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Announcement: ASR Will Be Measuring Speakers!

bobbooo

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Idk if anyone asked this yet, but would it be worth sometimes measuring both speakers of a pair separately to see what speaker to speaker production variances might be found, and if those differences may be audible?

Great idea, although I suspect a lot of people will only send one speaker in order to cut down on shipping costs. This also raises the question of how many measurements @amirm makes of each individual speaker within a pair. All scientific measurements should ideally be made multiple times and averaged in order to account for random error. Maybe the Klippel system does this automatically?
 

edechamps

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My guess is the LSR305 mkII is going to be first. So he can compare with Harman as a check he is getting good results.

As far as I know there's no good data for the LSR 305 MkII (a.k.a 305P). Only for the original LSR305. (I'd love to be proven wrong.)

I think if @amirm is looking for a good reference to sanity check his measurements, IMHO the best speaker for that purpose is the Genelec 8030A. It has been measured many times by many different labs (here's one example) and is often used as a test speaker in audio research. I think it should be possible to find at least 3 or more independent measurements of that loudspeaker.
 
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briskly

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as I presume this is not taken into account by the Klippel system as it's primarily for measuring single speakers?
Why do you think this is only for single speakers?

The NFS is a tool meant to determine the pressure and particle velocity from the sound source with a high degree of spatial resolution and do this expediently. The groups most desperately in need of such information are not the designers of conventional speakers who have worked with less pressure information, but the designers of arrayed speakers, line arrays and soundbars, where there are multiple wavefronts that are summed to achieve the desired spectral response and spatial coverage.
 

bobbooo

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Why do you think this is only for single speakers?

The NFS is a tool meant to determine the pressure and particle velocity from the sound source with a high degree of spatial resolution and do this expediently. The groups most desperately in need of such information are not the designers of conventional speakers who have worked with less pressure information, but the designers of arrayed speakers, line arrays and soundbars, where there are multiple wavefronts that are summed to achieve the desired spectral response and spatial coverage.

I just meant the Klippel set-up looks like it can only measure one speaker at a time, not two at once, typically spaced as in an average listening environment. Unless this is incorrect?
 

Matias

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They work on a dynamic basis so testing them with this system is not straightforward. For now, when I have heard it at shows, the "improvement" is due to changing the height of the speaker, something the measurements definitely show.
IsoAcoustics have lab tests showing they are effective with a Focal floorstanding speaker.

isoacoustics_techonology-explained-fig06-07.jpg


https://www.isoacoustics.com/isoacoustics-speaker-isolation-technology/
 
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amirm

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IsoAcoustics have lab tests showing they are effective with a Focal floorstanding speaker.
We had discussed this a while back in some thread. The question is the audible improvement. As I commented, at shows the difference is dramatic but that is because the height of the speaker changes.
 
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amirm

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As far as I know there's no good data for the LSR 305 MkII (a.k.a 305P). Only for the original LSR305. (I'd love to be proven wrong.)
I had searched and not found a proper one either. I am re-running the tests right now at higher resolution with more averaging. It is taking 2 hours now but is working on its own and other than tipping it, it has no other cost. :)

I plan to post the 305 as the first set of measurements. I am debating if I should post it as such, or first write a tutorial using it on what the measurements mean.
 

briskly

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Amir, do you have any expectations on how much angular resolution you need?

I just meant the Klippel set-up looks like it can only measure one speaker at a time, not two at once, typically spaced as in an average listening environment. Unless this is incorrect?

Do you mean L/R or L/C/R soundbars? The NFS can do that. There is no reason it cannot.
To answer your other question, the self-check is integrated into the function of the NFS. The inherently redundant measurements are what allows it to reduce sample points needed as well as isolate external reflections.
 

jtwrace

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mhardy6647

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I had searched and not found a proper one either. I am re-running the tests right now at higher resolution with more averaging. It is taking 2 hours now but is working on its own and other than tipping it, it has no other cost. :)

I plan to post the 305 as the first set of measurements. I am debating if I should post it as such, or first write a tutorial using it on what the measurements mean.
Speaking only for myself, some notion of the significance of the measurements (e.g., how they relate to audible qualities of a loudspeaker, especially if they're surrogates for things that are difficult or impossible to measure directly) would be greatly appreciated.
 
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amirm

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Amir, do you have any expectations on how much angular resolution you need?
CEA-2034 calls for 10 degrees. The measurement is at far higher resolution and accounts for spatial aliasing.
 

617

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CEA-2034 calls for 10 degrees. The measurement is at far higher resolution and accounts for spatial aliasing.

Geddes observes that less resolution is needed at the rear of the speaker since high frequencies aren't radiating back there but the Klippel system seems to have uniform sampling resolution?

Please indulge us with as much raw data as you can, I find the measurement technology more interesting than the speakers being tested.
 

briskly

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The Spinorama specifies 10° rotations, some people would even perform measurements with 5° rotations.
Klippel advertises the time-saving with 1° angular measurements. I would doubt that most loudspeakers need a very high order of harmonic expansion given that most drivers are run with a very limited range, not too far above ka. The structures of the wavefront would be limited, which gets to my point - how much resolution do you think you will need to capture the features of the wavefront? How much time do you want the measurement procedure to run for?
 

rgpit

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Love to see the Harbeth 30.1, 40.2, or the SuperHL5 plus tested.
 
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amirm

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