You can't say that. With the two-tone or multitone measurement there are other distortion mechanisms that do not occur with the THD measurement.
There are distortions caused by amplitude modulation (AM) and frequency modulation (FM).
More information can be found on the Klippel website and in the purifi-audio.com blog:
Doppler distortion vs IMD?
Low frequency harmonic distortion is almost inaudible. So what’s the point of low distortion drivers?
But you should also consider the result of the evaluation:
The masking of the test sound is thus no longer given at -53dB attenuation (with the 80dB masker) - for a test sound with 3x base frequency, which corresponds to our HD3 in terms of frequency.
The measured 1.5% [email protected] of the loudspeaker corresponds to a damping of only -36dB. This is far, far above the perception threshold of a test tone.
Have you actually read the paper and what are you trying to say?
@amirm does not only show THD in the distortion measurements, but also HD2...HD5.
What does Dr. Geddes say in this paper? Actually nothing more than that THD alone is not enough to reflect the hearing impressions realistically.
He therefore suggests weighting the individual harmonic distortions in a certain way and calls this "Gedlee Metric". As others suggested before, this depends on the masking of the harmonic distortions, but also on the amplitude itself (as shown in post#118, the masking also depends on the sound pressure). There is another peculiarity (inclusion of the phase) that is relevant for amplifier technology.
Especially after the GedLee-paper you have linked, the reference made by @amirm to the raised HD3 is relevant, because it is less well masked.
What do we do (at least I do that ;-)) here in the forum when the measured harmonic distortions are examined?
We consider the order of the harmonic distortions and "weight" them accordingly, since higher order HD are less well masked.
Then the sound pressure should also be taken into account during the measurement. Therefore, the measured 1.5% HD3 at 86dB is already pretty bad. Probably 5% HD3 at 105dB would be less of a problem.
Together with the 4dB peak between 4-5kHz and the possibly slow decay at 1.2kHz ... a combination from hell.
In this case, I am not a random dude reading research about controlled listening tests. It was part of my professional job and responsibility to practice it. Based on that, I am saying you must not play debating games saying you read that sighted tests are no good and that is that...
As I keep saying like a broken record, none of this means 100% reliability. If we have such a crystal ball, we would close this forum and just go by that data point. We don't have it. We need to instead rely on collective wisdom and make educated guesses.
At times it seems Amir is overstating the value of the professional listener (he sometimes seems to almost suggest they are immune to bias), but then he restates his argument, and he clearly is not suggesting they are infallible. Blumlein captures Amir's claim quite well, the pro is not infallible, but she or he is more likely to identify an issue and in a shorter amount of time than the layperson. Just like one cannot say with absolute certainty that a professional's sighted evaluation is free of bias, one cannot conclude that it is of no value.A pro is more likely to get it, and more likely to know what to ignore. Sometimes weird enough problems just need luck and perseverance finding the solution. A motivated layman with hours of time on his hands, and no other things to look at can find such things even pros miss. Problems take what they take to find solutions to.
For near field testing, I have tracks converted to mono. For far field testing, I just play the same channel, same music and same location for all speakers under test (give or take an inch or two). I am not trying to enjoy the tracks so conversion to mono is not necessary. It is just a test signal in this regard.hi,
since one speaker is used during listening are songs converted to mono ? And in evaluating are the tracks same ?
I am ok with anyway. Was just curious. Thanks for the good work and all the efforts.
best regards.
Well, I give you an example of googling. My doctor prescribed medication that I thought was causing a side effect. In the next visit I tell him and he says no, that is not likely to be the case. I go home and google. The first hit I get on side effects of that drug is what I was experiencing. Now get this: the hit was to the actual research results of the drug by the company! Right there, in black and white it says this is one of the known side effects.
So on next visit I tell my doctor he is wrong and that I read my side effect was caused by the medicine. He asked me where I had read it. I say it was in the documentation for the drug certification. He calmly explains to me that in drug trials they document anything that the subjects reports whether it is actually caused by the medication or not. He said doctors that prescribe these medications thousands of times build up their own body of evidence of what side effects are likely and what they are not. Well it turned out he was right as the side effect was caused by something else.
In this case, I am not a random dude reading research about controlled listening tests. It was part of my professional job and responsibility to practice it. Based on that, I am saying you must not play debating games saying you read that sighted tests are no good and that is that. The world doesn't turn that way. Not with your doctor. Not with the Ice Cream taster. Not with trained audio listeners.
As I keep saying like a broken record, none of this means 100% reliability. If we have such a crystal ball, we would close this forum and just go by that data point. We don't have it. We need to instead rely on collective wisdom and make educated guesses.
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 don't get this thread or review though, there seems to be so much energy put into irrelevancies, I don't understand the point of this thread, particularly if it's main purpose is to find out if Amir's Klippel rig is measuring accurately....there's simpler ways of doing it, I really don't understand all the detailed discussions about this speaker and how it relates. Like it was said in another thread, just test the same 'controversial' speaker that produces dubious results on Amir's Klippel....just test that speaker on Amir's rig & then send it to Klippel for independant testing to see if it marries. All the calorie burning in this thread about god knows what and the review (if that is the aim), just seems to be a lot of people spinning their wheels and burning calories for no reason. There's gotta be better ways of concluding if Amir's Klippel rig is accurate....and to be honest I can hardly believe that is the purpose of this thread (I still doubt it)...Amir didn't really say what the purpose of this thread was beyond comparing Klippel with anechoic on the same speaker model....but that was 20 yrs ago and the speaker is a different unit and the speaker has aged and anechoic does not equal Klippel....too many factors & uncertainties if the main reason for this review & thread is to establish Amir Klippel accuracy....there's gotta be a simpler way of doing it....I really don't get this thread, feel like I'm in a parallel universe! I still don't know the intended purpose of this thread and can't believe it's purpose is to establish Amir Klippel Accuracy like some have said....hopefully Amir can clarify the overall purpose of this review & thread.In this particular case though, Amir's measurements of the IL10 are practically identical to Harmans, as shown in the last image above.
I don't get this thread or review though, there seems to be so much energy put into irrelevancies, I don't understand the point of this thread, particularly if it's main purpose is to find out if Amir's Klippel rig is measuring accurately....there's simpler ways of doing it, I really don't understand all the detailed discussions about this speaker and how it relates. Like it was said in another thread, just test the same 'controversial' speaker that produces dubious results on Amir's Klippel....just test that speaker on Amir's rig & then send it to Klippel for independant testing to see if it marries. All the calorie burning in this thread about god knows what and the review (if that is the aim), just seems to be a lot of people spinning their wheels and burning calories for no reason. There's gotta be better ways of concluding if Amir's Klippel rig is accurate....and to be honest I can hardly believe that is the purpose of this thread...Amir didn't really say what the purpose of this thread was beyond comparing Klippel with anechoic on the same speaker model....but that was 20 yrs ago and the speaker is a different unit and the speaker has aged and anechoic does not equal Klippel....too many factors & uncertainties if the main reason for this review & thread is to establish Amir Klippel accuracy....there's gotta be a simpler way of doing it....I really don't get this thread, feel like I'm in a parallel universe!
I think what this comes down to is the need to implement the Gedlee metric in speaker ratings.
Admittedly I have found it much easier to (subjectively) assess performance with a single speaker playing -- rather than stereo!For near field testing, I have tracks converted to mono. For far field testing, I just play the same channel, same music and same location for all speakers under test (give or take an inch or two). (...)
Have you actually read the paper and what are you trying to say?
@amirm does not only show THD in the distortion measurements, but also HD2...HD5.
What does Dr. Geddes say in this paper? Actually nothing more than that THD alone is not enough to reflect the hearing impressions realistically.
He therefore suggests weighting the individual harmonic distortions in a certain way and calls this "Gedlee Metric". As others suggested before, this depends on the masking of the harmonic distortions, but also on the amplitude itself (as shown in post#118, the masking also depends on the sound pressure). There is another peculiarity (inclusion of the phase) that is relevant for amplifier technology.
Especially after the GedLee-paper you have linked, the reference made by @amirm to the raised HD3 is relevant, because it is less well masked.
What do we do (at least I do that ;-)) here in the forum when the measured harmonic distortions are examined?
We consider the order of the harmonic distortions and "weight" them accordingly, since higher order HD are less well masked.
I appreciate the efforts.
Harmonic distortion, which is what you have in the chart is one category of distortion. There are others.
I really want to point this out so that folks use the term Harmonic distortion when they refer to such distortion.
There are many types of distortion, so the general term "distortion" can be misleading. A frequency error is distortion, IMD is different from HD/THD, compression is different yet, lack of dynamic reach is a distortion, high noise floor, phase distortion, transient response, lack of scale, Noise such as port chuffing, woofer bottoming, resonances, ect
The list is longer than my hobbyist brain can remember.
This isn't to be picky but to keep moving toward some clarity. That way we can figure out what is what. Is the Harmonic distortion affecting Amirs listening in the way claimed or is it actually some other aspect of the replay.
Is Harmonic Distortion what is affect your experience JBL308 or is it something else or a combo?
I personally found the JBL308 (while sounding good enough)to sound a bit murky at all volumes. Maybe you notice it more at higher levels? Maybe it is compression? Maybe it is in fact HD?
Looking more closely at the predicted in room responses, I'd venture the excess and unsmooth response above 4 khz is where the grunginess is coming from. The variable being what Amir hears as grungy and lacking clarity. One of those cases where were I there and heard the same thing and Amir said this sounds grungy to me, then I'd have a good reference for what he means.
For all of the above I'd actually say this is the most interesting speaker Amir's measured yet; and perhaps it will end up being one of the most enlightening in terms of how well we can correlate measured data to listening tests.
Admittedly I have found it much easier to (subjectively) assess performance with a single speaker playing -- rather than stereo!
With loudspeakers, our brains adjust to them over a period of time, make allowances for their deficiencies and essentially "fill in the gaps" in their responses. In a quick A/B comparison, a new speaker, as compared to a "multi year loyal friend" is at a distinct disadvantage, even if it is better in some parameters.
The classic one speaker demo gives no comparisons and given enough time, the speaker will become the new normal (assuming no gross faults or anomalies).
For punters walking into a HiFi store, the old comparator setup enabled an instant, unbiased and effective way of deterining the best speakers in very short order.