Expanding on yesterday’s post for a moment, the question came up why some amplifiers seem to sound better despite their higher levels of THD and IM distortions than others. In fact, if you were around in the 1970′s when we had the “distortion wars” in consumer electronics, you’d probably remember how these battles created some of the worst sounding audio equipment ever heard.
The battles were pervasive throughout the industry with the Japanese audio companies leading the charge to ever lower distortion figures. Of course consumers, including Audiophiles, had no clue what all this meant but when an audio expert tells you that this amplifier has 0.01% something and another has 0.0001% something, naturally you’ll want the one with the lower measurement of bad. It sure works in other fields like food – lower pesticides, lower fat, lower gluten, etc. all resonate well with us as consumers – if we’re told that something is bad.
Distortion, by its very definition, is bad. We want something undistorted, pure and real so when we see a product with less bad, naturally it’s the better choice. We tend to ignore the baggage that goes along with lowering bad things.
It didn’t take people who listen to their equipment long to realize that less of one thing seemed to lead to more of another. In many cases as the distortion figures went down the sound quality went with it. What we wound up with was a lot of low distortion bad sounding audio equipment – and discouraged and disillusioned customers as a result of engineering efforts to meet the demands of marketing departments that simply didn’t know any better.
And here’s what’s interesting: lowering distortions like THD and IM don’t necessarily lead to bad sound. In fact, what we’ve learned in the interim is their relatively low importance when it comes to building good sounding equipment. Truth is, these figures do not play a big role in how a product sounds. Witness the many good sounding relatively high THD tube products on the market. We’ve learned that these simplistic measurements really aren’t very important when it comes to measuring how a product sounds.
The consequences of chasing lower distortion numbers, of these unimportant measurements, far outweigh the benefits to the marketing department of triple zero distortions.
Designing audio equipment should be a careful balance of all the parameters involved in an amplifier’s design. I cannot think of one aspect of designing an amplifier that doesn’t affect all the other parameters and these changes are, for the most part, all audible – yet we have no means of quantifying or measuring these except our ears.
As engineering people hoping to pass on our knowledge of design and good sound to future generations, it should be a priority to figure out a system of quantifiable measurements that really show us what makes a product sound different.
Our ear/brain measurement tools will always be the final arbiter of our work’s success, but the decades it takes to build those personal tools isn’t something easily passed on.
We can do better.
Paul McGowan – PS Audio, Intl.