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Research Project: Infinity IL10 Speaker Review & Measurements

SEKLEM

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First, thank you Amir for this review and research project!

I've had the Infinity Interlude 10 speakers for 18 years. I've had no other audio component longer than these. When I was "shopping" for my first serious speakers at Circuit City I was enamored with the idea of having floor standing speakers and they had MTX at the time in the price range Mom could afford. I also really liked how the Infinity Interlude series of speakers looked, which was bleeding edge at the time in my mind's eye. I really wanted the IL30s but they were over the budget. Still determined to have floor standing speakers I listened to the MTX first. I was far from impressed. They sounded extremely dull, almost no high end at all, and the bass was very one note and tubby. It was entirely possible the tweeters on these speakers could have been blown that's how bad they sounded. My whole plan of having floor speakers was now shot, the only ones Mom would agree to pay for sounded like dreck.

So I relented and demoed the IL10. My 16 year old ears could not believe how much sound came from comparatively smaller boxes. Bass was better, defined, treble was present and clear. They sounded very even and balanced. These were something I could live with! Mom get them for me I was happy as a lark. After having them a few months I "discovered" sound staging. I got a crystal clear center image I was transported to another level. An audiophile was born in that moment. I had always appreciated good sounding speakers before, but this was a revelatory experience. Having never heard of center image, sound staging, or psycho acoustics, I was beside myself.

I've kept the IL10s all these years because they were the landmark that changed my perception of good sound, and because they were a gift. I like to remind Mom once in a while of what that meant to me as a kid and how it's shaped my hobby to what it is now. I still like these speakers and they've on and off again been my main listening speakers. They've been dependable and consistent for almost 20 years. They aren't worth much money these days, but to me they are priceless. They certainly aren't the final word on performance, but I'd never sell them.

In my experience using the IL10 bookshelf speaker I've plugged the ports to somewhat tame the cabinet resonance, especially if I'm going to use a subwoofer. I also have a resonate mode from the terminal cup. I'm not sure how to rectify this other than to eliminate the terminal cup all together.
 

pierre

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Concordance between the Klippel and the Harmann data is very good.

EDITED after napilopez@ pointed an obvious mistake in this graph.

visualization (2).png


P.S.: I agree with others that this thread is deviating from a data driven approach ...
 
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ROOSKIE

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This is the case in the context of set of speakers that vary (sometimes greatly) in frequency response. It is natural for us to focus on tonality when comparing different sounding speakers. Distortion then becomes secondary. This doesn't say distortion is not important by itself as the only variable.

The test of distortion would involve using a single (good) speaker and varying its distortion level to see if it is detectable.
Just to be clear you are still referring to Harmonic Distortion? Not to nit pick, reality is that since there are so many things that fall into the distortion category it may be best to always be specific.
My understating and experience with Harmonic Distortion(which is ongoing learning & not expert) is that what the Harmonic distortion does is change the tonality similar to mild frequency aberations. (in the lower amounts, not the 30% of a distortion pedal)It is not usually a distorted sound, it is a warming or a cooling or a slight smearing or a brightening or an etching. It is harmonic after all and it can sound euphonic and or very welcome and it can sound aggressive and even harsh(which may be welcome in certain ways as well to some). Sometimes it can even be confused as more accurate /not less, as in 3rd order "etching" of the sound, this may sound crisper to some - cleaner.
I was interested to note I heard grain and an etched quality in the ELAC b5.2 (that I thought sounded good but likely would not be my ultimate choice)& now measured By Kipple I see that the b6.2 (same tweet) has some extra 3rd order distortion over some comparable systems. Was I hearing it? I don't know yet. Be interesting once I hear the b6.2 and go on from there.
 

pierre

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Tuga is correct, strictly speaking: because it is possible to create a mediocre sounding speaker with excellent spinorama measurements, the spinorama is inadequate to characterize speaker quality.

But it is a weak way of being right. Few would disaree, least of all Olive and Toole. Tuga makes no argument that Spinorama is not the best available estimator of preference, an important guide to engineering speakers, or an important consideration in purchasing speakers. (And far better than "X sounded better than Y to me or others" in a non-blind test, doubly so if position and room are not strictly controlled.)

All models of reality are wrong; some are useful. We should aspire to more useful models.

1. Do you have an example of a speaker with an excellent spinorama that sound mediocre (with data) if running at a reasonable level for the speaker? Without data, this looks like BS to me.

2. Do you have a "be(ter) available estimator of preference"?

3. I agree we need more data and more experiments. Except convincing a University to run one, I do not see how we can progress on this.
 

QMuse

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That's why I wrote:


In how far @amirm is able to hear distortions, I cannot judge.
But we can take a look at psychoacoustics and ask ourselves if it is possible from a scientific point of view.

Source: Psychoacoustics - Zwicker, Fastl
View attachment 70641

The masking is shown in the diagram for a critical-band wide noise around 1kHz (approximately 1kHz+-100Hz width), therefore the result can still be transferred quite well to 1.5kHz.

As blue lines I have drawn the audibility threshold of HD3 (a test tone at 3kHz) once with an 80dB and a 100dB masker.
With the 80dB masker, HD3 is theoretically audible from an attenuation of -53dB (0.2%), with the 100dB masker from about 1%.
Thus @amirm's perception may well be correct, since with 1.5% HD3 the detection threshold is far exceeded.

In comparison, HD2 (a test tone at 2kHz) with an 80dB masker would only be audible from about 1% distortion.
Due to the lack of masking, higher order harmonic distortions are therefore considered to be more "sound damaging".

Sure, that distortion may be audible but it would have to hit the right tone as the band in which distortion is happening is quite narrow. And even in the case he was able to hear the distortion it certainly wouldn't fit into his description of "grunginess and lack of clarity to everything it played". In fact, looking at the measurements I wasn't able to find anything that would fit such description.

But, as @edechamps correctly noted, Amir's listening test is only 1 sighted uncontrolled test vs 12 contolled double blind tests, so I see no reason to get excited about it. In this tests it is the Klippel NFS data that matters, not sighted uncontrolled listening impressions of 1 listener no matter how well trained (he claims) he is.
 
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napilopez

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I agree.
But we'd be in the dark with many of the issues that have been surfacing were it not for the THD measurements, as well as CSD and individual driver and port FR plots. And we are still "missing" step-response, IMD and Iin-room FR plots. There are many aspects to speaker performance and the more comprehensive set of measurements will produce the most accurate "picture".

The Spinorama alone is insuficient to characterise performance.

In absolute terms I agree too that the spinorama is insufficient to give a complete picture. But I do think on and off axis performance - I've complained several times about the lack of horizontal directivity information, for instance -- explains almost everything barring very audible distortion. Which in this case, I guess Amir heard, but I'd still look towards the frequency response and directivity before concluding it was distortion for sure (even though Amir is probably one of the most trained people at hearing distortions).

I still expect either EQ or extended testing with more listeners would show this speaker to be a good one. I mean, the speaker is a well-reviewed one otherwise.

On a separate note, you mentioned Genelec's slow listening paper earlier, and I do think there's merit to that. That said, in my personal experience, it mostly tends to support the frequency response and directivity stuff.

Other than Amir, I probably have some of the most experience correlating extensive on and off-axis measurements of various speakers to listening impressions around these parts. But unlike Amir I spend at least a week listening to a speaker and taking notes before I measure it, in both mono and stereo,. Usually several weeks, sometimes over a month. I also capture and look at CSDs, step response, and driver distortion, but I've yet to find a speaker where any of those things clearly describes something I'm hearing that's not present in already in the spinorama+ detailed off-axis measurements.

(Note I'm not talking about the preference score here, but rather the raw data. There are certain qualities I know I like, such as a bit of extra energy around 2kHz as wide directivity).

Of course, I'm sure others would disagree. Plenty of speaker designers focus on minimizing distortion or improving time domain response, after all.

And granted, I don't have Amir's distortion training, and I suspect at the very high end smaller differences matter not present in the spin matter proportionally more. Kevin Voecks had this to say in a sound and vision article where the Revel F208 (slightly) beat the Ultima Studio2 in a blind test at the company's speaker switching room:

As you know, many people argue about double-blind tests. Most of their arguments are without merit, but not all. One of the most important is that in my opinion and observation, it does indeed take extended listening sessions to hear the more subtle differences. The important thing is that these more subtle differences can indeed become more evident over time. Having listened to the Performa3 series and Ultima2 series both for very long periods of time, the difference at high frequencies especially is dramatic. The Ultima2 tweeter is so much "cleaner," with vastly lower distortion (even though the Performa3 distortion is far below most speakers) that it is much easier to listen to without fatigue. Combined with the advantages of low diffraction, it is the high frequency range that causes the Ultima2 series to win in long-term listening tests. Getting back to the blind testing, that kind of difference is best heard with longer sessions. There must be breaks between long sessions, as fatigue sets in, but that is where differences that audiophiles live for become apparent.

It's possible @amirm is kind of 'fast-tracked' into hearing those differences in distortion that show up in extended listening that Voecks describes.
 

QMuse

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I still expect either EQ or extended testing with more listeners would show this speaker to be a good one. I mean, the speaker is a well-reviewed one otherwise.

I'm guessing you meant "room EQ" when you said EQ as there's nothing much to EQ in terms of speakers response here. Sure, you can correct those small resonances at 700, 1100 and 4700 Hz and correct hot tweeter response north of 6kHz, but it's nothing major - this speaker is pretty good the way it is and Amir didn't complaint about tonality.

It's possible @amirm is kind of 'fast-tracked' into hearing those differences in distortion that show up in extended listening that Voecks describes.

I really can't relate those 2 narrow distortion peaks with the description of " grunginess and lack of clarity to everything it played".
1593102794586.png
 

Koeitje

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What is a joke, the fact that the IL10 disapointed when compared with the M16 in spite of all the hype surrounding its extraordinary spinning abilities?
The M16 is 15 years+ newer, there have been some developments in design over the years.
 
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amirm

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Amrim--Do you listen to the speakers before or after you run them through all the tests?
I run the measurements first and compute the response. I am not privy to the preference score. I do look at the frequency response. In this case, I had full knowledge of the score in the paper and from @MZKM although I had done most of my listening before he gave me the score.

Everything then was biasing me to say this is a great sounding speaker. The graphs looked good as did the scores. But after listening to it more than I do many other speakers, I just couldn't cross the threshold. When I switched to M16 and heard what I was looking for, I proceeded with my conclusions.

I should say that assessing speaker performance using listening tests is the hardest thing I do. A lot of times the results are content dependent. And at any rate, I could be pushed one way or the other. So despite using the best methodology than anyone else out there, there is going to be variability in my judgement.
 

JohnYang1997

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There's a difference between "changing tonality, changing balance" and "universally annoying". This is also very subjective to people. Some people accept tonal change but cannot stand any high q peak. Some people can accept peaks but cannot stand overall tonal shift.
Listening training can certainly shift what's more acceptable to the trained listener.
 

ROOSKIE

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That's why I wrote:


In how far @amirm is able to hear distortions, I cannot judge.
But we can take a look at psychoacoustics and ask ourselves if it is possible from a scientific point of view.

Source: Psychoacoustics - Zwicker, Fastl
View attachment 70641

The masking is shown in the diagram for a critical-band wide noise around 1kHz (approximately 1kHz+-100Hz width), therefore the result can still be transferred quite well to 1.5kHz.

As blue lines I have drawn the audibility threshold of HD3 (a test tone at 3kHz) once with an 80dB and a 100dB masker.
With the 80dB masker, HD3 is theoretically audible from an attenuation of -53dB (0.2%), with the 100dB masker from about 1%.
Thus @amirm's perception may well be correct, since with 1.5% HD3 the detection threshold is far exceeded.

In comparison, HD2 (a test tone at 2kHz) with an 80dB masker would only be audible from about 1% distortion.
Due to the lack of masking, higher order harmonic distortions are therefore considered to be more "sound damaging".
Howdy just to point out test tones are a far cry from music and so unfortunately only represent the audibility threshold with the tones.
 
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amirm

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But, as @edechamps correctly noted, Amir's listening test is only 1 sighted uncontrolled test vs 12 contolled double blind tests, so I see no reason to get excited about it.
That's not the case at all. I did not repeat the Harman test against they other speakers in the pool. Had I done that, my results could have very well agreed with the research as it has in two occasions I have taken that test.

My test does not repeat Harman's. It is an independent test that cannot be compared to theirs regardless of controls or lack thereof.

My data point then is different. It goes after a difficult challenge: how to judge speakers that for the most part all follow the research. We don't have this data from any controlled test.

Harman performs double blind controlled test prior to release of any new speaker. If the new design can't beat its older generation or the competitors, it cannot be released. It reasons then that my conclusion that say, a speaker like Revel M16 sounds better, is correct. And that newer speakers Harman has designed all beat the Infinity IL10.

My listening impressions may be wrong still but don't be in such a hurry to write them off this way.
 

stunta

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I just wanted to post here to show my appreciation towards this effort. I've dreamed of the day when I can go online and buy speakers based on whether I like how they look vs. sound. If we can nail the correlation between measurements and subjective preference, I feel like that dream will come true. Thank you to all those involved in this research.

I don't have trained ears, but every time I have listened to Infinity speakers (my brother has owned a few of them), the terms "grungy" and "ear-bleeding" have always come to my mind. I always asked my brother to turn down the volume as I could not tolerate the sound.
 
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amirm

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What I like to do is get this speaker in other people's hands to evaluate. I am right now the only person who has measured and listened to these speakers. I like to broaden this pool. If there are any local people that are interested, let me know and I can loan them out and have you post your impressions here.
 

Robbo99999

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@amirm , how come you are interested in seeing if you can replicate the anechoic chamber results of Sean Olive's 2004 work, what is it that you're trying to find out or conclude? I couldn't get a sense of the wider purpose from the lines you wrote on it.
 

ROOSKIE

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I'm sorry this might sound a bit disrespectful, but the whole premise of this thread is nonsense and goes hard against the "S" of ASR.
So Amir didn't like a certain speaker at a certain point of time with certain physical and psychological circumstances, which basically means we have no idea if his impression is even related to actual sound. So why is it even worth discussing?
Once ASR/Amir/one of the members set ups a proper blind testing facility then we can dig into the issue, emulate distortions/tonality imbalances/other speaker characteristics and faults and properly compare their impact on either preference or general audibility. As it is now this is a regression, a fodder for "I trust my ears, not measurements!!" people I hoped this forum tried to shoo away...
How could it possibly not be worth discussing that a speaker that measurers well and perhaps doesn't appeal as much?
Especially when it is driven by the comments of the sites founder.
Science is an investigation not a rote behavior.
This is part of that IMHO.
As far as shooing folks away, while it would suck if the site was overrun with snake oil salespeople, who wants to only preach to the choir?
I am totally on board with the blind test comments, can't wait for those. But even with in those there will be variations and obstacles that will still leave discussions open. (Such as do you toe in such and such speaker when it when perhaps it would sound better not toed in. What volume is playback. Does listening to a few tracks represent listening to hours of music. ECT)
 

Absolute

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Yep, and the issue is that we don't know what exactly was observed in Amir's subjective assessment.
No, which was the point of this whole discussion.

We should always listen to subjective feedback, but we should be careful to conclude based on it. In this case here's what I would do to get some valid data to use again in similar cases in the future;

1. Remove the resonances by careful EQ.

2. Blind-test with and without said EQ and check the results.

3. If the EQ version clearly beats non-EQ, compare Eq version again with M16.

4. If same result, try both high-passed at some frequency to remove the largest factor for preference differences.

5. If same, EQ to match tonality within listening window to M16. Re-run comparison blind.

6. If same result, there's a chance it's down to dispersion characteristics/quality, non-linearities or other esoteric stuff. Other than going nuts with absorbers around the speakers it's difficult to figure out exactly.

That's valid data worthy of noting for future research. One person can also do good research even if it doesn't qualify for conclusions on a general basis.
 

MZKM

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@amirm , how come you are interested in seeing if you can replicate the anechoic chamber results of Sean Olive's 2004 work, what is it that you're trying to find out or conclude? I couldn't get a sense of the wider purpose from the lines you wrote on it.
There have been a ton of comments regarding the accuracy of the Klippel, or at least Amir‘s setup. Buchardt uses one and Amir’s measurements weren’t identical. Neumann‘s KH80 showed a valley in the bass in 2 models, so Neumann sent 1 model to Klippel themselves and their measurements don’t have that valley.

Even noted in this review, his mic setup causes some wiggles in the response, this was worse in earlier measurements, and it makes it look as if the speaker has resonances.
 
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