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How to measure the loudspeakers actually work as they should?
How to measure the loudspeakers actually work as they should?
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Old 9th November 2018, 12:15 AM   #21
gedlee is offline gedlee  United States
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Originally Posted by mitchba View Post
Hi Earl, one would think that, but in Toole's research, as long as the speaker exhibited good directivity control, whether lower or higher directivity did not factor into the neutral preference. I have tried it on cones and domes and constant directivity speakers and the same target applies with no changes. The tonal response sounds the same to my ears. But the stereo presentation sounds different to my ears. Cones and domes more distant or diffuse, whereas waveguides more direct is how I would subjectively characterise it.
For what you say to be true the direct response would have to be dominant in tonal color, because, as even Toole notes, the reverberant response depends on the DI, as theoretically it has to. I don't disagree with this, but it is not what is commonly thought.
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Old 9th November 2018, 01:07 AM   #22
mitchba is offline mitchba  Canada
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Earl, agreed, not what is commonly thought.

Here is a measurement example. The Kii THREE's I measured use a dome tweeter in a small waveguide with controlled horizontal directivity of 150 degrees over most of the frequency range. You can see the Polar Map in the linked article. Whereas my JBL 4722 waveguide and compression driver setup is 90 degrees horizontal directivity. So one wide, one narrow, but both controlled:

How to measure the loudspeakers actually work as they should?-wide-versus-narrow-directivity-jpeg

I adjusted the Kii THREE tone contour to match my target reference (i.e. the DSP'd JBL 4722) and overlaid the responses. Sounds tonally the same to my ears, but as mentioned the stereo presentation is different due to the directivity (aside from the dynamic differences).

Anyway, just wanted to see if lamir35 has any measurement gear Sorry for the OT.
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File Type: jpeg wide versus narrow directivity.jpeg (288.2 KB, 273 views)

Last edited by mitchba; 9th November 2018 at 01:14 AM.
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Old 9th November 2018, 02:39 AM   #23
bentoronto is offline bentoronto  Canada
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How to measure the loudspeakers actually work as they should?
Quote:
Originally Posted by mitchba View Post
Ben, with Tooles and Olives research, there is indeed a standard referenced in the links above. The subjective/objective controlled tests in Harman's "typical" listening room using hundreds of listening test subjects shows there is. The results are repeatable and the prediction of those results are embodied in the new ANSI/CTA-2034-A standard. Olives slides are really worthwhile as are the AES papers....
I immensely value the work of Toole (and when I was on one of the Boards of Directors at NRC, I might even have been his landlord), but let's not confuse "standard" or "defined" or "AES" with "the real thing".

Yes, each of us can play the recording of those women singers he seemed to use too much. The sound is sort of "hey, that's how we record women singers" rather than something which actually has no meaningful definition which is "Diana Krall has come to dinner and is singing in your living room". Unless you are Elvis Costello, you just wouldn't know (did I get that right?).

While some of the Harman bass tests are in living room sized rooms, I recall the bigger tests with the rotating tables were not.

B.
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Old 9th November 2018, 03:31 PM   #24
gedlee is offline gedlee  United States
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Quote:
Originally Posted by mitchba View Post
Earl, agreed, not what is commonly thought.
Hi Mitch

Then let me see if we can agree on some more points, which are based on my experience and some recent (unpublished as yet) studies that Lidia and I have done.

The direct field is dominate in tone color and if we EQ two systems to the same in-room curve then they will have the same tone color. (This is the point that we agreed upon.)

But, as you say, and I agree, the stereo presentation is different, a more subtle effect than coloration, but still important.

In my experience (and data) the difference is that a higher DI presents a sharper and more well defined image, while the lower DI enhances spaciousness at the sake of image. If you agree, then we are on the same page.

But these attributes play into the types of music we listen to and what we are looking for (at least as far as image goes.) Studio recordings can have a strong image, while large venue in-situ recordings are virtually devoid of a strong image, however they are enhanced by the enhancement of spaciousness from a lower DI. But these are tradeoffs that two people may well want to make in different ways.

These later aspects are, however, never talked about. And even in Toole and Olives work, there is no rating for "image". Toole himself looks for spatial enhancement because that's his camp (which is neither good or bad, just different.) I am in the studio work camp. I prize imaging and disappearing speakers over all else. You have to pick you goals, there is no one universal solution.

You mention "dynamic differences", an issue that I have thought a lot about and wonder how you define it. I have looked for ways to measure this but all have come down with nothing.
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Old 9th November 2018, 06:36 PM   #25
mitchba is offline mitchba  Canada
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Hi Ben, yes, there is no confusion with the "real thing". Stereo sound reproduction is an illusion. Having spent 10 years as a recording/mixing engineer in a variety of studios and convert halls, there is no mistake between hearing live and hearing a reproduction of the live event. But doesn't stop us from trying

The sound reproduction "standard" I am referring to specifies what the anechoic and in-room frequency response measurements (i.e. correlation between measured and predicted) should look like for a "neutral" sounding loudspeaker in a typical listening room environment. Backed up by repeated controlled listening tests over the years with hundreds of test participants is what those links point to. I am in agreement with the research/findings as indicated in post 22. Two very different speakers being compared, but both have very similar "neutral" tonal response.

If lamir35 has the capability to measure and compare to post 22, will tell if the sound being heard is too bright, dull or ... How to make a neutral sounding loudspeaker has been known for sometime, even from Toole's presentation from 2002: https://www.harman.com/sites/default...RoomsPt2_0.pdf Now setting up a spinorama test environment with a Klippel scanner is another matter...
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Old 9th November 2018, 07:18 PM   #26
mitchba is offline mitchba  Canada
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Hi Earl,

Re: In my experience (and data) the difference is that a higher DI presents a sharper and more well defined image, while the lower DI enhances spaciousness at the sake of image. If you agree, then we are on the same page.

Yes, agreed. I have had several speakers come through my room over the years and I still come back to speakers with a higher DI. I find not only a sharper image, but perhaps larger as well... Also agree it may be somewhat music dependent as I do listen mostly to studio recorded/mixed rather than classical... If I were mostly listening to classical, maybe I would enjoy the Revel Salon2's better, which are neutral sounding speakers but lower DI than my JBL's.

Re: You mention "dynamic differences", an issue that I have thought a lot about and wonder how you define it. I have looked for ways to measure this but all have come down with nothing.

I am confounded by this as well, but acknowledge the audible difference. I once thought it was related to the size of the speaker, but I have compared Maggies, which are large in size, but much lower sensitivity to my JBL's for example. The SPL was matched and the Maggies don't sound subjectively close to being as dynamic as the JBL's... But then the Maggies have a different DI too...

So while it seems related to driver sensitivity, I thought of recording music at the same SPL and overlaying the result to see if there is a difference... Haven't got there yet.
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Old 9th November 2018, 07:31 PM   #27
Juhazi is offline Juhazi  Finland
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My guess is that "dynamics" comes largely from directivity at low frequencies which give bass slam, perhaps 100-300Hz. This happens naturally with 15" or 2x10" or bigger drivers - in a suitable room. Room size/volume vs. driver area must be an important factor. Also low RT at those frequencies helps.

It must be very difficult to measure, but there are also other real differencies like imaging, that we still can't (don't know how to) measure.
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Old 9th November 2018, 08:50 PM   #28
bentoronto is offline bentoronto  Canada
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How to measure the loudspeakers actually work as they should?
Quote:
Originally Posted by mitchba View Post
..The sound reproduction "standard" I am referring to specifies what the anechoic and in-room frequency response measurements (i.e. correlation between measured and predicted) should look like for a "neutral" sounding loudspeaker in a typical listening room environment.
Let me try a gedank experiment (or koan): if a speaker had the same FR measured anechoicly and at your chair, would music sound the same in the anechoic chamber as at your chair? Would it have the same tone colour, sound compass, timbre, or the same perceived FR?

Think again, if your answer is yes.

B.
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Old 9th November 2018, 09:03 PM   #29
bentoronto is offline bentoronto  Canada
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How to measure the loudspeakers actually work as they should?
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Originally Posted by gedlee View Post
In my experience (and data) the difference is that a higher DI presents a sharper and more well defined image, while the lower DI enhances spaciousness at the sake of image. If you agree, then we are on the same page.
Maybe you should spend more time listening to dipoles. Certainly seemed to engage Linkwitz as he grew older.

Now I don't mean to conflate DI and dipoles and azimuth localization and ambience, but I have to stand my large-panel ESLs 11 inches to one another (from my nose, about 30 angle apart) to counter-act the discombobulating ping-pong stereo effect.

And after reading your paean to point-source speakers, I dug out my ancient test record with the stereo localization snare-drum beats. Now, nobody could be less pointy than my large curved dipole panels a few feet from the back wall and less likely be intuitively accurate for localization, at least your by your intuition. Never the less, the azimuths were precise across the front panorama. And mono sources are pin-point in the little air space between the panels.

So, it anybody thinks point-source boxes are the key to azimuth localization, they should listen to good large dipoles... which also produce the glorious ambience that Toole favours.

Footnote: There really is little stereo recording going on. It's nearly all cooked by panning and other artificial tricks. So it is possible some over-cooked recordings will be horrible on point-source speakers and some horrible on dipoles.

B.
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Last edited by bentoronto; 9th November 2018 at 09:08 PM.
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Old 9th November 2018, 09:28 PM   #30
gedlee is offline gedlee  United States
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Quote:
Originally Posted by mitchba View Post
Hi Earl,

Re: In my experience (and data) the difference is that a higher DI presents a sharper and more well defined image, while the lower DI enhances spaciousness at the sake of image. If you agree, then we are on the same page.

Yes, agreed. I have had several speakers come through my room over the years and I still come back to speakers with a higher DI. I find not only a sharper image, but perhaps larger as well... Also agree it may be somewhat music dependent as I do listen mostly to studio recorded/mixed rather than classical... If I were mostly listening to classical, maybe I would enjoy the Revel Salon2's better, which are neutral sounding speakers but lower DI than my JBL's.

Re: You mention "dynamic differences", an issue that I have thought a lot about and wonder how you define it. I have looked for ways to measure this but all have come down with nothing.

I am confounded by this as well, but acknowledge the audible difference. I once thought it was related to the size of the speaker, but I have compared Maggies, which are large in size, but much lower sensitivity to my JBL's for example. The SPL was matched and the Maggies don't sound subjectively close to being as dynamic as the JBL's... But then the Maggies have a different DI too...

So while it seems related to driver sensitivity, I thought of recording music at the same SPL and overlaying the result to see if there is a difference... Haven't got there yet.
Mitch

I am with you all the way. If you ever get an idea about how to test for "dynamics" let me know. I can sometimes find funding for studies like this. Lidia and I just completed a study of the effects of the contralateral versus ipsilateral reflections. Some very interesting preliminary results, but not yet complete.

I had once thought that the more power handling the driver has the more dynamic it sounded and studied thermal effects on dynamic signals. I either F'd up badly, or there was nothing there.
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