If you have been reading our speaker reviews, you have no doubt seen the "Preference Scores" for speakers. This was ground breaking research by Sean Olive published back in 2004 with the goal of predicting listener preference using anechoic chamber speaker measurements. Seemed like an impossible task but Sean pulled it off going beyond people's intuition that "everyone prefers a different sound." Clearly if we can predict preference based on measurements, then it is listener independent.
As we dug into the research, we quick ran into niggling problems with specificity of the standard/measurement computations, lack of clarity in some areas, etc. I don't think anyone had zoomed in and analyzed the research remotely as much as we have done across so many reviews. Still, replicating the research impossible due to the need for controlled double blind testing. One thing we can do however, is see if we can at least replicate the anechoic chamber results.
To be "polite" the research did not list actual speaker names/models. Fortunately they reference the Consumer Reports magazine test that triggered this research (Harman speakers did not do well in that despite winning listening tests). Member
@napilopez beat me to the punch and got a copy of the old Consumer Reports magazine that had the list of speakers. See:
https://www.audiosciencereview.com/...ce-ratings-for-loudspeakers.11091/post-412375
On top of that list as far as the bookshelf speaker that produced the highest preference score was a long discontinued Infinity Interlude IL10. There was a pair on ebay and I snatched that immediate. It arrived a couple of days ago and I thought I measure it quickly and have a discussion around it.
This is a rather stout speaker compared the lightweight bookshelves we see today:
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Measurements that you are about to see were performed using the
Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise.
Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.
I used over 800 measurement point which was sufficient to compute the sound field of the speaker.
Spinorama Audio Measurements
Let's start with our measurements first:
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This is nice! Response is more or less flat until about 10 kHz with a couple of resonances (peaks) here and there. This is what was reported in Sean Olive's paper:
A Multiple Regression Model For Predicting Loudspeaker Preference Using Objective Measurements: Part I-Listening Test Results
Sean E. Olive, AES Fellow
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Note that they used a 70 dB scale for the vertical axis of the spinorama measurements which compresses things relative to 50 dB which we use (and complies with the standard). There is no question that our measurements match theirs proving that we are dealing with the same speaker as "L1."
Note the jagginess in the low frequency response from Harman. That indicates room modes interfering with the measurement in low frequencies. In contrast, my measurements are smooth as silk, not suffering from any reflections.
On the other hand, there is a bit of jagginess in the midfrequencies that is caused by the microphone "cage" that I am using which doesn't show up as much in Harman's measurements. So I think we can expect some numerical differences between their data and ours.
The mean for the listening score of the Harman panel was 6.16 (highest of any speaker). Other than lack of bass, it achieved almost perfect neutrality scores as shown in the bottom graphs for different frequency ranges.
Here is our early window measurements:
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Quit close to direct axis resulting in a predicted response that is well, very predictable in a good way!
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Depending on where I draw the line, there is some excess energy but overall, very good showing and a sign of a speaker that is neutral.
The horizontal "beam width" shows the speaker to be on the narrow side than wide:
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But it is smooth otherwise as it falls off:
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Here is vertical:
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Not the focus of our study here but for completeness here is the impedance and phase:
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And waterfall:
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The research found that level of distortion did not correlate with preference in the face of frequency response variations. But let's examine them anyway:
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There is definitely an issue between 1 and 2 kHz even at lower volume of 86 dB.
Here is the absolute level at 96 dB:
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Closely measuring each individual component we get:
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Seems like our peak around 600 Hz is a resonance inside the box escaping through the port as circled (someone should do the math).
Speaker Listening Tests
For me this was the heart of the project: how would I like the best preferred speaker in this test? I fired up the speaker and my "5 second impression" was good. This speaker sounded neutral. Female vocals were especially nice.
Try as I might though, i could not like this speaker. Again, tonality was right but there is this grunginess and lack of clarity to everything it played. I tried to take the resonances out to fix it but at the end, it was not conclusive, nor did it make much of a difference. I even pulled my wife over to listen and she said there was some small difference with EQ but not enough for her to care.
Frustrated, I pulled up the
Revel M16 which I reviewed a while back. Wow, what a difference. Smooth ask silk. Clean as clean can be. Tonality was similar mind you but boy did it sound nice compared to IL10.
Now, there are two possibilities here:
1. Placebo effect and the M16 being similar to IL10.
2. My brain is forever transformed to listen to distortions in small notes. Right after tonality, this is what I listen for in speakers.
The research used such different speakers with some so broken that clearly the mid goes for tonality difference. Combine that with the fact that unless one is trained, hearing distortion is difficult and you or at least I arrive at the fact that distortion matters once you take care of tonality.
Conclusions
There are none as yet. I expect this to be a living research thread where we discuss what we have found here, and whether we can better rationalize speaker preference from measurements. The preference score for this speaker will be high (
@MZKM will post shortly) putting me once again at odds with it. We have to figure out why before I lose all face.
For now, I don't recommend that you go and chase this speaker unless you are interested to research it as I did. Note that the speaker was cheap but shipping was a killer.
And oh, I also ordered a Bose 141 which got one of the worst ratings. It too was cheap with high shipping costs. Will be here next week.
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As always, questions, comments, recommendations, etc. are welcome.
Now here I go from just testing gear to conducting "research." Surely I deserve a raise for that. Please get out your paypal account infor and
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