Terrestrial Switchoff - sorry to labour the point but...

On 3/31/13 4:51 AM, Johny B Good wrote:
I still have a 3 inch reel of triple play tape with a recording of a
late night ghost story broadcast by Radio Caroline sometime in 1967.
One day
RSN, I plan on digitising it (and any other such recordings as I might
find) and resample the wav file to correct the speed error.

I was hoping that there would be a trace of 4 or 5 KHz heterodyne to
help in re-establishing the original speed but of that there was
absolutley no trace (I guess my homebrewed superhet transistor radio
was just too selective to allow such interference).

There could be a 9 kHz tone. You never know.
Anyway, there are people collecting old Caroline recordings. They would
be grateful for the restored version.

gr, hwh

In article ,
Jim Lesurf wrote:


I can't recall if the Blattnerphone or wire recorders used AC bias. But
over the history of magnetic recording people have repeatedly tried not
using any AC bias. They can generally get it to work on a lab bench. But in
practice is it like trying to balance a pencil on its tip to make it work
well! Any slight variations in the magnetic material, etc, upset the
results.

Slainte,

Jim

The Blattnerphone and its successor the Marconi-Stille used DC bias.
There were a number of different wire recorders, using both types (wire
was rarely used in broadcasting, at least in the UK) - the 1940 Armour
was one which used AC bias though others, particularly those intended
for dictation or portable use, used DC.

As far as I can see all the coated-tape recorders, starting with the
Magnetophon from 1940 onwards, all used AC bias. I don't see that there
was resistance to its use: it was known in the USA pre-war but at the
time the recording equipment wasn't good enough for the difference to be
noticeable. Some Magnetophons were captured and brought to the UK in
1945 and subsequently several were used by the BBC; the EMI BTR1 was
based on its technology.

Sources: 'Magnetic Recording' by S.J.Begun (Murray Hill, 1949), BBC
Engineering Division Training Manual 1942.

On Sun, 31 Mar 2013 08:20:36 +0200, hwh
wrote:

On 3/31/13 4:51 AM, Johny B Good wrote:
I still have a 3 inch reel of triple play tape with a recording of a
late night ghost story broadcast by Radio Caroline sometime in 1967.
One day
RSN, I plan on digitising it (and any other such recordings as I might
find) and resample the wav file to correct the speed error.

I was hoping that there would be a trace of 4 or 5 KHz heterodyne to
help in re-establishing the original speed but of that there was
absolutley no trace (I guess my homebrewed superhet transistor radio
was just too selective to allow such interference).

There could be a 9 kHz tone. You never know.

Ah yes, I was confusing AM's modulation bandwidth in a 9KHz spaced
system. The carrier heterodyne should have been 9KHz. I doubt, even at
2.5 ips, the tape recorder would have been able to record such a high
frequency (not helped by the narrow selectivity of the RX).

Anyway, there are people collecting old Caroline recordings. They would
be grateful for the restored version.

That's interesting. I thought it would only be of interest to me
alone as a piece of personal nostalgia. I'll keep that in mind when
I've restored the recording.
--
Regards, J B Good

On 3/31/13 5:26 PM, Johny B Good wrote:
Ah yes, I was confusing AM's modulation bandwidth in a 9KHz spaced
system. The carrier heterodyne should have been 9KHz. I doubt, even at
2.5 ips, the tape recorder would have been able to record such a high
frequency (not helped by the narrow selectivity of the RX).

Very likely.

Anyway, there are people collecting old Caroline recordings. They would
be grateful for the restored version.

That's interesting. I thought it would only be of interest to me
alone as a piece of personal nostalgia. I'll keep that in mind when
I've restored the recording.

More information at:
http://www.azanorak.com/

gr, hwh

In article , Johny B Good
writes

[1] Other than the fact that they gave me the opportunity to earn
myself a very large helping of "Fully Justified Smugness Points"(tm)
over the issue of the cheapened dolby B encoding / decoding boards in
the GX630DB. Said smugness arising out of my working out what
components had been removed to save a few pennies and, not only that,
but also calculating the correct resistor values, confirmed several
months later when I was looking at the classic dolby B circuit
published in an issue of the "Wirelss World" magazine. Boy! Was I
smug... If smugness could be displayed on a meter, mine would have
had the needle wrapped around the end stop marked "Smug *******" when
I read that article. ;-))

Was that the same circuit in the Linsley-Hood Dolby add-on unit? If so,
I've still got the reprint upstairs I think. That reprint collection
also has a pretty decent compressor and some other handy circuits IIRC.
--
SimonM

In article , J. P. Gilliver (John)
wrote:
In message , Jim Lesurf
writes:
In article , Johny B Good
wrote:


[1] Alternatively the other analogy commonly used was that it was
akin to the 'crossover distortion' that would ensue in a class B
amplifier lacking the necessary bias required to avoid the 'dead
zone'.

That's an interesting analogy as *Perfect* class-B would not give any
crossover distortion as described by theory. But reality tends to
defeat this hope once you go beyond any kind of lab demo that is
tweaked with insane levels of care and attention. :-)

I didn't know perfect class B actually existed; I thought it was always,
in practice, class AB.

Indeed. In practice Class B is too evanescent and fragile to have any
useful existence. Hard enough to balance a pencil on its tip without it
being held or supported. Impossible when you then want then the pencil to
write a message...

Slainte,

Jim

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

In article , tony sayer

wrote:
In article , Java Jive
scribeth thus

Yes. I really can't believe that people can seriously think that the
old analogue techniques produce better sound.

I've got a Studer B67 here which was rescued from a skip at a radio
station where they were "upgrading" the equipment.
[snip]

Its very very "real" sounding, and never fails to impress. When I tell
people how and when it was recorded they tend not to believe it was done
at that time on analogue equipment;!...

The problems are the usual ones...

In practice both ye olde analogue and new fangled digital are quite capable
of producing excellent results.

But in practice both have often been used to produce poor results.

So the potential of either approach is often lost by the lousy use.

Some then proceed to blame the container for the contained.

Hence insanity like CDs capable of dynamic ranges of over 80dB being filled
with music level-compressed into the top few dB. "Because loudness sells."
sic The result being CDs that sound worse than old LPs of the same source
material.

Add to that things like the abuse of methods like HDCD, etc, etc.

In effect, when the engineers devise techniques that might improve
performance *if* used with due care, some use them badly to produce poorer
results. Alas, in audio this "some" seems a depressingly large number.

Analogy, I guess, with all the wobblycam, over-saturated, filmic, flashing
lights, out of focus, etc, etc, garbage often deployed on TV to try and
hide the fact that those producing a program haven't a clue about the
content and assume the audience will be even dimmer than the producer! :-/

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

No problem setting the levels for one of those - constantly loud!

For a while I had a job with a firm who had a stand at a local annual
steam rally, and the year I was on the stand we were right next to an
organ.

At breakfast time, I thought: "How nice! Just like the fairgrounds
of my youth!". By lunchtime, it was: "I wish it'd give us a break!".
By teatime: "Jeez that thing's so f*cking loud!". By dinner time:
"Thank Christ it's time to go home to some peace and quiet!"

On Sat, 30 Mar 2013 20:22:26 +0000, tony sayer
wrote:

One of the ones that does sound good is a steam driven fairground organ
sometime mid to late 60's.
--
================================================== =======
Please always reply to ng as the email in this post's
header does not exist. Or use a contact address at:
http://www.macfh.co.uk/JavaJive/JavaJive.html
http://www.macfh.co.uk/Macfarlane/Macfarlane.html

In message , Jim Lesurf
writes:
In article , J. P. Gilliver (John)
wrote:
In message , Jim Lesurf
writes:
In article , Johny B Good
wrote:


[1] Alternatively the other analogy commonly used was that it was
akin to the 'crossover distortion' that would ensue in a class B
amplifier lacking the necessary bias required to avoid the 'dead
zone'.

That's an interesting analogy as *Perfect* class-B would not give any
crossover distortion as described by theory. But reality tends to
defeat this hope once you go beyond any kind of lab demo that is
tweaked with insane levels of care and attention. :-)

I didn't know perfect class B actually existed; I thought it was always,
in practice, class AB.

Indeed. In practice Class B is too evanescent and fragile to have any
useful existence. Hard enough to balance a pencil on its tip without it
being held or supported. Impossible when you then want then the pencil to
write a message...

Slainte,

Jim

I didn't know it could be created at all, in an amplification sense: I
thought all practical circuits had some distortion near the cutoff
(where the signal crosses zero). [I've said "in an amplification sense"
as I think precision rectifiers can be constructed for instrumentation
purposes.]
--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)[email protected]+H+Sh0!:`)DNAf

Never be haughty to the humble; never be humble to the haughty. -Jefferson
Davis, confederate president (1808-1889)

On Sat, 30 Mar 2013 20:22:26 +0000, tony sayer
wrote:

I've got a Studer B67 here which was rescued from a skip at a radio
station where they were "upgrading" the equipment.

I've got a few tapes which I demo to the odd visitor one is a band
recorded on midsummer common in 1974 on a high speed REVOX 77 the others
on various pro machines over the years.

One of the ones that does sound good is a steam driven fairground organ
sometime mid to late 60's.

Its very very "real" sounding, and never fails to impress. When I tell
people how and when it was recorded they tend not to believe it was done
at that time on analogue equipment;!...

I have a few stereo classical CDs made from recordings made in the
1950s that stand comparison with anything made today. They must have
been made on analogue tape, but don't sound like "historical"
recordings. Such equipment was evidently capable of superb results if
it was used properly.

Rod.