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Can you really hear the sound details over 20kHz?

bennetng

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The bottom line is high level, high frequency tones of any type should only exist in the electrical domain. By all means play to your heart's content in that domain. I do it all the time.

But it's utterly stupid in the extreme to play such signals through amplification and connected loudspeakers. Amplifiers can and do oscillate and tweeters expire instantly. A typical tweeter can absorb between 1Watt to maybe 10W maximum and that's in a 50-200W rated speaker. A high level, high frequency/inaudible tone can deliver the full power of the amplifier to the tweeter. Most speakers these days have zero protection for the treble units in the form of fuses, polyswitches, etc. Protection has gone out of fashion unfortunately. Even 5% level of a typical 100W amplifier will fry the tweeter in less than a few seconds.

Just because it's trivial to create such audio files, doesn't mean it's a good idea to distribute them to typical audiophiles as some form of "test".
Should I emphasize that my test signal has a fade-in stage, and there is no high level of inaudible tone (relative to the audible tones) so that there is no need to turn up the volume of the amp in order to do a successful test? Your previous replies implied that I put hidden, high amplitude tone in the inaudible range behind low-level audible tones, it is obviously not the case. If you acknowledge this I am happy to leave this thread.
 

restorer-john

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Your previous replies implied that I put hidden, high amplitude tone in the inaudible range behind low-level audible tones, it is obviously not the case. If you acknowledge this I am happy to leave this thread.

I was speaking generally and not implying you put a hidden high level tone in your file. I certainly didn't know you had created a widly distributed file. Don't take it personally, please. Apologies.

Regardless, accidents happen. Especially when audiophiles are "testing" things.

Imagine they are futzing around and the source isn't selected/connected or the muting/speakers are off or the fixed/variable input isn't correctly selected. They can't hear anything, so they turn up the volume and then hit the right button. Boom! It's happened to everyone in HiFi- me included, multiple times. Then you go and check all your drivers are still working and breathe a sigh of relief (or not..), and, at the same time promising never to be so stupid again. :facepalm:

A mid range high level signal will hurt your ears alright, but the drivers will handle it. A HF signal at high level in that instance will vaporize tweeters.
 

KSTR

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But it's utterly stupid in the extreme to play such signals through amplification and connected loudspeakers. Amplifiers can and do oscillate and tweeters expire instantly. A typical tweeter can absorb between 1Watt to maybe 10W maximum and that's in a 50-200W rated speaker. A high level, high frequency/inaudible tone can deliver the full power of the amplifier to the tweeter. Most speakers these days have zero protection for the treble units in the form of fuses, polyswitches, etc. Protection has gone out of fashion unfortunately. Even 5% level of a typical 100W amplifier will fry the tweeter in less than a few seconds.
Well, in that sense it's utterly stupid in the extreme that passive systems, separate amps and speakers still do exist. That's a failed concept right from the start.
Active speakers usually have excellent driver protection. When I was at HEDD a big part of the design effort was to make the speakers 100% bullet-proof wrt to any kind of overload, no matter how nasty the input signal. Something like 10kHz at 20Vrms, clipping the input stage right from the start, and volume turned fully up. 5Wrms tweeter running on a 300W amp in direct connection. Poor little AMT made it visually clear that it is on the edge of dissipation (pleats start to wrinkle) but it did not burn out.
 

restorer-john

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When I was at HEDD a big part of the design effort was to make the speakers 100% bullet-proof wrt to any kind of overload, no matter how nasty the input signal. Something like 10kHz at 20Vrms, clipping the input stage right from the start, and volume turned fully up. 5Wrms tweeter running on a 300W amp in direct connection.

Impressive and a compelling case for a bulletproof self contained system.

What's your take on the capabilities of MF and HF amps in actives- equal in performance and power or not? (assuming bulletproof protection)
 

KSTR

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Impressive and a compelling case for a bulletproof self contained system.

What's your take on the capabilities of MF and HF amps in actives- equal in performance and power or not? (assuming bulletproof protection)
You mean selection of power ratings?
Often, you have not much choice for different power ratings as that makes the system more complex and expensive. The only exception is traditional class A/B amp where the woofer section would be bridged-parallel whereas MF and HF running single ended. An example for this is the KH420, using TDA7293's throughout, with one single supply unit for everything.
 
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KSTR

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And you still can pad down the tweeter (series resistor), also for lower noise. did that, too.
In three-ways, often the midrange is the driver that maxes out first, not the tweeter.
As for quality, in the early days at ADAM we used class-A/B amps on the tweeter because the class-D stuff was nosier and a bit grainy sounding, at the time. Solved issues, today, with the current breed of class-D amps.
 
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weasels

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Non-linear distorsion, intermodulation, aliasing... that is not the point: the facts must come before the explanation. Ask first for data showing the audibility of fast transient beyond 20 kHz, then, and only then, an explanation can be proposed.

This is exactly my point - the actual hypothesis here is that "fast transients" are audible beyond 20khz, therefore the "show me the data" burden lies in demonstrating that it is more likely that the hypothesis is true vs. untrue. In this case that would mean devising an experiment that proved both that there is an audible signal above 20khz and it is caused by fast transients
 

andymok

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Provide a scientific definition of a "fast transient" that includes a qualitative distinction between a "fast transient" and a slow one. Then provide a hypothesis for how the speed of a change in volume could possibly impact humans' ability to detect sound at a particular frequency.

I’d like to give the words Jerk, Snap, Crackle and Pop. But since I know nothing I’ll probably just swallow them back in
 

rdenney

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It seems to me that testing square waves evaluates transient response. The maximum rise time produced by the amp is linked to frequency response, isn't it? There is always some ringing after the transient, and the frequency of that is important, too. So, can we hear a qualitative difference between a square wave (with the fundamental low enough to be hearable) through amps of different frequency response and rise-time capability, into various loads? Square waves, of course, have an unlimited supply of available overtones, so if frequencies above 20 KHz affect the sound of frequencies below 20 KHz, then we ought to hear the difference. It seems to me a square wave represents the fastest theoretical rise time.

Rick "always looks at square-wave shapes and transfer accuracy when testing provides it" Denney
 

Stokdoof

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My hearing frequency range is below 15 kHz or maybe worse.
Such a pittty my wife’s voice is also still below my hearing frequency range.
 

Katji

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Even so, stokdoof is not a good solution.
 

Wes

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It seems to me that testing square waves evaluates transient response. The maximum rise time produced by the amp is linked to frequency response, isn't it? There is always some ringing after the transient, and the frequency of that is important, too. So, can we hear a qualitative difference between a square wave (with the fundamental low enough to be hearable) through amps of different frequency response and rise-time capability, into various loads? Square waves, of course, have an unlimited supply of available overtones, so if frequencies above 20 KHz affect the sound of frequencies below 20 KHz, then we ought to hear the difference. It seems to me a square wave represents the fastest theoretical rise time.

Rick "always looks at square-wave shapes and transfer accuracy when testing provides it" Denney

The trick is to find some euphonic square waves and see how the speakers respond
 

Marmus

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Provide a scientific definition of a "fast transient" that includes a qualitative distinction between a "fast transient" and a slow one. Then provide a hypothesis for how the speed of a change in volume could possibly impact humans' ability to detect sound at a particular frequency.
Is'nt there a close up O scope time trace of a "high" speed real music transient using a transducer that can capture it? Like drum rim shot, metal stick on cymbal, or pick on string? Then A>D>A and compare. Scope all the way?
 

HiFidFan

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I was at a recording studio many years ago and this very topic was being discussed by a couple of the engineers. What they both agreed on was that frequencies above 20KHz may affect frequencies lower down the spectrum.

I have no idea if that's true, or has utility in regards to mixing a track, but I thought it was interesting.
 

PaulD

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I was at a recording studio many years ago and this very topic was being discussed by a couple of the engineers. What they both agreed on was that frequencies above 20KHz may affect frequencies lower down the spectrum.

I have no idea if that's true, or has utility in regards to mixing a track, but I thought it was interesting.
It is not true, and recording engineers are as susceptible to audio BS as anyone - I know because I was one... Best to check the science, all humans are susceptible to the perception and reasoning errors that good science avoids or debunks.
 
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