Speaker/Room Measurement Witchcraftery

[Tony L]

According to audioscience review these are typical of the tracks Toole uses

· Tracy Chapman, "Fast Car", Tracy Chapman
· Jennifer Warnes, "Bird on a Wire", Famous Blue Rain Coat
· James Taylor "That's Why I'm Here", “That’s Why I’m Here”
· Steely Dan “Cousin Dupree”, “ Two Against Nature”
· Paula Cole, “Tiger”,” This Fire”
· “Toy Soldier March”, Reference Recording
· Pink Noise (uncorrelated)

Mostly heavily “produced” and processed music with no objective reference - No speech, no opera, one classical piece, no choral music, the only acoustic piece - James Taylor - is most likely processed.. choose your colouration.

Interrsting point. Aside from the last two all close-mic’d studio recordings with added FX, i.e. ‘multi-track panned mono’. Don’t get me wrong, I like a few of the songs, but I’d far prefer to assess using a well recorded solo piano, string quartet or acoustic jazz recording.

Have you heard Quad electrostatics, or any other electrostatics?

I’ve been involved with HiFi for 40 years. I still can’t think of a speaker that would do better in a live vs recorded test of human speech.

Like the Martin Logans they would have been dismissed as they weren’t suitable for Harman’s very rigid test location. It is not a reference I would refer to, in fact far more can be learned from a copy of Gilbert Briggs’ wonderful ‘Loudspeakers’ book of the late 50s IMHO!

 

[tuga]

I think you also need to be careful what you conclude from Tooles work. He used trained subjects - a cynic might argue they were trained to prefer speakers designed by Tooles parent company - and he investigates their preferences. This is relevant if you are interested in marketing loudspeakers, but less relevant if you are interested in the accuracy of a transducer. The BBC for example would use natural, coloration free speech reproduction and intelligibility as a prime criteria for evaluating a loudspeaker, which would quite likely produce a completely different preferred loudspeaker from the kind preferred by Tooles listeners. I don’t think Toole even used speech reproduction in his tests. Tooles tests are more like the taste panels that Marks and Spencer’s use, and have the same weaknesses. If you really think Marks and Spencer’s lasagne is any good, or even food, well.. what more can I say.

I've taken this from one of the BBC Research Department's white papers:

ON THE DESIGN OF LOUDSPEAKERS FOR BROADCAST MONITORING
C.D. Mathers 1988 Jan
Report 1988-14
https://www.bbc.co.uk/rd/publications/rdreport_1988_14

9 LOUDSPEAKER EVALUATION

9.1 introduction
The obvious and definitive means of evaluating a loudspeaker is of course by listening to it.
An expert listener auditioning known programme material can learn a great deal from a listening test.
If all of the sound balancers who use a particular loudspeaker declare it to be excellent, then by definition it is excellent.
In the author's experience at least, such universal approbation is rare.
Although a group of users in an organisation like the BBC usually show remarkable accord in their evaluations, they tend to use adjectives like 'woolly, ‘hard’, or ‘chesty’, and nouns like 'honk', 'quack', or ‘lisp’.
One can often hear what they refer to, but such quirks can rarely be identified by objective measurement, and are very poor guides indeed to any design modifications that might effect significant tonal improvements.
(Very rarely, complimentary expressions like 'clean' or 'uncoloured' are applied; perhaps one reason for the rarity of these is that a perfect loudspeaker should presumably have no perceptible characteristics of its own.)

What is required, of course, is a well-defined relationship between subjective peculiarities, measurable deviations from 'ideal' acoustic output, and oddities in physical behaviour.
A 'dreadful quack at 800 Hz' should be confirmed by a disturbance in the otherwise serene acoustic time-frequency-acceptability plot, and by an agonised writhing at 800 Hz to disturb the otherwise exemplary piston-like movement of the diaphragm.

Reality is otherwise.
'Good' loudspeaker drive units appear to exhibit just as complex mechanical and acoustic behaviour as 'bad' ones.
The author is currently engaged in a project to try to find some relationship between the subjective, acoustic, and mechanical facets of loudspeaker behaviour.
This has been undertaken in the knowledge that previous attempts during four decades have not yielded a final solution.
Results (positive or negative) will be published in due course.
Two reference works only are listed relating to this subject, each includes an extensive bibliography.

9.2 Subjective evaluation
Experience shows that comparative judgements of loudspeaker quality can be made more consistently than absolute ones.
An absolute assessment of a new design is something which emerges gradually out of weeks or months of use in control rooms.
Often, a pair of new loudspeakers sent out for 'field trial' will be received with cautious approval, yet returned after a month or two with a list of criticisms detailing points that have emerged only gradually from continuos use.
For comparative tests, a reference loudspeaker is of course needed.
This is provisionally selected during the early stages of commercial production as being a typical unit of acceptable quality; once production is well established, a new reference may be adopted as a clearer picture emerges of what is 'typical'.
In fact, at least three such units are selected in normal BBC practice, to provide a working standard for acceptance testing: a spare (which is carefully stored): and a standard by which the manufacturers can assess the consistency of their output, whether by listening or by measurement.
An established standard is also of course the only reasonable reference available in appraising a new design.

In listening tests, it is important that the listener should begin with as few preconceived ideas as possible.
For example, a look at a response plot may cause him, consciously or otherwise, to listen for some expected peculiarities. Normally, an A/B switch is provided, and the loudspeaker to be used as reference is indicated.
The loudspeakers are placed behind an acoustically transparent but optically opaque curtain, especially if any aspect of the units under test might be visually identifiable.
To help eliminate room effects, the test may be repeated with the loudspeaker positions interchanged.
If several units are to be tested, it is useful to include one twice — anonymously — to test the listener's consistency.
(Experienced listeners expect this.)

Finally, it is essential that the listener delivers his judgement before any additional information is given to him; not (one would trust) that he might 'cheat', but rather that he might re-interpret what he thought he had heard in the light of further knowledge.
Subsequent discussion may well prove valuable, but must be subsequent.

Formal tests involving a number of listeners may need further care, particularly if, as is likely, they permit less in the way of personal communication between subjects and test organiser.
Past experience suggests that a particular hazard is the use of descriptive terms whose meaning seems obvious to everyone, but which can actually mean different things to different people.

 

[ToTo Man]

The BBC for example would use natural, coloration free speech reproduction and intelligibility as a prime criteria for evaluating a loudspeaker, which would quite likely produce a completely different preferred loudspeaker from the kind preferred by Tooles listeners. I don’t think Toole even used speech reproduction in his tests.

The approach of voicing speakers for accurate reproduction of the human voice intrigues me. On the face of it, it makes a lot of sense. However, what is used as a reference during the voicing process, and how well is the end listener able to judge whether the voicing has been a success? The human voice is arguably the most harmonically complex instrument we know of, and no two voices are the same, so unless the same vocalist that's been recorded and replayed through the speaker is also there in the flesh at the demonstration to give the listeners an authentic reference for comparison, then the evaluation is ultimately flawed is it not?

If loudspeaker designers or end-listeners aren't using the human voice (as in an actual person being present in the room) as a reference, then what is being used? A recording of a live, unamplified vocal that is subject to the technical limitations of the microphone used to make the recording and its placement? A vocal recording made in the studio that is subject to the former plus whatever artistic EQ and other effects have been applied? A recording of a radio broadcast announcer* that again depends on the mic used, the proximity of the announcer to the mic, and any compression etc that's been applied? There are many variables here that can pull you further and further away from the human voice in its rawest/purest state.

* Off-topic, but why do announcers on radio invariably sound larger than life, with males having a boomy lower registers and females displaying accentuated sibilants/consonants? Is it purely down to close-mic placement and compression, or do they EQ it is well? Whatever the cause, it sounds unnatural IMO.

 

[camverton]

What differences? What vocabulary did they have to describe speech reproduction for example? Over and over again Tooles work is being used on this thread and forum as some kind of authority for listener preferences, but it’s a Marks and Sparks taste test at the end of the day. Did they even test for accurate stereo imagery, like the BBC used to, a test that is quite simple, repeatable and objective?

According to audioscience review these are typical of the tracks Toole uses

· Tracy Chapman, "Fast Car", Tracy Chapman
· Jennifer Warnes, "Bird on a Wire", Famous Blue Rain Coat
· James Taylor "That's Why I'm Here", “That’s Why I’m Here”
· Steely Dan “Cousin Dupree”, “ Two Against Nature”
· Paula Cole, “Tiger”,” This Fire”
· “Toy Soldier March”, Reference Recording
· Pink Noise (uncorrelated)

Mostly heavily “produced” and processed music with no objective reference - No speech, no opera, one classical piece, no choral music, the only acoustic piece - James Taylor - is most likely processed.. choose your colouration.

I had forgotten about the recordings used, but at least the listeners heard the Martin Logan’s, however poorly set up, albeit with recordings that didn’t show them at their best.

I used to think that a good speaker should be good with all types of music. My experience with the Dutch&Dutch 8Cs has changed my mind. For rock and pop and ‘manufactured in the studio’ types of recordings my preference would be for the Dutch&Dutch to the extent that if the majority of my listening were for that sort of music I would have bought them in a heartbeat from Lee. I’m still thing of getting a pair of D&D for an upstairs room for my occasional forays in to Cream, LED Zep and King Crimson etc. Most of my listening, however, is to classical chamber music and for that genre my MBLs worked much better for me, as do a pair of Martin Logan’s that I still have in use in another room. I was wrong, different genres are best served by different types of speakers (IMO revised!). Perhaps Quad realised this as I have a brochure for Quad showing classical musicians with their Quad electrostatics, including a youngish Bernard Haitink.

The important thing in these threads is that we weight our response to those posts that describe speakers, properly set up, that have actually been heard, from those whose performance has been assumed from flawed tests or measurements.

 

[cooky1257]

I have a great deal of respect for Toole in general but Martin Logan’s are sufficiently different in the way they operate to make comparisons invalid when treated in the same way as speakers that do meet his definition of a good speaker. It seems reasonable to me that if making subjective comparisons of speakers than each speaker should be set up as the designer intended. If not then some speakers will have an unfair advantage and could lead to what some may see as a self fulfilling prophecy. In much the same way comparison of measurements of conventional and dipole s

Speaker models were hidden. He wasn't trying to find the 'best' speaker, 'unfair advantage' is just ludicrous. You're missing the point again.

 

[camverton]

The approach of voicing speakers for accurate reproduction of the human voice intrigues me. On the face of it, it makes a lot of sense. However, what is used as a reference during the voicing process, and how well is the end listener able to judge whether the voicing has been a success? The human voice is arguably the most harmonically complex instrument we know of, and no two voices are the same, so unless the same vocalist that's been recorded and replayed through the speaker is also there in the flesh at the demonstration to give the listeners an authentic reference for comparison, then the evaluation is ultimately flawed is it not?

If loudspeaker designers or end-listeners aren't using the human voice (as in an actual person being present in the room) as a reference, then what is being used? A recording of a live, unamplified vocal that is subject to the technical limitations of the microphone used to make the recording and its placement? A vocal recording made in the studio that is subject to the former plus whatever artistic EQ and other effects have been applied? A recording of a radio broadcast announcer* that again depends on the mic used, the proximity of the announcer to the mic, and any compression etc that's been applied? There are many variables here that can pull you further and further away from the human voice in its rawest/purest state.

* Off-topic, but why do announcers on radio invariably sound larger than life, with males having a boomy lower registers and females displaying accentuated sibilants/consonants? Is it purely down to close-mic placement and compression, or do the EQ it is well? Whatever the cause, it sounds unnatural IMO.

Interesting points except that Radio 3 presenters don’t seem to suffer from this on my MBLs or Logan’s! Can anyone remember which speaker manufacturer played a musical instrument at shows which then went to a reproduction through their speakers demonstrating how close the real sound was to the sound through the speakers?

 

[camverton]

Speaker models were hidden. He wasn't trying to find the 'best' speaker, 'unfair advantage' is just ludicrous. You're missing the point again.

Sorry not to agree with you but I am not missing the point. Have you listened to dipoles both set up poorly and well, and have you set them up for optimum performance?

 

[cooky1257]

Sorry not to agree with you but I am not missing the point. Have you listened to dipoles both set up poorly and well, and have you set them up for optimum performance?

He says still missing the point. What has that got to do with anything? You need to get over the fact that the ML's weren't positioned optimally-their response was all over the shop and this was confirmed by their less than stellar preference rating in Toole's tests. I have no doubt had the ML's been positioned better their in room response would've been 'better' ie close(r) to the subsequently averaged response preference established from the tests. They weren't a magazine style speakers tests rather it was designed to try to establish a listener preference for certain in room response/behaviours.

 

[camverton]

I don’t really feel the need to get over anything. If you are going to discuss whether or not the test methodology was appropriate for Logan’s it helps if you have experience of them upon which to base your view. Can you not see that? In the grand scheme of things Toole’s views of Martin Logan’s isn’t really that important, just a bit of a shame that people use those tests to make a point without experience of just how good they can sound when properly set up. Not for all tastes, agreed, but I have nothing to “get over”.

 

[AndyU]

The approach of voicing speakers for accurate reproduction of the human voice intrigues me. On the face of it, it makes a lot of sense. However, what is used as a reference during the voicing process, and how well is the end listener able to judge whether the voicing has been a success? The human voice is arguably the most harmonically complex instrument we know of, and no two voices are the same, so unless the same vocalist that's been recorded and replayed through the speaker is also there in the flesh at the demonstration to give the listeners an authentic reference for comparison, then the evaluation is ultimately flawed is it not?

If loudspeaker designers or end-listeners aren't using the human voice (as in an actual person being present in the room) as a reference, then what is being used? A recording of a live, unamplified vocal that is subject to the technical limitations of the microphone used to make the recording and its placement? A vocal recording made in the studio that is subject to the former plus whatever artistic EQ and other effects have been applied? A recording of a radio broadcast announcer* that again depends on the mic used, the proximity of the announcer to the mic, and any compression etc that's been applied? There are many variables here that can pull you further and further away from the human voice in its rawest/purest state.

* Off-topic, but why do announcers on radio invariably sound larger than life, with males having a boomy lower registers and females displaying accentuated sibilants/consonants? Is it purely down to close-mic placement and compression, or do the EQ it is well? Whatever the cause, it sounds unnatural IMO.

The BBC guys I knew had a whole shared vocabulary for describing colourations in speech reproduction - cuppy, boomy, nasal, sibilant and so on. There were even gestures to go along with each coloration, so that a speaker could be described - or dismissed - with a mere hand movement. Some colourations are easy enough to hear whether you know the voice or not. You yourself talk about boominess and sibilance. If you listen to a choir you can read the score and you know what the voices should be singing. You can ask yourself whether you can hear them. The ability to resolve inner detail and timbre is extremely important to people who listen to classical music. The BBC will have more ability than most to compare live to recorded sound. Obviously the BBC place a premium on the natural reproduction of human voice, and so value uncoloured loudspeakers like ESLs and LS3/5As which may well be hopeless if (like some of Harmans target audience) you want to listen to apocalyptic earthquakes in an AV system. I don't think it is the case that good speakers are voiced for the accurate reproduction of human voice, I think it is the case that a good speaker will just happen to accurately reproduce the human voice, and listeners like me will place particular value on that as well as expecting a small, well defined central image from a mono recording of a voice. If a stereo can't do that, it can't do a string quartet, a choir, or an orchestra. Someone who is into EDM won't really give a toss. They'll want subsonic punch and brain frying high end. Someone who wants to listen to heavy metal will likely prefer JBLs to ESLs, and for good reason. So preference for a speaker is not an absolute, and someone like me is more likely to respect the kind of listening tests the BBC do than the kind of listening tests Harman do. Harman test for preferences, like Marks and Sparks test chicken kebabs. The beeb test for accuracy on some parameters.

As to why your radio announcers sound boomy and sibilant and larger than life .. well, maybe it is your speakers! Sibilance often indicates problems at the crossover, or a hot tweeter, boominess might be down to a badly damped port or cabinet. Try listening on some LS3/5As, or ATCs, or Quads ...

 

[Ayya Khema]

I don’t really feel the need to get over anything. If you are going to discuss whether or not the test methodology was appropriate for Logan’s it helps if you have experience of them upon which to base your view. Can you not see that? In the grand scheme of things Toole’s views of Martin Logan’s isn’t really that important, just a bit of a shame that people use those tests to make a point without experience of just how good they can sound when properly set up. Not for all tastes, agreed, but I have nothing to “get over”.

amen

but Toole is now the reference for sellers trying to promote their speakers that ressemble anything like harman ( waveguide, controlled directivity), etc

 

[poco a poco]

" Can anyone remember which speaker manufacturer played a musical instrument at shows which then went to a reproduction through their speakers demonstrating how close the real sound was to the sound through the speakers?"

Bowers & Wilkins (B&W). I can't remember against which speakers (maybe DM6's) but they were demonstrated against a very competent clarinetist who I think also worked got them? I don't remember being very convinced though? I think it was really all a bit of 'well organised hype', expectation bias. Tell people they are not going to hear much difference and they don't. If I remember if I closed my eyes so that you did not see the musician standing between the speakers then it was not very convincing and you could hear the change over.

Ho and I owned B&W DM2A's at the times so I did think their speakers were good - just not quite that good.

 

[Purité Audio]

amen

but Toole is now the reference for sellers trying to promote their speakers that ressemble anything like harman ( waveguide, controlled directivity), etc

Harman developed loudspeakers based on the research started by Toole when he was at the NRC, I can’t think of any serious, ie one who measures manufacturer who has not adopted the flat on axis, smooth,even mirrors off axis approach, apart from the legacy manufacturers whose customer demographic precludes them from innovation.
Keith

 

[camverton]

Ah, it wasn’t a pair of DM70s was it? IIRC the ones with the electrostatic panel on the top of the bass cabinet. The “European” version looked very stylish. I always fancied a pair of those speakers. Having just left college I had to settle for their two way bottom of the range model. DM10?

 

[March Audio]

I had forgotten about the recordings used, but at least the listeners heard the Martin Logan’s, however poorly set up, albeit with recordings that didn’t show them at their best.

I used to think that a good speaker should be good with all types of music. My experience with the Dutch&Dutch 8Cs has changed my mind. For rock and pop and ‘manufactured in the studio’ types of recordings my preference would be for the Dutch&Dutch to the extent that if the majority of my listening were for that sort of music I would have bought them in a heartbeat from Lee. I’m still thing of getting a pair of D&D for an upstairs room for my occasional forays in to Cream, LED Zep and King Crimson etc. Most of my listening, however, is to classical chamber music and for that genre my MBLs worked much better for me, as do a pair of Martin Logan’s that I still have in use in another room. I was wrong, different genres are best served by different types of speakers (IMO revised!). Perhaps Quad realised this as I have a brochure for Quad showing classical musicians with their Quad electrostatics, including a youngish Bernard Haitink.

The important thing in these threads is that we weight our response to those posts that describe speakers, properly set up, that have actually been heard, from those whose performance has been assumed from flawed tests or measurements.

So they have to be in the precisely the right place, with the listener in precisely the right place, in a room with precisely the right amount of reflectivity and now playing the right kind of recording......

Does moon phase have an impact? Which is best, 1/4 1/2 3/4 or full?

 

[Ayya Khema]

Harman developed loudspeakers based on the research started by Toole when he was at the NRC, I can’t think of any serious, ie one who measures manufacturer who has not adopted the flat on axis, smooth,even mirrors off axis approach, apart from the legacy manufacturers whose customer demographic precludes them from innovation.
Keith

flat FR and smooth off axis was not invented by toole.
serious manufacturers have tried to attain as flat as possible FR for decades now

your point being?

 

[March Audio]

He says still missing the point. What has that got to do with anything? You need to get over the fact that the ML's weren't positioned optimally-their response was all over the shop and this was confirmed by their less than stellar preference rating in Toole's tests. I have no doubt had the ML's been positioned better their in room response would've been 'better' ie close(r) to the subsequently averaged response preference established from the tests. They weren't a magazine style speakers tests rather it was designed to try to establish a listener preference for certain in room response/behaviours.

This is the point. With respect Camverton you are being overly defensive about what you appear to perceive as criticism of your obviously favourite speaker.

The tests were to establish correlation with user preference. They were not to say this speaker good, this speaker bad. So I think you are very much over interpreting the data and what has been said in this thread.

They behaved poorly and we're rated poorly. You might be able to improve this if you idealised the situation for those speakers but that was not the point of the exercise.

If you understand the purpose of the test you will realise that it not concurring with your view on this speaker is not a reason to dismiss the findings. In fact its quite the opposite, it helped clearly demonstrate that people don't like a response that's all over the shop.

 

[March Audio]

flat FR and smooth off axis was not invented by toole.
serious manufacturers have tried to attain as flat as possible FR for decades now

your point being?

Ok, so what other references would you suggest that show data to support this? If you don't use Toole what do you use?

 

[March Audio]

The

* Off-topic, but why do announcers on radio invariably sound larger than life, with males having a boomy lower registers and females displaying accentuated sibilants/consonants? Is it purely down to close-mic placement and compression, or do the EQ it is well? Whatever the cause, it sounds unnatural IMO.

Directional microphones (cardioid etc) have a proximity effect which increases low frequency response.

https://www.neumann.com/homestudio/en/what-is-the-proximity-effect

Secondly you will be amazed at just how many mics deviate from a flat frequency response, especially to emphasise the higher voice registers.

It's deliberate to create a mic “sound“. What people have to remember is that most recordings are artistic endeavours and not exercises in accurate reproduction so artists and producers choose gear that gives the sound or effect they want.

 

[March Audio]

Interesting points except that Radio 3 presenters don’t seem to suffer from this on my MBLs or Logan’s! Can anyone remember which speaker manufacturer played a musical instrument at shows which then went to a reproduction through their speakers demonstrating how close the real sound was to the sound through the speakers?

Well if they use directional mics, don't know if they do, they should suffer. It's not a speaker issue it's a mic issue. The physics of of pressure gradient designs.