On 2008-06-19, Alan White wrote:
On Thu, 19 Jun 2008 09:34:57 +0100, Jim Lesurf
wrote:


That is also my recollection. I can't remember when the first work on
dither was done, but I think it was produced a long time ago. Hence there
really isn't much excuse for someone writing magazine articles like NKs not
to understand it. I was certainly reading about such matters long ago.
...

Dither was certainly used in the BBC thirteen channel PCM coders used
for the BBC radio distribution network in 1972(?)

In which case the speculation I have occasionally seen on the web that
some early CDs lacked dither is probably inaccurate.

--
John Phillips

John Phillips wrote:

Alan White wrote:
Jim Lesurf wrote:

That is also my recollection. I can't remember when the first work on
dither was done, but I think it was produced a long time ago. Hence there
really isn't much excuse for someone writing magazine articles like NKs not
to understand it. I was certainly reading about such matters long ago.
...

Dither was certainly used in the BBC thirteen channel PCM coders used
for the BBC radio distribution network in 1972(?)

In which case the speculation I have occasionally seen on the web that
some early CDs lacked dither is probably inaccurate.

Most of the inherent noise from an analogue mix is enough to provide plenty of
dither.

Graham

"John Phillips"

In which case the speculation I have occasionally seen on the web that
some early CDs lacked dither is probably inaccurate.


** Hate to be the one to tell ya this pal - but there ain't no Santa
Clause and the Tooth Fairy is just a gay dentist.

Sure hope you don't need any expensive therapy after finding out this
possibly shocking news.




..... Phil

In article , John Phillips
wrote:
On 2008-06-19, Alan White wrote:


Dither was certainly used in the BBC thirteen channel PCM coders used
for the BBC radio distribution network in 1972(?)

In which case the speculation I have occasionally seen on the web that
some early CDs lacked dither is probably inaccurate.

Not necessarily. The fact that some people knew what dither was, and why it
might be required, does not guarantee that everyone making every CD falls
within this class of people. Although they may well have been saved by the
noise levels on the original analogue tapes where they were used as the
source. :-)

Slainte,

Jim

--
Change 'noise' to 'jcgl' 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

Jim Lesurf wrote:

Arny Krueger

The noise floor of a well-made recording is on the order of 75-80 dB.
Below that is the noise floor, usually from analog (thermal) sources.
This is many times more than is required to properly dither a proper 16
bit conversion.

I'd be interested in seeing data on the noise performance of studio mics
and preamps, etc.

Neumann TLM103. Equivalent noise floor of 7dBA
http://www.neumann.com/?lang=en&id=c...id=tlm103_data
Dynamic range of the microphone amplifier (A-weighted) 131 dB

Graham

"Eeyore" wrote in
message
Jim Lesurf wrote:

Arny Krueger

The noise floor of a well-made recording is on the
order of 75-80 dB. Below that is the noise floor,
usually from analog (thermal) sources. This is many
times more than is required to properly dither a proper
16 bit conversion.

I'd be interested in seeing data on the noise
performance of studio mics and preamps, etc.

Neumann TLM103. Equivalent noise floor of 7dBA
http://www.neumann.com/?lang=en&id=c...id=tlm103_data
Dynamic range of the microphone amplifier (A-weighted)
131 dB

That's real good. The Rode NT1-A is a bit more economical and speced to have
self noise of 5 dB.

The fly in the ointment is coming up with a musical acoustical source that
goes up to 138 dB when played in a typical sort of way.

Arny Krueger wrote:

"Eeyore" wrote
Jim Lesurf wrote:
Arny Krueger

The noise floor of a well-made recording is on the
order of 75-80 dB. Below that is the noise floor,
usually from analog (thermal) sources. This is many
times more than is required to properly dither a proper
16 bit conversion.

I'd be interested in seeing data on the noise
performance of studio mics and preamps, etc.

Neumann TLM103. Equivalent noise floor of 7dBA
http://www.neumann.com/?lang=en&id=c...id=tlm103_data
Dynamic range of the microphone amplifier (A-weighted)
131 dB

That's real good. The Rode NT1-A is a bit more economical and speced to have
self noise of 5 dB.

The fly in the ointment is coming up with a musical acoustical source that
goes up to 138 dB when played in a typical sort of way.

What fly would that be ?

Have you any idea what PEAK acoustic levels some unamplified instruments can
reach ?

Graham

"Eeysore the ****ing LIAR"
Jim Lesurf wrote:

I'd be interested in seeing data on the noise performance of studio mics
and preamps, etc.

Neumann TLM103. Equivalent noise floor of 7dBA

** The CCIR "equivalent noise level " figure is 17.5 dB.

http://www.neumann.com/?lang=en&id=c...id=tlm103_data


** However - the s/n ratio quoted is mere ** 76.5 dB ** CCIR relative to a
SPL of 94 dB.

94 dB SPL is about the max level of a singing voice at 50 cm and is rather
more than the level from an acoustic guitar at that same distance.




....... Phil

Phil Allison wrote:

"Eeysore the ****ing LIAR"
Jim Lesurf wrote:

I'd be interested in seeing data on the noise performance of studio mics
and preamps, etc.

Neumann TLM103. Equivalent noise floor of 7dBA

** The CCIR "equivalent noise level " figure is 17.5 dB.

Unweighted of course.

Do you think unweighted measurements are relevant when close to the auditory
theshold ? I'd have thought they might actually OVER estimate them.

As usual, you're simply being an ass.

Now bugger off.

Graham

"Jim Lesurf" wrote in message

In article
, Arny
Krueger
wrote:
"John Phillips"
wrote in message

On 2008-06-16, Jim Lesurf wrote:


IIRC Lipschitz and Vanderkooy were publishing about
dither in JAES in about 1984 and just after. Although
dither had been know for a long time I suspect you are
right that noise floors for material transferred to CD
were probably sufficient in the early days of CD
(1982-ish) to render external dither unnecessary.

AFAIK Vanderkooy and Lip****z were knowingly publishing
old news, in an effort to overcome some pretty strange
false claims that were being circulated at the time by
people who should have known better.

That is also my recollection. I can't remember when the
first work on dither was done, but I think it was
produced a long time ago. Hence there really isn't much
excuse for someone writing magazine articles like NKs not
to understand it. I was certainly reading about such
matters long ago.

The author that V&L were "answering" was a professor Professor PB Fellgett,
and published in 1981.

I comment on a posting of it in this post:

http://groups.google.com/group/rec.a...e7d88bbec10f81

Much of its contents are quoted.


I'd be interested in seeing data on the noise performance
of studio mics and preamps, etc. If I recall correctly,
their bandwidths also may cast some doubt on the idea
that LP recordings provide wide ultrasonic bandwidths of
genuine recorded sounds. (As distinct from distortion
products, etc.)


The quietest mics have A-weighted noise equivalent to an acoustical level
that is just under 10 dB. Most serious mics have A-weighted noise equivalent
to an acoustical level that is 20 dB or less. The weighting curve is
significant because the spectral contents of microphone internal noise can
vary depending on the technology used to build the mic.

IME it is not difficult to find mic preamps and converters that are quiet
enough that they don't materially add to the noise coming out of a typical
capacitor microphone.