High Frequencies

[Dave A]

Tinkering around with the tweeters on the MCM 1900 this past week and being shocked at how such comparative low wattage output can have such a significant effect on the aggregate out put of these. So my question is why do high frequencies so readily pierce vastly larger wattage mid and bass speaker output?

[moray james]

I think it is because they add the leading edge transients to instruments then they float all the harmonics bring a sense of reality to what you hear.

[baron167]

I think it's the nature of the length and shape of the sound waves.


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[windashine]

… o O (the word tweet was first used between 1835-1845) as imitative … o O (just glad someone didn't think the word "birdie" would suffice lol)

[ClaudeJ1]

That's an easy one. Tweeters only have to move very fast, but not very far. The opposite of woofers. So it takes a very tiny voltage swing to do the job. On the other extreme end of the scale, providing I have a 30 Amp circuit breaker (it will trip a 20 Amp breaker in a second) my OThorn Subwoofer can plug DIRECTLY into an AC outlet, pulling about 4,000 watts of power at 60 Hz. while providing enough amplitude to both scare and sterilize anyone in the same room in about 30 seconds and causing minor structural damage to the house. Look up the Danley Sound Labs Matterhorn, which knock a Honda Civic over when it's on a slight incline.

[Chris A]

Forgetting just for the moment the devices that produce the acoustic energies, as the frequency goes up, the inherent perceived power of the waveform itself goes up, too--at a proportional rate. 

 

Secondly, if you look at the power spectral density of most recordings--plotted on log-log coordinates, the natural output of the musicians (and human speakers, etc.) follows a natural -16 dB/decade curve (remember the demastering stuff?).  Everything in nature seems to do that.  So there just isn't much SPL up there to begin with, and the ear is okay with that, but plenty of perceived inherent power resides in the waveforms themselves. 

 

Thirdly, devices that make high frequency sound are usually very efficient. Look at the length of the horns attached and they will show you that the wavelengths are very short (comparatively) to midrange and bass frequencies, so the drivers load with the air more efficiently, and at little cost in terms of real estate that your eyes see (i.e., the size of the horn). These high frequency waves are also easy to collimate into energy coming directly at you instead of reflected off the walls, floor and ceiling.

 

Fourthly, the human ear canal is also a horn--tuned to about 2-4 kHz at the resonant frequency. 

 

Fifthly, the human hearing system separates all incoming sound into frequencies--it's a little frequency analyzer.  So low frequencies generally don't get in the way of higher frequencies--the little hairs in the cochlea resonate at the proper places in the curved resonant horn tube and don't step on each other's toes as their output makes their way to the brain.

 

It's all about the physics and psychophysics (i.e., how we hear), and how sound pressure levels are stratified by frequency--naturally.

 

Remember that a K-77 tweeter diaphragm will self-destruct at about 4 watts continuous input, so that should give you an idea of how much the tweeters are padded down in Klipsch Heritage passive crossovers--but there is still plenty reserve there to serve all that your ears can take (in a home environment).

 

Chris

[Delicious2]

What is inherent power ?

[Chris A]

It's actually an abstraction of the concept of pink noise, and how the human hearing system operates.  This is a lot easier to use than grey noise which is actually much more correct to the response of the human hearing system--i.e., equal loudness, as in sones or phons.

[wuzzzer]

On 12/20/2018 at 6:42 AM, windashine said:

… o O  … o O 

 

I don't get what this is supposed to represent or why you always use it in your posts.  😲

[windashine]

… lol, I always wonder too, so my keyboard fingers figured thought bubbles thoroughly, and the conclusion was the closest approximation (at hand)…. 

 

 

(hint) <--- these things are huge conglomerations (outline's of cloud's more defined by cloudiness) which are cut off by the single line spacing phenonium.... I think icq invented them, nevertheless... o O (thinking terrific tweeters tweet the tunes to transient tantrums towards the total tinkering's)...

[Dave A]

On 12/20/2018 at 4:48 PM, Chris A said:

Forgetting just for the moment the devices that produce the acoustic energies, as the frequency goes up, the inherent perceived power of the waveform itself goes up, too--at a proportional rate. 

 

Secondly, if you look at the power spectral density of most recordings--plotted on log-log coordinates, the natural output of the musicians (and human speakers, etc.) follows a natural -16 dB/decade curve (remember the demastering stuff?).  Everything in nature seems to do that.  So there just isn't much SPL up there to begin with, and the ear is okay with that, but plenty of perceived inherent power resides in the waveforms themselves. 

 

Thirdly, devices that make high frequency sound are usually very efficient. Look at the length of the horns attached and they will show you that the wavelengths are very short (comparatively) to midrange and bass frequencies, so the drivers load with the air more efficiently, and at little cost in terms of real estate that your eyes see (i.e., the size of the horn). These high frequency waves are also easy to collimate into energy coming directly at you instead of reflected off the walls, floor and ceiling.

 

Fourthly, the human ear canal is also a horn--tuned to about 2-4 kHz at the resonant frequency. 

 

Fifthly, the human hearing system separates all incoming sound into frequencies--it's a little frequency analyzer.  So low frequencies generally don't get in the way of higher frequencies--the little hairs in the cochlea resonate at the proper places in the curved resonant horn tube and don't step on each other's toes as their output makes their way to the brain.

 

It's all about the physics and psychophysics (i.e., how we hear), and how sound pressure levels are stratified by frequency--naturally.

 

Remember that a K-77 tweeter diaphragm will self-destruct at about 4 watts continuous input, so that should give you an idea of how much the tweeters are padded down in Klipsch Heritage passive crossovers--but there is still plenty reserve there to serve all that your ears can take (in a home environment).

 

Chris

Now that is an answer and covers every base. Thanks for this reply.