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3rd edition of Floyd E. Toole's "Sound Reproduction"

Thinking about the point Tony L made I am wondering if the Harman MLL (Multichannel Listening Laboratory) pneumatic positioner as shown in the photo above from merlin may indeed favour more conventional loudspeakers over panels. The subjective testing mechanism is covered in section 3.5 of the book (another photo in figure 3.14). I will read it again.

However, the Harman portfolio may well be dominated by cabinet-based loudspeakers so it would make sense for this mechanism to be appropriate in research to measure and improve the subjective impact of such a product range. But it is possible that marketing demonstrations using such research tools may not be quite so appropriate.
 
Harman use this room when appraising prototypes against their price point competitors-the philosophy being if they don't subjectively surpass their competitors then they go back to the drawing board(if they do they go back and try to make it cheaper...)..this is different to the purpose in Olive/Toole's research.
 
My point is *all* speakers, even ones in the same general class need care in positioning, e.g. Linn Kans, JR149s and ProAc 1SCs are all small two-way mini-monitors, yet the former needs to be hard against a rear wall, the 149 wants about 10” to a foot behind it, and the 1SC wants to be out very far from boundaries. Get any one in the wrong position and you won’t hear even a fraction of what they are capable.

The biased Harman dem would not account even for this, let alone for real curveballs like a Quad ESL or a Klipschorn, and as such I rate it as a useless advertising puff-piece rather than real science. Sorry, but that is just the way I see it. Proper science has to stand up to independent peer review, and to my mind this just doesn’t.
 
My point is *all* speakers, even ones in the same general class need care in positioning, e.g. Linn Kans, JR149s and ProAc 1SCs are all small two-way mini-monitors, yet the former needs to be hard against a rear wall, the 149 wants about 10” to a foot behind it, and the 1SC wants to be out very far from boundaries. Get any one in the wrong position and you won’t hear even a fraction of what they are capable.

The biased Harman dem would not account even for this, let alone for real curveballs like a Quad ESL or a Klipschorn, and as such I rate it as a useless advertising puff-piece rather than real science. Sorry, but that is just the way I see it. Proper science has to stand up to independent peer review, and to my mind this just doesn’t.

I think we may have a magnitude issue to discuss here. The frequency response curves even from well regarded loudspeakers from the 1980s show serious deviations from flat (if that is your aim) and the off-axis response curves show some large discontinuities (if smooth is your aim). My own experience with positioning loudspeakers in a room (all cabinet based so far) is that you may get better imaging (but Toole's tests are mono as this keeps the relative ranking but widens the scoring range) and improvements in bass. I think that the magnitude of the problem that was being addressed in the research was somewhat greater than this.

If loudspeakers have improved substantially now then I agree that better testing facilities are needed now. However I think that criticizing research over the last thirty years for not solving todays problems, of a smaller magnitude because of that research, is not entirely fair even though I do think your point about panel speakers may have validity.
 
My point is *all* speakers, even ones in the same general class need care in positioning, e.g. Linn Kans, JR149s and ProAc 1SCs are all small two-way mini-monitors, yet the former needs to be hard against a rear wall, the 149 wants about 10” to a foot behind it, and the 1SC wants to be out very far from boundaries. Get any one in the wrong position and you won’t hear even a fraction of what they are capable.

The biased Harman dem would not account even for this, let alone for real curveballs like a Quad ESL or a Klipschorn, and as such I rate it as a useless advertising puff-piece rather than real science. Sorry, but that is just the way I see it. Proper science has to stand up to independent peer review, and to my mind this just doesn’t.
Agreed speakers all need care in positioning to give of their best and I may be being a bit thick here but what biased Harman dem are you referring to?
 
It was a YouTube talk liked here a good while ago, I think by Keith, but maybe not. I can’t remember enough to identify it without watching through loads, but it had footage of the dem system and in effect presented ‘evidence’ as to how good the Harman product was whilst making several rather more interesting general points. It was certainly not billed as a product promotion, but had enough about it to make such accusations unavoidable IMHO. I don’t usually react to these things, but as a fan of both panel speakers and corner horns (as well as most other forms of speakers) I was disappointed by that aspect of test methodology and I think I turned it off at that point.

PS I may actually be thinking of two videos, one of FT talking and using some of the Harman evidence, and another showing the automated speaker switching system in action.
 
I just googled ‘Floyd Toole Martin Logan’ and I’m very far from the only one to pick up on this. The internet is full of criticism regarding the speaker switching system and the way it is not right for many designs such as dipoles. There are several videos linked too, so easy to research.
 
Ooh, my discussion with Keith on the Wam comes up no.2 in the list.

Such a shame as so much of what he says makes so much sense; still, we’re all allowed the occasional bias!
 
My point is *all* speakers, even ones in the same general class need care in positioning, e.g. Linn Kans, JR149s and ProAc 1SCs are all small two-way mini-monitors, yet the former needs to be hard against a rear wall, the 149 wants about 10” to a foot behind it, and the 1SC wants to be out very far from boundaries. Get any one in the wrong position and you won’t hear even a fraction of what they are capable.

Which given their size is only a fraction of what can be achieved with large speakers. :p
 
Which given their size is only a fraction of what can be achieved with large speakers. :p

Which again kind of makes my point for me. As an example I have a pair of JR149s that I use in the extreme nearfield in one room and a simply huge pair of Lockwood Tannoy monitors in another. Each is used in a different context in a different environment, and both meet my requirements in that specific context though would not be ideal in the other. There is simply no ‘one size fits all’ in audio as user requirements and listening environments differ so hugely. I’m lucky as I can indulge with several perspectives. Many manufacturers sensibly cater to the countless niches and tastes and IMHO it is highly foolish to try and compare chalk with cheese as a PR exercise as far too many folk will notice!
 
My point is *all* speakers, even ones in the same general class need care in positioning, e.g. Linn Kans, JR149s and ProAc 1SCs are all small two-way mini-monitors, yet the former needs to be hard against a rear wall, the 149 wants about 10” to a foot behind it, and the 1SC wants to be out very far from boundaries. Get any one in the wrong position and you won’t hear even a fraction of what they are capable.

The biased Harman dem would not account even for this, let alone for real curveballs like a Quad ESL or a Klipschorn, and as such I rate it as a useless advertising puff-piece rather than real science. Sorry, but that is just the way I see it. Proper science has to stand up to independent peer review, and to my mind this just doesn’t.

I agree with your point, although the room could be very dry and in that case distance to side and back walls wouldn't make so much difference as you'd be listening to the speaker.

Regarding blind testing, Toole's listeners were comparing loudspeaker frequency response and if you look at the measurements he published you'll see wildly varying response between samples.
Big differences are easy to spot.
 
Regarding blind testing, Toole's listeners were comparing loudspeaker frequency response and if you look at the measurements he published you'll see wildly varying response between samples.
Big differences are easy to spot.

Indeed, all the more so if the speaker is used away from its design context, e.g. place an AR3, Naim SBL, Klipsch Heresy or whatever wall proximity speaker in a location without boundary reinforcement and it will have no bass whatsoever. Similarly if one places a free-space speaker against a wall it will boom and fart, and any dipole will be hopeless. As a bare minimum any test should take into account full-space, half-space or quarter-space placement as the science behind this was known way back in the 1940s and 50s as soon as people started building speakers cable of reproducing low frequencies. There are so many pioneering papers and books by Gilbert Briggs, Paul Klipsch and others on the subject that it simply staggers me that any serious loudspeaker test would neglect what is core acoustic knowledge and as such I question its motives. I'd argue one needed to go far beyond this again to really get the best out of any speaker as so many exist somewhere between two of the three defined full/half/quarter-space definitions.
 
Books that cover vast eng based topics often seem to get worse as new editions appear. The sales are small so they pad them with new topics and they become ever more bloated. Williams filter book and Colloms loudspeakers are good examples. Even Vance's book might have been readable when it first appeared.
 
OK after some digging I came across Sean Olive's response to a question that the ML was disadvantaged in the test;

Hi Duke,

Yes, we were aware that these electrostatic panels are directional and have a small listening sweet spot, as revealed in our anechoic measurements. You can clearly hear the timbre of the speaker change (it gets duller) when moving your head a few inches, or walking past it. In my opinion, that an undesirable characteristic of a loudspeaker: An ideal loudspeaker should sound good in any room, in any position, and in any seat. Of course, not many speakers do all these things, but this one is particularly poor in that regard.

The problem is that this speaker will never sound good, no matter where you put it. No loudspeaker, listening room or listening position can change the fact that the speaker has an extremely poor octave-octave balance and multiple resonances visible in the on and off-axis measurements (look at the measurements of speaker C in slide 28 ).

To answer your specific questions:

1. The speakers were located about 3 feet from the back wall (which is reflective), near the center of the listening room, pointed at the primary listening seat, far away from the side walls. This is the optimal position according to the owners' manuall on page 10.

2. The speakers were evaluated using both high school and trained listeners. The high school students were tested as two groups of 9 each sitting in two rows around the primary seat. More of these students were sitting in non-ideal off-axis positions than the trained listeners who all sat in the primary seat or "sweet spot" in separate sessions. Yet the trained listeners were more harsh about the colorations and imbalances of this speaker than were the high school students - even though they were supposedly hearing the optimal sound from the speaker.


So to conclude, I don't think the electrostatic speaker was disadvantaged in any way. According to the owners manual we set it up according to instructions (which are frankly not every well written, vague and contradictory. It's almost like they are saying put it wherever you think it sounds best, which is not very helpful).

The electrostatic loudspeaker didn't do well because it is technically and sonically inferior to the other loudspeakers in the test. The subjective and objective measurements support this statement, as does 30+ years of loudspeaker research at Canada's National Research Council, and more recently at Harman International.

Sorry, you can't get blood from a stone.
Last edited: Jun 19, 2010
Cheers,
Sean Olive
Audio Musings
 
Perhaps Sean should read the manual more carefully; you don’t listen to Logan’s head on but about 30 degrees off. Yes you do need to place them where they sound best, and in that they are more critical than box speakers. By toeing them in they are not parallel (as much as a curved panel can be) to the wall behind. I say “them” because in my experience they don’t sound at all good used as a single mono speaker. Their defining glory is a sense of realism and space that when set up well trumps their shortcomings, at least for a solo listener.
 
Get over it.

Every public presentation by a commercial entity like Harman is in part a marketing exercise. That's how the world works.

That does not negate that the science in the book is sound, that the book is well written, and that it contains
an excellent and probably unique overview of decades of (non-Toole, non-Harman) research into auditory perception.

It is a total gem.
 
My point is *all* speakers, even ones in the same general class need care in positioning, e.g. Linn Kans, JR149s and ProAc 1SCs are all small two-way mini-monitors, yet the former needs to be hard against a rear wall, the 149 wants about 10” to a foot behind it, and the 1SC wants to be out very far from boundaries. Get any one in the wrong position and you won’t hear even a fraction of what they are capable.

The biased Harman dem would not account even for this, let alone for real curveballs like a Quad ESL or a Klipschorn, and as such I rate it as a useless advertising puff-piece rather than real science. Sorry, but that is just the way I see it. Proper science has to stand up to independent peer review, and to my mind this just doesn’t.

And my point is how, given the image I have presented, is the Logan "sub optimally positioned" in order to throw a "curveball" and ignore the science?

As a former Logan owner I'm genuinely interested. There appears to be sufficient distance and absorption to make the back wave unobtrusive. The panel is at least a meter from a well damped rear wall and well clear of any side walls that might impact bass interference unduly.

You are suggesting that this is a puff piece. I'd ask how you could possibly come to that conclusion when looking at it from an empirical POV?
 
You are suggesting that this is a puff piece. I'd ask how you could possibly come to that conclusion when looking at it from an empirical POV?

If a tool for blind test auditioning places the Harman speaker in its optimal location but ignores positioning requirements or positional tuning for competitors product it can only sensibly be viewed as a advertising device IMHO. I've been running decent audio systems for all but 40 years now and I learnt decades ago that a couple of inches here and there can make or break a speaker/room interface. Every credible reviewer knows that and will asjust location until the speaker gives its best,and as such the test should do similar.

Please note I am not making any case for Martin Logan speakers. The audition system would be just as flawed for any speaker that has very precise positioning requirements (ESLs, corner horns, wall-proximity speakers etc). And as I pointed out earlier most speakers actually lie somewhere in no-mans land between full and half-space location and need very precise adjustment for best response.
 


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