The problems with testing/measuring

Good article with good points. The line about "we exist at the bottom of a sea of air" made me thing about altitude and weather where things sound and perform differently. I have never purchased something for it's measurements because everyone also hears the same things a little different than the next person. Every pair of speakers will sound different in every room and with different amps. My ears, trusted recommendations and known product reputation are what drives my purchases.

As far as Reviews go, I take them all with a grain of salt. Many reviewers will not state all the flaws and shortcomings of a product because the MFG pays to keep their publications afloat. I sometimes trust independent no affiliation reviews more than major magazine reviews.
 
Shadowfax said:
Good article with good points. The line about "we exist at the bottom of a sea of air" made me thing about altitude and weather where things sound and perform differently. I have never purchased something for it's measurements because everyone also hears the same things a little different than the next person. Every pair of speakers will sound different in every room and with different amps. My ears, trusted recommendations and known product reputation are what drives my purchases.

As far as Reviews go, I take them all with a grain of salt. Many reviewers will not state all the flaws and shortcomings of a product because the MFG pays to keep their publications afloat. I sometimes trust independent no affiliation reviews more than major magazine reviews.
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Good points Brian. I also think that sometimes a reviewers system may simply not have synergy with the gear they are reviewing. I trust Mike @ Suncoast and a friend I have in the recording industry who taught me much of what I know today about sound and understanding what I was hearing.

Other than that I read and watch reviews solely for entertainment value and I think any honest reviewer will tell you that is their main purpose. In no way am I diminishing their reviews, I just know what I like and want to listen to the gear in my system. However a good reviewer will certainly make me aware of gear I'd like to listen to for sure, I just would never make a buying decision based on a review or measurements.
 
Instead, the opposite is often true. For example, using negative feedback has long been known for the improvement it makes lowering distortion and increasing the linearity of the frequency response of amplifiers and speakers. Unfortunately, listening tests have found that negative feedback creates a sterile sound. It is simply unnatural and most good designs try to minimize or eliminate its use.
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This statement from the article is false.

Its because of a lack of understanding how feedback works that it might cause an amplifier to sound sterile. Its not because of feedback itself as a design element.

Further, we have test equipment now that we didn't 35-40 years ago; its now possible to measure everything (in an amplifier at least) that we need to know in order to predict exactly how an amp will sound. The measurement guys hate this and so do the subjective guys. But that is how far testing has come. What is really lacking now is the understanding of what the measurements actually mean.

So IMO insofar as amplification is concerned, this article is promoting myth and should be ignored.

Now why feedback can cause problems has two different issues. The first was addressed by Norman Crowhurst a good 60 years ago and the truth of that has not changed: the point where feedback is applied in an amplifier is non-linear. So when feedback is applied in this fashion the feedback signal is distorted and so higher ordered harmonics, sensed by the ear as harshness and brightness, are generated. IMD is generated too. This can be avoided by simply using a linear feedback means; IOW mixing it with the incoming signal outside of the amp, the way opamps do.

The second problem has to do with Gain Bandwidth Product. GBP is defined as the frequency at which the gain of the circuit has fallen to unity, or a value of 1. For a lot of amplifier circuits that's not very high- 1 MHz is common. If the amp also needs 30dB of gain, you divide 1MHz by 1000 (IOW 30dB) and you get 1KHz, which will be the frequency that the feedback falls off on a 6 dB slope, and possibly more as frequency is increased. As the feedback falls off, distortion rises on a similar mirrored slope. So distortion is rising with frequency and this is usually not reflected in the THD measurement. If it really has a turnover at 1KHz, a 7HKz harmonic of 1KHz will likely be unmasked, and a 7th harmonic is well known for causing an amp to sound 'metallic'.

I can't speak to his comments about speaker design. But IMO/IME his comments about measurement WRT electronics should simply be ignored.
 
Ralph ,

Can you post some measurements of your amplifiers for clarification, would love to see something on your toob and new class D amps, i cant recall ever seeing a bench test or measurements of any kind on your stuff ..!


Some good old square waves would also be appreciated..! Makes it easy to compare to other industry test measurements in print ..!


Regards
 
The problem with testing/measuring is that it deconstructs an industry based on a belief system that posits that you can hear what you can’t measure.
 
MichaelsMinute said:
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Other than that I read and watch reviews solely for entertainment value and I think any honest reviewer will tell you that is their main purpose...
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Indeed. Reviewers are "chosen" primarily for their ability to write well and tell an entertaining story. There are no listening "tests" or other qualifications; some reviewers have a background in journalism, some are actual published authors (e.g., Jonathan Valin, Garrett Hongo). There is no reason to think that a reviewer "hears" better than those of us posting here (in fact, given many reviewers' ages, what happens in the top octave - 10kHz to 20kHz - of the accepted range of human hearing may be completely inaudible to the reviewer).
 
W9TR said:
The problem with testing/measuring is that it deconstructs an industry based on a belief system that posits that you can hear what you can’t measure.
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Can you "hear" an amplifier, or cables, or a DAC? No, only a transducer produces sound that then reaches your ears. Even more, "hearing" is perception, i.e., how one's brain interprets the electrochemical signals that reach the auditory cortex and from there to your awareness. So of course people "hear" a sound differently; the memory of that sound will differ even more. There is little disagreement about this for other senses (sight, taste, smell); why do so many "objectivists" insist this is not true when listening to recorded and reproduced music?

We can certainly measure the sound coming out of speakers (or headphones, or whatever), but that measurement will almost always depend on the performance of yet another transducer (the microphone), whose performance will differ from the performance of the tympanic membrane and middle ear bones. There are as yet no "measurements" to determine how different individuals "hear" any given sound.

Using the value of something in the middle of a chain of events is called using a surrogate marker. As an example from a different area of science, if a drug company makes a drug that effectively lowers LDL-cholesterol (for example), that doesn't mean that a person with high cholesterol who takes it will live longer or have a lower risk of cardiovascular disease. The serum LDL cholesterol is a surrogate marker for a lower risk of cardiovascular disease and/or longer life, and in fact some cholesterol lowering drugs do not increase life span (actually the opposite), just as some blood pressure drugs do a great job of lowering blood pressure but also lower lifespan (and this doesn't even get into effects on quality of life - even statins that have been shown to increase lifespan across population groups have very undesirable or even dangerous side-effects in some people).
 
All I know, is we humans all do not hear the same and as we age as our hearing suffers in some little way. I say F it and enjoy the music and the entertainment reviewers and Youtubers provide. As least we or some of us can still hear well enough to enjoy music. And I really don't think I can hear well enough to even hear " measurements" but my Cat or Dog can. :D
 
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