Ferrograph History

[Gamer]

Please, is anyone able to shed any light on the history of the
Ferrograph Company, once makers of reel to reel tape recorders?

Thanks very much,

Peter
Collector of reel to reel tape recorders.

[Michael Harrison]

In article <35C2D2...@pgbaxter.demon.co.uk>, Gamer
<Pe...@pgbaxter.demon.co.uk> writes

I think the name of the company was Wright and Weare - not sure of
spelling. I used these machines in my ITV days - they were dreadful by
today's standards. I also had a Vortexian, which used the Ferrograph
machinery (I think).
--
Michael Harrison

[Alex Loh]

In article <NAd8eWAh...@weybr.demon.co.uk>, Michael Harrison
<Mi...@weybr.demon.co.uk> writes

Heh! Series 5/6 machines? Big old clunkers, built like tanks though. I
see these turning up in secondhand shops every so often - unfortunately
all the ones I have come across are too knackered to be any good.

There was a Series 7 [Super 7] in my old school - that was a far better
machine for sound quality, and lighter [i.e only about 16 kilos as
opposed to 30..]

I think Ferrograph got taken over / merged with Neal [North East audio
Limited] some time in the 1970s. Not sure what happened to them
afterwards - AFAIK NEAL still exist though, making dual cassette
machines for Mr Plod's interview rooms. Perhaps Canford Audio might know
something, they seem to sell a lot of NEAL kit and used to do the
Ferrograph audio test set [now discontinued], not to mention being based
in the same part of the country..

BTW how much does a s/h Uher [in decent nick, and preferably not having
previously been used for Roger Cook's Checkpoint :) ] sell for these
days? What about a Revox B77 or similar?

Alex
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[Andrew Emmerson]

The firm is still very much alive....

"FERROGRAPH Ltd, Suite 7, Cookson House, River Drive, South Shields,
NE33 1JX (0191-427 7774). A full repair and documentation service is
available on all Ferrograph products, also Revox and Uher. Refurbished
products bought and sold, also a users/enthusiasts group. Ring up for
details."

[Gamer]

Andrew Emmerson

If only it was...
This sounds like Ferrograph Spares who were at this address a couple of
years ago. However I will check it out. The Ferrograph Co. is still in
existance but has nothing to do with audio products.
Where did this info come from please?

Thanks anyway,

Peter.

[Gamer]

Andrew Emmerson wrote:
>
> The firm is still very much alive....
>
> "FERROGRAPH Ltd, Suite 7, Cookson House, River Drive, South Shields,
> NE33 1JX (0191-427 7774). A full repair and documentation service is
> available on all Ferrograph products, also Revox and Uher. Refurbished
> products bought and sold, also a users/enthusiasts group. Ring up for
> details."

Sadly as I thought this number is disconnected.

Peter.

[Tony Leech]

In article <35CA16...@pgbaxter.demon.co.uk>, Gamer <Peter@pgbax
ter.demon.co.uk> writes

A while ago in uk.rec.audio Bernard M (Sound Clinic) suggested:

"Try Ferrograph Spares & Service,
Cookson House,
106, River Drive,
South Shields,
England.
Tel (+44) (0) 191 4277772"

I wonder whether this number is OK. I saved the article in case I ever needed
it.

I have a couple of Ferrographs - a Type 88 (or is it 808?) and a Series 7.
Neither is used regularly but I couldn't part with them. The type 88 is a
stereo variant of the Series 4. I have (but can't lay my hands on instantly) a
supplement to the Series 4 manual covering the differences and I seem to
remember that the circuit diagram was drawn in 1958. I've only owned it
since 1974, however.

I also have the Series 4 hardback owner's manual and an A4 format Series
7/Super 7 'workshop manual', if anyone is in need of any technical details.
--
Tony Leech

[bas...@my-dejanews.com]

In article <uZU9VBA8...@leech.demon.co.uk>,

I have been collecting old reel to reels for a few years, have a ferrograph 2N
in A1 condition including hardback manual with circuit diagrams. I have a
website Get Reel http://www.ozemail.com.au/~bassboy/getreel and I am happy for
contributions. Also seeking service data/manuals for my Telefunken M24
professional reel to reel (1961-2)
Geoff Rosenberg Sydney Australia

-----== Posted via Deja News, The Leader in Internet Discussion ==-----
http://www.dejanews.com/rg_mkgrp.xp Create Your Own Free Member Forum

[ps.in...@gmail.com]

On Saturday, August 1, 1998 8:00:00 AM UTC+1, Gamer wrote:
> Please, is anyone able to shed any light on the history of the Ferrograph Company, once makers of reel to reel tape recorders?Thanks very much,Peome terCollector of reel to reel tape recorders.

I have just come across some bits of odds and ends that I personally bought in the closing down sale in South Shields many years ago !

[Dave Plowman (News)]

In article <9aed86b0-a153-45d4...@googlegroups.com>,

The OP has probably died of old age by now.

--
*Stable Relationships Are For Horses. *

Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.

[John Williamson]

On 27/12/2013 16:28, Dave Plowman (News) wrote:
> In article <9aed86b0-a153-45d4...@googlegroups.com>,
> <ps.in...@gmail.com> wrote:
>> On Saturday, August 1, 1998 8:00:00 AM UTC+1, Gamer wrote:
>>> Please, is anyone able to shed any light on the history of the
>>> Ferrograph Company, once makers of reel to reel tape recorders?Thanks
>>> very much,Peome terCollector of reel to reel tape recorders.
>
>> I have just come across some bits of odds and ends that I personally
>> bought in the closing down sale in South Shields many years ago !
>
> The OP has probably died of old age by now.
>

Is this a new record? Any advance on 15 years to reply to a post?

--
Tciao for Now!

John.

[Brian Gaff]

A bit late from the original Date I'd say. I gather that for a while North
East Audio Limited, made them as well as their own Neal Cassette decks based
on the Wollensack deck, then later on their own deck seeminly fashioned out
of lumps of steel.

Grin
Brian

--
From the Sofa of Brian Gaff Reply address is active
<ps.in...@gmail.com> wrote in message
news:9aed86b0-a153-45d4...@googlegroups.com...

[Brian Gaff]

I am probably going to get into trouble here, but I was on the net in those
days and recalled reading it on my dial up account.


I'm still in the market for a good reel to reel machine with quarter track
stereo capability or some nice person to repair my old Tandberg machine at a
non mortgage needing price...

Brian

--
From the Sofa of Brian Gaff Reply address is active

"John Williamson" <johnwil...@btinternet.com> wrote in message
news:bi5pdu...@mid.individual.net...

[Dave Plowman (News)]

In article <l9ktc6$lse$1...@dont-email.me>,

Brian Gaff <Bri...@blueyonder.co.uk> wrote:
> I'm still in the market for a good reel to reel machine with quarter
> track stereo capability or some nice person to repair my old Tandberg
> machine at a non mortgage needing price...

Something like an Akai 4000 - built like a tank and lots were made. Seem
to go for under �100 on Ebay.

--
*People want trepanners like they want a hole in the head*

[Brian Gaff]

Well maybe they do, but I've heard a lot of disappointed folk with these
where they are not as working order as might have been suggested!
May give it a try though.
The Tandberg is built like a tank, but it seems to have both electronic and
mechanical issues.
Brian

--
Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email: bri...@blueyonder.co.uk
______________________________________________________________________________________________________________


"Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
news:53c0db3...@davenoise.co.uk...

[Dave Plowman (News)]

In article <l9mir3$11g$1...@dont-email.me>,

Brian Gaff <Bri...@blueyonder.co.uk> wrote:
> Well maybe they do, but I've heard a lot of disappointed folk with these
> where they are not as working order as might have been suggested! May
> give it a try though. The Tandberg is built like a tank, but it seems to
> have both electronic and mechanical issues. Brian

If you pay by Paypal you should have no problems getting your money back
if it is not as described. But such things generally are OK from Ebay, in
my experience.

Of course some may buy one to play tapes they've had for ages and not
heard for ages and expect them to sound like a modern recording. I've had
that when transcribing old tapes.

--
*Hard work has a future payoff. Laziness pays off NOW.

[Woody]

<ps.in...@gmail.com> wrote in message
news:9aed86b0-a153-45d4...@googlegroups.com...

Funny you should say that. A colleague (a Geordie) attended
the same sale and bought me a Quad 33 pre-amp. It was
without amp cards but I soon acquired some of them. I later
made my own amps which by-passed the tone controls.

Only last weekend I decided I had not used it for nearly two
decades, it didn't have enough inputs and they were all DIN,
and I couldn't find anyone interested in it, so along with a
Kenwood 2020 tuner I took it to the tip. Sad, but that's
life as they say.

Ferrograph were taken over/became part of North East Audio
if that helps.


--
Woody

harrogate three at ntlworld dot com

[The Other John]

On Sat, 01 Mar 2014 12:06:03 +0000, Woody wrote:

>> On Saturday, August 1, 1998 8:00:00 AM UTC+1, Gamer wrote:

Did you miss that bit? He might have lost interest by now! :)

--

TOJ.

[charles]

In article <lesif9$3th$1...@dont-email.me>,

and I think the name now belongs to Canford.

--
From KT24

Using a RISC OS computer running v5.18

[Roderick Stewart]

On Sat, 01 Mar 2014 13:47:37 +0000 (GMT), charles
<cha...@charleshope.demon.co.uk> wrote:

>> Ferrograph were taken over/became part of North East Audio
>> if that helps.
>
>and I think the name now belongs to Canford.

They always use NEAL recorders in TV cop dramas. There doesn't seem to
be any other brand in the game. Do the police really still use tape?

But then nearly everybody in any TV drama with a laptop has a Mac
laptop, unlike the real world where they're only about 10%, so perhaps
we shouldn't expect too much realism.

Rod.

[Brian Gaff]

I think the reason cops use tapes is that its easy on tape to detect if its
an original recording. Not so easy on digital.



I had a neal 103 once, had to dump it as the pressure roller went liquid and
it ate regulators and all the pots went noisey. good design, pitty about the
quality of the parts.

Brian

--
From the Sofa of Brian Gaff Reply address is active

"Roderick Stewart" <rj...@escapetime.myzen.co.uk> wrote in message
news:gjp3h95271blaviqa...@4ax.com...

[Jim Lesurf]

In article <lev98m$b58$1...@dont-email.me>, Brian Gaff <brian...@gmail.com>
wrote:

> I think the reason cops use tapes is that its easy on tape to detect if
> its an original recording. Not so easy on digital.

My understanding is that the recorders used by the police have to meet some
specific requirements for legal / evidential reasons. e.g. they record to
*two* tapes symultaenously. This is to allow one to be kept by the police
and the other given to over to the person being interviewed or their legal
eagles. The point being to establish on both side an agreed version of what
was said.

I guess this also means the recorders have to be validated or approved to a
specified standard of performance before being acceptable for such a
purpose.

Jim

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

[Roderick Stewart]

On Sun, 02 Mar 2014 17:15:03 +0000 (GMT), Jim Lesurf
<no...@audiomisc.co.uk> wrote:

>In article <lev98m$b58$1...@dont-email.me>, Brian Gaff <brian...@gmail.com>
>wrote:
>> I think the reason cops use tapes is that its easy on tape to detect if
>> its an original recording. Not so easy on digital.
>
>My understanding is that the recorders used by the police have to meet some
>specific requirements for legal / evidential reasons. e.g. they record to
>*two* tapes symultaenously. This is to allow one to be kept by the police
>and the other given to over to the person being interviewed or their legal
>eagles. The point being to establish on both side an agreed version of what
>was said.
>
>I guess this also means the recorders have to be validated or approved to a
>specified standard of performance before being acceptable for such a
>purpose.
>
>Jim

I would have thought it just as easy to validate and approve the
design of a digital recorder as an analogue tape one, and if tampering
is ever suggested, comparing two digital files on two memory sticks
(or any digital recording medium) could be done in seconds.

Rod.

[Jim Lesurf]

In article <i2n8h994rcnfur1nt...@4ax.com>, Roderick Stewart

<rj...@escapetime.myzen.co.uk> wrote:
> On Sun, 02 Mar 2014 17:15:03 +0000 (GMT), Jim Lesurf
> <no...@audiomisc.co.uk> wrote:

> >
> >My understanding is that the recorders used by the police have to meet
> >some specific requirements for legal / evidential reasons. e.g. they
> >record to *two* tapes symultaenously.
> >

> >I guess this also means the recorders have to be validated or approved
> >to a specified standard of performance before being acceptable for such
> >a purpose.

> I would have thought it just as easy to validate and approve the design
> of a digital recorder as an analogue tape one, and if tampering is ever
> suggested, comparing two digital files on two memory sticks (or any
> digital recording medium) could be done in seconds.

In principle, I'd agree it could be done. Have no idea if anyone has
already done so. However the legal professions tend to be rather
'conservative'. And I assume the question is if anyone able to do this
thinks/decided it worth the development and validation costs up-front. I'm
not sure it would be "just as easy" though.

The problem isn't making two copies of a memory stick or CDRs. It is being
able to show evidential trace to confirm how and when their contents were
produced. Simply looking at file datestamps isn't enough.

Analogue tape systems have the advantage that you can confirm duplicate
recording simply by tracing physical wiring and ensuring the box hasn't
been tampered with. A device to record two CDRs symultaenously would either
need special hardware or be essentially a 'computer' burning two discs.
Thus all its software/firmware would need checking and you'd have to
establish it hadn't been tampered with.

Similarly, tapes could be pair-checked using mains frequency and bias
frequency comparisons. Also sometimes by the effects on the tape of being
dragged past heads, etc. Not sure what the equivalent would be for digital
when it comes to bias frequency.

[Dave Liquorice]

On Mon, 03 Mar 2014 14:41:21 +0000 (GMT), Jim Lesurf wrote:

> Similarly, tapes could be pair-checked using mains frequency and bias
> frequency comparisons. Also sometimes by the effects on the tape of
> being dragged past heads, etc. Not sure what the equivalent would be for
> digital when it comes to bias frequency.

The mains frequency will still be embedded in the recording. Seem to
remember that they could now extract that and link it with a database
fo mains frequncy and time and identify when a particular recording
was made.

I'd have thought taking the MD5 (or similar) signature of the files
would be enough to show them to be the same, no need to have clever
duplication recording machinery. Though having the box record to two
memory devices at the same time might be a bit more convient and
provides a safety net if one fails to record.

--
Cheers
Dave.

[Roderick Stewart]

On Mon, 03 Mar 2014 14:41:21 +0000 (GMT), Jim Lesurf
<no...@audiomisc.co.uk> wrote:

>> I would have thought it just as easy to validate and approve the design
>> of a digital recorder as an analogue tape one, and if tampering is ever
>> suggested, comparing two digital files on two memory sticks (or any
>> digital recording medium) could be done in seconds.
>
>In principle, I'd agree it could be done. Have no idea if anyone has
>already done so. However the legal professions tend to be rather
>'conservative'. And I assume the question is if anyone able to do this
>thinks/decided it worth the development and validation costs up-front. I'm
>not sure it would be "just as easy" though.

Yes, the Law always seems to be a few decades behind whatever's going
on in real life, so it's probably no surprise nobody has bothered to
look at why they're still using an obsolete recording system when the
rest of the world has moved on. But that doesn't mean the system
couldn't or shouldn't be improved.

>The problem isn't making two copies of a memory stick or CDRs. It is being
>able to show evidential trace to confirm how and when their contents were
>produced. Simply looking at file datestamps isn't enough.

If the recorder in the interview room produces two simultaneous
digital recordings on memory sticks or CDRs, the files can easily be
compared bit for bit if either side later questions that the other's
has been altered. And if that's not enough, it would be trivially easy
to make a third copy which is immediately filed in a sealed envelope,
signed by both parties present at the interview. I think a sealed
envelope is all they use for physical evidence anyway, so it should be
good enough for a memory stick.

>Analogue tape systems have the advantage that you can confirm duplicate
>recording simply by tracing physical wiring and ensuring the box hasn't
>been tampered with. A device to record two CDRs symultaenously would either
>need special hardware or be essentially a 'computer' burning two discs.
>Thus all its software/firmware would need checking and you'd have to
>establish it hadn't been tampered with.

I'm sure a company like NEAL could easily come up with something
suitable. CDR drives are pretty standard, and the device doesn't need
to be an actual "computer" in the everyday sense, with easily
accessible software. If it's possible to make a network backup device
which is nothing more than a special purpose computer full of hard
drives, then the same thing with several CDR drives should be easy.

>Similarly, tapes could be pair-checked using mains frequency and bias
>frequency comparisons. Also sometimes by the effects on the tape of being
>dragged past heads, etc. Not sure what the equivalent would be for digital
>when it comes to bias frequency.

Bias frequency?! We're in a new century now. All you need to do to
confirm two digital recordings are identical is to compare all the
bits on one file with all the bits on the other. Trivial.

Rod.

[Jim Lesurf]

In article <nyyfbegfubjuvyypb...@srv1.howhill.co.uk>, Dave

Liquorice <allsortsn...@howhill.com> wrote:
> On Mon, 03 Mar 2014 14:41:21 +0000 (GMT), Jim Lesurf wrote:

> > Similarly, tapes could be pair-checked using mains frequency and bias
> > frequency comparisons. Also sometimes by the effects on the tape of
> > being dragged past heads, etc. Not sure what the equivalent would be
> > for digital when it comes to bias frequency.

> The mains frequency will still be embedded in the recording. Seem to
> remember that they could now extract that and link it with a database fo
> mains frequncy and time and identify when a particular recording was
> made.

Indeed. That's how any changes to a recording can often be detected.

> I'd have thought taking the MD5 (or similar) signature of the files
> would be enough to show them to be the same, no need to have clever
> duplication recording machinery.

How do you then tell *which* copy was the one that has been altered when
the checksums differ?

[Jim Lesurf]

In article <3sf9h91dbooos4cb3...@4ax.com>, Roderick
Stewart

The problem isn't simply what happens when they are the same. It is to
decide which version was altered, and how, if they differ.

I don't doubt all such problems can be dealt with. But my point was that
systems already in place have become accepted and trusted, whilst a new
system not only has to be developed, but become approvied and accepted and
trusted.

For all I know, modern interviews *do* use CDRs. I'm just pointing out the
basic requirements.

Jim

[Dave Liquorice]

On Tue, 04 Mar 2014 09:50:34 +0000 (GMT), Jim Lesurf wrote:

>> I'd have thought taking the MD5 (or similar) signature of the
files
>> would be enough to show them to be the same, no need to have
clever
>> duplication recording machinery.
>
> How do you then tell *which* copy was the one that has been altered when
> the checksums differ?

The MD5 checksums are generated at the time of recording, verfied as
being the same for both copies and recorded on the associated
paperwork. If the media holding the files has enough space it can be
applied to that as well.

--
Cheers
Dave.

[SpamTrapSeeSig]

In article <53e30ca...@audiomisc.co.uk>, Jim Lesurf
<no...@audiomisc.co.uk> writes

>How do you then tell *which* copy was the one that has been altered when
>the checksums differ?

The checksum is displayed to the parties involved, recorded (printed out
or written down, or whatever, and countersigned. It's no different to
other 'chain of custody' issues. In forensic computing this is
commonplace.

Anyway, it's still a significantly higher standard than contemporaneous
notes, as anyone using the Downing St. gates will probably
acknowledge...

The police who are using cassettes are doing so probably because (a)
there's no budget allocated to re-equip, and (b) they have a support
contract ongoing meaning the kit will continue to be serviceable.

It's slightly ironic that tapes are likely to be far longer lived than
most other media.
--
SimonM

[Roderick Stewart]

On Tue, 04 Mar 2014 09:53:48 +0000 (GMT), Jim Lesurf
<no...@audiomisc.co.uk> wrote:

>
>> Bias frequency?! We're in a new century now. All you need to do to
>> confirm two digital recordings are identical is to compare all the bits
>> on one file with all the bits on the other. Trivial.
>
>The problem isn't simply what happens when they are the same. It is to
>decide which version was altered, and how, if they differ.

Best of three? Put a third copy in a sealed bag or envelope and if the
user copies are found to differ, just compare them with the third
reference copy.

If they wanted to do it, they could, but I think you're right to
suggest that they probably just can't be bothered to change.

Rod.

[NY]

"Roderick Stewart" <rj...@escapetime.myzen.co.uk> wrote in message

news:59jbh9tt43gcn51gi...@4ax.com...

When the recordings are being used in-house by the CPS and the defence
lawyers, are tape copies (eg copies of one of the two master copies) still
used, or are the masters copied to digital WAV/MP3 files for internal use
and or playing to the court? In other words, are cassettes and cassette
recorders actually still used throughout the legal system or just for the
initial authentication stage.

[Jim Lesurf]

In article <nyyfbegfubjuvyypb...@srv1.howhill.co.uk>, Dave
Liquorice <allsortsn...@howhill.com> wrote:

For a CDR, anyone wanting to make a fake 'altered' disc could presumably do
an MD5 for their 'changed' content. Which brings us back to my question.

[Jim Lesurf]

In article <N_-dnZK7HNCVTIjO...@brightview.co.uk>, NY

I assume it is a case of "when/if there is a dispute. each side have to
produce their original copy to check against what it being claimed". Fine
to use a generational 'copy' for convenience *until* a dispute that
something isn't as recorded at the time.

This is all assuming the UK/USA adversarial approach. Countries where the
judge is supposed to determine the truth presumably do things differently.

[Jim Lesurf]

In article <e$cfIOOAD...@virginmedia.net>, SpamTrapSeeSig

<no-...@nospam.virginmedia.net> wrote:
> In article <53e30ca...@audiomisc.co.uk>, Jim Lesurf
> <no...@audiomisc.co.uk> writes

> >How do you then tell *which* copy was the one that has been altered
> >when the checksums differ?

> The checksum is displayed to the parties involved, recorded (printed out
> or written down, or whatever, and countersigned. It's no different to
> other 'chain of custody' issues. In forensic computing this is
> commonplace.

However it divorces the chain of evidential trace from the object to some
other paperwork.

> Anyway, it's still a significantly higher standard than contemporaneous
> notes, as anyone using the Downing St. gates will probably
> acknowledge...

> The police who are using cassettes are doing so probably because (a)
> there's no budget allocated to re-equip, and (b) they have a support
> contract ongoing meaning the kit will continue to be serviceable.

Can't argue with either of the above points. :-)

[Dave Liquorice]

On Tue, 04 Mar 2014 15:32:35 +0000 (GMT), Jim Lesurf wrote:

>>> How do you then tell *which* copy was the one that has been
altered
>>> when the checksums differ?
>>
>> The MD5 checksums are generated at the time of recording, verfied
as
>> being the same for both copies and recorded on the associated
>> paperwork. If the media holding the files has enough space it can
be
>> applied to that as well.
>
> For a CDR, anyone wanting to make a fake 'altered' disc could presumably
> do an MD5 for their 'changed' content. Which brings us back to my
> question.

That MD5 might be consistent with an MD5 check done on that file at a
later date but I doubt it would be consistent with the manually
recorded or regenerated MD5 of its supposed twin.

--
Cheers
Dave.

[Paul Ratcliffe]

On Tue, 04 Mar 2014 09:50:34 +0000 (GMT), Jim Lesurf <no...@audiomisc.co.uk>
wrote:

>> I'd have thought taking the MD5 (or similar) signature of the files
>> would be enough to show them to be the same, no need to have clever
>> duplication recording machinery.
>
> How do you then tell *which* copy was the one that has been altered when
> the checksums differ?

How do you tell which copy of a tape has been altered when they are
different?

[Dave Liquorice]

On Wed, 05 Mar 2014 00:33:43 GMT, Paul Ratcliffe wrote:

>> How do you then tell *which* copy was the one that has been
altered
>> when the checksums differ?
>
> How do you tell which copy of a tape has been altered when they are
> different?

You look for the bits of sticky tape. B-)

--
Cheers
Dave.

[David Taylor]

If you use MD5, it could well be...

http://en.wikipedia.org/wiki/MD5#Collision_vulnerabilities

You probably want to stick to SHA-256/SHA-512 or maybe SHA-3 once
it's a bit more understood.

--
David Taylor

[Dave Liquorice]

On Wed, 5 Mar 2014 08:54:03 +0000 (UTC), David Taylor wrote:

>>>>> How do you then tell *which* copy was the one that has been
>>>>> altered when the checksums differ?
>>>>
>>>> The MD5 checksums are generated at the time of recording,
verfied
>>>> as being the same for both copies and recorded on the associated
>>>> paperwork. If the media holding the files has enough space it
can
>>>> be applied to that as well.
>>>
>>> For a CDR, anyone wanting to make a fake 'altered' disc could
>>> presumably do an MD5 for their 'changed' content. Which brings us
back
>>> to my question.
>>
>> That MD5 might be consistent with an MD5 check done on that file
at a
>> later date but I doubt it would be consistent with the manually
>> recorded or regenerated MD5 of its supposed twin.
>
> If you use MD5, it could well be...

The thought that MD5 might not be good enough, FSVO "good enough" did
cross my mind but for this it's just an example of a file signature.

--
Cheers
Dave.

[Ashley Booth]

Jim Lesurf wrote:

> In article <3sf9h91dbooos4cb3...@4ax.com>, Roderick
> Stewart
> <rj...@escapetime.myzen.co.uk> wrote:
> > On Mon, 03 Mar 2014 14:41:21 +0000 (GMT), Jim Lesurf
> > <no...@audiomisc.co.uk> wrote:
>
>
> > > Similarly, tapes could be pair-checked using mains frequency and
> > > bias frequency comparisons. Also sometimes by the effects on the
> > > tape of being dragged past heads, etc. Not sure what the
> > > equivalent would be for digital when it comes to bias frequency.
>
> > Bias frequency?! We're in a new century now. All you need to do to
> > confirm two digital recordings are identical is to compare all the
> > bits on one file with all the bits on the other. Trivial.
>
> The problem isn't simply what happens when they are the same. It is to
> decide which version was altered, and how, if they differ.
>
> I don't doubt all such problems can be dealt with. But my point was
> that systems already in place have become accepted and trusted,
> whilst a new system not only has to be developed, but become
> approvied and accepted and trusted.
>

> For all I know, modern interviews do use CDRs. I'm just pointing out

> the basic requirements.
>
> Jim
>
>
> Jim

NEAL do make dual CDR recorders.
http://www.neal.co.uk/products/9102.htm

--

[NY]

"Ashley Booth" <a...@snglinks.com> wrote in message
news:S9qdncnE97thj4rO...@bt.com...

>> For all I know, modern interviews do use CDRs. I'm just pointing out
>> the basic requirements.
>>
>> Jim
>>
>>
>> Jim
>
> NEAL do make dual CDR recorders.
> http://www.neal.co.uk/products/9102.htm

I hadn't thought of recording to CD-R. I'd assumed that any successor to
cassettes would write to SD cards, to give greater capacity than 1 hour. I
suppose CD-R recorders could use a lower bit-rate, mono format (44 kHz
stereo isn't needed!) but such a format would be non-standard and so
possibly not playable in a normal CD player.

Digital formats have the big advantage that you can skip directly to
specific sections when pointing to statements that the witness made, without
having to laboriously wind the tape backwards and forwards, especially as
most (all) cassette recorders have counters that register arbitrary units
rather than minutes and seconds, unlike VHS recorders, presumably because
there is no control track on which to count pulses as the tape is being
wound at high speed.

What format is used for recording videos of police interviews - is that
digital (DVD or SD card) or is that also on analogue VHS tape with a
dual-tape recorder?

[Roderick Stewart]

On Wed, 05 Mar 2014 06:05:16 -0600, "Ashley Booth" <a...@snglinks.com>
wrote:

>>
>> For all I know, modern interviews do use CDRs. I'm just pointing out
>> the basic requirements.
>>
>> Jim

>NEAL do make dual CDR recorders.
>http://www.neal.co.uk/products/9102.htm

Ah, that explains it. The Police are using CDRs, and their old tape
machines have ended up with the TV props departments.

Rod.

[Jim Lesurf]

In article <nyyfbegfubjuvyypb...@srv1.howhill.co.uk>, Dave
Liquorice <allsortsn...@howhill.com> wrote:

The problem still would be that - given just two discs - *which one* has
been altered after the original matching pair were made?

[Jim Lesurf]

In article <slrnlhcs77...@news.pr.network>, Paul Ratcliffe

'Defects' like the ones I mentioned. The standard forensic audio now looks
at details like:

A) The mains frequency (and its harmonic structure) as recorded in the
background. These both vary with time and place.

B) The residual bias oscillator recorded onto the tape. Again this varies
with time and from one machine to another.

C) Transverse physical differences due to head imperfections. These can be
traced to a given machine.

etc.

There is now quite a body or academic work on this. The 'Forensic Audio'
section of the AES and IEEE is quite a healthy one! :-)

I'm sure there are equivalents for digital. But they would need to have
been found, verified, and established for a court to accept in any dispute
when two 'copies' of an interview, etc, differ. And in addition to spotting
they differ, the need is to tell which copy is the 'original version'.

[Graham.]

In TV drama police interviews there is a flat plate attached to the wall, which I presume is the microphone. Odd looking mic, is there just an electret capsule inside?

Also the recorder makes a noise for a few seconds after starting, presumably so the interview doesn't get recorded on the leader.

[SpamTrapSeeSig]

In article <e0a86c2d-1563-44b0...@googlegroups.com>,
Graham. <i.need.a.us...@gmail.com> writes

>In TV drama police interviews there is a flat plate attached to the
>wall, which I presume is the microphone. Odd looking mic, is there just
>an electret capsule inside?

Boundary layer mic. Canford used to sell them - good idea really, as
they're more violence-resistant, and flat in a wall they work quite
well.
--
SimonM

[Roderick Stewart]

On Wed, 05 Mar 2014 11:42:48 +0000 (GMT), Jim Lesurf
<no...@audiomisc.co.uk> wrote:

>> > For a CDR, anyone wanting to make a fake 'altered' disc could
>> > presumably do an MD5 for their 'changed' content. Which brings us
>> > back to my question.
>
>> That MD5 might be consistent with an MD5 check done on that file at a
>> later date but I doubt it would be consistent with the manually recorded
>> or regenerated MD5 of its supposed twin.
>
>The problem still would be that - given just two discs - *which one* has
>been altered after the original matching pair were made?

Exactly the same doubt would apply, given just two of *any* type of
recording medium, and it could easily be solved by saving a third copy
in a sealed evidence bag as a reference in case of any doubt.

Or, if you are restricted to two copies for economic reasons,
tampering could be made much more difficult by recording a timecode as
part of the digital bitstream.

Rod.

[Roderick Stewart]

When I first encountered them they were called PZMs, or Pressure Zone
Microphones. The microphone itself is mounted on a plate leaving a
small air gap, so it samples the air pressure at the surface of the
plate, and when the plate is fixed to a wall, the entire wall
intercepts the wavefront, so it hears everything in the room. A
colleague responsible for sound recording on a drama once got some to
try out, in the hope that they might make it less bother than waving a
boom mic about or rigging actors with radio mics. Unfortunately they
were just too good at picking up absolutely every little sound in the
room, which rendered them useless for our purpose, where there was
typically one actor whose voice we wanted in a room with half a dozen
crew members whose extraneous shuffling sounds we didn't.

Rod.

[NY]

"Graham." <i.need.a.us...@gmail.com> wrote in message
news:e0a86c2d-1563-44b0...@googlegroups.com...

I think it's so it's very obvious to everyone in the room every time the
recorder is started or stopped - the lawyer and the police will probably
make notes of each occasion so if there are any allegations of tampering (ie
discontinuities in mains frequency or bias frequency) the intentional and
well-recorded stops and starts can be discounted from being thought to be
tampering.

[NY]

"Jim Lesurf" <no...@audiomisc.co.uk> wrote in message
news:53e39b3...@audiomisc.co.uk...

> In article <slrnlhcs77...@news.pr.network>, Paul Ratcliffe
> <ab...@orac12.clara34.co56.uk78> wrote:
>> On Tue, 04 Mar 2014 09:50:34 +0000 (GMT), Jim Lesurf
>> <no...@audiomisc.co.uk> wrote:
>
>> >> I'd have thought taking the MD5 (or similar) signature of the files
>> >> would be enough to show them to be the same, no need to have clever
>> >> duplication recording machinery.
>> >
>> > How do you then tell *which* copy was the one that has been altered
>> > when the checksums differ?
>
>> How do you tell which copy of a tape has been altered when they are
>> different?
>
> 'Defects' like the ones I mentioned. The standard forensic audio now looks
> at details like:
>
> A) The mains frequency (and its harmonic structure) as recorded in the
> background. These both vary with time and place.
>
> B) The residual bias oscillator recorded onto the tape. Again this varies
> with time and from one machine to another.
>
> C) Transverse physical differences due to head imperfections. These can be
> traced to a given machine.

Presumably digital recording media could have some random "defects" built in
to the process (eg a watermark signal in the least significant bits). Or a
time code.

I hadn't realised that mains frequency varied depending on location. I
thought every single generator on the national grid was locked to the same
frequency due to the "inertia" of a large number of generators (which in
turn is probably related to physical inertia of the rotors). I know when a
new generator is brought on line it has to be spun up to the correct
frequency as it happens to be at that moment and then adjusted to be in
phase (in the olden days, judged by phase-lock lights); only when these are
correct will the switch be thrown, after which its speed will be locked to
the national grid frequency is that varies due to varying load.

[Paul Ratcliffe]

On Wed, 05 Mar 2014 01:40:41 +0000 (GMT), Dave Liquorice
<allsortsn...@howhill.com> wrote:

>> How do you tell which copy of a tape has been altered when they are
>> different?
>
> You look for the bits of sticky tape. B-)

<smacks head>

[SpamTrapSeeSig]

In article <slrnlhfdpr...@news.pr.network>, Paul Ratcliffe
<ab...@orac12.clara34.co56.uk78> writes

That only works on helical scan (DAMHIK!).

I've just realised that too many now broadcastering won't have got it
anyway.

Technolorgy scares Oi.

--
SimonM

[SpamTrapSeeSig]

In article <3n3fh9hn1324egldq...@4ax.com>, Roderick
Stewart <rj...@escapetime.myzen.co.uk> writes

Twenty+ years ago, I used a couple as a spaced stereo pair at the back
of a hall, to provide monitoring for a remote PA/recording installation.
The mix point was a TV sound gallery, isolated from the venue proper but
with an observation window.

We bought the "Realistic" ones (made by Crown for Radio Shack), and did
a popular mod so they ran from 48V phantom (basically re-engineering
them back to Crown's original spec). They were spaced about 15-20ft
apart. on a very flat back wall.

They worked brilliantly for the purpose, with an unexpectedly good
stereo image (monitoring on 3/5As).


--
SimonM

[Paul Ratcliffe]

On Thu, 6 Mar 2014 10:46:36 +0000, SpamTrapSeeSig
<no-...@nospam.virginmedia.net> wrote:

>>>> How do you tell which copy of a tape has been altered when they are
>>>> different?
>>>
>>> You look for the bits of sticky tape. B-)
>>
>><smacks head>
>
> That only works on helical scan (DAMHIK!).

"DAMHIK!" ?

> I've just realised that too many now broadcastering won't have got it
> anyway.

Soon we won't have any double-enders left. Old studio sound desk was
carted away at the weekend and the new one has minimal plug-up capability.
'They' wanted none, but 'we' have won that one. Everything else is via
audio routers (using up more capacity on that one I told you about a few
months back - no idea how we'd have achieved this project without it!).

[NY]

"Paul Ratcliffe" <ab...@orac12.clara34.co56.uk78> wrote in message
news:slrnlhh1rm...@news.pr.network...

> On Thu, 6 Mar 2014 10:46:36 +0000, SpamTrapSeeSig
> <no-...@nospam.virginmedia.net> wrote:
>
>>>>> How do you tell which copy of a tape has been altered when they are
>>>>> different?
>>>>
>>>> You look for the bits of sticky tape. B-)
>>>
>>><smacks head>
>>
>> That only works on helical scan (DAMHIK!).
>
> "DAMHIK!" ?

Don't ask me how I know. Often supplemented by IJD - I just do.

[Jim Lesurf]

In article <ds2fh9hc09etqktm2...@4ax.com>, Roderick Stewart

<rj...@escapetime.myzen.co.uk> wrote:
> On Wed, 05 Mar 2014 11:42:48 +0000 (GMT), Jim Lesurf
> <no...@audiomisc.co.uk> wrote:

> >> > For a CDR, anyone wanting to make a fake 'altered' disc could
> >> > presumably do an MD5 for their 'changed' content. Which brings us
> >> > back to my question.
> >
> >> That MD5 might be consistent with an MD5 check done on that file at a
> >> later date but I doubt it would be consistent with the manually
> >> recorded or regenerated MD5 of its supposed twin.
> >
> >The problem still would be that - given just two discs - *which one*
> >has been altered after the original matching pair were made?

> Exactly the same doubt would apply, given just two of *any* type of
> recording medium, and it could easily be solved by saving a third copy
> in a sealed evidence bag as a reference in case of any doubt.

So who keeps the 'third copy' and is acceptable to *both* sides in a
dispute?

> Or, if you are restricted to two copies for economic reasons, tampering
> could be made much more difficult by recording a timecode as part of the
> digital bitstream.

Alas, once again, digital systems that can easily do such things can also
then easily copy them.

[Jim Lesurf]

In article <7ZWdnYf-lp_QCYrO...@brightview.co.uk>, NY

<m...@privacy.net> wrote:



> Presumably digital recording media could have some random "defects"
> built in to the process (eg a watermark signal in the least significant
> bits). Or a time code.

Possibly the most logical way of doing that is to use the SACD protection
scheme. That modulates the *width* of pits in a way that most optical
drives can't read. So you need an SACD drive to read the data as the
encyrption lock is in the width modulation patterns. That could then be
used as a disc ID.

No idea what approach NEAL use. And they may not tell.

> I hadn't realised that mains frequency varied depending on location. I
> thought every single generator on the national grid was locked to the
> same frequency due to the "inertia" of a large number of generators
> (which in turn is probably related to physical inertia of the rotors).

FWIW I wasn't simply talking about the UK.

[Roderick Stewart]

On Thu, 06 Mar 2014 10:02:00 +0000 (GMT), Jim Lesurf
<no...@audiomisc.co.uk> wrote:

>> >
>> >The problem still would be that - given just two discs - *which one*
>> >has been altered after the original matching pair were made?
>
>> Exactly the same doubt would apply, given just two of *any* type of
>> recording medium, and it could easily be solved by saving a third copy
>> in a sealed evidence bag as a reference in case of any doubt.
>
>So who keeps the 'third copy' and is acceptable to *both* sides in a
>dispute?

Whoever currently keeps evidence in sealed bags. That's all a sound
recording would be, after all; just another piece of evidence.

>> Or, if you are restricted to two copies for economic reasons, tampering
>> could be made much more difficult by recording a timecode as part of the
>> digital bitstream.
>
>Alas, once again, digital systems that can easily do such things can also
>then easily copy them.

Analogue recordings can be faked too. If detection of tampering relies
on mains hum, then there's no reason why digital recordings would have
any less of it, because whatever device makes the recording it must
start with a microphone. For interviewees who are *really* paranoid,
perhaps the interview room could have a popular radio station playing
in the background. That would be tantamount to a timecode and make it
very difficult to conceal edits.

Rod.

[SpamTrapSeeSig]

In article <slrnlhh1rm...@news.pr.network>, Paul Ratcliffe
<ab...@orac12.clara34.co56.uk78> writes

>Soon we won't have any double-enders left. Old studio sound desk was
>carted away at the weekend and the new one has minimal plug-up capability.
>'They' wanted none, but 'we' have won that one. Everything else is via
>audio routers (using up more capacity on that one I told you about a few
>months back - no idea how we'd have achieved this project without it!).

Are there digital-only channels and a few analogue ones? I can see the
sense then, but there's still enormous value in the simplicity of a
well-made jackfield. For a start, you're not at the mercy of some dodgy
Chinese switch-mode PSU or someone's decision to use a BGA-mounted
processor because it was cheap.

I know I don't really want to know the answer, but which way round are
the faders - sensible or commercial?

Now where did I put that red Spanish cape...
--
SimonM

[Roderick Stewart]

On Fri, 7 Mar 2014 09:56:37 +0000, SpamTrapSeeSig
<no-...@nospam.virginmedia.net> wrote:

>In article <slrnlhh1rm...@news.pr.network>, Paul Ratcliffe
><ab...@orac12.clara34.co56.uk78> writes
>>Soon we won't have any double-enders left. Old studio sound desk was
>>carted away at the weekend and the new one has minimal plug-up capability.
>>'They' wanted none, but 'we' have won that one. Everything else is via
>>audio routers (using up more capacity on that one I told you about a few
>>months back - no idea how we'd have achieved this project without it!).
>
>Are there digital-only channels and a few analogue ones? I can see the
>sense then, but there's still enormous value in the simplicity of a
>well-made jackfield. For a start, you're not at the mercy of some dodgy
>Chinese switch-mode PSU or someone's decision to use a BGA-mounted
>processor because it was cheap.

I remember being shown how to tie a knot in a double-ender while only
holding it by the plug at one end, and being told that mastery of this
trick was required for full social acceptance in the technical areas
of Bush House.

>I know I don't really want to know the answer, but which way round are
>the faders - sensible or commercial?
>
>Now where did I put that red Spanish cape...

Oh no! not the Comfy Chair!

Rod.

[Paul Ratcliffe]

On Fri, 7 Mar 2014 09:56:37 +0000, SpamTrapSeeSig
<no-...@nospam.virginmedia.net> wrote:

> Are there digital-only channels and a few analogue ones?

There are AES and analogue interface cards in the system. The studio
wallboxes are now things called Hydra boxes which turns all your ins/outs
to/from IP and it's fibre to the desk crate.
Control surface is just that - there is no audio going through it any more,
so just like a vision mixer really.

> but there's still enormous value in the simplicity of a well-made
> jackfield.

You are out of step with modern thinking!

> I know I don't really want to know the answer, but which way round are
> the faders - sensible or commercial?

Believe it or not, they are the sensible way round. Everyone relevant was
asked which they preferred and it was unanimous. We didn't expect Calrec
to be able to do it, but they did. I believe they said this was positively
the last time though!

[Jim Lesurf]

In article <iqhhh95iktorg7vqm...@4ax.com>, Roderick Stewart

<rj...@escapetime.myzen.co.uk> wrote:
> On Thu, 06 Mar 2014 10:02:00 +0000 (GMT), Jim Lesurf
> <no...@audiomisc.co.uk> wrote:

> >> >
> >> >The problem still would be that - given just two discs - *which one*
> >> >has been altered after the original matching pair were made?
> >
> >> Exactly the same doubt would apply, given just two of *any* type of
> >> recording medium, and it could easily be solved by saving a third
> >> copy in a sealed evidence bag as a reference in case of any doubt.
> >
> >So who keeps the 'third copy' and is acceptable to *both* sides in a
> >dispute?

> Whoever currently keeps evidence in sealed bags. That's all a sound
> recording would be, after all; just another piece of evidence.

Which would make the third copy a pointless redundancy.

> >> Or, if you are restricted to two copies for economic reasons,
> >> tampering could be made much more difficult by recording a timecode
> >> as part of the digital bitstream.
> >
> >Alas, once again, digital systems that can easily do such things can
> >also then easily copy them.

> Analogue recordings can be faked too. If detection of tampering relies
> on mains hum,

Your error here is the presumtion that it *only* depends on "mains hum"
(sic).

> then there's no reason why digital recordings would have
> any less of it, because whatever device makes the recording it must
> start with a microphone. For interviewees who are *really* paranoid,
> perhaps the interview room could have a popular radio station playing in
> the background.

The challenge isn't paranoia. It is that lawyers are employed to find any
way they can to dispute evidence, and their clients may seek any method
they can use to escape conviction.

[NY]

"Jim Lesurf" <no...@audiomisc.co.uk> wrote in message

news:53e4981...@audiomisc.co.uk...

> In article <iqhhh95iktorg7vqm...@4ax.com>, Roderick Stewart

>> Analogue recordings can be faked too. If detection of tampering relies
>> on mains hum,
>

> Your error here is the presumption that it *only* depends on "mains hum"

> (sic).
>
>
>> then there's no reason why digital recordings would have
>> any less of it, because whatever device makes the recording it must
>> start with a microphone. For interviewees who are *really* paranoid,
>> perhaps the interview room could have a popular radio station playing in
>> the background.
>
> The challenge isn't paranoia. It is that lawyers are employed to find any
> way they can to dispute evidence, and their clients may seek any method
> they can use to escape conviction.

So a system which has a greater number of variabilities in the recording
process (variations in mains frequency and bias frequency, and "footprint"
left by the individual tape heads) is harder to challenge than one which
only includes variations in mains frequency, if there are more parameters
that match between the defence and prosecution copy of the tape.

The only time I've been interviewed by the police - as a WITNESS (not
suspect!) to a smash-and-grab robbery: I helped catch the thief as he tried
to cycle away - I was amazed by how laborious the process of taking a
statement was. The policeman asked me various questions then paraphrased
them in police-English and wrote them long hand in capital letters (which
took him ages). It would have been so much easier and quicker (both for them
and for me) if they'd recorded the interview on tape.

Luckily I didn't have to worry about overstaying my parking charges because
another witness who was being interviewed was the traffic warden who would
have otherwise have given me a ticket, and he'd already given me a
hand-written exemption to leave in my car so his colleagues wouldn't ticket
me.

And I got an official police commendation out of it, presented at a ceremony
where some people (police and civilians) had done much braver things than I
had. Grabbing a thief's coat, making him swerve so he fell off his bike and
then standing astride the bike to prevent him riding off on it again is
brave, but not in the same league as facing a man armed with a knife or
running into a burning building to rescue a child.

[SpamTrapSeeSig]

In article <slrnlhj7as...@news.pr.network>, Paul Ratcliffe
<ab...@orac12.clara34.co56.uk78> writes

>On Fri, 7 Mar 2014 09:56:37 +0000, SpamTrapSeeSig
><no-...@nospam.virginmedia.net> wrote:
>
>> Are there digital-only channels and a few analogue ones?
>
>There are AES and analogue interface cards in the system. The studio
>wallboxes are now things called Hydra boxes which turns all your ins/outs
>to/from IP and it's fibre to the desk crate.
>Control surface is just that - there is no audio going through it any more,
>so just like a vision mixer really.

It's good. I don't know if they still do them, but the knobs with a ring
of LEDs (to indicate 'position') were a great idea.

I was quite a fan of the early assignable stuff. Unfortunately the
concept was way ahead of the technology - too complex and unreliable
initially.

I expect the new one will be really nice to use, actually - they've had
a while to optimize the UI now. Just as long as there are 'grabbable'
controls where they're needed and the minimum of modality (so you're not
having to think 'second-layer meta' in a live situation).

>
>> but there's still enormous value in the simplicity of a well-made
>> jackfield.
>
>You are out of step with modern thinking!

Only if the construction quality is up to the task. But you said it's
Calrec, so one could reasonably assume it is.

>
>> I know I don't really want to know the answer, but which way round are
>> the faders - sensible or commercial?
>
>Believe it or not, they are the sensible way round. Everyone relevant was
>asked which they preferred and it was unanimous. We didn't expect Calrec
>to be able to do it, but they did. I believe they said this was positively
>the last time though!

Neat.

I wonder if they've actually tried them on non BBC people recently. I
remember that several people from the commercial sector caved-in and
admitted a preference (for the BBC way) after a while. For live work
accept no substitutes (especially if there's overpress).

I suppose that might just have been that we got fed up with rotating the
ones in Dubbing during morning line-up and back again at the end of the
day, but you'd like to hope it was genuine.

S.

--
SimonM

[LumpHammer]

On 03/03/2014 16:35, Dave Liquorice wrote:

> On Mon, 03 Mar 2014 14:41:21 +0000 (GMT), Jim Lesurf wrote:
>
>> Similarly, tapes could be pair-checked using mains frequency and bias
>> frequency comparisons. Also sometimes by the effects on the tape of
>> being dragged past heads, etc. Not sure what the equivalent would be for
>> digital when it comes to bias frequency.
>

> The mains frequency will still be embedded in the recording. Seem to
> remember that they could now extract that and link it with a database
> fo mains frequncy and time and identify when a particular recording
> was made.

>
> I'd have thought taking the MD5 (or similar) signature of the files
> would be enough to show them to be the same, no need to have clever

> duplication recording machinery. Though having the box record to two
> memory devices at the same time might be a bit more convient and
> provides a safety net if one fails to record.
>
To take the MD5 idea slightly further, this seems like a situation where
public-key cryptography could be used to make it very difficult to
tamper with digital recordings in an undetectable manner.

The Digital Tachograph units installed in lorries across the EU use
public key cryptography to digitally sign the data (speed, driver
details, etc.) they record on their internal storage.

One drawback would be that the digital audio recording devices would
need to be allocated their own key-pair in a secure area of the factory
where they are made, which might increase costs.

Such a big change in the technology would probably be subject to
challenge by defence lawyers, unless it was very carefully implemented.

[jimguthrie]

On Fri, 07 Mar 2014 10:50:12 +0000, Roderick Stewart
<rj...@escapetime.myzen.co.uk> wrote:

>I remember being shown how to tie a knot in a double-ender while only
>holding it by the plug at one end, and being told that mastery of this
>trick was required for full social acceptance in the technical areas
>of Bush House.

Definitely a crime on shift at the old control room in BH, so only
attempted on night shift when the management were asleep. :-) I
can't remember if I could do it or not. You had to twist the double
ender as you flicked it up to get the other plug in the loop. Maybe
I should find a two foot double ender and try to perfect it in my
dotage. :-)

Jim.

[Jim Lesurf]

In article <Eb2dnXUk_Nl_I4TO...@brightview.co.uk>, NY

<m...@privacy.net> wrote:
> "Jim Lesurf" <no...@audiomisc.co.uk> wrote in message
> news:53e4981...@audiomisc.co.uk...

> > The challenge isn't paranoia. It is that lawyers are employed to find
> > any way they can to dispute evidence, and their clients may seek any
> > method they can use to escape conviction.

> So a system which has a greater number of variabilities in the recording
> process (variations in mains frequency and bias frequency, and
> "footprint" left by the individual tape heads) is harder to challenge
> than one which only includes variations in mains frequency, if there
> are more parameters that match between the defence and prosecution copy
> of the tape.

Yes. So far as I can tell from AES papers, etc, on 'Forensic Audio' the
methods are of two kinds.

1) The 'provenance' - putting evidence into sealed containers that are
signed and documented, etc. Then shared/declared between the prosecution
and defence. Or some accepted equivalent. Hence things like the writing in
longhand and having a witness sign statements, etc.

2) 'Watermarks' that stem from the individual recorder and the time and
place the recordings were made. Important when potential evidence comes
from a machine of some kind rather than a person who can sign and swear an
oath.

How long it takes a court system to accept specific examples will be down
to the courts, etc.

Both 'sides' in a legal process will be looking for weaknesses that allow
them to have some presented material either excluded as evidence or have
its reliability doubted if that suits their purpose. And to similarly have
some evidence accepted when it suits them despite the 'opposition' wanting
to have it rejected.

However I've only seen info on this for audio in the UK/USA and similar
systems. Have no idea what they do in other places where the police and
court assume you are guilty and its your problem to convince them
otherwise, or where a 'judge' runs the whole process and looks for the
'truth' rather than the usual court 'battle'.

[J. P. Gilliver (John)]

In message <jljlh9t4alf4v6pbt...@4ax.com>,

Was/is there an actual technical purpose to this knot?
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

One death from beef on the bone might be expected every 20 years at the current
rate, but 40,000 people will die falling downstairs in that time. Should we make
bungalows compulsory? ("Equinox" on Risk, April 1999, paraphrased by Polly
Toynbee in Radio Times)

[jimguthrie]

On Sun, 9 Mar 2014 09:55:49 +0000, "J. P. Gilliver (John)"
<G6...@soft255.demon.co.uk> wrote:

>Was/is there an actual technical purpose to this knot?

Not as far as I remember. :-) Unless it was bu**ering up two foot
double enders. :-)

Jim.

[SpamTrapSeeSig]

In article <7esph91s1ftgedan6...@4ax.com>,
JimGuthrie@?.?.invalid writes

It was significantly easier to do with a four-footer. The two-footers
weren't really flexible enough.

Apparently a rite of passage in the old control room (basement, avec
balcony) was to do it with a 12 footer. I remember Bryan Lintell (who
lectured me at Evesham) making a string of knots in a 10-footer over the
baluster rail in the Bredon Wing, circa 1978.

I feel sorry for the 'bantam' patchbay generation. All that fruitless
practising.

:-)
--
SimonM

[jimguthrie]

On Mon, 10 Mar 2014 09:12:56 +0000, SpamTrapSeeSig
<no-...@nospam.virginmedia.net> wrote:

Simon,

>It was significantly easier to do with a four-footer. The two-footers
>weren't really flexible enough.

That might explain my lack of success. :-)

>Apparently a rite of passage in the old control room (basement, avec
>balcony) was to do it with a 12 footer. I remember Bryan Lintell (who
>lectured me at Evesham) making a string of knots in a 10-footer over the
>baluster rail in the Bredon Wing, circa 1978.

I remember a fellow member of "D" shift - Ray Pilling - being quite an
expert but I don't remember doing it off the balcony. :-)

>I feel sorry for the 'bantam' patchbay generation. All that fruitless
>practising.

I transferred to Glasgow which was uniselector, so it had a
comparatively minute patchbay and selection of double enders - and the
knot tying was not looked on kindly there either. :-) IIRC the
punishment in both places was being made to get the Brasso tin out and
cleaning the all the double enders. :-)

Jim.