Radio 4 on Freeview has started hissing

In article , Roderick Stewart
wrote:
On Fri, 20 Oct 2006 17:13:29 +0100, Johnny B Good
wrote:

Judicious use of the AM transmitter's modulation limiters can double
the effective range. Source the modulation from a recording involving a
duet where the studio microphones weren't phase matched between the two
vocalists (an actual example,but the name of the album escapes me) and
the transmitter's limiters will dramatically reduce the modulation
level with detrimental effect.

I can't vouch for the accuracy of this, but I recall a discussion about
the asymmetry of voice waveforms where someone gave the example of a
duet between Elton John and Kiki Dee that was popular as a single at the
time.

The story has been around for some time, but I haven't personally verified
it.

[snip]

The pop duet mentioned had apparently been recorded close-miked with the
two mikes in opposite polarities, an effect that can be clearly seen on
a scope (apparently), and which the person giving the example claimed to
be able to hear.

IIRC the idea what they had stood on opposite sides of a single microphone
with a dipole pattern.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

On Sat, 21 Oct 2006 08:54:19 +0100, Roderick Stewart
wrote:

...
The discussion was about whether the absolute polarity of loudspeaker
wiring was important (rather than the less contentious relative
polarity between left and right speakers), with some people saying
that turning the high pressure excursions into low pressure ones made
sounds completely different, with others saying they sounded exactly
the same.
...

There was some discussion about this in 'Hi-Fi News' in the 1960s. The
consensus was that absolute polarity of loudspeaker wiring did make a
difference to the reproduced quality.

--
Alan White
Twenty-eight miles NW of Glasgow, overlooking Lochs Long and Goil in Argyll, Scotland.
Webcam and weather:- http://windycroft.gt-britain.co.uk/weather
Some walks and treks:- http://windycroft.gt-britain.co.uk/walks

The message
from Roderick Stewart contains these
words:

On Fri, 20 Oct 2006 17:13:29 +0100, Johnny B Good
wrote:

Judicious use of the AM transmitter's modulation limiters can double
the effective range. Source the modulation from a recording involving a
duet where the studio microphones weren't phase matched between the two
vocalists (an actual example,but the name of the album escapes me) and
the transmitter's limiters will dramatically reduce the modulation level
with detrimental effect.

I can't vouch for the accuracy of this, but I recall a discussion
about the asymmetry of voice waveforms where someone gave the example
of a duet between Elton John and Kiki Dee that was popular as a single
at the time.

I do believe that was the actual example quoted! :-)

The discussion was about whether the absolute polarity of loudspeaker
wiring was important (rather than the less contentious relative
polarity between left and right speakers), with some people saying
that turning the high pressure excursions into low pressure ones made
sounds completely different, with others saying they sounded exactly
the same. It seemed a bit like the old oxygen-free multistranded
expensive cable nonsense argument, except that in this case there is a
real physical difference that can be shown on a scope, and the
argument was about whether it was audible or not.

The fact that an analogue tape recording of a square wave sounds just
like the origional, but looks nothing like when displayed on an
oscilloscope, suggests that absolute phase 'errors' are inaudible.
Obviously, for dissemination via AM broadcast radio, _relative_ phase
(at least between a group of close-miked vocalists) is a very important
consideration, if only on account of the effect due to the way the AM
transmitter audio processing deals with such material.

The pop duet mentioned had apparently been recorded close-miked with
the two mikes in opposite polarities, an effect that can be clearly
seen on a scope (apparently), and which the person giving the example
claimed to be able to hear.

Under this circumstance (a sort of instant A-B comparision, albeit
between two different vocalists), it might just be possible to detect
the subtle difference between correct and reversed absolute phase. It
could only be a very subtle difference otherwise the music industry
would have taken measures to standardise all equipment wrt absolute
phase long ago.

Clearly, an asymmetric audio waveform will fare differently depending
on its polarity when presented to a piece of equipment with asymmetric
characteristics, such as an amplitude modulator, but we should not
confuse this with the matter of whether acoustic asymmetry is audible
itself, and the importance of absolute and relative polarities.

Agreed!

--
Regards, John.

Please remove the "ohggcyht" before replying.
The address has been munged to reject Spam-bots.

In article ,
Alan White wrote:
There was some discussion about this in 'Hi-Fi News' in the 1960s. The
consensus was that absolute polarity of loudspeaker wiring did make a
difference to the reproduced quality.

Yes - it has to be kept in phase with the mains, otherwise the sound
strobes.

--
*Don't worry; it only seems kinky the first time.*

Dave Plowman London SW
To e-mail, change noise into sound.

In article , Alan White
wrote:
On Sat, 21 Oct 2006 08:54:19 +0100, Roderick Stewart
wrote:

... The discussion was about whether the absolute polarity of
loudspeaker wiring was important (rather than the less contentious
relative polarity between left and right speakers), with some people
saying that turning the high pressure excursions into low pressure ones
made sounds completely different, with others saying they sounded
exactly the same. ...

There was some discussion about this in 'Hi-Fi News' in the 1960s. The
consensus was that absolute polarity of loudspeaker wiring did make a
difference to the reproduced quality.

May need to untangle various things here, as there have been articles
discussing various topics where 'polarity' or 'phase' is used as the term
to describe what the article is about.

There have been articles in HFN, etc, about the choice of the *relative*
polarity of the connections to the HF and LF units in each loudspeaker. For
some orders of crossover having them different can give a smoother
transition region. This has led to articles, etc, debating the audibility
of this. (HFN published one by Keith Howard a year or so ago IIRC, so this
is still under debate.)

There have also been articles about the audibility of the 'absolute'
phase. However there have also been some professional investigations of
this by AES members which IIRC conclude that any effect tended to be
between 'slight' and 'undetectable' depending on the circumstances. Use
with equipment which showed asymmetric nonlinearity - unsurprisingly - may
make this more obvious. Hence could be arranged to be audible with
'special cases', but might be of little relevance with most real
recordings and broadcasts (cf below).

There have also been articles on time-alignment of multiple-unit speakers,
and this is sometimes mixed in with some of the above.

One snag is that recordings/broadcasts may symultaneously contain different
'polarity' contributions from different instruments or voices. Hence the
idea of 'absolute polarity' may not mean much.

Another is that many of the claims made in magazines, etc, are not based
on careful and controlled comparisons, so are of dubious reliability.
Something which is sadly common in consumer audio...

FWIW if you look at the waveforms you get from some voices, and some
instruments, the asymmetry varies from one note to another, as well
as depending on the relative microphone location.

So if anyone can hear 'absolute polarity' they may find anything other
than a single note from a single instrument with a single mic a bit of
a bother to enjoy when listening to the resulting recording/broadcast.
:-)

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

The message
from Alan White contains these words:

On Sat, 21 Oct 2006 08:54:19 +0100, Roderick Stewart
wrote:

...
The discussion was about whether the absolute polarity of loudspeaker
wiring was important (rather than the less contentious relative
polarity between left and right speakers), with some people saying
that turning the high pressure excursions into low pressure ones made
sounds completely different, with others saying they sounded exactly
the same.
...

There was some discussion about this in 'Hi-Fi News' in the 1960s. The
consensus was that absolute polarity of loudspeaker wiring did make a
difference to the reproduced quality.

My own feelings on this subject of "Absolute Polarity" are that it does
matter for loud levels (i.e. realistic levels) of music but hardly
noticeable at "Easy Listening"(tm) levels (i.e. aural wall paper /
elevator muzack levels).

A google search on the phrase "polarity of loudspeaker wiring" threw up
some interesting articles on the subject, Although digital recording has
removed a major source of polarity ambiguity from the recording process,
no attention seems to have been paid to attempting to at least maintain
coherency of phase within any one recording session, let alone a whole
album's worth of tracks.

If the studios got their act together over the absolute phase issue,
there would be some point in offering the end users a means of readily
reversing the phase of the signals being sent to their speakers or
headphones. As it stands, it's down to the individual Hi Fi buff to fit
his own phase reverser or be prepared to manually reverse the speaker
connections.

BTW, any mention of the directional properties of interconnects
(speaker cable, phono leads etc.) is a load of bull ****.

--
Regards, John.

Please remove the "ohggcyht" before replying.
The address has been munged to reject Spam-bots.

Edster wrote:
"
wrote in message

the point I was making (actually, agreeing with) is that almost _every_
complaint on feedback gets a "you're wrong, we're right, and this is
why" response.

What do you think is the purpose of Feedback? It's to dissuade as many
people as possible from complaining. It's broadcast on the BBC and
will be subject to the same internal orders as any other programme
broadcast on the BBC. Apparently Radio 1 DJs have been chastised for
criticising the quality of DAB radio or even mentioning that 6Music,
etc are also available on Freeview and Sky. So what makes you think
Feedback would be any different?

Hardly the same. Plenty of complaints get aired fully...

http://groups.google.co.uk/group/alt...4451cc0ec62a23

....it's just that nothing gets done about it!

What you say about R1 DJs is sad though - what's your source?

Cheers,
David.

On Sat, 21 Oct 2006 16:19:45 +0100, Edster wrote:

Are people attracted to stations that are louder than the others?

No. Radios normally HAVE volume controls.

When flicking through channels it just makes me more likely to
change to another more quickly to get away from the noise.

Yes.

wrote in message
s.com...

Hardly the same. Plenty of complaints get aired fully...

http://groups.google.co.uk/group/alt...4451cc0ec62a23

...it's just that nothing gets done about it!

It's probably around five years ago now but the previous Feedback
production company was given the elbow by the BBC for allegedly being
too critical of it. I expect the current lot are only given a certain
amount of rope. OTOH, and to be uncharacteristically generous to the
BBC, the sacking may have been under the Birt regime.
--
Malcolm

On Fri, 20 Oct 2006 01:01:53 +0100, Edster wrote:

Did anyone in the Beeb actually admit to having been *wrong* about
that, though, and apologise for it?

How can it be wrong to broadcast Radio 4 in stereo and still have a
minority interest station like Radio 3 at a much higher quality than
any of the other music stations that people actually listen to?

That's a separate issue. What was wrong was to reduce the bitrate
of R3 and claim that quality was unaffected and that this had been
assured by listening tests, when the quality was clearly perceived
as inferior by the listening public.

--
Ronan Flood
working for but not speaking for
Network Services, University of London Computer Centre
(which means: don't bother ULCC if I've said something you don't like)