David Looser wrote:
"Trevor Wilson" wrote

I said nothing about audibility, or not. I was SPECIFICALLY
referring to the square wave capability of the different formats. I
was careful enough to specify the frequency too. MY ears are not
under dicussion. The relevant performance of the cited formats is.

Whilst it is possible to line up analogue tape machines to give a
30kHz bandwidth, that is at the expense of in-band flatness and
distortion. I've seen the results of recording squarewaves on
professional tape recorders, and the results aint' pretty!

**Perhaps our experience differs. Whilst the results of such a waveform are
not perfect, they are considerably superior to Red Book CD. I've even run
such tests on high performance (double speed) Compact Cassette machines and
the square wave response is surprisingly good. Of course, such machines can
easily manage -3dB @ 30kHz.

In any
case we are talking about expensive studio machines here, the
relevant comparison would be to 96 and 192kHz sampled audio, which
clearly has a far greater bandwidth.

**Strawman noted.


As for vinyl, a typical minimum groove radius is 6cm. That means a
linear velocity of about 210 mm/sec. So the wavelength of a 60kHz
signal is .0035mm. What is the sidewall contact area of even the
smallest stylus?

**This one seems to do the trick:

http://www.dynavector.com/etechnical/microstylus.html

The cartridge has an upper frequency limit of 100kHz.

I have some 10kHz square wave CRO photos somewhere around the place. I'll
post them in a week or two. I've examined this stylus under a binocular
microscope. I was more than a little suprised to see pretty much what the
photos show. The stylus is a beautiful thing.


--
Trevor Wilson
www.rageaudio.com.au