SUPER TWEETERS-anybody heard them?

The sense of hearing is remarkable. I don't know what is my present upper frequency range, but at one point although I could not hear a 15Kc tone (pure sine wave), I could very plainly hear the effect of a 15Kc HF filter on broad spectrum sound. I think that I could have sensed an even higher frequency filter, but that was the highest one available in my electronics. I found this interesting, and formulated the following theory.

The difference between a 15Kc sine wave and a 15Kc square wave is the presence of higher harmonics. The sinewave vs squarewave difference in sound can be sensed even if the harmonics responsible for the difference would, by themselves, be inaudible. I think that the ear senses the rate of change of pressure, which can be high for a low frequency signal if the signal is not sinusoidal.

So, to address the question, I don't think most people can hear a supertweeter (higher than 20Kc) but I do think that they can sense its effect.

I just checked out information on the Tannoy supertweeters, and was surprised by the high price. Considering that you can get a decent tweeter that goes to 20Kc for $100 or less, why should it cost so much more to extend to 30 or 40 Kc?

Seems to me that piezoelectric technology is perfectly suited to this application, and piezoelectric supertweeters are made. Their low cost may be an embarassment, but do they do the job?

Viridian...thanks for the info. I figure the wavelength of a 30Kc signal to be less than 1/2 inch. Even if the Piezo driver were perfect regarding phase, how could one ever get it time-aligned with the other drivers of the system? Maybe the phase problem isn't important.

If I were to try out a Piezo, is there one brand that you would suggest? I would just hide it behind my MG1.6 speaker, and bounce its sound off the ceiling.

Regarding Low Frequency...In any large hall used for recording there is a very low frequency rumble that is always present even when the musicians have gone out to lunch. It represents the natural frequency of the hall, and is excited by such things as the air conditioning system and passing road trafic. This subsonic noise is plainly audible on some recordings if you have suitable speakers and you don't activate your rumble filter.

But is it "noise"... something undesirable. It can be argued that this "hall sound" is part of the musical experience, and reproducing it adds to the realism of the recording. I find that is true for some recordings and not for others, probably depending on how severe the background rumble is.