Open quote : ??Distortion is another controversial one : second harmonic distortion ( a signal at twice the frequency of the stimulus) is also subjectively innocuous. Third harmonic adds sharpness, but at low levels gives the sound incision and a hard edged quality that some like seem to like as it seems to ?sharpen things up?. Much above this however and the ear starts to hear distortion not as a change in quality of the music, but as a separate interfering signal. Then there?s the modulation pattern of the distortion, or whether it is correlated with the music.
Cartridge mistracking is an interesting as an illustrative example : just before mistracking a pickup cartridge produces lots of distortion, but it isn?t heard as such. As soon as the stylus let?s go, the signal starts to take on the modulation pattern as higher harmonics join lower ones ( that characteristic zzz?zzz) and this the ear hears immediately.
Digital distortion is often uncorrelated with the music and possesses components that may be of fifteen times higher frequency than the stimulus; the ear detects this as something totally removed from the music, as greyness, harsh, hardness and what have you. So there?s distortion ? and distortion! So products can measure badly, but sound quite good all the same.
The converse is more difficult to explain : products that measure well and sound bad. That is where argument breaks out! My oft quoted example was one of the first MOSFET amplifiers, launched in the late 1970?s, the Hitachi HMA-7500. This was distortion-free, even at high frequencies, and measured perfectly in every other respect, yet there was no sound quality benefit. The reverse in fact had the a peculiarly unengaging sound, characterized by a lack of stage depth and a slightly opague quality. It was lifeless and unengaging to listen to, one reviewer said amplifiers like this sound ?boring? and, in a nutshell, he was right. Yet, it measured perfectly, so here was a total contradiction. Why?
Many people have put forward reasons, but to this day I am unaware of any measurable proof. Some amplifiers today, often based around MOSFET?s, still measure perfectly and yet seem to benefit little, if at all, in sound quality. The general suspicion is that excessive feedback is the culprit, and, in case of the HMA- 7500, poor 1970?s component quality.
These days component quality has improved and so has sound quality, but still it is difficult to measure any difference between then and now, so what is the ear hearing, heaven knows! Thankfully, this situation, where a product measures perfectly but doesn?t necessarily sound so good, mainly affects amplifiers and we just have to live with it. It doesn?t negate the value of measurement, but it does suggest that with amplifiers the measurements we use are best at determining general operability rather than ultimate sound quality.
Unfortunately, whilst this contradiction between measurement and sound quality exists with amplifiers there will always be room for argument, the most common being that our subjective assessment is flawed, not the amplifier. If this was the case then an awful lot of people around the world are deluded. All the same, at Hi-Fi World we endeavour to have more than one person listen to a product, often under different circumstances and always without prior discussion, to ensure there is consistency of view.
Generalising then, if a product measures well then there is a good chance it will at least sound respectable. If it measures badly then the reason why is the issue when it comes to influence upon sound quality. In this case measurement usually warns that sound quality traits are due to measured imperfection, avoiding the unfortunate situation, where a reviewer hears the effect, likes it and declares the product a winner. Doh!
??? End quote. In the last paragraph he opines on the use of room treatments.
Hi-Fi WORLD, May 2007, page 105. Noel Keywood, Publisher 9 and engineer whom measures all the equipment reviewed).
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Now, is that a more balanced perspective we can live with? How does that affect you personal view and opinions ? As the old adage goes, ?You be the judge?.
( Any mistakes in the typing are mine).
Cartridge mistracking is an interesting as an illustrative example : just before mistracking a pickup cartridge produces lots of distortion, but it isn?t heard as such. As soon as the stylus let?s go, the signal starts to take on the modulation pattern as higher harmonics join lower ones ( that characteristic zzz?zzz) and this the ear hears immediately.
Digital distortion is often uncorrelated with the music and possesses components that may be of fifteen times higher frequency than the stimulus; the ear detects this as something totally removed from the music, as greyness, harsh, hardness and what have you. So there?s distortion ? and distortion! So products can measure badly, but sound quite good all the same.
The converse is more difficult to explain : products that measure well and sound bad. That is where argument breaks out! My oft quoted example was one of the first MOSFET amplifiers, launched in the late 1970?s, the Hitachi HMA-7500. This was distortion-free, even at high frequencies, and measured perfectly in every other respect, yet there was no sound quality benefit. The reverse in fact had the a peculiarly unengaging sound, characterized by a lack of stage depth and a slightly opague quality. It was lifeless and unengaging to listen to, one reviewer said amplifiers like this sound ?boring? and, in a nutshell, he was right. Yet, it measured perfectly, so here was a total contradiction. Why?
Many people have put forward reasons, but to this day I am unaware of any measurable proof. Some amplifiers today, often based around MOSFET?s, still measure perfectly and yet seem to benefit little, if at all, in sound quality. The general suspicion is that excessive feedback is the culprit, and, in case of the HMA- 7500, poor 1970?s component quality.
These days component quality has improved and so has sound quality, but still it is difficult to measure any difference between then and now, so what is the ear hearing, heaven knows! Thankfully, this situation, where a product measures perfectly but doesn?t necessarily sound so good, mainly affects amplifiers and we just have to live with it. It doesn?t negate the value of measurement, but it does suggest that with amplifiers the measurements we use are best at determining general operability rather than ultimate sound quality.
Unfortunately, whilst this contradiction between measurement and sound quality exists with amplifiers there will always be room for argument, the most common being that our subjective assessment is flawed, not the amplifier. If this was the case then an awful lot of people around the world are deluded. All the same, at Hi-Fi World we endeavour to have more than one person listen to a product, often under different circumstances and always without prior discussion, to ensure there is consistency of view.
Generalising then, if a product measures well then there is a good chance it will at least sound respectable. If it measures badly then the reason why is the issue when it comes to influence upon sound quality. In this case measurement usually warns that sound quality traits are due to measured imperfection, avoiding the unfortunate situation, where a reviewer hears the effect, likes it and declares the product a winner. Doh!
??? End quote. In the last paragraph he opines on the use of room treatments.
Hi-Fi WORLD, May 2007, page 105. Noel Keywood, Publisher 9 and engineer whom measures all the equipment reviewed).
-----------------------------------------------------------------------------------------------------------
Now, is that a more balanced perspective we can live with? How does that affect you personal view and opinions ? As the old adage goes, ?You be the judge?.
( Any mistakes in the typing are mine).
