What sort of machine made this distortion?

[J. P. Gilliver]

- 2:51 in.

Banded into about four horizontal, fairly static bars. And then briefly
at the end of the bad patch - about 3:05 - a large number of bars.

The show is 1978, so I presume well after 2" formats were in general
use; of course, who knows what it's been stored on subsequently. Audio
solid throughout.

Not being in the profession, I can't really guess - other than that I
can't think of any mechanism whereby this distortion could have come
from a domestic machine. (Though from the bandwidth, I think it's been
stored on one at the final level - though one in excellent condition.)

[John Williamson]

Post by J. P. Gilliver
http://youtu.be/dCOcmGyqnLU - 2:51 in.
Banded into about four horizontal, fairly static bars. And then briefly
at the end of the bad patch - about 3:05 - a large number of bars.
The show is 1978, so I presume well after 2" formats were in general
use; of course, who knows what it's been stored on subsequently. Audio
solid throughout.
Not being in the profession, I can't really guess - other than that I
can't think of any mechanism whereby this distortion could have come
from a domestic machine. (Though from the bandwidth, I think it's been
stored on one at the final level - though one in excellent condition.)

Quad tape was in regular use until the mid 1980s, and the four bars are
a common fault. Somebody will likely be along shortly to explain how it
happened here.

The recording has also been through a domestic system, probably VHS,
which has left the trademark noise bar from a poorly aligned machine or
dirt on the head drum at the bottom of the picture. That may also be
where the total breakdown of the picture into noise bars came from,
indicating that the edge of the tape may have been damaged, causing loss
of sync.

[J. P. Gilliver]

Post by John Williamson

Post by J. P. Gilliver
http://youtu.be/dCOcmGyqnLU - 2:51 in.
Banded into about four horizontal, fairly static bars. And then briefly
at the end of the bad patch - about 3:05 - a large number of bars.

[]

Post by John Williamson
Quad tape was in regular use until the mid 1980s, and the four bars are

Ah, I didn't know that.

Post by John Williamson
a common fault. Somebody will likely be along shortly to explain how it
happened here.
The recording has also been through a domestic system, probably VHS,
which has left the trademark noise bar from a poorly aligned machine or
dirt on the head drum at the bottom of the picture. That may also be
where the total breakdown of the picture into noise bars came from,
indicating that the edge of the tape may have been damaged, causing
loss of sync.

Just before or after the noise, there were multiple picture bars - 10 to
13 I would say.

[John Williamson]

On 25/01/2024 21:10, J. P. Gilliver wrote:
ss of sync.

Post by J. P. Gilliver
Just before or after the noise, there were multiple picture bars - 10 to
13 I would say.

As the sync pulses degrade, the rest of the circuitry tries to keep
things running, then gives up until the pulses come back. You can see
the start of the breakup as the colour problems get worse, and the image
starts breaking up inside each bar. My guess would be damage to the edge
of the quad tape due to poor storage or a problem with a previous playback.

[J. P. Gilliver]

Post by John Williamson
ss of sync.

Post by J. P. Gilliver
Just before or after the noise, there were multiple picture bars - 10 to
13 I would say.

As the sync pulses degrade, the rest of the circuitry tries to keep
things running, then gives up until the pulses come back. You can see
the start of the breakup as the colour problems get worse, and the
image starts breaking up inside each bar. My guess would be damage to
the edge of the quad tape due to poor storage or a problem with a
previous playback.

I can understand the four-banding - AIUI, there are four head passes to
a field? - but the 15- or 16-banding (I've been back to count)? Is that
that, as things fall apart, the heads pass across adjacent tracks? 16
(or even 4 each main band, though the 16 look even and not grouped into
4) seems quite a lot of mistracking.

[John Williamson]

Post by J. P. Gilliver

Post by John Williamson
ss of sync.

Post by J. P. Gilliver
Just before or after the noise, there were multiple picture bars - 10 to
13 I would say.

As the sync pulses degrade, the rest of the circuitry tries to keep
things running, then gives up until the pulses come back. You can see
the start of the breakup as the colour problems get worse, and the
image starts breaking up inside each bar. My guess would be damage to
the edge of the quad tape due to poor storage or a problem with a
previous playback.

I can understand the four-banding - AIUI, there are four head passes to
a field? - but the 15- or 16-banding (I've been back to count)? Is that
that, as things fall apart, the heads pass across adjacent tracks? 16
(or even 4 each main band, though the 16 look even and not grouped into
4) seems quite a lot of mistracking.

Quad head video is very intolerant of incorrect tape speed, so even
slight corruption of the sync pulses will cause all sorts of problems.
This is why it can not be used for things like still frames and slow
motion. The tape speed was either 7.5 or 5 inches per second,and the
tape is 2 inches wide, so the slope of each track is pronounced enough
for a head to cross many tracks if the tape speed if not correct.

[J. P. Gilliver]

Post by John Williamson

Post by J. P. Gilliver

Post by John Williamson
ss of sync.

Post by J. P. Gilliver
Just before or after the noise, there were multiple picture bars - 10 to
13 I would say.

As the sync pulses degrade, the rest of the circuitry tries to keep
things running, then gives up until the pulses come back. You can see
the start of the breakup as the colour problems get worse, and the
image starts breaking up inside each bar. My guess would be damage to
the edge of the quad tape due to poor storage or a problem with a
previous playback.

I can understand the four-banding - AIUI, there are four head passes to
a field? - but the 15- or 16-banding (I've been back to count)? Is that
that, as things fall apart, the heads pass across adjacent tracks? 16
(or even 4 each main band, though the 16 look even and not grouped into
4) seems quite a lot of mistracking.

Quad head video is very intolerant of incorrect tape speed, so even
slight corruption of the sync pulses will cause all sorts of problems.
This is why it can not be used for things like still frames and slow
motion. The tape speed was either 7.5 or 5 inches per second,and the
tape is 2 inches wide, so the slope of each track is pronounced enough
for a head to cross many tracks if the tape speed if not correct.

Wow, that's quite fast! I can see that it will indeed cross many tracks,
if it gets to a poor speed (or stops).

[John Williamson]

Post by J. P. Gilliver
Wow, that's quite fast! I can see that it will indeed cross many tracks,
if it gets to a poor speed (or stops).

I've just seen the typo. Early machines ran at 15 ips, later ones at 7.5.

[J. P. Gilliver]

Post by John Williamson

Post by J. P. Gilliver
Wow, that's quite fast! I can see that it will indeed cross many tracks,
if it gets to a poor speed (or stops).

I've just seen the typo. Early machines ran at 15 ips, later ones at 7.5.

(I was wondering why only a 3:2 ratio.) Wow, that's even faster -
somebody was being _very_ conservative!

And/or, perhaps - did they do linear audio tracks and that influenced
the speed choice? (Presumably before they'd thought of audio subcarrier
- or at least chosen frequencies that weren't visible.)

[John Williamson]

Post by J. P. Gilliver

Post by John Williamson
I've just seen the typo. Early machines ran at 15 ips, later ones at 7.5.

(I was wondering why only a 3:2 ratio.) Wow, that's even faster -
somebody was being _very_ conservative!

No, the limit was how small they could make the heads when the standard
was drawn up. In 1956 when the format was invented, they were actually
pushing the limits, and as a result,the earlier machines were horribly
unreliable, and needed setting up for every tape individually. By 1978,
the format was pretty reliable.

Post by J. P. Gilliver
And/or, perhaps - did they do linear audio tracks and that influenced
the speed choice? (Presumably before they'd thought of audio subcarrier
- or at least chosen frequencies that weren't visible.)

Both audio and sync were on linear tracks. The electronics of the time
could not handle anything more complicated. Even the later hi-fi audio
in the video area on VHS and Betamax used separate audio and video
heads, with different azimuth angles so the audio head didn't respond to
the audio and vice versa.

[J. P. Gilliver]

Post by John Williamson

Post by J. P. Gilliver

Post by John Williamson
I've just seen the typo. Early machines ran at 15 ips, later ones at 7.5.

(I was wondering why only a 3:2 ratio.) Wow, that's even faster -
somebody was being _very_ conservative!

No, the limit was how small they could make the heads when the standard
was drawn up. In 1956 when the format was invented, they were actually
pushing the limits, and as a result,the earlier machines were horribly
unreliable, and needed setting up for every tape individually. By 1978,
the format was pretty reliable.

Post by J. P. Gilliver
And/or, perhaps - did they do linear audio tracks and that influenced
the speed choice? (Presumably before they'd thought of audio subcarrier
- or at least chosen frequencies that weren't visible.)

Both audio and sync were on linear tracks. The electronics of the time
could not handle anything more complicated. Even the later hi-fi audio
in the video area on VHS and Betamax used separate audio and video
heads, with different azimuth angles so the audio head didn't respond
to the audio and vice versa.

Ah, hence "4 head" machines. I vaguely remember 6 head towards the end -
presumably for video effects.

[Bill Posters]

Post by John Williamson

Post by J. P. Gilliver
Wow, that's quite fast! I can see that it will indeed cross many tracks,
if it gets to a poor speed (or stops).

I've just seen the typo. Early machines ran at 15 ips, later ones at 7.5.

7.5 was incredibly rare (and required replacement of the head assembly - which was (fortunately)very simple), and of course inb the UK it was 15.625 ips not 15.

AIUI, the BBC never used 7.8125 ips.

[charles]

Post by John Williamson

Post by J. P. Gilliver

Post by John Williamson
ss of sync.

Post by J. P. Gilliver
Just before or after the noise, there were multiple picture bars - 10 to
13 I would say.

As the sync pulses degrade, the rest of the circuitry tries to keep
things running, then gives up until the pulses come back. You can see
the start of the breakup as the colour problems get worse, and the
image starts breaking up inside each bar. My guess would be damage to
the edge of the quad tape due to poor storage or a problem with a
previous playback.

I can understand the four-banding - AIUI, there are four head passes to
a field? - but the 15- or 16-banding (I've been back to count)? Is that
that, as things fall apart, the heads pass across adjacent tracks? 16
(or even 4 each main band, though the 16 look even and not grouped into
4) seems quite a lot of mistracking.

Quad head video is very intolerant of incorrect tape speed, so even
slight corruption of the sync pulses will cause all sorts of problems.
This is why it can not be used for things like still frames and slow
motion.

Not quite true. BBC Designs Dept developed a slow motion facility for quad
machines. It was used in the 1966 World Cup coverage.

Post by John Williamson
The tape speed was either 7.5 or 5 inches per second,and the
tape is 2 inches wide, so the slope of each track is pronounced enough
for a head to cross many tracks if the tape speed if not correct.

[John Williamson]

Post by charles

Post by John Williamson
Quad head video is very intolerant of incorrect tape speed, so even
slight corruption of the sync pulses will cause all sorts of problems.
This is why it can not be used for things like still frames and slow
motion.

Not quite true. BBC Designs Dept developed a slow motion facility for quad
machines. It was used in the 1966 World Cup coverage.

<Grin> In the days when the BBC employed real engineers...

[charles]

Post by John Williamson

Post by charles

Post by John Williamson
Quad head video is very intolerant of incorrect tape speed, so even
slight corruption of the sync pulses will cause all sorts of problems.
This is why it can not be used for things like still frames and slow
motion.

Not quite true. BBC Designs Dept developed a slow motion facility for
quad machines. It was used in the 1966 World Cup coverage.

<Grin> In the days when the BBC employed real engineers...

The chap who designed it went on to be Chief Engineer at Dolby Europe. We
played amateur theatre together at university.

[J. P. Gilliver]

[]

Post by charles

Post by John Williamson
Quad head video is very intolerant of incorrect tape speed, so even
slight corruption of the sync pulses will cause all sorts of problems.
This is why it can not be used for things like still frames and slow
motion.

Not quite true. BBC Designs Dept developed a slow motion facility for quad
machines. It was used in the 1966 World Cup coverage.

[]
I thought the "instant replay" - used for sporting events, football
goals mainly - used a spinning magnetic disc (capable of storing, I
don't know, a second or less)?

[Bill Posters]

Post by J. P. Gilliver
[]

Post by charles

Post by John Williamson
Quad head video is very intolerant of incorrect tape speed, so even
slight corruption of the sync pulses will cause all sorts of problems.
This is why it can not be used for things like still frames and slow
motion.

Not quite true. BBC Designs Dept developed a slow motion facility for quad
machines. It was used in the 1966 World Cup coverage

I thought the "instant replay" - used for sporting events, football
goals mainly - used a spinning magnetic disc (capable of storing, I
don't know, a second or less)?

Ampex HS-100, 36 seconds PAL, 30 seconds NTSC

[NY]

Post by Bill Posters

Post by J. P. Gilliver
[]

Post by charles

Post by John Williamson
Quad head video is very intolerant of incorrect tape speed, so even
slight corruption of the sync pulses will cause all sorts of problems.
This is why it can not be used for things like still frames and slow
motion.

Not quite true. BBC Designs Dept developed a slow motion facility for quad
machines. It was used in the 1966 World Cup coverage

I thought the "instant replay" - used for sporting events, football
goals mainly - used a spinning magnetic disc (capable of storing, I
don't know, a second or less)?

Ampex HS-100, 36 seconds PAL, 30 seconds NTSC

I remember a summer job that I had in the mid 1980s while I was at
university. It involved being the poor sod who digitised a lot of
U-Matic tapes of <censored> for a defence company. Tedious and
repetitive work. They had a slow motion recorder that used what looked
like an 8-inch floppy disk.

They had a computer which triggered the slo-mo to record one frame every
n frames of video from the U-matic, and then played it back frame by
frame, with the computer triggering frame advance after it had finished
digitising one of the still frames. I think it took about 5 seconds to
digitise a frame - it was very definitely not real-time.

The slo-mo was broadcast-spec, a cast-off of BBC or ITV sport. Its own
inherent logic (ie without being driven by the computer) allowed it to
record normal video and then play it back at 1/2, 1/3, 1/4 etc speed, as
well as slightly more esoteric rates like 1 frame of slo-mo taking 3
fields, 5 fields etc (1.5, 2.5 etc frames) rather than the normal 4, 6,
8 fields (2, 3, or 4 frames). I found a manual for it, and there was a
hand-written note that someone at BBC/ITV had made, saying that
mixed-field rates (one frame displayed for 1.5, 2.5, etc frames) was not
to be used if a certain make of VTR was used to record the output
because it confused the VTR's sync track. I'm not sure why a frame made
up of two fields taken at the same time was any better than a frame made
up of two fields taken with a time interval between them.

[Mark Carver]

Post by Bill Posters

Post by J. P. Gilliver
[]

Post by charles

Post by John Williamson
Quad head video is very intolerant of incorrect tape speed, so even
slight corruption of the sync pulses will cause all sorts of problems.
This is why it can not be used for things like still frames and slow
motion.

Not quite true. BBC Designs Dept developed a slow motion facility for quad
machines. It was used in the 1966 World Cup coverage

I thought the "instant replay" - used for sporting events, football
goals mainly - used a spinning magnetic disc (capable of storing, I
don't know, a second or less)?

Ampex HS-100, 36 seconds PAL, 30 seconds NTSC

Yep, only ever I gather three in the UK, the Beeb had one, LWT had
another, and the third was owned by a facilites house in Soho ?

[Michael Bailey]

Post by Mark Carver

Post by Bill Posters

Post by J. P. Gilliver
[]

Post by charles

Post by John Williamson
Quad head video is very intolerant of incorrect tape speed, so even
slight corruption of the sync pulses will cause all sorts of problems.
This is why it can not be used for things like still frames and slow
motion.

Not quite true. BBC Designs Dept developed a slow motion facility for quad
machines. It was used in the 1966 World Cup coverage

I thought the "instant replay" - used for sporting events, football
goals mainly - used a spinning magnetic disc (capable of storing, I
don't know, a second or less)?

Ampex HS-100, 36 seconds PAL, 30 seconds NTSC

Yep, only ever I gather three in the UK, the Beeb had one, LWT had
another, and the third was owned by a facilites house in Soho ?

Bill Posters has answered most of the questions here on this. All I can add is that the number of clogged heads passes (4) tells us that is not a UK PAL 625 playback most likely NTSC. NTSC quad machine heads rotated at 4 times field frequency whereas in the UK where we obviously used the 625/50 line standard the heads rotated at 5 times field frequency. 15.625 ips was the standard linear tape speed used in the UK for intercompany compatibility.

Julie recorded two shows in the UK around that time, the first was recorded at LWT's Wycombe Road studios where The Muppets were Julie's guests on her show. The second was The Muppets regular show recorded at ATV"s Elstree complex where Julie was their guest star.

[NY]

Post by Mark Carver

Post by Bill Posters

Post by J. P. Gilliver
I thought the "instant replay" - used for sporting events, football
goals mainly - used a spinning magnetic disc (capable of storing, I
don't know, a second or less)?

Ampex HS-100, 36 seconds PAL, 30 seconds NTSC

Yep, only ever I gather three in the UK, the Beeb had one, LWT had
another, and the third was owned by a facilites house in Soho ?

As few as that? I imagined that they were an integral part of any
scanner van that was used for sports where action replays were needed.
Or are you saying that there were many other models of slo-mo, and that
it is specifically the Ampex HS-100 of which there were only three
instances in the UK?

[Bill Posters]

Post by NY

Post by Mark Carver

Post by Bill Posters

Post by J. P. Gilliver
I thought the "instant replay" - used for sporting events, football
goals mainly - used a spinning magnetic disc (capable of storing, I
don't know, a second or less)?

Ampex HS-100, 36 seconds PAL, 30 seconds NTSC

Yep, only ever I gather three in the UK, the Beeb had one, LWT had
another, and the third was owned by a facilites house in Soho ?

As few as that? I imagined that they were an integral part of any
scanner van that was used for sports where action replays were needed.
Or are you saying that there were many other models of slo-mo, and that
it is specifically the Ampex HS-100 of which there were only three
instances in the UK?

There were other types, the deeply inferior Machtronics, for example.

http://www.vtoldboys.com/slo60_7.htm

The disk (behind VT 9 and VT10) was a bookable resource, I'm pretty sure that it was only moved once for an early colour Wimbledon. It could obviously be routed back to an OB as a source on their mixer.

This was in the days before AST, so even higher quality 1" helical scan machines (e.g IVC-700 series) couldn't do slo-mo - even the IVC-9000 (2 inch helical scan - a bit like B formnat) wasn't capable.

There was, as has been pointed out, an abortive attempt to do it on Quad for the 1966 World Cup.

http://www.vtoldboys.com/slo6001.htm

http://www.vtoldboys.com/smvid01.htm

[Mark Carver]

Post by NY

Post by Mark Carver

Post by Bill Posters

Post by J. P. Gilliver
I thought the "instant replay" - used for sporting events, football
goals mainly - used a spinning magnetic disc (capable of storing, I
don't know, a second or less)?

Ampex HS-100, 36 seconds PAL, 30 seconds NTSC

Yep, only ever I gather three in the UK, the Beeb had one, LWT had
another, and the third was owned by a facilites house in Soho ?

As few as that? I imagined that they were an integral part of any
scanner van that was used for sports where action replays were needed.
Or are you saying that there were many other models of slo-mo, and that
it is specifically the Ampex HS-100 of which there were only three
instances in the UK?

The HS100s usually stayed at home ! They were not the sort of devices to
have on board a truck. There's an article in one of the IBA Yearbooks,
where ITV were covering an international football match in Glasgow. The
HS100 remained 400 miles away at LWT, and a video link established back
and forth to it from the football ground.

[The Other John]

Post by Mark Carver
The HS100s usually stayed at home ! They were not the sort of devices to
have on board a truck. There's an article in one of the IBA Yearbooks,
where ITV were covering an international football match in Glasgow. The
HS100 remained 400 miles away at LWT, and a video link established back
and forth to it from the football ground.

I worked on the 1976 Winter Olympics in Austria and we had a HS100 in the
VTR truck along side three Ampex 2" quad machines. We had to keep the
truck warm because it was -17C where we were parked half way up a mountain!

[Bill Posters]

Post by J. P. Gilliver

Post by John Williamson
ss of sync.

Post by J. P. Gilliver
Just before or after the noise, there were multiple picture bars - 10 to
13 I would say.

As the sync pulses degrade, the rest of the circuitry tries to keep
things running, then gives up until the pulses come back. You can see
the start of the breakup as the colour problems get worse, and the
image starts breaking up inside each bar. My guess would be damage to
the edge of the quad tape due to poor storage or a problem with a
previous playback.

I can understand the four-banding - AIUI, there are four head passes to
a field? - but the 15- or 16-banding (I've been back to count)? Is that
that, as things fall apart, the heads pass across adjacent tracks? 16
(or even 4 each main band, though the 16 look even and not grouped into
4) seems quite a lot of mistracking.

Each (almost) verical head pass has 15 or 16 LINES of video (the head drum spins at 250 revolutions per second and each of the 1000 video tracks (per second) contains an average of 15.625 lines of video).. the fault is not mistracking but a severe head clog, with attemped dropout compenation visible.

Provided that the head playing back the field interval is good and the control track is solid, lock should remain OK.

[Brian Gaff]

The old VCR double decker tapes used to fold the bottom of the tape at
times, though I never saw it on Scotch tapes, most of the other non back
coated ones did it, and whether it was top or bottom both had tracking or
audio, the performance was marred in all sorts of unusual ways I found.

Brian
--
--:
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
***@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!

Post by J. P. Gilliver

Post by John Williamson

Post by J. P. Gilliver
http://youtu.be/dCOcmGyqnLU - 2:51 in.
Banded into about four horizontal, fairly static bars. And then briefly
at the end of the bad patch - about 3:05 - a large number of bars.

[]

Post by John Williamson
Quad tape was in regular use until the mid 1980s, and the four bars are

Ah, I didn't know that.

Post by John Williamson
a common fault. Somebody will likely be along shortly to explain how it
happened here.
The recording has also been through a domestic system, probably VHS, which
has left the trademark noise bar from a poorly aligned machine or dirt on
the head drum at the bottom of the picture. That may also be where the
total breakdown of the picture into noise bars came from, indicating that
the edge of the tape may have been damaged, causing loss of sync.

Just before or after the noise, there were multiple picture bars - 10 to
13 I would say.
--
The death of democracy is not likely to be an assassination from ambush.
It will be a slow extinction from apathy, indifference, and
undernourishment.
-Robert Maynard Hutchins, educator (1899-1977)

[NY]

Post by Brian Gaff
The old VCR double decker tapes used to fold the bottom of the tape at
times, though I never saw it on Scotch tapes, most of the other non back
coated ones did it, and whether it was top or bottom both had tracking or
audio, the performance was marred in all sorts of unusual ways I found.

I was always intrigued by the tape path within the VCR which got the
tape from the "upper-storey" reel to the "lower-storey" reel, with the
spinning tape head scanning the tape somewhere in the transition from
one level to another. They did that on the Philips N1500 format.

But then Super 8 cine film did the same: the film was transported from
one reel to another below it, with the shutter gate somewhere between
the two reels.

[Bill Posters]

Post by John Williamson

Post by J. P. Gilliver
http://youtu.be/dCOcmGyqnLU - 2:51 in.
Banded into about four horizontal, fairly static bars. And then briefly
at the end of the bad patch - about 3:05 - a large number of bars.
The show is 1978, so I presume well after 2" formats were in general
use; of course, who knows what it's been stored on subsequently. Audio
solid throughout.
Not being in the profession, I can't really guess - other than that I
can't think of any mechanism whereby this distortion could have come
from a domestic machine. (Though from the bandwidth, I think it's been
stored on one at the final level - though one in excellent condition.)

Quad tape was in regular use until the mid 1980s, and the four bars are
a common fault. Somebody will likely be along shortly to explain how it
happened here.
The recording has also been through a domestic system, probably VHS,
which has left the trademark noise bar from a poorly aligned machine or
dirt on the head drum at the bottom of the picture. That may also be
where the total breakdown of the picture into noise bars came from,
indicating that the edge of the tape may have been damaged, causing loss
of sync.

The quad errors are is typical of one badly clogged head and with the dropout comp working overtime to generate the stepped effect visible on the 15/16 line segments - the sudden disappearance is typical of a judiciouly applied thumbnail.

The tearing at the bottom is from a domestic format.