinion, and I think in a free world, I can have one; this methodology can only tell part of the picture. I totally understand the limitations and the complexity of testing a pair of speakers in stereo, but in the end, it is what the vast majority of us have in our listening rooms. What we have here it the evidence to corroborate the topic. But I'm not alone with this opinion; you can see some other comments or other literature covering the speakers' different performance when evaluated as mono or a stereo pair. The book - Sound Reproduction: Loudspeakers and Rooms - by Floyd Toole - is a good example.
Or maybe I'm not just a simple guy.
As I explained in the video, results of mono testing translate to stereo testing. No speaker changes ranks from mono to stereo in controlled tests as presented. Also, there is such thing as center speakers and sounds that only play out of one speaker. For me to test in stereo, it would also heaving drag in my room's design. Surely that is not applicable to your setup.
Most important thing is this: you want the most reliable information you can get from a reviewer. To the extent stereo listening heavily reduces the chances of a reviewer hearing the flaws in speaker design, that is NOT the type of data you should seek.
@@AudioScienceReview Thank you for coming here to explain your point of view. Much appreciated. I'm not expecting to see from your reviews the results of a stereo setup in your living room, although even for mono testing, this effect cannot be ignored. My opinion, corroborated by the tests described in the book I've mentioned, is that a poorly rated speaker in a mono test can archive better results when evaluated in a stereo configuration (page 131). Undoubtedly, if the speaker performs well in a mono test, its performance will be equal or better when in a stereo configuration. Anyway, I don't want to make this a big discussion; it's just my opinion that the final verdict is to listen to the setup in our own listening rooms.
I'll give alot of the new guys a hint I was given, ( Zero Fidelity) Tone is really the factor I want to include when choosing new equip.
I see. Without knowing any science about it before, i was on correct path allready. When doing A vs B testing i connect one speaker to left channel and the other one to right channel. Then turn amp to mono or use mono recording. And i sit between speakers aimed at me from sides, relatively close to them. To hear only one speaker i tilt myself closer to it. That way i can "switch" between speakers fast and i dont forget what i heard. Works best with smaller speakers, where drivers are closer together.
That is how I test near-field monitors. I have one on the left, and another on the right. Then using my workstation software I can play one or the other channel (with content I have converted to mono).
If the improvements in mono listening is not translating to stereo listening, does it mean that the improvement is headed in the wrong direction as the ultimate goal is not mono listening? I.e. may be frequency response is not that important for stereo listening? Why not instead improve on other aspect that would matter in stereo?
Improvements do apply to stereo listening. It simply is the case that as humans, we are worse at comparing speakers in stereo versus mono.
It would be instructive if you could comment on the time domain impacts of equalization when correcting frequency domain anomalies.
Generally,
As loudspeakers are minimum phase devices, when using “conventional” EQ which is also comprised of minimum phase filters, when you create the inverse of a magnitude response (level/frequency) anomaly you also, by virtue of the default nature of minimum phase behavior, create the inverse of the time domain anomaly (phase/frequency) that accompanied it.
This can be observed often and with great repeatability in rooms, cars, and large outdoor or indoor venues where loudspeakers are used.
It is often assumed that “because EQs also shift the phase, this must be a bad thing and negatively impact the time domain behavior of the system being EQ’d”. The reality is, When you EQ or “linearize” or “flatten” the frequency response you have also “flattened” the phase response. In other words, you have improved the time domain behavior, not made it worse.
This reality is independent of the fact that a multi-way speaker system has a summed, full bandwidth response that is not in itself a minimum phase response. It is also independent of the fact that room reflections which have acoustically summed with the direct sound from the loudspeaker also can yield non-minimum phase responses. This does not change the fact that using EQ has an equally “flattening” or “corrective” effect on the time domain as it does on the frequency domain.
This process is used by many also when mixing and mastering tracks.
Very similar observation with 3D in cinematography, the brain is easily fooled :-) The illusions of delayed signals...
Ah yes!
What speakers were used in the study from the 80s?
I am pretty sure they did not say.
Completely agree. Mono
Thanks. I can go to sleep now knowing the comments are going to go the right direction. :)
I always test in Mono - its just more clear whats going on.
Do you have any favorite tracks/albums in mono? For just enjoyment?
I do not but as I commented to another poster, I routinely continue enjoying sound from a single speaker that performs well, after I am doing reviewing it. It is remarkable what enjoyment you can have with great music and one well-engineered speaker. Mind you, I suspect stereo would be even nicer but it doesn't exclude a great experience from single speaker listening.
@@AudioScienceReview Would this be even more truthful regarding listening to just one omni speaker? Thank you for your reply in advance, Amirm.
Not sure I agree with you Amir. I can accept testing a single speaker using equipment to measure frequency response, impedance etc. is a valuable endeavour and valid comparisons can be made listening to different single speakers. However, testing two speakers in stereo is an essential part of evaluating performance that can be expected in a home situation. Reproducing the sound stage as the engineer intended can only be done in stereo. Also the width of the sweet spot can only be determined in stereo. These are important aspects of sound reproduction. In my view, testing a single speaker in mono and not testing a stereo pair is an incomplete test of limited value. Might be a good idea to turn down the “I am always right” attitude, it is a bit grateing.
@Douglas Blake imaging and soundstage can be measured in headphones it's not just source file mastering and recording thing...
You sound like he insulted you personally or something. All he presented was what Floyd Toole and Sean Olive have proven years ago. Seems to me you didn't even watch the whole video but hurried to dash off a knee jerk reaction response. This was about comparing different speakers and how using only one will help determine which of several sounds better or worse.
@Douglas Blake yeap I agree with you, and about Geoffs words, amir said one does not invalidate the other, he just said listening to one speaker will make your job easier to determine if the speaker is good or not. About his attitude, I think he took the time to study the science, the methods, try to be as objective as possible and he has come to his conclusions and present them to you summarized, conclusions of which he is quite sure about, yet he is human. Do you not agree? Present your evidence, shut him up or just go your own way, does it really matter? I think here in the internet we tend to jump to the other throat when he/she crosses some imaginary line we have created, but in my humble and ignorant opinion, if one does not like the tone or atitude, one can just always move on.
@Douglas Blake my friends and I we usually joke saying "some people just don't wank enough" 😂
Some speakers are built as left and right pairs with offset tweeters or side firing drivers. If testing only one speaker in mono which speaker do you choose, left or right? A speaker that tests well in mono may have serious imaging problems when used in a stereo pair. Also some speakers are designed to be listened to way off axis. Listening to only one of these speakers firing straight at the listener is of questionable value. Single speaker A May sound better than single speaker B but the opposite may be true when listening to a stereo pair. The video title statement “mono is better” is just not true.
Only now seeing this. It seems to me that the brain's limited capacity to process stimuli has a lot to do with this. Going from mono to stereo and then to multichannel means feeding the brain a lot more to process (if the eardrums can convert all the stimuli to action potentials, that is) and so people are not able to distinguish as well between speakers. IMO this is a good thing: if I'm not able to tell the difference between a good and a (little) better (costing double the price) speaker when listening in stereo or multichannel even if I am A/Bing them, then what are the chances that I would be able to tell the difference when leisurely listening to music and movies? All I have to do is not to do a terrible job choosing my equipment (which is easy having knowledge like this available).
Do you test peoples personal equipment?
As far as I know, the measurements are made mono - sometimes even for each speaker separately.
I don't think correct measurements can be made in stereo.
Very true. Sometimes for in-room EQ people measure bass with both speakers playing but that domain is a function of the room more than the speaker.
next time when I go to buy speakers I will ask if I can listen to one so mono. Question: will the amplifier not break if only 1 channel is connected? That will probably be the answer of the shopkeeper, no that is not possible, the amplifier breaks down.
Indeed simpel, disconnect one channel of the input.
Nice work
I'll try mono next time!
mono testing is nice.... but only if the recording was recorded in mono.... the decades of research you refer to is i believe from the Quad period.. when testing a stereo track nowaday and put it in mono.... you will lose half off the effects due to effects (phase crap) keepink only one channel in tact is no option either since you mis a part of the music...
For this type of testing with one speaker should you mix your stereo music back to mono then?
Only if your content is heavily panned into one channel or the other. With modern music, I find both channels have enough of the music in them to not matter in my testing.
I'm OK with Mono, but I wish "we" could measure speakers with subwoofers to see the benefit.
Logistically it is very hard for me to do that as the measurement gear doesn't accommodate a sub sitting next to a speaker. Subs also couple to the room greatly so their response anechoically is not that exciting.
Just imagine that the speaker response is flat till 20hz. Well calibrated subwoofers have great impact on the enjoyment of the speakers. Unless you have giant speakers like amir.
Amir is getting haircut but where since hairdressers are on lockdown. Amir what do think of trinnov 32, it worth throwing it in the cat litter box.
As for mono how many home theaters can actually play academy mono. I can it is on my cinema processor. mono denon avc-x8500h can't do it I doubt even trinnov 32 can.
Academy mono has certain frequency curve roll-off.
I blind listen when I go into the THX cinema the screen may not be used with 4k laser projection all time mostly only the oled sat on the floor below the AT screen. We all used to blind listen when going to the cinema - substandard Dolby vs Dolby THX , what speakers behind the screen and how is it designed behind the screen, blind listening.
When most home theatres play a mono movie on bluray 4k they play in dual mono, they forgot to switch the AVR to mono or Dolby pro-logic where the sound will come from there mismatched centre channel and it is going to sound terrible. Well nothing wrong with dual mono is there?
Often I play the mono movie switch it though the five screen channels checking imaging tone on the HF horns the bass LF, and all together often for hours.
which mono movies.
Casablanca
Coma
Future World
Hangar 18
Airport '75
Airport '77
Airport '79 the concorde
King Kong
Ah, you noticed! I forced my poor wife to give another covid haircut. It has been that way for over a year now.
@@AudioScienceReview covid-haircuts are cheap even if they look botched a pair of clippers has saved me hundreds £££ no need to go to a hairdressers again.
So convincing, now reviewing speakers in stereo does make much less sense.