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In Reply to: RE: About Magico speakers ... extremely impressive posted by beppe61 on January 13, 2015 at 01:46:06
It is not really clear how audible simple harmonic distortion from motor non-linearity would be. Much of it will be masked as it is generally of a low harmonic order.
I think an interesting experiment is to have a speaker in the free field (so outdoors would work) playing music and then suddenly cutting off the signal and measuring how long it takes sound to stop emanating from the speaker and at what level. This could give an idea as to the residual "self noise" the speaker is creating under the main signal.
Follow Ups:
I've read most of the back-and-forth between the two of you, and several good points have been made. I'd like to offer a few thoughts which may help to complicate things.First, in reply to Beppe's question/thought about distortion measurements being ignored in loudspeaker design, what self-respecting audiophile would buy a speaker if it is known to produce as much as 10 percent THD? ;) I'm certain that many - if not all - major manufacturers perform such tests, but simply don't publish the results.
Second, there are some excellent tests which reveal important and useful information about a speaker's performance, and these tests are quite common. One is the 'typical' impulse response measurement, and another is the MLSSA "waterfall" analysis. I'm a big fan of both. While looking up the MLSSA info, I stumbled upon this very readable link to a Stereophile article written by our good buddy John Atkinson:
http://www.stereophile.com/reference/290mlssa/
Third, John Meyer (www.meyersound.com) also has in-situ/live measurement software which can use the music being performed as the test signal. Pretty intriguing.
Fourth - and this is very exciting to me - there is a system called "IRIS" which uses a tetrahedral array of four small microphones to measure not only amplitude and frequency, but also direction. This is VERY useful for measuring sound in rooms.
Lastly, speaker system designers have known since forever that the enclosure contributes to the sound. Some try to avoid or at least minimize it, some use it to make their speakers sound the way they do.
:)
Edits: 01/15/15
Hi and thanks for the helfpul reply.
My first reaction, and i am not trolling here, is why they do not pubblish?
1) they do not think they are telling anything (then why go thorugh the hassle of performing them ?)
2) the problem is the results that can be too telling.
But it is a old story ... without clear conclusion.
" MLSSA "waterfall" analysis " is very very interesting
I think that most big manufacturers have facilities to perform this test
If i am not wrong it is a full bandwidth impulse test ?
" tetrahedral array of four small microphones "
i am more intrigued by measurements carried out with a well designed artificial head. It is more like the real listening conditions.
But any test can be telling something and a useful tool to get info on speakers and listening rooms.
" speaker system designers have known since forever that the enclosure contributes to the sound "
yes and this is very easy to demonstrate
But during this very interesting discussion, for which i thank you and all the kind Inmates, i am more convinced about the drivers impacting the sound timbre more than other aspects (someone can say obviously)
I think this way now.
That the best enclosure gives to drivers the opportunity to sound as they can, at their maximum and without adding colorations.
And it is not a small thing.
And i am not sure that really good performance needs 200 kg of cabinet.
Separating the big woofer from the rest can simplify life.
This would be my approach like the example in the picture.
Thanks a lot again.
Kind regards,
bg
"i am more intrigued by measurements carried out with a well designed artificial head. It is more like the real listening conditions."
Four microphones arranged in a tetrahedron are required to give the up-down/left-right/front-back information. Two microphones only define one plane, three mics can define two planes, and four mics give you the entire sphere, enabling you to pinpoint sources in any direction.
This is actually an idea I had started to pursue in the late 1970s, but did not have the resources (money, time, math skills, programming skills) to see it through. (The late great Michael Gerzon used this principle in his original "soundfield" microphone, produced by Calrec, about that same time. See linky.) I attended Malcolm Dunn's (Marshall Day Acoustics) presentation at the October 2014 AES convention, and was coming unglued that they have a working system for measurement and analysis! Later, I went to their exhibit space and had a nice long talk with Hans Forschner (NAVCON consultants). (See other linky.)
Gerzon Soundfield: http://en.wikipedia.org/wiki/Soundfield_microphone
IRIS: www.iris.co.nz
Hi and thanks again for the very interesting information
This special microphone could be the best also for listening room treatments maybe ?
Nice to hear about the progress of technology
I would follow an approach a little extreme, with speakers with narrow dispersion aimed at the listening spot and a full treatment of the wall behind the listening spot to stop any possible reflection.
It should work quite ok in a normal home
Maybe also some kind of acoustic panel placed on the front wall.
If a wall does not reflect sound i should not hear it i guess.
Thanks again for the explanation and link.P.S. just to add that i have spotted maybe what can be considered the AudioMachina and Magico "ancestors" ... the Celestion sl600/sl700
A sublime cabinet made out of aluminum honeycomb ... and they delivered an extremely good sound
So the concept is not that new in the end
Kind regards,
bg
Edits: 01/19/15
But Trinnov's boxes are also ghastly expensive for what they are.
THAT is some funny stuff!
:)
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