On 05/10/2014 10:21, Jim Lesurf wrote:
In article , Eiron
wrote:
On 04/10/2014 14:50, Jim Lesurf wrote:
In article , Eiron
wrote:

http://www.telegraph.co.uk/...

Erm. At least it gave my eyebrows some exercise. :-)

Given the topic of this thread, you might also want to add in the
comments about the dynamic range of LP in this months Hi Fi Whirled.

Is there a URL or do I have to pedal down to WHSmith and read it there?

No idea about a URL. But if it saves time in WHS the relvant bits are on
pages 28-9.

Oh, and another point. The comment about "tracking limit of 20dB higher" is
also suspect. IIRC The track in question peaks at about +8dB wrt 5cm/sec
RIAA. And I doubt many people have a cartridge that would cope with 20dB
higher.

FWIW the people who cut the LPs said they didn't keep to the limits that
EMI would have restricted themselves to for LP. But even so the max level
I've found on any of the Beatles Mono Box LPs is +18dB. This is one track
on the 'Mono Masters' . Nearly all the rest peak around +8dB. I suspect
the people making the cuts would have felt that peaking to +28dB would
be insane, and probably more than the lathe could cope with even in
mono which dodges the risk of L-R going 'above surface'! 8-]

As for the Telegraph article, weren't noise-cancelling headphones in use
for a couple of decades before Amar invented them?

That's what I'd thought, but my memory is too hazy to be certain without
checking back. However why let facts get in the way of PR presented as a
Torygraphy story? :-)

Jim


I think that although Bose are often credited (especially on the web)
they were late to the game. I remember discussing a noise cancelling
headset with Cosmocord in the 70s.

This reference is interesting since it is much earlier but refers to
noise blocking rather than cancelling - but you can see where it's leading:

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=AD0919903


I found this in a paper "Engineering Silence: Active Noise Cancellation"


"In 1933, a German patent was issued to a
Paul Lueg for the concept of active noise
cancellation; he was the first to realize
the possibility of attenuating background
noise by superimposing a phase flipped
wave [5]. In the 1950s, Olsen
successfully demonstrated Lueg’s
concept in rooms, ducts, and headsets
[5]."

I haven't followed up the references but the patent should be locatable.

Michael Kellett