What are benefits of adding HF driver 7khz up?

[speaker dave]

Try this web site.

Beat Frequencies

Look down the page to the section showing the waveforms.

The beating is a phenomonon of the envelope and, in the absence of nonlinearity, there is no actual tone at the difference frequency. You perceive the variation in the envelope. Again, with a 440 and 441 pairing, you hear a 440 (ish) tone with a 1 Hz warble to it. 1Hz does not exist. You can not hear 1 Hz. The piano can not radiate 1 Hz. But you will sense the periodic variation in the envelope.

The beating is the artifact of the two near waves going in and out of phase. If they start in phase, 1/2 second later they are exactly out of phase and their outputs will cancel. 1/2 second later they are back in phase and their amplitudes add to double. So the combined amplitude envelope comes and goes at a 1 Hz rate. Now if you move the frequencies far enough apart, say 440 and 900, there is no perception of beating and you perceive 2 independent tones.

440 and 441 are true tones. A spectrum analyzer would indicate 440 and 441 are present. 1 Hz is not a true tone, it is a beat. The spectrum analyzer would not detect it.

David

[gedlee]

I don't understand your definition of "tone"

What he said.

A "tone" is a real signal, a beat is an envelope modulation. It really is important to understand the difference here. It is not just semantic.

And Dave was right on the money when he talked about how nonlinearities of inaudible VHF signals can fold down into the audible passband yielding all kinds of things that are not what are intended. For example, we hear the folded signals and think that we are hearing the inaudible ones. Its a real can of worms.

[weltersys]

Originally Posted by speaker dave

Now if you move the frequencies far enough apart, say 440 and 900, there is no perception of beating and you perceive 2 independent tones.

440 and 441 are true tones. A spectrum analyzer would indicate 440 and 441 are present. 1 Hz is not a true tone, it is a beat. The spectrum analyzer would not detect it.

David

David,

Obviously we can’t hear 1 Hz at less than earthquake levels :^).
However, we can clearly hear the 2 kHz difference tone created by the frequency of beating of an 18 and 20 kHz tone reproduced by two BMS drivers on efficient horns driven by about one watt each.
The spectrum analyzer clearly can and does detect the 2 kHz difference tone, it is therefore a true "tone".
In fact, the spectrum analyzer and our ears can clearly detect the beat frequency tone down to the 100 Hz range when one horn is broadcasting 19,900 Hz and the other 20000 Hz.

Perhaps you have not read my posts #179 #182, or listened to the recordings.
I welcome any questions regarding how the test was conducted.
The fact is audible tones are generated by ultrasonic tones.
You may argue that the sub harmonic tone would not be audible in a “normal” listening environment, I would not care to join in that argument, as subjective perception is difficult to measure.

As Earl says in post #189:
“Maybe a little bit of semantics, but my main point was that "beats" are not "tones". Words matter.”

I agree completely.

The audio files and RTA screen shots in my posts #179 #182 prove conclusively that the beat frequency of two ultrasonic tones create an audible tone visible on an RTA in addition to the ultrasonic tones, the lower tone generated by the difference between the two ultrasonic tones.
The fact that the ultrasonic tones are causing the audible beat frequency tone is quite obvious in the recording in post #179 when I put my hand between the microphone and the two horns, blocking the 18 and 20 kHz tones, blocking the 18 and 20 kHz tones, which kills the 2 kHz tone the beat frequency caused.

Had the 2 kHz (and 4, 8, 10, & 12 kHz) tone been generated in either of the horns, some portion of the tone would have gone around my hand and reached the microphone.
In post #182 the output of the two individual horns is shown, they are not generating sub harmonics.

The 2 kHz tone is not a “subjective tone” heard only by our ears, it is clearly visible on the RTA graph.

The 18 and 20 kHz tones emanating from the two horns were at a level of 103.9 and 104 dB SPL.
Although our hearing is nonlinear, air is still quite linear at 104 dB.
The audible beat frequency tones generated by the 18 and 20 kHz tones were 71.6 dB at 4000 Hz,
54/6 dB at 8000 Hz, 57.5 dB at 12000 Hz.

A 10000 Hz tone is visible on the RTA at 44.2 dB, in the level range of the electrical and wind noise.
The screen shot below is the B&K 4004 microphone “hearing” the two horns, the level has been raised by 20 dB so the noise floor is visible.

The wind was fairly low for this time of year hear, it is responsible for the noise under 60 Hz, most of the noise at 60 Hz and above are AC line noise harmonics visible in all my tests using the same gear.

Again, perhaps you and others don’t understand the details of my test, I welcome any specific questions.

Cheers,
Art Welter

[speaker dave]

Originally Posted by weltersys

David,

Obviously we can’t hear 1 Hz at less than earthquake levels :^).
However, we can clearly hear the 2 kHz difference tone created by the frequency of beating of an 18 and 20 kHz tone reproduced by two BMS drivers on efficient horns driven by about one watt each.
The spectrum analyzer clearly can and does detect the 2 kHz difference tone, it is therefore a true "tone".
In fact, the spectrum analyzer and our ears can clearly detect the beat frequency tone down to the 100 Hz range when one horn is broadcasting 19,900 Hz and the other 20000 Hz.

Perhaps you have not read my posts #179 #182, or listened to the recordings.
I welcome any questions regarding how the test was conducted.
The fact is audible tones are generated by ultrasonic tones.
You may argue that the sub harmonic tone would not be audible in a “normal” listening environment, I would not care to join in that argument, as subjective perception is difficult to measure.

Cheers,
Art Welter

I have read your posts but I haven't listened to your samples yet, but will later.

I've chosen my words carefully and several times pointed out that difference tones and subharmonic tones are clearly possible if nonlinearity is present. Since you are clearly seeing real tones generated, then this has to be due to nonlinearity in the system, either in the drivers or perhaps the air itself. Of course, these are not beats but are intermodulation products.

As I have said several times, the only subharmonic tones that I would want reproduced are those that had already occured at the location of the original recording (knowing they are likely inharmonic, we could probably do without them as well). Subharmonics generated during reproduction (either in the drivers, in our amplifiers or even in the air) are clearly distortions that we should strive to eliminate. If it takes strict bandlimits to reduce in-band products then thats what we should do.

David S.

[gedlee]

Art

Dave is completely correct in this -he "beat" me to it. The only way that a real tone could be present at the beat frequency is if there is a nonlinearity in the system somewhere.

[Telstar]

Originally Posted by Soundminded

To those who can hear the highest two octaves between 5 khz and 20 khz, components of sound in this region are extremely critical in both quantity and quality. Even though as a percentage of the total sound it is usually relatively small, its importance is way out of proportion to the quantity. That may explain why there are probably more kinds of tweeters than all other types of drivers combined and why they attract so much interest. To those who can hear in this region, if this part of the spectrum is poorly reproduced, nothing else matters, nothing else is sufficent to compensate for it.

QFT.
My fullrange speakers go to about 15k like the ones of the OP and i feel a lot of harmonics, ambience and air missing from them.
At the time, i preferred to NOT listen to HF distortion of the poor digital sources that i had in the past.

[Telstar]

Originally Posted by weltersys

Harmonic content differentiates instruments and voices, that content extends to 40 kHz in some instruments.

More, to about 200khz, IIRC.

[Telstar]

Originally Posted by Pano

FWIW, I think most tweeters suck. And I have since I was a young whipper-snapper who could hear >16Khz. Very few sound natural to me, they don't sound like what I hear in natural sounds. I'd rather not have the content up there than the artificial sizzle that most speakers provide. Is it the tweeters themselves or the implementation? I dunno, but I don't like most of them - they sound fake. They sound like tweeters.

+2.
But wait, i'm only at page3 of 11, probably we are not alone.

[Telstar]

Originally Posted by gedlee

Or of sound quality.
The position that "if its in the source then it has to be in the reproduction" is a weak argument and quite frankly a cop-out.

And what high-fidelity means?
HFs are not that hard to reproduce from speakers (although hard to do it WELL), why not even trying? Nobody is saying that it's more important than doing the midrange right...

[weltersys]

Originally Posted by speaker dave

I have read your posts but I haven't listened to your samples yet, but will later.

I've chosen my words carefully and several times pointed out that difference tones and subharmonic tones are clearly possible if nonlinearity is present. Since you are clearly seeing real tones generated, then this has to be due to nonlinearity in the system, either in the drivers or perhaps the air itself. Of course, these are not beats but are intermodulation products.

As I have said several times, the only subharmonic tones that I would want reproduced are those that had already occured at the location of the original recording (knowing they are likely inharmonic, we could probably do without them as well).

David S.

David,

From all I have read, air non linearity is not much of a problem until around 150 dB SPL.
The test level was 104 dBA (and 103.9) at the microphone, if air non-linearity exists at such a low level, please show us some documentation as to that, even moderate levels at the listening position require that SPL near a tweeter.

Sub harmonic distortion is clearly visible, albeit at a low level, when 18 kHz and 20 kHz was fed to a single driver, but none with discreet tones to the separate drivers
The RTA screen shots of the individual horn output show no non-linearity, if there was any in the tone generators, DSP, amp channels, drivers or horns they would be clearly visible, but they are clean down to the noise floor.

You seem to be missing the fact that this test, typical of any multitrack recording (the vast majority of modern music recordings) , unlike your oft-repeated field mic example in which "sub harmonic tones already occurred at the location of the original recording", sends discreet information (tones) to each loudspeaker.
The only way one can hear any sub harmonic tones generated by ultrasonics recorded with a discreet signal path is to have speakers capable of reproducing those ultrasonics.

You can argue that accurate reproduction of inharmonic aspects of recorded music is not desirable.
Everyone is entitled to their opinion, but that opinion is perhaps the first time I find myself in disagreement with you.
I prefer that a reproduction system should reproduce music as accurately as possible, regardless of the content, "if the music sucks, let it suck out loud".

Please listen to the recordings and review the supporting graphics again, I think you will be quite surprised, I certainly was.

After decades of doing my own tests, and reviewing others, finding a real surprise is kind of refreshing.

Art