Interesting new Hyper-tweeter discussed in this newsletter. Just scroll down about half way for the article "Hi-fi for Fido."

Hyper-tweeter

Interesting.

If these up to 80kHz hyper-tweeter's start showing up in consumer electronics in the future I guess my cat's and dog's can start listening to my Metal collection with me.

Could someone explain what the point is?
The normal audio spectrum is 20Hz-20kHz, some people can head down to 15 or so or up to 25kHz or so, give or take, but 80kHz? Why?

I think it's because the super-audible frequecies create audible intermodulation distortion in the non-linear system which is the air. So, allthough you can't hear 80KHz, you can (theorettically) hear products of it in the normal spectrum. I know this because I needed to find out why my "inaubible" ADSL modem screeches like a banshee on my phone. It' becuase my phone is a very cheap, nasty, non-linear system and I'm hearing the intermodulation distortion.

Somebody here who didn't drop out of maths want to explain sum and difference?

Adsl uses frequencies above 4000hz, perfectly within the audible range.

Hmm 80Khz noise.., so these DVD-A discs that can deliver up to 96Khz will have something to make use of it? Maybe it can have some scientific aplications, altho humans can pretty much remain the same.

Ah, at least you won't need a dog whistle, you could use your pc instead, thehehe. Hmm and replace those "pest repellers" too

Supposedly some instruments like violin have some nice harmonics up there, but ppl can't hear them. Will they feel them then? Can't wait for abx... On the other hand, is the people making the recordings actually recording any content beyond 20khz?

Aww poor bats, are they going to lose their bearings more often with those crazy humans polluting their bands with noise they can't hear anyway...

Absolutely not

http://www.speedtouchdsl.com/about_adsl.htm



Besides, POTS (Plain Old Telephone Service) never uses frequencies above 4kHz.

prozaic: Your splitter is probably bork.

When I was picking up my venerable old Townshend Rock after a bearing overhaul a year or so back (hence the moniker, BTW) I had the pleasure of spending a couple of hours with Max Towhshend in front of his home/R&D system.

He was running his supertweeters, which respond to >50KHz, as a permenant part of this system. We listened to a variety of DVDAs SACDs, LPs, and even CDs, all on sources which it's safe to say, are probably as good as it gets. The 'optical disc' player was Max's heavily modded Pioneer 747.

During a DVDA of a Jazz recording, a piece with upright/double bass being played I asked Max what it would sound like without the super-tweeters, so he obligingly paused the disc, super-tweeters were switched off and the disc resumed.

What I heard is still hard to believe or understand, but I will say this, the difference was not subtle. The snap at the release of each string being released on the bass was completely gone. The whole sense of tactile realism I had being hearing was gone. Supertweeters switched back in and the difference was absolutely clear.

I'm no 'audiophool', and Max Townshend is one of the most pragmatic and empirical people working in the hifi industry - there is something going on here that needs to be investigated.

http://www.townshendaudio.com/


ciao,
RF

Depending on his service, he may not have a splitter and require one of those $15 filters for every POTS connection in use at his house. They're basically just a balanced LC filter with some minor protection that cuts off around 20KHz.

ADSL upstream channels begin around 30 KHz, so the only thing you could be hearing with a proper filter is a tiny bit of usptream enveloping above the noise floor...unless your filter needs replacing (lightning strike, power cross, etc).

My ADSL connection is similar to this, however, without the filters the sounds are not subtle or extremely high pitched, it produces a very loud staticy white noise. It would be impossible to hear anyone over this sound.

This wouldn't allow super tweeters to sound more natural, on the contrary. The natural intermodulation, within the audible range, would be recorded and perfectly reproduced by standard CD 44100 Hz 16 bits.
The addition of high definition and super tweeters would double the intermodulation, because the high frequencies would travel first from the source to the microphone, where the natural intermodulation has reached the audible range, then from the super tweeter to the listener, which would cause additional and artificial intermodulation.



ABX is there : http://jn.physiology.org/cgi/content/full/83/6/3548 (actually not ABX, but ABA, with p values successful by far).
What we are waiting for is a confirmation by an independent team or people.
"Listen" began a good work, but left for a few weeks before we could analyze his results (the question was if he did one test per experiment, or repeated tests until one works). : http://www.hydrogenaudio.org/forums/index....howtopic=17118&
Other tests has failed :
http://world.std.com/~griesngr/intermod.ppt , experiment confirmed by me, and by some people at George Massenbourg forum (Nika Aldrich, IIRC).
I tried to ABX the 48 kHz 16 bits recording of a vinyl against a 96 kHz 16 bits one, and failed (Marian Marc 2 soundcard, Senheiser HD600 headphhones (up to 30 kHz)).


Thank you for your insight, RockFan, I've seen that you helped other members with their problems, and your participation is welcome.
However, as I already pointed in another thread, HydrogenAudio is a community based on blind test listening only. This is a rule which is strictly enforced in all discussions about soundquality, and it applies even if the differences are obvious, especially in such controversial fields as ultrasonic content (by the way, are you sure that the filter used to drive the tweeters did really cut everything below 20 kHz ?).

Here is a good example of absolutely obvious differences that vanish under blind conditions : http://www.nytimes.com/library/tech/99/12/...les/23down.html

Thus, without blind test description and results, your comment about the sound of the super tweeters can't be taken into account here.

There was a thread regarding SACD and DVD-A that featured the article which I believe is contained the first link (VIA has also linked it from their Envy24 site) PIO has so obligingly posted.

To summarize: there appears be some difference in the "feeling" that one gets when ultrasonic frequencies are played with audible content versus when the hypersonics are removed. I believe it is noted that the subjects cannot hear the isolated hypersonic frequencies by themselves at all, but do have a preference for the material that includes ultrasonic components.
This is seemingly verified by blood flow monitoring via PET and alpha-EEG measurements. There are a variety of issues with the study that make me somewhat nervous about concrete pronouncements, not least of which is the limited number of test subjects and material.

An interesing experiment to conduct if one has access to a sound system with DVD-A or SACD and supertweeters (that only produce hypersonic frequencies, i.e. a crossover point of >22KHz) would be to perform an ABX with someone in a hidden location switching the supertweeter at defined time intervals. While not double-blind, provided the switcher wasn't visible or audible other than for the initial time synchronization event, it would be close enough.

They say ultraconic frequencies cannot be heard by human ears. Instead of that they begin resound in bones, so you can feel them by whole body. And who can say, if it's less important then human ear ability to hear just a part of range of existing sound frequencies.

This is so. With the low-pass filter in series with the telphone, the noise is greatly reduced but still clearly audible. Without the filter, the phone is unusable.

How about for a close miked source? Microphones are placed much closer to many sources than a normal listening position. The intermodulation that occurs between speaker and listening position may be benificial here.

That's right. This would be a valid theory if the audibility of super high frequency content was confirmed. It can be easily tested : recording the intermodulation at different distances from the speaker with a microphone.


In this case, how is it that the subjects of Oohashi's experiment can't hear the super tweeter alone ?
I was going to ask about all people who can't hear past 18 kHz, but I realized that all listening tests about high frequencies are done with headphones

From what I've read in a hifi magazine some time ago, it is implied that the impulse response of these "super tweeters" is greatly improved in the audible range up to 20~25 kHz which could be audible for people with trained and sensitive ears.

Hi Pio - this is indeed the issue, I did listen to Max's supertweeters on their own, and with the volume maxxed (?) out, I thought perhaps I heard a kind of very faint 'rustling', but it was more an impression than a definite sound.

I know my ears don't go much beyond about 16KHz (I recently tested them with a tone generator via my Senn 580's).

BTW, I did realize after I'd posted further up on this thread that I should have been less 'subjectve' and emphatic about it, so your reminder about board policy is noted and will be heeded!

If I ever get the chance, I would very much like to blind test a system with these gizmos.

RF

I used to sell hi-fi gear for a long time. Everyone was always advertising "super" this and "extended range" that.

How does it sound? That's the only question that counts.

Perhaps the ability to extend so high contributes some benefit to the audible range.

IMHO tweeters screw up in the 6 to 12Khz way more often than not.

This is a common misinterpretation of oscilloscope graphs. When you include the ultrasonic content of a pulse, the impulse looks better (higher amplitude, narrower shape).
Assuming that the impulse response is better because the pulse peak is higher is completely wrong. A perfect lowpass applied to a pulse reduces its peak level.

This is used as a misleading marketing trick (not to say dishonest) for SACD, with this famous graph :



Showing crystal clear perfect behaviour from all format within their frequency range, but tricking the consumer to believe that higher definition has a better quality.

Here is a 44100 Hz sampled pulse :



Apply a 1000 Hz lowpass :



The result :



Exept for the clicks and the ends of the filter, this represents a perfect pulse in a 1000 Hz frequency range.

Hey guys, 'we' actaully have proto tannoy monitors in studio two. The have the 'super tweeter' ;-). They peak @ ~60Khz. The sound no different to the standard 20-20 second set of monitors in the studio. Well, except for a destince lack of bass kick If you'd like me to do any specific test on them let me know...

On another note, because they go up so high, it means they can be killed without you even knowing it's happening. I'd prefer to hear my feedback. Not that I;ve ever actually had any in the studio

Tony