New page on Squares waves and amplifier performance
 

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

New page on Squares waves and amplifier performance
 

Don Pearce wrote:
On Sun, 10 Jan 2010 20:30:46 +1100, "Trevor Wilson"
wrote:

**Let me go back to the original claim:

**If you REALLY want to laugh, look at a 7kHz square wave from a CD
player (even 5kHz is barely passable from most CD players). A good
R-R or high end vinyl playback can do a MUCH better job.


Ok, I'll bite. Here's a 7kHz square wave as produced by a CD.

http://www.soundthoughts.co.uk/look/7ksquare.png

I'm not laughing - I call that a pretty damn perfect piece of audio.

**You're kidding, right? LOL!


Meanwhile, the nearest I could find for a cartridge was this at 1kHz -
an immensely easier job, and yet still barely handled by a V15.

**Of course.


http://gallery.audioasylum.com/cgi/v...&w= 641&h=607

I'm going with the CD, thank you.

**Me too. We're not discussing personal preference, noise levels, wear
levels or any other factor. We're discussing square wave performance.


Meantime, will you please post your 7kHz vinyl waveform? I need to
make a true comparison.

**I will do so when I locate it. The photos are of a 10kHz waveform, but
you'll get the idea.


--
Trevor Wilson
www.rageaudio.com.au

New page on Squares waves and amplifier performance
 

Brian Gaff wrote:
Now, don't get all hot about it.
I have a dbx recorder or two here, and one can actually record
bandwidth limited squarewaves at higher levels. The one artefact you
tend to see of cours, is down to the finite time the processor takes
to do things. You tend to get level overshoots and undershoots and an
obvious worsening of the noise performance on louder recordings
I never really understood why everyone went toDolby, it was terrible
if the heads and eq were not exact, and was inherently non linear in
an obvious way. I would imagine if DBX had been adopted more widely,
people would have been a lot happier to have cassettes for home
recording.

**Actually, dbx is MUCH more difficult to get right than DolbyT.

[Anecdote]

When I went for an interview for my last job (ca. 1975), I was ushered into
the demo room for a major audio equipment importer into Australia. I was
left alone, with the instructions that I could listen to the equipment if I
wished, whilst I waited for the boss. I dutifully selected an LP, placed it
on the turntable, and gradually advanced the volume control, 'till I could
just hear the surface noise on the Marantz 1200b (100 Watts per channel) and
sat down to listen to the Klipsch Corner Horns.

The room exploded. I ran for the volume control and the sales-guy popped his
head into the room and said:

"I see you've found our stash of dbx encoded LPs."

I got the job. I spent 5 years working on the entire dbx range, all the way
from the humble 117 single ended stuff, to the mighty 301 processors. It
rapidly became apparent that dbx encode/decode systems magnify flaws in
recording equipment in a way that DolbyT does not (as much).


--
Trevor Wilson
www.rageaudio.com.au

New page on Squares waves and amplifier performance
 

Brian Gaff wrote:
Well, obviously, in the days I was talking about, digital recording
was still in the domain of the pro, and tended to sound very furry by
comparison to good analogue.

**Huh?


However I remember having a bit of a heated argument about the
realism or otherwise with some test luminary at a Heathrow Hotel
show back then. Pointing out that the dc coupled amp was a complete
waste of time as speakers could not really do constant air pressure
unless you lived inside an infinite baffle enclosure in any case.

**Nonsense. It's all about phase shift.


I agree crossovers by their design had phase shift, after all they are
basically fillters.

I then got into some heated discussion about doppler with a lowther
enthusiast..

**No point. Lowther enthusiasts are either brain damaged or hearing
impaired. Either way, I don't waste my time with them.

Please consider NOT top posting. It is confusing and poor netiquette.




--
Trevor Wilson
www.rageaudio.com.au

New page on Squares waves and amplifier performance
 

On Mon, 11 Jan 2010 14:52:48 +1100, "Trevor Wilson"
wrote:

**Nonsense. It's all about phase shift.

Which of course speakers themselves don't have...

d

New page on Squares waves and amplifier performance
 

"Trevor Wilson" wrote

**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.

"easily"? at 9.5cm/sec? I don't think so!

If a double-speed CC has been lined up to be -3dB at 30kHz than it has been
wrongly lined up. 30kHz is quite unnecessary for audio, and in the case of
analogue tape can only be obtained at the expense of poorer *audio*
performance.

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.

Hardly a "strawaman". You were comparing a digital format unfavorabley to
some analogue formats. I was merely pointing out that higher sampling rate
digital systems easily beat the analogue ones you are praising.


ontact area of even the
smallest stylus?

**This one seems to do the trick:

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

And how much does one of those cost?

The cartridge has an upper frequency limit of 100kHz.

To what point? Who needs 100kHz in an audio system?
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.


It may be "beautiful", but it's pointless (and no doubt very expensive). How
long does it last?

I question the ability of even that sort of thing to consistently deliver
100kHz. One of the reasons the CD4 'quadraphonic' system failed was the
inabilty of vinyl technology to reliably deliver the subcarrier to the
decoder.

David.

New page on Squares waves and amplifier performance
 

In article , Trevor Wilson
wrote:
David Looser wrote:
"Trevor Wilson" wrote



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

Due to the deformation of the wall, simply having a physical contact area
of 2 microns does not gurantee that is the actual resolution.

The cartridge has an upper frequency limit of 100kHz.

How was that value measured? I can't see it on the above page.

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.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

New page on Squares waves and amplifier performance
 

"Trevor Wilson" wrote in message
...


DolbyT.

What's DolbyT?

David.

New page on Squares waves and amplifier performance
 

"bcoombes" bcoombes@orangedotnet wrote in message
o.uk...

Ah yes bit's all coming back to me now, there were a bunch of us at work
who were 'into hi-fi' and we'd spend much time studying the slew rate
figures from various amp tests and then deciding which one we'd like to
own. ISTR that Radford amps were the ones to die for back then.

They still a-)

Iain

New page on Squares waves and amplifier performance
 

Iain Churches wrote:
"bcoombes" bcoombes@orangedotnet wrote in message
o.uk...

Ah yes bit's all coming back to me now, there were a bunch of us at work
who were 'into hi-fi' and we'd spend much time studying the slew rate
figures from various amp tests and then deciding which one we'd like to
own. ISTR that Radford amps were the ones to die for back then.

They still a-)


Just had look on ebay and found this, it was used with Tannoy Chatsworths back
in 1960, with the right source probably a setup as good as most today (it's been
hacked around apparently, I'm assuming nobody wrecked it by injudicious
component choice.)
http://cgi.ebay.co.uk/A-Working-Radf...item3ca923e1d9
Starting bid of £1500...ouch! :)