Research Project: Infinity IL10 Speaker Review & Measurements

[pozz]

I don't think that a Harman-style shootout is even adequate for determining preference let alone assess performance... Spins tell you how a speaker wees into the room but little about the characteristics of the fluid.

Have you found evidence or is this at the level of hunch?

 

[RayDunzl]

The current test was also performed on a used loudspeaker

My loudspeakers are all "used" now.

 

[amirm]

Is there any particular online resource that offers at least part of the training you have? I'd be curious to see what it offers.

No, I never seen one. Training also takes a long time. I spent months getting there. I can teach someone to go much faster but it will require effort.

 

[amirm]

http://harmanhowtolisten.blogspot.com/2011/01/welcome-to-how-to-listen.html?m=1

That is for learning tonality differences, not distortion. Mostly it helps with identifying what is wrong than threshold of detection.

 

[maverickronin]

What I am wondering is for Rock, electronic and really anything that uses synthetic or modified sound how capable are folks at picking up on the distortions? I mean essentially all pedals and amps and different things are adding massive amounts of harmonic distortion in on purpose to a achieve a really unknown sound on the recording, some guitar amps have stratospheric harmonic distortion.

In an actual mix, the distortion (could be IMD instead of THD though) is much easier to hear. All the individual tracks and effects will start to fall apart and become indistinct.

Dense metal mixes can be just as busy as full orchestras.

 

[Blumlein 88]

I understand that for classical type instruments and such harmonic distortion may stand out quite a bit.
What I am wondering is for Rock, electronic and really anything that uses synthetic or modified sound how capable are folks at picking up on the distortions? I mean essentially all pedals and amps and different things are adding massive amounts of harmonic distortion in on purpose to a achieve a really unknown sound on the recording, some guitar amps have stratospheric harmonic distortion. Even keyboards and such have mind altering properties. So much is altered in most contemporary music with a lot of 2nd and 3rd added at the recording level.
Essentially is .6% 3rd order harmonic distortion really only an issue with well recorded classical music and such?

https://distortaudio.org/

Download Pkane's software and you can create many types of distortion and test yourself. Might take a bit to figure out the adjustments you are able to do, but it isn't too complicated. Distort your own music files and compare to undistorted or to different levels/kinds of distortion.

 

[bobbooo]

Is it ludicrous to conceived that the M16 could be a better speaker?

No, but the reason it's not ludicrous is that the M16's preference rating is higher than the IL10's, all produced solely from spinorama data. In fact, @edechamps calculates there to be a 61% probably that the average listener will prefer the M16, as shown in his very useful matrix comparison chart. @amirm is just part of that 61% majority predicted by the preference ratings.

 

[xarkkon]

No, but the reason it's not ludicrous is that the M16's preference rating is higher than the IL10's, all produced solely from spinorama data. In fact, @edechamps calculates there to be a 61% probably that the average listener will prefer the M16, as shown in his very useful matrix comparison chart. @amirm is just part of that 61% majority predicted by the preference ratings.

That's a good point. The write up assumed then that the IL10's were the very pinnacle (given Amir didn't have the rating and that's where the IL10 stood in the original test). Given the preference rating now shows that the better rated speaker sounds better, would that change your view in any way Amir?

 

[amirm]

That's a good point. The write up assumed then that the IL10's were the very pinnacle (given Amir didn't have the rating and that's where the IL10 stood in the original test). Given the preference rating now shows that the better rated speaker sounds better, would that change your view in any way Amir?

My view is evolving. Regardless, a speaker with IL10's rating should very much be liked so the fact that I didn't is notable in itself.

The other theory I have is that even tiny 1 dB differences in different parts of the spectrum may matter. The research only compared speakers with large disparity. Developing a formula to predict preference among excellent speakers is what we need.

 

[napilopez]

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.

------------
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 donate generously using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Thank you for this! It's a really interesting experiment, and it's nice to see than old model can measure well. The real test will be how the Bose compares

The way you talk about being able to hear distortions reminds me somewhat of how much I hate clipping in photography. Doesn't matter how pretty a photo is, if the clouds are clipped, I can't get past that distraction.

Since you found the speaker unexciting, I think it's interesting that in the Olive Paper 1 the most common negative comment levied at this speaker was that it sounds 'dull', followed by 'mid depression' and the more ambivalent 'mellow.'

If I had to look for a reason for this in the spin, it would be the broad depression in the early reflections curve around 2-3 kHz(in Harman's spin which weight the vertical reflections more heavily). I find this can quick make a speaker sound dull if it not balanced out by the on-axis.

So we have a box that has excellent dispersion characteristics and a nearly flat on-axis response (albeit marred by port and mid-woofer resonances) which sounds bad.
What better way to illustrate how frequency response and directivity are manifestly insuficient to characterise the performance of a loudspeaker.

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?

This really quite stretch of a conclusion. And because it's worth repeating, as @bobbooo said, the Revel sounded better, but it also scores better, so the formula is still doing quite well for itself in this particular example.

If Amir ends up liking the bose more than the IL10, then I'd start to be a little worried. But even then: one listener, listening to a single speaker at a time (as in not comparative- not talking about stereo), in an uncontrolled setup. As Amir points out, he also has particular sensitivities to distortion.

Spin aside but still following the basic frequency and directivity logic, the Revel M16 also has slightly better directivity control, which could partially explain it sounding cleaner, although the IL10 is certainly still very good.

That said this isn't to say I don't believe there can be other causes for it. I'd be curious if the IL10 is still 'to spec' in other respects. But if I were a betting man, I'd still put my money towards the IL10 over newer speakers that scored significantly lower.

It's been 16 years since that test. Is it ludicrous to conceived that the M16 could be a better speaker? Or do you expect loudspeakers with similar Spins to sound the same?

Yes, yes I do. Or at least, very similar. Assuming a similar spin means similar directivity characteristics. I find it strange you think they wouldn't.

 

[Blumlein 88]

Yeah I think Amir might have liked this better with a broad 1.o to 1.5 db boost over the 2-4 khz range. With a 1 db dropped shelf for everything above 4500 hz. Any chance of you trying that @amirm ? I know backtracking slows everything down, but this is an easy to handle speaker you have on hand. And I understand you can't try all the suggestions of dozens of us.

 

[napilopez]

Yeah I think Amir might have liked this better with a broad 1.o to 1.5 db boost over the 2-4 khz range. With a 1 db dropped shelf for everything above 4500 hz. Any chance of you trying that @amirm ? I know backtracking slows everything down, but this is an easy to handle speaker you have on hand. And I understand you can't try all the suggestions of dozens of us.

I imagine he was planning on listening to the IL10s again along with the Bose when those arrive, so maybe something to try then!

 

[RayDunzl]

@amirm

Since these speakers are nearly 20 years old, and the original post mentions "pair"...

Do they both sound equally disappointing, or at least, the same?

 

[amirm]

@amirm

Since these speakers are nearly 20 years old, and the original post mentions "pair"...

Do they both sound equally disappointing, or at least, the same?

I haven't tried the other one.

 

[GXAlan]

My view is evolving. Regardless, a speaker with IL10's rating should very much be liked so the fact that I didn't is notable in itself.

The other theory I have is that even tiny 1 dB differences in different parts of the spectrum may matter. The research only compared speakers with large disparity. Developing a formula to predict preference among excellent speakers is what we need.

What if we compared the KEF R3/Revel F208 against the IL10 (high score, sounds bad) and the Canon S-50 (low score, sounds better). See where the Canon has similarities to the flagships and where it differs from the IL10.

@amirm, relying purely on memory, did the IL10 or S-50 sound better?

 

[test1223]

Hello,

the consistent best guess backed by a lot of research is that none linear distortions aren't very important if they aren't oddly high.

How exactly the speaker radiates the sound is what separates one form another. I think it would be very interesting for you @amirm to buy and experiment with the smyth realizer. It is a device which captures the sound of speakers in the room for headphones. It works astonishingly well the weak part is the lack of vibration from the bass which can not be produced by any headphone. With this device you can capture the "magic" of any speaker and as fare as I know its algorithms doesn't consider non linearities.

The fine details of the sound radiation in the range form 500 to 20kHz are very important. If you have a look at different very good sounding speakers you will find that the room and the listening distance become much more important. The preference will not be the same if you change the listening distance and other room/speaker related parameter. I think doing more research in this direction will extent the very good foundation established by @Floyd Toole and others.

The german speaker brand Musikelectronic Geithain is not well-known in the US. They build state of the art studio monitors which consider the listening distance and room by engineering the radiation of the speakers. The measurement are "flat" and are not very different if you have a look at it as an inexperienced speaker developer. But there are fine details in the measurement which are more important the behavior of the radiation in the frequency range from 700Hz to 4kHz is much more important and there is a none-linear "importance curve" to it, so is not so easy to see the differences if you don't know this. One interesting fact Geithain is following is to take the differences in the tonal perception of direct sound to diffuse sound into account for balancing the overall tonality and imaging of the speaker. Similar things are done if you deal with good sounding omnidirectional speakers. Since you have only one recording and stereo requires reflections from the room it is very important how much direkt and how much later sound you have at your listening position to get the details of the tonality right.
The Geithain speakers get very high ratings in listening test and are used in a lot of studios and are worth to experiment with.

Best
Thomas

 

[amirm]

How exactly the speaker radiates the sound is what separates one form another. I think it would be very interesting for you @amirm to buy and experiment with the smyth realizer. It is a device which captures the sound of speakers in the room for headphones. It works astonishingly well the weak part is the lack of vibration from the bass which can not be produced by any headphone.

I know the founder and listened to a prototype some 12 years ago in Cambridge UK AES chapter. It was uncanny how the Stax headphones he was using sound essentially identical to speakers he was emulating.

 

[amirm]

Hello,

the consistent best guess backed by a lot of research is that none linear distortions aren't very important if they aren't oddly high.

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.

 

[maty]

Crossover
https://www.ebay.com/itm/Infinity-IL10-2-way-crossover-/133039660870

Optimized and rotated

 

[test1223]

I know the founder and listened to a prototype some 12 years ago in Cambridge UK AES chapter. It was uncanny how the Stax headphones he was using sound essentially identical to speakers he was emulating.

The stax are really good headphones. Yes it works also with with other headphones and as I said there are no nonlinearities involved in the emulation and you will get the sound of the speaker with your headphone, which indicated that nonlinear distortions are not that important.

I agree that distortion become also more important if everything else it very good. But the radiation is by fare the most important part.