Distortion in loudspeakers

[watchnerd]

Precisely ...

Subjectively, the sound becomes more "interesting", there is more apparent detail, you can hear "deeper into the mix" - pretty easy to test, get two pairs of the same model of speakers, check that they match each other, especially audibly, using all the methods that you care to apply - put one pair aside for 24 hours, and keep the other running at relatively high volume for that period; then, hook up the "cold" set, and compare immediately, before the virgin pair get into their stride.

How do you know that's the suspension and not related to the voice coil warming up and expanding?

 

[Thomas savage]

We arguing against science and known understanding again?

 

[Blumlein 88]

We arguing against science and known understanding again?

Nope, just asking why one would eschew that science. Compliance, response, and a number of things are easily measured to see if they change for a recently used speaker vs one silent since yesterday. So if one posits an effect why not just measure for it. Too easy to do.

 

[fas42]

How do you know that's the suspension and not related to the voice coil warming up and expanding?

I'm sure there is some effect in that as well - but, the thermal mass of the voice coil is extremely low, that is, it will cool down very rapidly, far quicker than the loss of perceived quality.

Just so you don't get your hopes up too much, , I had this very conversation with a hard core objectivist on diyAudio some time ago, someone who's made it a bit of a life's work to create drivers from scratch - and he agreed that suspension is a problem - so, if necessary I can bring his comments to the 'fight' ...

 

[Thomas savage]

I'm sure there is some effect in that as well - but, the thermal mass of the voice coil is extremely low, that is, it will cool down very rapidly, far quicker than the loss of perceived quality.

Just so you don't get your hopes up too much, , I had this very conversation with a hard core objectivist on diyAudio some time ago, someone who's made it a bit of a life's work to create drivers from scratch - and he agreed that suspension is a problem - so, if necessary I can bring his comments to the 'fight' ...

It seems to me Frank you actively isolate yourself from the possibility of being 'proved' wrong by maintaining a distance from even the most easily verifiable knowns.

 

[Don Hills]

Well, first acquire two sets of a speaker model which match ...

I don't think you're that stupid, Frank. And neither are we, so don't insult our intelligence.

 

[Blumlein 88]

Well, to start, follow this thread, http://www.diyaudio.com/forums/multi-way/100392-beyond-ariel-949.html#post3685833 - and note where people mention "stiction". Kindhornman is the member to look out for, as the one who probably has the best technical knowledge.

I doubt stiction is a thing to worry about in a spider or other part of the speaker. Hysteresis is a likelier suspect for effects being attributed to stiction.

 

[March Audio]

You keep doing things the hard way, because you insist on measuring with your most unreliable test instruments. Any change in the compliance of the suspension is easily measurable with far more accurate instruments. Its effect on the reproduced waveform is also easily measurable.

This

 

[Blumlein 88]

This quote from Gedlee makes plenty of sense:

Stiction comes about because there can be a difference in motional resistance and the static friction. This difference can be great and it can be negligible or it can even be that the motional friction is greater than the static friction meaning that the device wants to be moved. In all cases it is nonlinear and as a result is partially correlated with the signal in that the odd harmonics are correlated while the even harmonics are not. So the correlation will depend on the nature of the stiction, and can be anything from not correlated to almost completely correlated. It will not be noise.

The nonlinear effects of stiction will require that the harmonic content, as a percent, i.e. THD, will rise as the signal level falls. Thus it would be very easy to test for this by simply plotting THD versus signal level (must not be THD + noise!) as the signal level is dropped.

I have never seen any data that would indicate this to be a significant effect, but I will agree if I see some data that shows that it is significant. Data is king, hypothesis is easy.

 

[Thomas savage]

Posts moved over to here http://audiosciencereview.com/forum...-fas42-back-and-forth.1136/page-27#post-33910

We had a really good thread going until this latest breakout of forum vs fas42 .. I have left more in this thread than I would ideally like but in future please think of the consequence of quoting fas42 as the resulting back and forth is very seldom of any value.

I will endeavour to move content as I have done in this thread over to fight club when a thread gets bogged down in unfruitful non evidenced based ( or good humoured banter) back and forth.

Thanks for your understanding on this, I'm sorry if some content gets caught up as collateral damage . Please lend me your understanding as I'm trying to maintain our threads/forums real value, value you all provide and that's greatly appreciated

Let's just try and avoid every thread getting in a mess in the first place, you don't have to answer fas42 . Well all know his views and they won't change nor their challenge bring any content of value. I do understand it's easy to get drawn in, I'm laying no blame I just want your excellent contributions to sing as clear as possible.

As always we welcome challenge and opposing views , we do however want constructive argument

 

[March Audio]

Erm, why dont you just lock his posting rights in fight club only? Or if he is that disruptive and only winds people up by posting total bollocks all the time, ban him and save all the trouble?

 

[Thomas savage]

Erm, why dont you just lock him in fight club? Or ban him and save all the trouble?

Let's get back to the subject of the op please

 

[RayDunzl]

I don't know how far you are from the speakers -- what do you think the SPL is at 1 m?

10 feet.

Panels don't get much "louder" as you get closer to them. In my case the sound is produced over about 720 square inches. In the past, close eyes, spin around, try to find the speaker (playing music), my nose would be touching the speaker and the "sound" still seemed 2-3 feet away. Cone is easily located.

Cones and domes get "louder" as you get closer to them, the sound is "concentrated" in a hot spot of a few square inches - 4" mid cone = 12.5 square inches.

720 / 12.5 = 57.6 times the radiating area, so, 12.5 sq in of the panel produces 1/57th the energy of a 4" cone (maybe), like having 57 cones sharing the load.

If I put my ear to the panel, there's like no sound there - its coming from all around that point.

Moving close to and away from the panel producing a steady tone with a meter - SPL varies about 2dB - about the same as moving anywhere else in the room.

 

[oivavoi]

10 feet.

Panels don't get much "louder" as you get closer to them. In my case the sound is produced over about 720 square inches. In the past, close eyes, spin around, try to find the speaker (playing music), my nose would be touching the speaker and the "sound" still seemed 2-3 feet away. Cone is easily located.

Cones and domes get "louder" as you get closer to them, the sound is "concentrated" in a hot spot of a few square inches - 4" mid cone = 12.5 square inches.

720 / 12.5 = 57.6 times the radiating area, so, 12.5 sq in of the panel produces 1/57th the energy of a 4" cone (maybe), like having 57 cones sharing the load.

If I put my ear to the panel, there's like no sound there - its coming from all around that point.

Moving close to and away from the panel producing a steady tone with a meter - SPL varies about 2dB - about the same as moving anywhere else in the room.

Interesting. This is the kind of precise subjective impressions I like very much

Is this something that has to do with the fact that they are electrostats, or rather that they are line source-ish? Does the dipol thing come into play?

My understanding is that something similar applies to the CBT (line source) speakers, for example. They play almost equally loud in the near field and further away towards the room boundaries. I won't even pretend that I undertsand the technical reasons why, though.

 

[RayDunzl]

Is this something that has to do with the fact that they are electrostats, or rather that they are line source-ish? Does the dipol thing come into play?

I suppose it has to do with the "source" being spread out, instead of concentrated in a "point".

Consider lighting a room with an open window (panel) vs a very strong LED (point).

Martin Logan reQuest - 1998 or so. 48 x 15 inch panel.

(almost) Point Source:

 

[oivavoi]

I suppose it has to do with the "source" being spread out, instead of concentrated in a "point".

Consider lighting a room with an open window (panel) vs a very strong LED (point).

Martin Logan reQuest - 1998 or so. 48 x 15 inch panel.

(almost) Point Source:

View attachment 5345

Thanks. Interesting. Intuitive question: A priori, what kind of source "format" is most similar to how we perceive live music? Point source or line source? Now the single point source is often conceived of as a kind of holy grail among some audio folks, for a variety of reasons. But live musical ensembles emanate sound from many "points". Can panel speakers etc. come closer to recreating this?

 

[watchnerd]

Thanks. Interesting. Intuitive question: A priori, what kind of source "format" is most similar to how we perceive live music? Point source or line source? Now the single point source is often conceived of as a kind of holy grail among some audio folks, for a variety of reasons. But live musical ensembles emanate sound from many "points". Can panel speakers etc. come closer to recreating this?

Based on the two different panels I own, an some Maggies my friend has, my completely no data subjective assessment is:

Kind of, for large venue recordings. But it's kind of fakey, too.

 

[RayDunzl]

I prefer my reQuests to the little JBLs when listening critically at the sweet spot.

Initial impression switching back and forth is that the panel has a smaller dimmer image, the JBL a little more brilliant and spread out.

But as I continue to listen, the JBL sounds artificial, too much happening off to the sides (maybe my room isn't dead enough), where the panels take on the sensation of listening a little farther away. The "image" turns out to be just as big, or bigger, more like "life size" but at a more appropriate distance than the more "in your face" of the JBL.

Since it seems less loud, maybe you turn it up a few decibels, and then it really comes into its own.

I suppose it is preference, or acclimatization, or any number of other excuses, but I like it better.

Often, when a writer reviews some latest/greatest speaker, there will be a reference to electrostats/panels.

Even Kal did it in his recent Beolab 90 Review:

"In Wide mode, the BeoLab 90s sounded like very good conventional loudspeakers, with a two-channel sound that was on a par with the best I've heard in this room: well balanced, with powerful, extended bass and wide, deep soundstages. However, when I switched to Narrow mode, it became apparent that the standard stereo presentation of Wide mode—and, indeed, of most other pairs of speakers I've used—was flawed. Narrow mode simply erased a hash of spurious ambience that flanked the central soundstage. That hash exaggerated the width, and contributed to the impression of "audiophile air." Also, in Narrow mode, the stereo image snapped into a new level of precise stability.

In Narrow mode, the BeoLabs delivered what I heard as increased resolution, detail, and tonal honesty, unsullied by the interference of short-latency reflections. Users of dipole speakers, in which the interference of the outputs of the front and rear drivers causes cancellation of lateral dispersion, will have experienced something similar—but not to this degree. From that point on, I used Wide mode mostly to demonstrate to myself and to others just how remarkable the BeoLab 90s could sound in Narrow mode, in which I did all of my critical listening."

I consider my little JBLs to correspond to "wide mode" and the Martin Logans to correspond, perhaps to a lesser degree (as he put it), to his preferred "narrow mode".

Again.

"Narrow mode simply erased a hash of spurious ambience that flanked the central soundstage. That hash exaggerated the width, and contributed to the impression of "audiophile air." Also, in Narrow mode, the stereo image snapped into a new level of precise stability."

"In Narrow mode, the BeoLabs delivered what I heard as increased resolution, detail, and tonal honesty, unsullied by the interference of short-latency reflections. Users of dipole speakers, in which the interference of the outputs of the front and rear drivers causes cancellation of lateral dispersion, will have experienced something similar—but not to this degree."

That's as good an explanation as I could give.

Short-Latency reflections in my room - hash, as Kal names it:

Red, JBL. Blue, MartinLogan, impulse response, 40ms time range:

1-2ms - reflection at couch - microphone on a small desk stand on the top of the couch behind where my head would be.
7ms - blue - dipole reflection off front wall - very low amplitude (5%) compared to direct (100%) sound
25ms - blue - sound has traveled down the room, and back, and is reflected off the front wall (behind the speakers) and back to the mic.
-
red - who knows? reflections from walls, ceiling, floor, all contributing to the "sound energy" but reducing (my opinion) the clarity/focus of the direct sound. The Reflection Amplitude is much higher (25 and 30% seen) compared to direct sound (100%).

 

[oivavoi]

I prefer my reQuests to the little JBLs when listening critically at the sweet spot.

Initial impression switching back and forth is that the panel has a smaller dimmer image, the JBL a little more brilliant and spread out.

But as I continue to listen, the JBL sounds artificial, too much happening off to the sides (maybe my room isn't dead enough), where the panels take on the sensation of listening a little farther away. The "image" turns out to be just as big, or bigger, more like "life size" but at a more appropriate distance than the more "in your face" of the JBL.

Since it seems less loud, maybe you turn it up a few decibels, and then it really comes into its own.

I suppose it is preference, or acclimatization, or any number of other excuses, but I like it better.

Often, when a writer reviews some latest/greatest speaker, there will be a reference to electrostats/panels.

Even Kal did it in his recent Beolab 90 Review:

"In Wide mode, the BeoLab 90s sounded like very good conventional loudspeakers, with a two-channel sound that was on a par with the best I've heard in this room: well balanced, with powerful, extended bass and wide, deep soundstages. However, when I switched to Narrow mode, it became apparent that the standard stereo presentation of Wide mode—and, indeed, of most other pairs of speakers I've used—was flawed. Narrow mode simply erased a hash of spurious ambience that flanked the central soundstage. That hash exaggerated the width, and contributed to the impression of "audiophile air." Also, in Narrow mode, the stereo image snapped into a new level of precise stability.

In Narrow mode, the BeoLabs delivered what I heard as increased resolution, detail, and tonal honesty, unsullied by the interference of short-latency reflections. Users of dipole speakers, in which the interference of the outputs of the front and rear drivers causes cancellation of lateral dispersion, will have experienced something similar—but not to this degree. From that point on, I used Wide mode mostly to demonstrate to myself and to others just how remarkable the BeoLab 90s could sound in Narrow mode, in which I did all of my critical listening."

I consider my little JBLs to correspond to "wide mode" and the Martin Logans to correspond, perhaps to a lesser degree (as he put it), to his preferred "narrow mode".

Again.

"Narrow mode simply erased a hash of spurious ambience that flanked the central soundstage. That hash exaggerated the width, and contributed to the impression of "audiophile air." Also, in Narrow mode, the stereo image snapped into a new level of precise stability."

"In Narrow mode, the BeoLabs delivered what I heard as increased resolution, detail, and tonal honesty, unsullied by the interference of short-latency reflections. Users of dipole speakers, in which the interference of the outputs of the front and rear drivers causes cancellation of lateral dispersion, will have experienced something similar—but not to this degree."

That's as good an explanation as I could give.

Short-Latency reflections in my room - hash, as Kal names it:

Red, JBL. Blue, MartinLogan, impulse response, 40ms time range:

1-2ms - reflection at couch - microphone on a small desk stand on the top of the couch behind where my head would be.
7ms - blue - dipole reflection off front wall - very low amplitude (5%) compared to direct (100%) sound
25ms - blue - sound has traveled down the room, and back, and is reflected off the front wall (behind the speakers) and back to the mic.
-
red - who knows? reflections from walls, ceiling, floor, all contributing to the "sound energy" but reducing (my opinion) the clarity/focus of the direct sound. Amplitude is much higher (25 and 30% seen) compared to direct sound (100%).

Thanks. Truly excellent reply.

 

[Fitzcaraldo215]

Thanks. Interesting. Intuitive question: A priori, what kind of source "format" is most similar to how we perceive live music? Point source or line source? Now the single point source is often conceived of as a kind of holy grail among some audio folks, for a variety of reasons. But live musical ensembles emanate sound from many "points". Can panel speakers etc. come closer to recreating this?

I prefer the line source notion. The rationale for the point source idea is naive and oversimplified, IMHO.

Yes, a point source might approximate the radiation pattern of certain individual instruments in an anechoic chamber. But, put those instruments in a hall and it becomes a different ball game entirely, when direct and huge quantities of omnidirectional, reflected sound predominate. Real life wavefronts no longer represent the point source ideal. We do not hear point sources at all in the concert hall.

Note that I am not saying that the line source better replicates the wavefronts we hear in the hall. It is believing that if we simulate certain theoretical dispersion patterns which are characteristic of many instruments anechoically, we will better produce musical "realism". Hogwash. That is only a step up from and akin to believing that only horns reproduce trumpets best. Or, that Heil AMTs reproduce accordions best.

So, why do I, like Ray, prefer the line source notion? (Excellent job, as always, Ray). Partly, I think he has touched on it. If dispersion is controlled in the LISTENING room such that it has minimal influence from reflective surfaces, it stands a good chance of being truer to the source recording. Dipole line sources do that to a great extent, except for the infernal rear wave, of course. But, they do eliminate many issues of side and especially ceiling and floor reflections that wide dispersion, true point sources do not.

BTW, I think omni speakers, which are truest to point sources, are the worst in this regard. I personally have found ceiling and floor bounce to be big problems to contend with over the years. Line sources potentially reduce that substantially, as I discovered.

Yes, Harman, with their emphasis on horns for JBL, but not for Revel, believes in controlled dispersion. Their speakers disperse sound more broadly than most line sources, but introduce minimal tonality shifts via reflections within that controlled dispersion pattern.

We also note how much better the Beolab 90 sounds in narrow mode than in wide mode, as nearly all listeners, including Kal, attest.

Perhaps, line source is just another manifestation of the same underlying process.