Snake oil from AV123?

[cgk]

I was on AV123's web site last night and saw something that looked like snake oil to me. I want to see what ya'all think of it.

They are advertising the tweeter equivalent of a subwoofer ... a tweeter that supposedly extends your speakers frequency response to 45KHz. Check out the listing here. Given that most adults' hearing cuts out around 15KHz, I really doubt that these are useful. In fact, can you even tell if they are working? Also, what is the high frequency cut-off of PCM encoding? Is it worth $350 to add a device that is beyond what you can hear and probably beyond the range of most recordings?

 

[MDS]

Frequency response is generally speced with a range of error - a tolerance if you will. So you will see something like 20 - 20 kHz +/- 3 dB, which means that the response can vary from flat (no deviation - the amplitude of the output signal is exactly the same as the amplitude of the input signal) by as much as 3 dB too high or too low. [Naturally the characteristics of the room can affect the actual response too].

So the advantage of a speaker speced to a frequency much higher than we can hear is probably that the response will be closer to flat in the critical range that we can hear.

As far as PCM encoding goes, it depends on the sampling rate. Increasing the bit depth makes the sampling more accurate as well. Briefly, the Shannon/Nyquist sampling theorem states that you must sample at a frequency at least twice the highest frequency you want to reproduce accurately. The 44.1 kHz sampling rate used for CD audio is theoretically accurate to 22.05 kHz, which is higher than most can hear (given that 20 kHz is the generally accepted upper range of human hearing).

'Theoretically' because that's not the whole story. The digital data must be reconstructed into an analog waveform and that requires a filter and no filter is a perfect 'brickwall' (meaning it can cut off at exactly the frequency it is designed to cut). Some frequencies slightly below 22.05 kHz will get attenuated slightly (whether you can hear that is debatable). Extending the sampling rate to a much higher rate moves the Nyquist limit higher, making the job of the filter much easier (and cheaper to build). For example, if the sampling frequency were 96 kHz instead of 44.1 kHz, it should be accurate to 48 kHz which is way above what we can hear. Even if the filter affects frequencies slightly below 48 kHz, they will still be way beyond our hearing range. So it's the same deal for designing a speaker that can reproduce frequencies beyond our hearing range.

 

[silversurfer]

So the advantage of a speaker speced to a frequency much higher than we can hear is probably that the response will be closer to flat in the critical range that we can hear.

True, but in this instance, it very much depends on how this "tweeter" is integrated.

If the internal crossover of the speaker is not changed, it is not going to change the response of the frequencies sent to the speaker.

Some may argue that while you can not hear what this tweeter is playing, there is some kind of perception.

IMO, snakeoil.

 

[MacManNM]

Frequency response is generally speced with a range of error - a tolerance if you will. So you will see something like 20 - 20 kHz +/- 3 dB, which means that the response can vary from flat (no deviation - the amplitude of the output signal is exactly the same as the amplitude of the input signal) by as much as 3 dB too high or too low. [Naturally the characteristics of the room can affect the actual response too].

So the advantage of a speaker speced to a frequency much higher than we can hear is probably that the response will be closer to flat in the critical range that we can hear.

As far as PCM encoding goes, it depends on the sampling rate. Increasing the bit depth makes the sampling more accurate as well. Briefly, the Shannon/Nyquist sampling theorem states that you must sample at a frequency at least twice the highest frequency you want to reproduce accurately. The 44.1 kHz sampling rate used for CD audio is theoretically accurate to 22.05 kHz, which is higher than most can hear (given that 20 kHz is the generally accepted upper range of human hearing).

'Theoretically' because that's not the whole story. The digital data must be reconstructed into an analog waveform and that requires a filter and no filter is a perfect 'brickwall' (meaning it can cut off at exactly the frequency it is designed to cut). Some frequencies slightly below 22.05 kHz will get attenuated slightly (whether you can hear that is debatable). Extending the sampling rate to a much higher rate moves the Nyquist limit higher, making the job of the filter much easier (and cheaper to build). For example, if the sampling frequency were 96 kHz instead of 44.1 kHz, it should be accurate to 48 kHz which is way above what we can hear. Even if the filter affects frequencies slightly below 48 kHz, they will still be way beyond our hearing range. So it's the same deal for designing a speaker that can reproduce frequencies beyond our hearing range.

Great explanation.

 

[Buckeyefan 1]

Taken from the website:

Why bother with frequency response to 45KHz if humans can not hear frequencies higher than about 20KHz? Just because you can not hear 45KHz does not mean your brain does not process it. The tiny bones in your ear still vibrate and that information is still transmitted to your brain. In several studies, when an audience listened to a piece of music through a playback system capable of 45KHz reproduction, they reported a much more emotionally connected and involved feeling towards the music versus listening to the same piece of music on a system limited to 20KHz playback. In a sense, it was more “real” like a live performance is. There is good cause for this as acoustic instruments have overtones that greatly exceed 20KHz.

We recommend experimentation with the ERT’s two crossover points, 11KHz and 15KHz to find what will work best for you. You’ll likely have a preference for one over the other depending on your listening habits, speakers, and room. The ERT has the capability to add 'air' and a sense of effortlessness to your playback system. You can even use the ERT to help achieve a new tonal balance in your room. For example, if your room is very 'dead' and thus your speakers don't sound bright enough, you can boost the gain on the ERT to compensate.

Driver: Magnetostatic Super Tweeter
Frequency Response: 8KHz – 45KHz (+/- 3dB)
Crossover Points: 11KHz & 15KHz
Gain: Stepped attenuator for controlling output. Four available output levels: 92dB, 90.5dB, 89dB and 87.5dB @ 1w/1M
Connection: Includes one crystal OFC wire for connecting to your speaker's binding posts
Impedance: 4 ohms
Sensitivity: 92dB (@ 1 Watt / 1 Meter). Each pair of Onix ERT’s are precisely measured for mutually matched sensitivity.
Dimensions: (WxDxH) 12.0 x 13.0 x 12.8 cm
Weight: 2.0 Kgs / pair

Rather than slam the product, lets see if Audioholics might demo a pair (I'm sure someone will). I'm sure everyone is thinking the same thing here, so lets give 'em a shot to prove this "emotional connection."

 

[MDS]

I've read many books and articles by mastering engineers over the years and they seem to be split over whether or not we really 'perceive' more when the music has overtones greater than our hearing range.

I think Piezo tweeters reproduce frequencies well above 30 kHz and have been used for a long time. Maybe there is something to it, maybe not, but I wouldn't slam the product as snake oil. I bet it does a fine job of reproducing the frequencies we CAN hear.

 

[mtrycrafts]

IMO, snakeoil.

In this application, yes, it is
When you have two different drives covering the same spectrum, you are asking for trouble. One only has to look at the crossover regions of speakers and the frequency aberrations in that region where both are active.

 

[Sheep]

Hey! You can just use this with a bose setup!

Thats what it really was intended for.

I agree with MDS on this one. Tweeters tend to rolloff way before 20KHz. Have extention to 30 or 40KHz should help flatten the response in the audible range. Same goes with subwoofers IMO.

SheepStar

 

[mtrycrafts]

Hey! You can just use this with a bose setup!

Thats what it really was intended for.

I agree with MDS on this one. Tweeters tend to rolloff way before 20KHz. Have extention to 30 or 40KHz should help flatten the response in the audible range. Same goes with subwoofers IMO.

SheepStar

Maybe, if properly crossed over, not overlapped. Besides, many cannot hear above 16kHz so it would be a waste.

 

[mtrycrafts]

Taken from the website:



Rather than slam the product, lets see if Audioholics might demo a pair (I'm sure someone will). I'm sure everyone is thinking the same thing here, so lets give 'em a shot to prove this "emotional connection."

Actually, before this web site should review this snake oil product, they should search the AES for papers on this subject

But, if they want to do it right, better be a good DBT

There are a few. No, the brain would make mush of that and not be translated into anything meaningful.

While there is a journal paper :

http://jn.physiology.org/cgi/content/full/83/6/3548

However, please read the very bottom of the article under footnotes:

The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

ADVERTISEMENT!!! These authors tried to make the rounds at AES.
There are several refutations of any findings of ultrasonics affecting the brain in a meaningful manner.

Bogus claims for anything above 20kHz.

Where is WmAx when you need him.

OK, here are a couple:

Perceptual Discrimination between Musical Sounds with and without Very High Frequency Component, Nishiguchi, Hamasaki, et al, NKH Laboratories Note No 486- Same as AES print no 5876

http://www.nhk.or.jp/strl/publica/labnote/lab486.html

Detection Threshold for Tones above 22kHz, Kaoru, Shogo, AES print 5401, May 2001

In several studies, when an audience listened to a piece of music through a playback system capable of 45KHz reproduction, they reported a much more emotionally connected and involved feeling towards the music versus listening to the same piece of music on a system limited to 20KHz playback. In a sense, it was more “real” like a live performance is. There is good cause for this as acoustic instruments have overtones that greatly exceed 20KHz.


I want to see those research papers, replicated by others. Besides, the level of ultrasonics is rather low and such short wavelengths disperse and attenuate rather rapidly in aid.

 

[so_cal_forever]

I was curious about these myself a little while ago, and there was a thread in the forum with impressions. Go ahead and check this out:

http://av123forum.com/showthread.php?threadid=10659&perpage=15&highlight=extended response tweeter&pagenumber=4

Interesting to say the least. Would love to hear them for myself.

 

[mtrycrafts]

I was curious about these myself a little while ago, and there was a thread in the forum with impressions. Go ahead and check this out:

http://av123forum.com/showthread.php?threadid=10659&perpage=15&highlight=extended response tweeter&pagenumber=4

Interesting to say the least. Would love to hear them for myself.

You would most likely hear anomalies as reported at the web site. That is not an indication that they are the product of the 18kHz and above frequency range of the speaker but other issues when integrating another tweeter into an existing design and overlapping responses.
This is what the company is hoping will happen and will sell like hot cakes.

 

[gixxerific]

Not sure of the ultra high frequencies but there have several studies of the effects of ultra low frequencies on humans. Maybe they have something there. Here is one thing i dug up.



Infrasound Toxicological Summary, November 2001 - "When male volunteers were exposed to simulated industrial infrasound of 5 and 10 Hz and levels of 100 and 135 dB for 15 minutes, feelings of fatigue, apathy, and depression, pressure in the ears, loss of concentration, drowsiness, and vibration of internal organs were reported. In addition, effects were found in the central nervous system, the cardiovascular system, and the respiratory system. Synchronization phenomena were enhanced in the left hemisphere. Visual motor responses to stimuli were prolonged, and the strength of the effect was reduced. Heart rate was increased during the initial minutes of exposure. Depression of the encephalic hemodynamics with decreased venous flow from the skull cavity was observed. Heart muscle contraction strength was reduced. Respiration rate was significantly reduced after the first minute of exposure."
Long pipe organs, such as those found in churches and cathedrals produce infrasound. In one UK study, the extreme bass frequencies instilled strange feelings at a concert hall. Effects were "extreme sense of sorrow, coldness, anxiety, and even shivers down the spine." (source; Organ Music Instills Religious Feelings,' by Jonathan Amos, 9/8/2003)

 

[mtrycrafts]

Not sure of the ultra high frequencies but there have several studies of the effects of ultra low frequencies on humans. Maybe they have something there. Here is one thing i dug up.



Infrasound Toxicological Summary, November 2001 - "When male volunteers were exposed to simulated industrial infrasound of 5 and 10 Hz and levels of 100 and 135 dB for 15 minutes, feelings of fatigue, apathy, and depression, pressure in the ears, loss of concentration, drowsiness, and vibration of internal organs were reported. In addition, effects were found in the central nervous system, the cardiovascular system, and the respiratory system. Synchronization phenomena were enhanced in the left hemisphere. Visual motor responses to stimuli were prolonged, and the strength of the effect was reduced. Heart rate was increased during the initial minutes of exposure. Depression of the encephalic hemodynamics with decreased venous flow from the skull cavity was observed. Heart muscle contraction strength was reduced. Respiration rate was significantly reduced after the first minute of exposure."
Long pipe organs, such as those found in churches and cathedrals produce infrasound. In one UK study, the extreme bass frequencies instilled strange feelings at a concert hall. Effects were "extreme sense of sorrow, coldness, anxiety, and even shivers down the spine." (source; Organ Music Instills Religious Feelings,' by Jonathan Amos, 9/8/2003)

Well, these seem to be good studies, most likely, unlike the one I posted a link to where the authors paid to publish
Others showed no ability to differentiate when the ultrasonics were played.

 

[StopherJJ1980]

I recently was reading a study where they tested the effects of these so-called "supertweeters" that reproduce frequencies beyond human hearing. In these tests while the participants could not hear the tweeters when used alone, in a double blind test they all responded more favorably by a significant margin when the supertweeters where used in addition to the normal speaker.

How true this is I dont know, food for thought.

I think that there are definitely elements to sound that contribute to it being more real beyond just the 20-20K frequency response.

 

[malvado78]

I recently was reading a study where they tested the effects of these so-called "supertweeters" that reproduce frequencies beyond human hearing. In these tests while the participants could not hear the tweeters when used alone, in a double blind test they all responded more favorably by a significant margin when the supertweeters where used in addition to the normal speaker.

How true this is I dont know, food for thought.

I think that there are definitely elements to sound that contribute to it being more real beyond just the 20-20K frequency response.

It would be great if you could post the link to this study for the rest of us to read this. Do you think you could find it again?

 

[mtrycrafts]

It would be great if you could post the link to this study for the rest of us to read this. Do you think you could find it again?

I posted just above for one on line:
While there is a journal paper :

http://jn.physiology.org/cgi/content/full/83/6/3548

However, please read the very bottom of the article under footnotes:

The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

ADVERTISEMENT!!!

Just make sure you read that footnote as well

The other citation I posted is not on line but available from AES.org, for a fee

The claim has not been demonstrated in a credible manner.