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RE: You cannot measure joy or relaxation, but that doesn't mean they are not real.

"As humans, our ability to measure all things pertaining to electricity and sound waves etc are likely to be very limited. "

I will capitulate to certain things. First of all the range of human hearing is taken to be 20-20,000 Hz. But who tests higher than that ? Whoever said that at 20,000 Hz your hearing just cuts off completely ? To my knowledge nobody ever actually specifically said that.

If your hearing is that good that you can hear an actual difference of even a 15 KHz sine wave and square wave of the same RMS level, then you might have those golden ears. Your ears might not be all that efficient at hearing up there but they can to it at least, and the brain will accentuate the differences that you hear.

But to hear that you need tweeters that can go beyond 20,000 Hz. Speaker manufacturers usually don't bother, but there are some units out there...

Like piezos. Much distortion but can go well beyond the normal human hearing range. In fact people have tried to use them for pest control with varying success. Piezos tend to have odd order distortion at high levels, but it is the inverse of most dynamic tweeters, the opposite polarity. In other words, as a dynamic tweeter will tend to compress the waveform at higher power levels, a piezo tends to expand it. Some people like the sound and really if you only have normal ears, if you crossover into them at at least 8 KHz you might just like it because it will be almost impossible to hear the actual distortion. You might however hear an apparent increase in dynamic range.

"Otherwise we would be able to explain why two different amplifiers from different stables with identical spec's sound so very different."

Bob Carver actually did it. He did double blind studies to prove it, there is a wiki on it. He took any amp, and they gave hi some tough ones they thought, and he was not to take them apart nor did he get the prints. It was to be treated as a black box. By measuring damping, phase shift and not only distortion but what KIND of distortion he proved that he could duplicate the sound of those amps, and proved it in double blind testing. And these are people who could tell the difference between different amps with the same specs.

And there is always the matter of distortion even more than damping, depending on the load. What KIND of distortion. The SET crowd exists for even order distortion, which is harmonious. If you play a middle A on a piano, the second harmonic is 440 X 2 = 880. You can play those two keys together and they harmonize. But if you multiply by three, not so much.

And then there is phase shift. Old, slow ass transistors that get beefed up by negative feedback, there's the problem. And that is one of the biggest problems with class D, it needs an output filter. As such there will be phase shift.

Understanding phase shift is not that easy. You could have an amp that is ruler flat from 20 to 20 K, but because maybe it is cap coupled it has some phase shift in the low end. Ad because of that little coil on the output, if they have to use one too big because their design is not stable, there will be phase shift at the high end as well.

It will measure ruler flat because they use sine waves and ignore phase altogether, which is a folly that Carver discovered and overcame. Thing is, CAN IT REPRODUCE A SQUARE WAVE ? A simple 1,000 Hz square wave.

Most modern amps (I mean since the mid 1970s actually) can faithfully reproduce that square wave on a scope, but before that not so much. The upper and lower ends of the spectrum are the hardest to get straight.

The 1,000 Hz square wave is good for finding faults in components that can affect frequency response. For distortion you want either a sine wave and a distortion analyser or to use triangle waves and try to measure it on the scope. I'll go with the former rather than the latter because I have an HP 339A which has a measurement floor of 0.0016 % total THD and noise. The design of the unit is such that it is almost impossible for it to underread distortion, any fault will cause it to overread. And though I have not tested much I have never seen anything below 0.5 %. At any level. I have not yet tested the Flame Linear yet but to do that at high power levels I will need a few more things. Or I'll just sell it.

"I have yet to meet an electrical engineer who wasn't of the frame of mind that 'if it cannot be measured, it isn't a reality'."

Well now you have. Let's say your ears are a micrometer. A good one that measures down to the ten thousands of an inch. I have a simple caliper that measures down to one thousandth of an inch. I cannot measure it but you can. Tell you what, my hearing was destroyed by a disease and sometimes I can't even tell if a tweeter is blown.

So YOU are the measuring instrument. I used to be pretty damn good. I could hear a conversation from three rooms away and surprised people like "HEY, you talking about me ?". They were like damn, he could hear us ? And that is when we were going to concerts and band practices and all that. My one buddy had a party with TWO live bands in his house at the same time. (big house) I got a loud music complaint from the next city over, seriously I lived in Rocky River and Lakewood came. (Ohio)

But I could still hear. If any speaker blew or was about to I could hear it and I would say "Something is wrong here".

I don't have those ears anymore and I miss them. I miss my eyesight even more. That sweet sound of those Boston A-150s, which were the only speaker I would tolerate after hearing the Cantons.


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  • RE: You cannot measure joy or relaxation, but that doesn't mean they are not real. - JURB 20:11:49 12/20/16 (0)

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