045Be and ~50kHz ultrasonic hearing

[hapy._.face]

When I discovered JBL had made a tweeter that was capable of reproducing frequencies in the 48kHz neighborhood, my immediate question was- why?

I know- to slay bats and train dolphins, right? :)

...but seriously:


http://www.audioheritage.org/html/projectmay/technology/045be.htm


'The new DVD formats can record information to 50khz and beyond'


Frequencies above the 20kHz are considered ultrasonic. So what human can even hear anything at 48kHz? I discovered that children can hear higher frequencies adults cannot. I also learned that if ultrasound is coupled directly into the skull bone and reaches the cochlea without passing through the middle-ear, much higher frequencies (up to about 200 kHz) will be audible. This effect (sometimes called ultrasonic hearing) was first discovered by divers exposed to a high-frequency (50 kHz) sonar signal.

Still my question remains- 'why'? Assuming that the ultrasound can couple with our skulls and an audible sound is generated- what would it sound like? Is it musical? Is it a marketing gimmick?

[Zilch]

035TiA plays to 27 kHz, and 2407H (and similar), presumably, to 30 kHz.

Does anyone perceive these to be of any consequence other than specsmanship?

The TV still whistles, no doubt. Does it have subliminal sub- (or supra-) auditory effect when on, now that I (gratefully) can no longer hear it?

[Mr. Widget]

Does anyone with a normal sized room average sensitivity speakers need a kilowatt amp? I really don't know the answer to that question... but I will tell you the the part of the spectrum that I can hear sounded significantly better through the 045Be than it does through a 077/2405 or even most dome tweeters.


Widget

[Titanium Dome]

There's a phenomenon by which frequencies generated above human hearing can interact to create audible tones due to the intermodulation of the unhearable frequencies. I believe this occurs naturally in "live" sound, and can be imitated in generated sound. This interaction assists in directionality if I remember correctly.

Of course, I have no source for the moment, but you can rest assured I'll get one for you. :yes:

Where's that darn book? :hmm:

[Ian Mackenzie]

They cost enough..one would hope so.

I think the 48 khz is the marketing grab taken from ADAT. The reality is that the new transducers have incredibly low moving mass and alot of other clever wiz bang technology that makes them more accurate at the lower end of their working spectrum. The drivers that traditionally run from 1 khertz up to 20khertz on paper as a rule run out of puff (transient speed) due to the greater moving mass and other stuff.

However this is only true of current art, future Art may tell a different tale. We will have to wait and see.

[Titanium Dome]

From http://www.nae.edu/NAE/bridgecom.nsf/weblinks/MKEZ-695TMR?OpenDocument


Ultrasonic Audio
Ultrasonics can be used to produce highly directional audible sound beams. This technology is based on physical properties of air, particularly that air becomes a nonlinear medium at high sound pressures. Hence, it is possible to transmit two high-intensity ultrasonic tones, say at 100 kHz and 101 kHz, and produce an audible 1 kHz tone as a result of the intermodulation between the two ultrasonic tones. However, the demodulated signal will be significantly distorted, so the audio must be preprocessed to reduce the distortion after demodulation (Pompei, 1999). Although this technology is impressive, it cannot reproduce low-frequency sounds effectively, and it has lower fidelity than standard loudspeakers.

Check out some of the relevant references at the bottom of the Web page. This information is four or more years old, BTW, and a lot has developed in the years between 2002 and 2006.

[Titanium Dome]

Lord, I love eggheads. They do so much good work and share it freely with their peers and with us.

Here's an ASA presentation from NOISE-CON 2005. I'll bet they partied that night! :yes:

http://www.acoustics.org/press/150th/Lenhardt.html

[Titanium Dome]

At least one company is developing a market already.

http://www.atcsd.com/pdf/HSS%20Product%20Sheet.pdf

[hapy._.face]

Hi(gh) Ti(de),

Thanks for the info! That's interesting stuff, indeed.



At least one company is developing a market already.

http://www.atcsd.com/pdf/HSS%20Product%20Sheet.pdf


Now that is interesting- a column of ultrasonic signals that isolates the audible portion of the program material so that the material itself can be focused into a given target. Shopping will never be the same- Gee, I can't wait to get beamed advertising jingles as the ultrasonic frequencies are coupled into my freakin skull. Does this mean the audible jingle will play in my head for several seconds after leaving the audible target/store? :p




Hence, it is possible to transmit two high-intensity ultrasonic tones, say at 100 kHz and 101 kHz, and produce an audible 1 kHz tone as a result of the intermodulation between the two ultrasonic tones



Like an out-of-tune guitar, eh?


I think it's cool to see all of this technology and sound experimantation, but my question stems from a high fidelity sound reproduction perspective. I gather the 045Be it is not an intermodulated tone generator (on purpose). Nor do I think it will be beaming columns of USF so that I will have a greatly diminished sweet spot.

I guess (as Widget indicates) it's not what it can do at 48kHz that makes it what it is- it's what it does as a (listenable) UHF device that makes it special. Hey Widget- do you really think it can ground a bat!? :D

[moldyoldy]

Hi, H. .F,

Here's what I thought to be a very interesting read on the topic, in particular, how it relates to music;

http://www.cco.caltech.edu/~boyk/spectra/spectra.htm

As pointed out already, even though we may deny perceiving UHF, some of it can even penetrate half-deaf, thick skulls like mine. What surprised me were the effects as they relate to music, and our perception of it. My impression, after reading the linked article completely, was that it might be wise to filter out everthing over 20kHz for the best enjoyment of music playback in systems that can go beyond it. Your analogy to the warble or "beat" frequencies made by an out-of-tune guitar is appropriate. I was also surprised to learn that 40% of the energy of a cymbal crash is over 20kHz.

Also, Roger Russell noted that subharmonics of UHF resonances can be audible, in a musically-negative way, at least with aluminum diaphragms, which may be a little OT, as I'm not familiar with the driver you mentioned.

[hapy._.face]

snip....'Roger Russell noted that subharmonics of UHF resonances can be audible, in a musically-negative way...


More interesting stuff!

Regarding the quote above- do you interpret this as meaning the subharmonics of UHF "cut" into other frequencies to compete for SPL's? ...as in the concept behind using bass traps- but on the other end of the spectrum?

[moldyoldy]

More interesting stuff!

Regarding the quote above- do you interpret this as meaning the subharmonics of UHF "cut" into other frequencies to compete for SPL's? ...as in the concept behind using bass traps- but on the other end of the spectrum?

I interpret it as 'in addition to' the recorded material, in an IM distotion kind of way.

[hapy._.face]

I interpret it as 'in addition to' the recorded material, in an IM distotion kind of way.

OK.

I read the article, and it made me wonder if some of the "X" factor that live music has could be attributed to the stuff we can't hear but rather feel. If that is the case- there could be a genuine, phsychological affect ultrasonic frequencies have on us. Imagine if that were found to be true. Imagine if it were perfected. Imagine if movie makers could force audiences to cry!! Oh the horror!! ;)

[moldyoldy]

Perhaps with a live orchestra, or other acoustic performances, but at a rock concert, it's just the stuff the guys in front of you are smokin'....

(edit)Most of the movies I've seen lately make me wanna cry anyway...

(re-edit) It may all be a rather moot issue anyway, as any UHF from a recorded performance would have to pass every link in the audio chain, starting at the mic or pickup, to ever make it to a UHF-capable transducer. The distortion effects however, bear further investigation.

[speakerdave]

I'm with Ian. I think uber frequency response translates by implication to transient response and clean waveform (no ringing) in the audible range.

David

[Mr. Widget]

I'm with Ian. I think uber frequency response translates by implication to transient response and clean waveform (no ringing) in the audible range.I have to admit, I really haven't given it a moment's intellectual energy... I only have a few of those moments so I must parse them out carefully...

My principal criterion for quality in tweeters and the like is how they sound. I have noticed that tweeters that sound really good to me, several ribbons, some of the better Dynaudio fabric domes, the Scan Speak ring radiator, the 045Be... and yes the TAD ET-703... coincidentally all extend way beyond my hearing range... I do not look for this ability, but the tweeters I have used and really liked have all had UHF extension.

I didn't mention any of the JBL dome tweeters since I have only heard them in JBL systems and don't have the same level of experience with them as these other tweeters. I didn't mention any of the JBL ring radiators since they don't have the extension and I don't think they sound as good as those mentioned above... I have only heard the new JBL/BMS ring radiator at Zilch's so it isn't a fair comparison... I have no idea what it's UHF performance is like, but it didn't have the air and ease that I attribute to a tweeter that has the UHF extension.

After all that... on to my point in response to the quote!

If the purpose of UHF extension is to lower some form of HF ringing in the audible range, why would JBL add super tweeters that start at 20KHz? As most of you know adding a tweeter at that frequency will add a heck of a lot of comb filtering and I can't see how that would help the ringing situation.


Widget

[speakerdave]

After all that... on to my point in response to the quote!

If the purpose of UHF extension is to lower some form of HF ringing in the audible range, why would JBL add super tweeters that start at 20KHz? As most of you know adding a tweeter at that frequency will add a heck of a lot of comb filtering and I can't see how that would help the ringing situation.


We could ask them, I guess, or we could speculate on the possibilites, one of which might be that, like you, they think it sounds better.

Related question: I have often wondered: In music it is not really sine waves we are talking about. Question: does the first rise of a fast transient of a lower frequency go to the HF driver instead (or both).

David

[speakerdave]

If the purpose of UHF extension is to lower some form of HF ringing in the audible range, why would JBL add super tweeters that start at 20KHz? As most of you know adding a tweeter at that frequency will add a heck of a lot of comb filtering and I can't see how that would help the ringing situation.

I have also seen (can't remember where, except it was not a flakey source) it said that above 10kHz all you need is noise for the effects you describe--air, that is.

David

[johnaec]

If the purpose of UHF extension is to lower some form of HF ringing in the audible range, why would JBL add super tweeters that start at 20KHz?Personally, in the case of UHF crossed over at 20KHz, I'm willing to bet this was done to "keep up with the Jones" more than anything else, however unfortunate that motivation might be. Word probably got around that JBL's were "only" good up to 20K - 27K, and by extending this up to 40K, (and probably "quality" 40K), JBL is able to promote the new Studio L series as at least equal to so many other "audiophile" series speakers that promote this specification, regardless of how relevant it might be. In other words - marketing.

Of course, I could be wrong in this, though JBL usually releases some kind of Tech Note when they want to publicize significant new technology gains, (think of all the tech notes at the Pro site about technological innovations, and all the tech info on the K2 series). The lack of such info makes me question the significance of 40K UHF, at least in JBL's opinion.

John

[hapy._.face]

Another thing to ponder- is the frequency extension (in part) simply one of the inherent characteristics of beryllium?

[Mr. Widget]

Related question: I have often wondered: In music it is not really sine waves we are talking about. Question: does the first rise of a fast transient of a lower frequency go to the HF driver instead (or both).It absolutely goes to both. If you play a square wave through a multiway speaker system and disconnect the tweeter it rounds the corners of the square wave (reduces the attack) and subjectively dulls the sound as expected.


I have also seen (can't remember where, except it was not a flakey source) it said that above 10kHz all you need is noise for the effects you describe--air, that is.I believe this is a topic that is still controversial among noted professional audio system designers. It is certainly part of the logic behind upsampled low res digital audio.


Personally, in the case of UHF crossed over at 20KHz, I'm willing to bet this was done to "keep up with the Jones" more than anything else...I hope that is not the case, but it may be. In the vagaries of the real world marketplace, businessmen will do anything to make a buck... JBL is not immune.


Another thing to ponder- is the frequency extension (in part) simply one of the inherent characteristics of beryllium?I guess you are talking about the 045Be? Two ways to extend frequency response are by adding magnetic horsepower and by using a stiffer lighter diaphragm. In the case of compression drivers the phase plug also comes into play... but we were talking about the effects of UHF on sound and their relevance.


Widget

[gtimbers]

The plain and simple reason for the existance of the 045Be and 045Ti is that the 435Be and 435Al (2430 and 2435 are similar) have a substantial response problem around 10 kHz on many horns and are ceratinly dead by 15 kHz. In the digital age of SACD, our friends in Japan who requested the development of the K2.S9800 insisted on good response at least to 40 kHz. There is no way we could have just used the 435 and had it dump at 15 kHz. We needed to do something at least to clear 20 kHz and we didn't want to make a toy add-on device for a product of this stature. With this said, we did the best we could to develop a dedicated UHF compression driver using a 1" diaphragm. We have two diaphragm materials available for cost reasons. The raw Be diaphragm costs us $100 each! The Ti diaphragm we form in house for about $1.50

The Ti unit is pretty level out to 30 kHz (at 100 dB for 2.83v), then has a bit of a peak and finally dies around 40 kHz. The Be diaphragm is a straight line from 5 kHz, where it is 105 dB (2.83v) to about 60 kHz where it has declined to 95 dB. This is on a horn that holds a 60 H by 30 V pattern all the way out to 40 kHz before it starts to narrow. So there actually is a valid Engineering and Marketing reason for this device to exist.

Does it really matter that we go to 40 kHz or even 60 kHz? Good luck in figuring that out because I'm not going to touch that discussion with a 10 foot pole. I will say that this is our 60th year anniversary and the question may not be unanswered very much longer.

[Robh3606]

Thanks Greg for the post.

Rob:)

[JonathanKeehn]

I think some of the respondents to this thread have it backwards. The high frequency extension of the beryllium diaphram is a by-product and function of its inherent physical characteristics of super light mass, sound propagation velocity and pistonic stiffness, which incidentally, result in superior sound reproduction. The resulting high frequency extension is a nice collateral result to brag about on a spec sheet. In addition to my prized JBL speakers I still have a 29-year old pair of Yamaha NS-1000's which have beryllium domed tweeters and midranges. From my perspective, their tweeters sound better than the 2405's except for dynamics. I am glad that JBL finally went to beryllium in their best drivers. As to being able to hear a diference at 50Khz, I think there may be some psych-acoustic impact, but that is secondary. The main benefit is the overall sound improvement. Kudos to JBL. I am saving up for a pair of used K2-S9800's.

[speakerdave]

So cool.

[Mr. Widget]

....and the question may not be unanswered very much longer.Hmmm thanks for the intrigue!

I'll add... I have listened to the 045Be extensively and love their sound quality and air. Yeah, yeah, I've said that before :blah: ...however I am able to enjoy this air with a digital front end that does not produce signal above ~24KHz... as with all digital devices any signal above a certain frequency determined by the designers and based on the sampling rate is filtered out... gone, nada... so if I can hear air with the 045Be and not so much with the 2405... well, I don't think it is due to the reproduction of the frequencies above my hearing range... it very well may be due to the fact that the distortion and break up have been pushed beyond my hearing.


Widget

[hapy._.face]

Well....that explains it all. They needed something to go over an already high frequency hurdle-

However, this is the best part:



The raw Be diaphragm


Note the word 'RAW'.

I always wondered if the Be was a coating, or "true" or 'raw'; Now I know.




The raw Be diaphragm costs us $100 each!



I'd also like to buy several boxes of those diaphragms at the "whopping" $100 each price!! ;)

Seriously, it's nice to see that there were few compromises made in your desire to make a wonderful statement speaker. Your posts are extremely enlightening and highly welcomed. Thank you for taking the time to explain it to us! One last thing: did you guys ever do any animal testing (bats) when developing the 045be? :)

[Maron Horonzakz]

Now if I could only find a microphone that go,s to 60 K.;)

[hapy._.face]

Now if I could only find a microphone that go,s to 60 K.;)

http://www.bksv.com/pdf/Bp1844.pdf

Also here: http://www.acopacific.com/chart.html (models 7016 and 7017)

..and here: http://www.bksv.com/pdf/Bp1851.pdf

Actually, a google search will turn up many more. Manley has been making the gold ref mics for some time and they are rated flat (mind you) to 30kHz, but the roll off is much much higher.




Getting back to the origins of the thread, I stumbled on an interesting article while learning about the affects/effects of >20kHz response. It would appear that there is something altered with respect to phase (and it's relationship to overall sound quality) when sampling rates are diminished in UHF response; If so, it would stand to reason that preserving the actual frequency response of certain instruments throughout the entire sound reproduction chain could result in "better sound". This stuff is fascinating. A very good read: http://www.resolutionmag.com/pdfs/TECHNO~1/CAREAB~1.PDF

[Maron Horonzakz]

B&K 4938.....long term stability 1000 years I should live so long.:D

[hapy._.face]

B&K 4938.....long term stability 1000 years I should live so long.:D


Actually, a 1000 yr life span is not so "out there" when it is mounted on equipment that is "out there" in space.

[moldyoldy]

According to "Reference Data for Radio Engineers", the band from 20-50kHz is designated as Very Low Frequency (VLF) radio waves, and is allocated for use for maritime mobile (ship-to-ship and ship-to-shore) communications. Kind of raises the questions;

At what point does a tweeter become an antennae?

and

Do I have to license my tweeter with the FCC as a radio transmitter if I throw enough watts at it?
:dont-know

[4313B]

According to "Reference Data for Radio Engineers", the band from 20-50kHz is designated as Very Low Frequency (VLF) radio waves, and is allocated for use for maritime mobile (ship-to-ship and ship-to-shore) communications. Kind of raises the questions;So THAT'S why I've noticed bumper boat games and other funny goings on here on Lake Erie recently... :hmm:

[moldyoldy]

So THAT'S why I've noticed bumper boat games and other funny goings on here on Lake Erie recently... :hmm:
The FCC version of the infamous black chopper is merely an unmarked van bristling with antennae. Just to be safe, I'd head for your power switch if I saw one of those cruising the 'hood.

[JonathanKeehn]

For those who might find it interesting, I have attached a scan from a page of my Yamaha NS-1000m brochure from 1976 that explains the relative benefits of beryllium over titanium and aluminum diaphragms. Yamaha vaporizes the beryllium in a vacuum and deposits it on a pre-shaped copper mold target which is then dropped in an acid bath to dissolve away the copper and yield a diaphragm that is super-strong and only 30 microns thick. Because the diaphragm breakup distortion is well above the range of human hearing, the driver produces extremely low distortion and super-fast response which gives the sound more air and micro-resolution. I can hear a definite difference over the 2405 in terms of air and 3-dimensionality, even when the crossover caps in the 3105 network are bypassed with Audio Cap .01 bypass caps. Of course, the 2405 blows the Yamaha away in the dynamic range department. Since the 045Be is horn-loaded, it must be an awesome driver.

One can’t help but wonder if JBL could get its beryllium diaphragm vendor to tool up some beryllium upgrades for its older generation 2400-series units at a low enough cost to make them marketable. (I realize that this is a big “if.”) It could bridge the gap for us hard core types until the 435Be and 045Be might possibly become available in a few years in the U.S. market.

[Titanium Dome]

That's quite a process. Of course, vapor deposit has been around for a while, but usually as an adjunct to another material.

I wonder what the rate of failure was during the process.

[Rudy Kleimann]

035TiA plays to 27 kHz, and 2407H (and similar), presumably, to 30 kHz.

Does anyone perceive these to be of any consequence other than specsmanship?

The TV still whistles, no doubt. Does it have subliminal sub- (or supra-) auditory effect when on, now that I (gratefully) can no longer hear it?

The TV "Whistle" is at 15,750 Hz: 30 image frames/sec X 525 horizontal scan lines per frame.

[Rudy Kleimann]

There's a phenomenon by which frequencies generated above human hearing can interact to create audible tones due to the intermodulation of the unhearable frequencies. I believe this occurs naturally in "live" sound, and can be imitated in generated sound. This interaction assists in directionality if I remember correctly.

Of course, I have no source for the moment, but you can rest assured I'll get one for you. :yes:

Where's that darn book? :hmm:

This is highly likely, as intermodulation is very audible.

The best, simplest, and recognizable form of Intermodulation products can be heard when two instruments play the same note to tune their instruments. Any difference in frequency generates a "beat frequency" that is equal to the difference in frequency between the two instruments. It sounds like a "waah-waah-waah-waah-waah" that becomes slower in speed until, as the two instruments are playing the exact same frequency, disappears. This is how the musicians know they are in tune -or not.

Intermodulation products don't necessarily sound out-of-tune, or bad; in fact they can be harmonious frequencies to the sounds produced by the instrument itself, creating overtones unique to that particular instrument that allow us to recognize a flute, trumpet, alto saxophone, tenor saxophone, guitar, ... .

I'd bet that Intermodulation frequencies are in fact major contributors to the timbre, or "sonic signatures" of different instruments, whether the actual frequencies generated by the instrument are above or below 20KHz. After all, we can easily detect when these instruments are 1, 2, or 10 Hz out-of tune with each other, and these frequencies are considered to be "subsonic".

Something to think about...

[Rudy Kleimann]

We could ask them, I guess, or we could speculate on the possibilites, one of which might be that, like you, they think it sounds better.

Related question: I have often wondered: In music it is not really sine waves we are talking about. Question: does the first rise of a fast transient of a lower frequency go to the HF driver instead (or both).

David

You are right, speakerdave, about music being much more than simple sine waves. The initial "attack" af a musical note does have a lot of HF information that is the job of the tweeter to produce, and the crossover sends to it.

A surprising example: a bass 'kick" drum in a typical pop music drum set has a primary resonant frequency of 55-80 Hz, depending on how large the drum is set up. But, as any live sound engineer will tell you, the "slap" and "click" sound of the drum's initial attack is primarily in the frequency range of 2.5~6KHz, and can be modified (accentuated more) by rolling the sweep frequency of the Mid-Hi EQ on the mixer channel up and down while boosting the response in this region.