what he said... (in three parts) Part 2

ALL212
ALL212 Posts: 1,553
edited March 2019 in The Clubhouse
Ears cannot be trusted

Those who don't measure, don't know. Period. They can pretend they know, but rest assured they don't. The human ear, as it is connected to the human brain, is not very smart and easily fooled. If something is wrong with a speaker, people have a hard time telling what it is. Using ears only, the quality of a speaker can only be described in extremely subjective terms. Treble is often described as bright, dull, edgy, recessed, etc. Bass is often described as warm, boomy, deep, lean, tight, etc. But without any accurate basis of comparison, comments like that are meaningless. Don't even get me started by describing how many "veils have been lifted" from the music or how a speaker's "pace rhythm and timing" is affecting the sound. Those vague, meaningless statements are made by people who lack the proper technical vocabulary to describe a speaker's performance. In summary, a driver should be fully measured before a person is qualified to comment on the sound of that driver.

Look at it this way: who is more believable, the guy who says "This tweeter sounds edgy" or the guy who says "This tweeter has moderate 3rd and high 5th order harmonic distortion." Again, who is more believable: the guy who says "This tweeter sounds dull" or the guy who says "The average level of this tweeter is 1.5 dB lower than the woofer above the crossover point." So, while "this tweeter sounds dull" does imply that something might be wrong, there is absolutely nothing there to say what is wrong or even offer any proof that something actually is wrong.

To make a point, some statements could have many different translations. Here's a bunch of examples. We'll start with a single statement made by folks that have been listening to crap.
•This tweeter sounds dull. Translation: "I've been listening to a speaker without baffle step compensation for 10 years, and this new design sounds different than my personal standard."
•This tweeter sounds dull. Translation: "My last system had Dynaudio D21 tweeters, and now anything without a peak at 10kHz sounds recessed and doesn't have sizzle I need."
•This tweeter sounds dull. Translation: "My current speaker has a woofer that did not have the breakup node properly filtered, and now I've accepted that type of sound as normal."
Then we'll try the statements made by folks with well trained ears but other problems. •This tweeter sounds dull. Translation: "I misunderstood the crossover diagram, hooked the tweeter up with the polarity reversed and now I have a broad 40dB null at 2.5kHz."
•This tweeter sounds dull. Translation: "My living room is very sound absorptive, and any system with a flat response just isn't enough to overcome the lack of room reflection."
•This tweeter sounds dull. Translation: "Oops, my kid pulled the treble knob off my preamp, put it back rotated 45 degrees to the right, and then adjusted it so it visually centered."
Go ahead openly laugh at that last one... but it has happened. Here we have addressed about 1% of the potential reasons why a tweeter may sound dull, and we have not even considered that there may be a problem with the design or an out of spec driver. And good lord, "this tweeter sounds bright" has a potential 500% more translations. Obviously, words can't cut it. A picture may be worth a thousand words, but in a case like this, an actual measurement is priceless.
All that said, it's not impossible to speak in terms of distortion types when listening with ears. But be aware that it takes years of working with real distortion measurements before types of distortion at various frequencies can be properly identified using only ears. Enough said.

Drivers cannot be evaluated in a system

I see this all the time. Statements like "I used **** driver in my last YYY design and it sounded ZZZ." Replace X, Y and Z with anything. It doesn't matter what, because statements like that don't have any merit. When a driver is used in a system, only the system as a whole can be evaluated. (and even then, as mentioned above, not without measurements) Of course the drivers are making sound, but what you really hear is the crossover, design choices and the listening environment. So many people evaluate drivers while they are in a poorly designed system and then blame the result on the drivers themselves. Only individual and extensive driver measurements are acceptable in evaluating an individual driver.

If distortion measurements aren't part of the first step in selecting and using a driver, the system "tweaking time" will multiply exponentially as the designer struggles to find a configuration that helps hide a driver's faults. All drivers have faults. Without distortion measurements, improper usage of a driver may cause a person to simply give up and come to the wrong conclusion that a driver is a poor performer. In a case like that, the only poor performer is the designer who failed to work around a driver's faults.

Aaron
Enabler Extraordinaire