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Discussion Starter · #1 ·
Choosing a loudspeaker may be the biggest challenge for music and home theater lovers. There are countless brands from which to choose, and even more claims and counter-claims. Since the room has such a profound impact on the sound of a loudspeaker at lower frequencies, and it is impossible to listen in a blind test at an audio store, if they can find one, there is little that an audiophile can do to make a rational decision. Fortunately, science has come to the rescue with a set of measurements that have been proven to demonstrate an extremely close correlation with sound quality, as based on carefully controlled double-blind listening tests. This group of measurements have been adopted as the industry standard for measuring loudspeakers, as ANSI/CEA-2034-A. https://standards.cta.tech/apps/group_public/project/details.php?project_id=165

Contradicting the oft-repeated claim that choosing a loudspeaker is a very personal choice, research has proven that regardless of age, culture, or listening experience, all people with nominally normal hearing generally agree on which speakers sound better than others. Indeed, there is a universal definition of what sounds good. http://www.aes.org/e-lib/browse.cfm?elib=12794 and https://secure.aes.org/forum/pubs/conventions/?elib=12847

In this thread, we will publish the results of these measurements. In addition, we will discuss their correlation to double-blind listening tests, http://seanolive.blogspot.com/2008/12/part-3-relationship-between-loudspeaker.html as well as publishing the results of formal listening tests, when available. We will add measurement results as they become available. The intention of this thread is for it to be reality-based, and to inform and discuss loudspeaker measurements and listening tests. The papers that really started it all are now available for free from the Audio Engineering Society here: http://www.aes.org/e-lib/browse.cfm?elib=5276 and here: http://www.aes.org/e-lib/browse.cfm?elib=5270
 

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Discussion Starter · #3 ·
An explanation of ANSI/CEA-2034-A ("Spinorama") Data

Years of experiments and studies conducted by Harman Research Scientists https://www.routledge.com/Sound-Rep...f-Loudspeakers-and/Toole/p/book/9781138921368 and https://secure.aes.org/forum/pubs/journal/?ID=524 has led to a series of 70 measurements which, after post-processing, provide an excellent indication of a loudspeaker's sound quality. This group of measurements, dubbed "Spinoramas," have proven to be so meaningful in characterizing the sound of loudspeakers in rooms that they have been codified as the industry standard method with which to measure loudspeakers as ANSI/CEA-2034-A. https://www.techstreet.com/mss/products/preview/1868536

These 70 measurements, measured as a sphere surrounding the loudspeaker, are post-processed to provide six curves that, taken together, correlate closely with carefully controlled double-blind listening tests. http://www.aes.org/e-lib/browse.cfm?elib=3833



On-axis
The on-axis frequency response is and has been the most commonly used loudspeaker measurement. However, when used by itself it is a questionable indicator of the speaker's sound quality. If it is poor, the speaker will not sound good, but the on-axis response can be good, while the speaker does not sound good. The measurements described below are necessary to more fully characterize the sound of a loudspeaker. It is no wonder that speaker measurements have had such a poor reputation regarding their relationship to sound quality, given that they have generally been of the simple on-axis variety.

Listening Window
This updated measure of a speaker's direct sound output is composed of an average of nine frequency response measurements on-axis, at ± 10° vertical, and at ± 30° horizontal off-axis angles. Since this measurement is a spatial average, it attenuates small fluctuations that are merely the result of acoustical interference that is far less sonically significant than it appears to be based upon a single on-axis measurement. These relatively acoustically-benign local interference phenomenon change with tiny adjustments in the microphone position, and their visual distraction can mask actual performance problems--resonances in particular. Resonances are "bumps" in the response that can be significant sonic problems. Since resonances tend to radiate over a wide area, they will remain visible in the spatially-averaged Listening Window response, while insignificant fluctuations that would change with tiny microphone position adjustments are suppressed. Loudspeakers with smooth and flat listening window responses tend to excel in Harman's Double-blind Listening Tests.

First, or Early Reflections
Most of the sound we hear in rooms is reflected. The second-loudest sound, after the direct sound, is the first reflected sound from the loudspeakers. In fact, Harman research has discovered that the first reflection from side walls, both from the wall adjacent as well as the opposite side wall are critically important. The acoustic output of a loudspeaker far off-axis horizontally is very significant, and should match the response of the Listening Window as much as possible. This goal is technically challenging, but is essential for optimum timbre, as well as to provide a sense of seamless coherency. Revel's waveguides, along with optimum engineering choices such as crossover points and slopes, relatively small midranges and tweeters that can be safely used to lower frequencies than typical designs contribute to far off-axis responses that are close to the direct sound, as seen in Listening Window measurements. http://www.aes.org/e-lib/browse.cfm?elib=6079

Sound Power
Sound Power is composed of the weighted average of all 70 measurements. Each measurement is weighted to properly represent an area of a sphere. Sound Power is a measure of the total sound radiated by a loudspeaker. One of its uses is to detect resonances, since response aberrations seen in both the Sound Power and other curves are likely true resonances. Harman research has determined the threshold of audibility of resonances. All Revel speakers are designed to keep resonances below the threshold of human audibility using the most sensitive stimulus. http://www.aes.org/e-lib/browse.cfm?elib=5163

Directivity Indices
The Directivity indices describe how the speaker's radiation changes as a function of frequency. The Sound Power Directivity Index is defined as the difference between the Listening Window curve and the Sound Power, while the First Reflection Directivity Index utilizes the Listening Window curve and the First Reflections curve. Both curves should be smooth and change gradually. A DI of 0 dB indicates an omnidirectional speaker, while a larger DI indicates greater directivity.
 

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Discussion Starter · #4 · (Edited)

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Choosing a loudspeaker may be the biggest challenge for music and home theater lovers. There are countless brands from which to choose, and even more claims and counter-claims. Since the room has such a profound impact on the sound of a loudspeaker at lower frequencies, and it is impossible to listen in a blind test at an audio store, if they can find one, there is little that an audiophile can do to make a rational decision. Fortunately, science has come to the rescue with a set of measurements that have been proven to demonstrate an extremely close correlation with sound quality, as based on carefully controlled double-blind listening tests. This group of measurements have been adopted as the industry standard for measuring loudspeakers, as ANSI/CEA-2034-A. https://standards.cta.tech/apps/group_public/project/details.php?project_id=165

Contradicting the oft-repeated claim that choosing a loudspeaker is a very personal choice, research has proven that regardless of age, culture, or listening experience, all people with nominally normal hearing generally agree on which speakers sound better than others. Indeed, there is a universal definition of what sounds good. http://www.aes.org/e-lib/browse.cfm?elib=12794 and https://secure.aes.org/forum/pubs/conventions/?elib=12847

In this thread, we will publish the results of these measurements. In addition, we will discuss their correlation to double-blind listening tests, http://seanolive.blogspot.com/2008/12/part-3-relationship-between-loudspeaker.html as well as publishing the results of formal listening tests, when available. We will add measurement results as they become available. The intention of this thread is for it to be reality-based, and to inform and discuss loudspeaker measurements and listening tests. The papers that really started it all are now available for free from the Audio Engineering Society here: http://www.aes.org/e-lib/browse.cfm?elib=5276 and here: http://www.aes.org/e-lib/browse.cfm?elib=5270
Thank-you! 😀 Great thread topic!!

Are you accepting requests for subjective speaker comparos and/or measurements? 😁
 

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Discussion Starter · #7 ·
Thank-you! 😀 Great thread topic!!

Are you accepting requests for subjective speaker comparos and/or measurements? 😁
Thank you Gooddoc. We do not have the personnel available to put speakers through our testing by request. However, feel free to make requests, and if we have them available, I will add them. I will be adding both Revel and other competitors as time permits, so you might find your request fulfilled without even asking.
 

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would be awesome if we had the measurements of the speakers after the users got to adjust eq...ya know to see what they really liked the sound to be
 

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Thank you Gooddoc. We do not have the personnel available to put speakers through our testing by request. However, feel free to make requests, and if we have them available, I will add them. I will be adding both Revel and other competitors as time permits, so you might find your request fulfilled without even asking.


Could you do the KEF Q100 or 500s? Thanks!


Sent from my iPhone using Tapatalk
 

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Since the 228BEs show better measurements through most of the FR range, particularly off-axis compared to the Salon 2, yet the Salon2 was preferred on average, should the explanation primarily be that the highs are rolled off (8K+?) in comparison? It seems to me the old NRC research showed a preference for rolled off highs for most people, so the only downside to the PerformaBe series is the tweeter is a little hot in the higher frequencies?
 

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science probably says that those that can afford 10k + speakers cant hear abover 15khz if lucky...
 

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I'm surprised by the choice of Magico to compare to the Revels, it seems most people in the high end community prefer TAD Evolution or KEF Blades over the Magicos.

On the other hand, I sort of understand it from a marketing perspective, since KEF and TAD are using concentric designs which have much better polar response measurements than a typical multi-way dome speakers. Perhaps it would be harder to sell promotional material for Revel when the speakers you are comparing to measure better than what you are selling using your preferred measurement techniques...
 

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Ah, I think I see why the Salon2 might be preferred. It's got a large dip at 2KHz in the off-axis measurements as well. I know many high end headphone companies (like HFM) intentionally engineer 2KHz dips with high end electrostatic headphones to give a larger sense of staging, and this is also where British brands traditionally put a frequency dip (also known as the BBC dip) because their own research found people often prefer a dip in that region.
 

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On the other hand, I sort of understand it from a marketing perspective, since KEF and TAD are using concentric designs which have much better polar response measurements than a typical multi-way dome speakers. Perhaps it would be harder to sell promotional material for Revel when the speakers you are comparing to measure better than what you are selling using your preferred measurement techniques...
I guess we'll just have to see if any comparos or measurements have been done. It was clearly stated there was more to follow.
 

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Ah, I think I see why the Salon2 might be preferred. It's got a large dip at 2KHz in the off-axis measurements as well. I know many high end headphone companies (like HFM) intentionally engineer 2KHz dips with high end electrostatic headphones to give a larger sense of staging, and this is also where British brands traditionally put a frequency dip (also known as the BBC dip) because their own research found people often prefer a dip in that region.
I've always preferred about a 3db dip in the 1-4khz fatigue area, but I didn't know that it can also give a larger sense of staging, that's a nice bonus.
 

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after diving head first into headphone game I hear alot more...nothing close to my stereo fullrange home setup...but way easier to focus and listen and hear stuff different.
 
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