Is nonlinear distortion of (small) speakers unimportant??

[edechamps]

I'd also contest the point that listening tests are irrelevant here as speaker measurements are only valuable insofar as we can correlate them to listening tests. Put another way, I'd argue everyone here knows that distortion matters to some extent! The problem is that 'some' extent. The audibility of frequency response problems and how they relate to preference is very well documented. Meanwhile speaker designers and acousticians are still trying to figure out how much distortion actually matters in music and the best way to measure it in a relevant manner.

I'll add to this that it doesn't seem that hard to setup a controlled blind test experiment to correlate non-linear distortion in loudspeakers and subjective impressions. You just need a high quality loudspeaker of known low distortion, a typical room, and a "virtual" (software) distortion generator that is capable of adding the same kind of non-linear distortion that a loudspeaker driver would introduce. Then get some test subjects and off you go.

Are there any published studies that have tried the above?

(Though I guess one limitation of that protocol is that you wouldn't be able to test the case where the non-linear distortion depends on off-axis angle.)

 

[QMuse]

Problem is that Gedd-Lee metric, however good it is and verified through proper listener tests, never managed to become CEA/ANSI standard. Until some distorion metric manages that it is hard to expect companies like Klippel to imeplement it.

Also, Toole didn't really help with distortion issue. He was (righteously) focused on smooth on- and off-axis FR and while doing his tests obviously the speakers he used on the SPL levels he needed managed to handle it well so he didn't wanted to bother we that. But distortion IS an issue and some metric will show correctly that some speakers at some frequencies and at some SPLs do produce audible distorion. But again, mo matter how much Gedd-Lee metric seem to be able to do just that as long as it is not accepted as CEA/ANSI standard we can hardly expect it to be of any practical use to us, as devices like Klippel will not use it - they will continue to use simple distortion spectrum graphs although we know they don't correlate with listening tests.

 

[tuga]

I'll add to this that it doesn't seem that hard to setup a controlled blind test experiment to correlate non-linear distortion in loudspeakers and subjective impressions. You just need a high quality loudspeaker of known low distortion, a typical room, and a "virtual" (software) distortion generator that is capable of adding the same kind of non-linear distortion that a loudspeaker driver would introduce. Then get some test subjects and off you go.

Are there any published studies that have tried the above?

(Though I guess one limitation of that protocol is that you wouldn't be able to test the case where the non-linear distortion depends on off-axis angle.)

You would also have to train the listeners to identify non-linear distortion.

 

[mjwin]

I'll add to this that it doesn't seem that hard to setup a controlled blind test experiment to correlate non-linear distortion in loudspeakers and subjective impressions. You just need a high quality loudspeaker of known low distortion, a typical room, and a "virtual" (software) distortion generator that is capable of adding the same kind of non-linear distortion that a loudspeaker driver would introduce. Then get some test subjects and off you go.

I think this is an excellent idea (logistics permitting). Samples of different styles of music could be subject to a non linear process, and arranged for blind A/B comparisons.

Although in these tests we would be looking only for non-linearity in the transfer function, I do think we need to get away from THD as the primary metric as, by its very definition, it sums all distortion spectra into one single figure of merit, and has failed to bear much correlation with experimental results to date.

I would suggest that, in order to have some relevance to real world (speaker) nonlinearities, it would probably be best to begin by adding either square or cubic law distortions. Anecdotally, square law distortion (second harmonic) has been perceived as less pernicious than that of more complex transfer functions, although it will still lead to intermodulation products.

In any case, we can define the function exactly and then look at how this correlates with listening tests. Ultimately, this can be referred back to THD if needs be, but also to the specific distortion spectra produced, simply by mathematically subjecting a sinusoid to the same process.

We would also need to think about whether the test is seeking a listener preference A/B or identity A/B/X.

 

[restorer-john]

@pma Excellent thread.

Those of us who have heard and owned/own speakers with truly excellent, low distortion performance through the critical mid-range understand that silly little 6.5" 2 way speakers are a whole lot of fun (I own heaps of them), but not remotely a serious path to high quality reproduction.

Can I suggest some intermodulation distortion tests at a reasonable excursion to demonstrate what happens to the midrange THD when modulated by the low frequencies?

 

[q3cpma]

Using a ~90€ pair of speakers to prove that all "small" speakers are just toys is nothing more than a strawman. Compare with something like the KH80DSP or 8020D and you'd have a point, since almost everyone here agree that you can't find better at that size.
Anyway, I don't think anybody will disagree if you say that woofer size matter, but those small speakers are to be used with subwoofers if you want a fair comparison.

The entire "toy" theory I see posted here smells very much like some nostalgic audiophilia that doesn't want to admit that we can do some good small stuff these days.

 

[andreasmaaan]

The main issue with smaller woofers is not usually THD in the midrange, but IMD. Of course not all (equally-sized) woofers are equal, but at a certain point (output level) it gets difficult for a small woofer to produce low frequencies without creating IM distortion in the rest of its operating range as a result of increasing nonlinearity in the driver's motor force and suspension as the low frequencies cause its voice coil to displace beyond its linear range of operation.

So a harmonic distortion sweep might show a woofer to have low levels of THD throughout its midrange, even at quite high SPLs, but when that woofer is asked to reproduce low frequencies while also producing midrange frequencies, you start to see the strain it is put under, and the effects of that strain on its midrange performance.

There are of course many small woofers that have a far wider range (in terms of coil displacement) of linear operation than others, but this won't necessarily show up in a harmonic distortion sweep, which is one reason why IM distortion measurements at a variety of output levels are so important (or Klippel analysis, which literally shows you the motor system and suspension system's levels of linearity and symmetry plotted against displacement).

There are some smaller woofers that perform vastly more linearly than others though.

But even the best small woofer will find it impossible to keep up with any decent larger woofer (in the midrange I mean) when asked to also reproduce high SPLs in the low frequencies.

This is one of the concerns I have about the way CEA-2034 specs distortion measurements. I don't think they tell us much at all really about how a speaker might sound.

 

[restorer-john]

The entire "toy" theory I see posted here smells very much like some nostalgic audiophilia that doesn't want to admit that we can do some good small stuff these days.

These days? Small speakers have been good for many, many decades. Nothing new or amazing "these days". Amazing for their size, but that's it- no substitute for full range, large drivers and proper midranges. Real audiophiles never p#ssed around with little speakers pretending they were anything other than a massive compromise. Nobody bought a small two way as an end-game speaker.

People were realistic and not duped by group-think like they are so often "these days". Look at the Pioneer Andrew Jones hype train- they are an utterly dreadful speaker, no two ways about it. Even for a toy speaker, they are shocking.

Single small speaker in a room demonstrations playing audiophile essential wimpering female "singers" or some "unplugged" acoustic garbage, enable mutton dressed up as lamb to be sold to the gullible. Put them side by side with the real speakers and it all falls apart very quickly.

Active speakers have been around for many decades, as has motional feedback and DSP. It has evolved now to the point where you can get a whole lot of tech shoved in shoe box that sounds good for the money. That's a good thing, but having grown men fawn on a forum over "toy"* speakers is a bit like arguing about which VW Polo goes the fastest to 60mph on a V8 performance car chat site.

*I agree with Pavel and his designation of toy speakers. I may have used it myself on a number of occasions. Henceforth, I propose any 2-way speaker with a single mid-bass driver smaller than 6.5" should be classified as a "toy" speaker.

 

[Doodski]

These days? Small speakers have been good for many, many decades. Nothing new or amazing "these days". Amazing for their size, but that's it- no substitute for full range, large drivers and proper midranges. Real audiophiles never p#ssed around with little speakers pretending they were anything other than a massive compromise. Nobody bought a small two way as an end-game speaker.

People were realistic and not duped by group-think like they are so often "these days". Look at the Pioneer Andrew Jones hype train- they are an utterly dreadful speaker, no two ways about it. Even for a toy speaker, they are shocking.

Single small speaker in a room demonstrations playing audiophile essential wimpering female "singers" or some "unplugged" acoustic garbage, enable mutton dressed up as lamb to be sold to the gullible. Put them side by side with the real speakers and it all falls apart very quickly.

Active speakers have been around for many decades, as has motional feedback and DSP. It has evolved now to the point where you can get a whole lot of tech shoved in shoe box that sounds good for the money. That's a good thing, but having grown men fawn on a forum over "toy"* speakers is a bit like arguing about which VW Polo goes the fastest to 60mph on a V8 performance car chat site.

*I agree with Pavel and his designation of toy speakers. I may have used it myself on a number of occasions. Henceforth, I propose any 2-way speaker with a single mid-bass driver smaller than 6.5" should be classified as a "toy" speaker.

I agree that size is important although many Euros, Asians and others in America are size limited due to smaller residences and they constitute a large part of the speaker market. Is the trend toward small speakers? I think yes. I think the marketing of small speakers took over since maybe the mid 1980's when retailers sound rooms filled with dozens of models of bookshelf (toy) speakers and they only carried maybe a half dozen large audiophile type speakers. People are now familiarized with bookshelf speakers and now they expect them and regard large 3, 4 and more way speakers as behemoths and outdated. The market has been groomed for decades and toy speakers is now the norm. There's no replacing quality large speakers but to label bookshelf speakers as toys denigrates the demand of the consumers that carry the power of committing their money.

 

[LTig]

@pma
Can I suggest some intermodulation distortion tests at a reasonable excursion to demonstrate what happens to the midrange THD when modulated by the low frequencies?

What about the multi tone (I think) test as done by Sound&Recording?

 

[restorer-john]

The market has been groomed for decades and toy speakers is now the norm.

Groomed, that is so true. Here is Yamaha's range in 1990 from one of my old price lists. I only sold NS-5X to people who lived in an apartment or wanted something really compact.

Notice, the 6.5" (7) two way was the baby in the range...

You could still buy the NS10M and the 1000M- note the 1000X (47kg per speaker) above was nearly twice the price.

 

[Wombat]

I agree that size is important although many Euros, Asians and others in America are size limited due to smaller residences and they constitute a large part of the speaker market. Is the trend toward small speakers? I think yes. I think the marketing of small speakers took over since maybe the mid 1980's when retailers sound rooms filled with dozens of models of bookshelf (toy) speakers and they only carried maybe a half dozen large audiophile type speakers. People are now familiarized with bookshelf speakers and now they expect them and regard large 3, 4 and more way speakers as behemoths and outdated. The market has been groomed for decades and toy speakers is now the norm. There's no replacing quality large speakers but to label bookshelf speakers as toys denigrates the demand of the consumers that carry the power of committing their money.

"Everybody gets a prize".

 

[andreasmaaan]

Groomed, that is so true. Here is Yamaha's range in 1990/91 from one of my old price lists. I only sold NS-5X to people who lived in an apartment or wanted something really compact.

Notice, the 6.5" (7) two way was the baby in the range...
View attachment 51591

You could still buy the NS10M and the 1000M- note the 1000X (47kg per speaker) above was nearly twice the price.
View attachment 51592

Your (very valid) point aside, what's an "infinite baffle design" in a closed box speaker?

 

[LTig]

These days? Small speakers have been good for many, many decades. Nothing new or amazing "these days". Amazing for their size, but that's it- no substitute for full range, large drivers and proper midranges. Real audiophiles never p#ssed around with little speakers pretending they were anything other than a massive compromise. Nobody bought a small two way as an end-game speaker.

It depends on the application. In my living room I run a 2.1 setup with small active 3-ways and active sub. However on my desktop there's no place for big speakers and I'm quite happy with tiny Genelec 8020 and an old KEF sub. Even without sub the 8020 plays louder than I can handle. Still they sound different than the O300D. Maybe the KH80 would be a better match ...

 

[Doodski]

Groomed, that is so true. Here is Yamaha's range in 1990/91 from one of my old price lists. I only sold NS-5X to people who lived in an apartment or wanted something really compact.

Notice, the 6.5" (7) two way was the baby in the range...
View attachment 51591

You could still buy the NS10M and the 1000M- note the 1000X (47kg per speaker) above was nearly twice the price.
View attachment 51592

I've never sold a pair of Yamaha speakers but I have sold truckloads of Yamaha electronics because it's good gear. I used the Yamaha speakers to up sell to Euro or American made speakers. It worked for me although it took more time and effort and I was labelled as, "The entertainer" because I took too much time in the sound rooms with the customers.

 

[restorer-john]

what's an "infinite baffle design" in a closed box speaker?

Sealed. Acoustic suspension, infinite baffle relatively interchangeable terms.

 

[restorer-john]

I used the Yamaha speakers to up sell to Euro or American made speakers. It worked for me although it took more time and effort and I was labelled as, "The entertainer" because I took too much time in the sound rooms with the customers.

You'd be flat out "upselling" off a NS-700X or NS-1000X. If someone was looking at some JBLs down the road, you could ruin them forever with a demo of the NS-1000X.

 

[direstraitsfan98]

Just a few measurment hints at the beginning:

- as speaker's sensitivity varies you should adjust power so that average SPL is say 90dB at 2m distance instead of using fixed power
- y log scale is ok but it would be better to have it in SPL dB

Now to the point.. hearing distortion of sine wave is very much different then hearing distorion with music. While we don't have much trouble detecting THD>0.5% even with low freqs it is not that simple with music because of masking. For that reason it turns out that THD is actually not a good metric for our perception of distortion with music. Earl Geddes and Lidia Lee have done very nice research on that topic and they proposed new metrics, more info can be found in their AES papers, Part I and Part II.

On this link you will find discussion and download link for a XLS calculator based on their metric.

It's a double standard. We hold dac manufactures responsible for designing products with a SINAD of of 100db or lower, we call that unacceptable performance, even if its aundibile. Well guess what? Same thing with THD in the bass regions of a speaker. Why can't we expect better from manufactures? Why can't we also hold them up to the standard we hold manufactures for all the dac reviews?

It's why I think large woofers are better, they can handle louder SPL at much lower levels of distortion. Ok. It's inaudible due to the masking. SO IS THE DAC THAT HAS AN 80DB SINAD!!! Blows my mind that such a double standard exists, and is persisting, and nobody cares except me, restorer.john, OP and maybe a handful of others.

 

[direstraitsfan98]

To be honest, the reviews on ASR somewhat of a joke. The way Amir treats his measurements as gospel, his hostile towards valid criticisms of his tests, his dismissal of said valid critisims, and the sensationalist nature of a lot of his conclusions when it comes to products. Myself, I see it as not very genuine. I think I'm in the minority here in thinking this though.

Whatever. There's still a lot of good to be had from here, and being here, so I usually set all of that aside. It's easy to turn a blind eye from it. And even if I wanted to voice my lone voice of dissent, it would just get drowned out by 500 parrots all screeching the same thing.

 

[mhardy6647]

Sealed. Acoustic suspension, infinite baffle relatively interchangeable terms.

My understanding is a bit different to that, FWIW.
Infinite baffle, at least historically, meant isolating the back wave by an essentially infinite physical barrier -- e.g., a wall. The next best thing is a very large sealed box. Indeed, the Electrovoice drivers of the 1950s suggested installing the driver (woofer or "fullrange" driver) in a closet door, using the closet as a chamber approximating infinite baffles for good bass performance. Somewhat more practical in the monaural days.

source: https://www.electrovoice.com/binary/Bulletin10A.pdf

Acoustic suspension uses a very floppy (ahem, "high compliance" ) cone suspension and relies on air trapped behind the driver in a relatively small, airtight enclosure (Villchur's AR) for restorative force (again, to the best of my limited understanding). T/S parameters for an acoustic suspension woofer are, I think (!) fairly different to those for a good IB woofer.

https://www.stereophile.com/interviews/105villchur/index.html