On 16/09/2024 22:09, NY wrote:

I'm digitising selections from my archive of cassette tapes, so I've dug
out my trusty Technics cassette deck.

It has two cassette drives - one has just developed a fault with the
take-up spool not working (but only when playing; REW or FF is fine) and
the other has an intriguing and intermittent distortion on some tapes - sometimes only affecting one side of a tape and not the other.

The decks are capable of auto-reverse, so they have two lots of heads covering the two directions, and can play the tape in either direction.

https://jmp.sh/s/rXY8XwaTOxtWuoELJnQQ (hosted on Jumpshare)

is a link to a 44 kHz WAV file (60 seconds) played on the deck with the distortion.

I forgot to add. The problem is not clipping at the sound card. I've
adjusted the analogue level so the sound card peaks at about -3 dB and
looking at the digital waveform in CoolEdit (25 years old, but I find it
easier to use than Audacity) there is no evidence of clipping.

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I'm digitising selections from my archive of cassette tapes, so I've dug
out my trusty Technics cassette deck.

It has two cassette drives - one has just developed a fault with the
take-up spool not working (but only when playing; REW or FF is fine) and
the other has an intriguing and intermittent distortion on some tapes - sometimes only affecting one side of a tape and not the other.

The decks are capable of auto-reverse, so they have two lots of heads
covering the two directions, and can play the tape in either direction.

https://jmp.sh/s/rXY8XwaTOxtWuoELJnQQ (hosted on Jumpshare)

is a link to a 44 kHz WAV file (60 seconds) played on the deck with the distortion.

There are three consecutive excerpts from a tape, with gaps between:

1. Play tape forwards
2. Turn tape over and play it backwards (therefore using the opposite
pair of heads)
3. Play tape on a different deck to prove that the tape itself is OK

The tape was recorded in mono; there is slight imbalance between the L
and R tracks when played on the stereo deck.

Apologies for the HORRIBLE pitch shift at 49 seconds. I suspect that the
very cheap tape recorder on which I originally recorded the tape 40-odd
years ago had a problem with its motor speed, maybe varying according to
the signal level.


The tape-digitising project was instigated when my parents asked me to
digitise a tape of me narrating a school nativity play when I was about
six. Did I *really* sound so precocious? Mega-cringe!


Can anyone suggest what is causing the distortion. It sometimes happens
when I start playing and then rights itself after a few seconds. The
heads and capstans and rollers look clean of oxide. As far as I can tell
the rubber drive belts are OK. Some tapes play better that others.
Sometimes the same section of a distorted tape will play fine. They were
not recorded with Dolby.

Is it likely to be electronic, or a stick-and-slip problem causing the
tape to vibrate as it passes over the head?



The other drive in the Technics was playing fine until today but now
will not turn the take-up spool in either direction at play speed, and
tends to be a bit reluctant to turn at REW/FF speed, activating the
end-of-tape detection which stops and reverses the tape (*). Shame: it
was a wonderful deck (part of a separates system which I bought with my
first pay rise in 1987) and I'd just fixed a problem with the main
volume control on the amp (I think it used a slotted spindle which
interrupted a beam of light to sense rotation, and I blew the dust out
of it!), so to have both tape decks die for different reasons is a bummer.


(*) My first thought was a drive belt but the belt that drives the
spools from the capstan drum is revolving its pulley OK, so it must be
another rubber wheel that isn't making good contact with the belt-driven pulley, where one wheel or the other is moved into contact depending on direction of play. But that's not easy to get at without dismantling the
whole drive. Lucky that I spotted that the take-up spool wasn't turning
before too much tape had shed itself into loops within the mechanism and
before it had wrapped itself round the rubber pinch roller...

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On Mon 16/09/2024 22:13, NY wrote:

On 16/09/2024 22:09, NY wrote:

I'm digitising selections from my archive of cassette tapes, so I've
dug out my trusty Technics cassette deck.

It has two cassette drives - one has just developed a fault with the
take-up spool not working (but only when playing; REW or FF is fine)
and the other has an intriguing and intermittent distortion on some
tapes - sometimes only affecting one side of a tape and not the other.

The decks are capable of auto-reverse, so they have two lots of heads
covering the two directions, and can play the tape in either direction.

https://jmp.sh/s/rXY8XwaTOxtWuoELJnQQ (hosted on Jumpshare)

is a link to a 44 kHz WAV file (60 seconds) played on the deck with
the distortion.

I forgot to add. The problem is not clipping at the sound card. I've
adjusted the analogue level so the sound card peaks at about -3 dB and looking at the digital waveform in CoolEdit (25 years old, but I find it easier to use than Audacity) there is no evidence of clipping.

44KHz??? How are we supposed to hear it? Do you mean 4KHz?

Have you tried cleaning the heads, pinch wheel face and drive shaft with
a cotton bud soaked in meths? If any are dirty it will show up.

The other problem that can cause this is is the felt friction pad under
the tape spool carrier. That is a remove and replace job but thankfully
you don't need a manufacturer spare (at 25 years + not much chance
anyway!) Such felt can be bought at sewing shops etc.

--- SoupGate-Win32 v1.05
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On 16/09/2024 22:48, Woody wrote:

On Mon 16/09/2024 22:13, NY wrote:

On 16/09/2024 22:09, NY wrote:

I'm digitising selections from my archive of cassette tapes, so I've
dug out my trusty Technics cassette deck.

It has two cassette drives - one has just developed a fault with the
take-up spool not working (but only when playing; REW or FF is fine)
and the other has an intriguing and intermittent distortion on some
tapes - sometimes only affecting one side of a tape and not the other.

The decks are capable of auto-reverse, so they have two lots of heads
covering the two directions, and can play the tape in either direction.

https://jmp.sh/s/rXY8XwaTOxtWuoELJnQQ (hosted on Jumpshare)

is a link to a 44 kHz WAV file (60 seconds) played on the deck with
the distortion.

I forgot to add. The problem is not clipping at the sound card. I've
adjusted the analogue level so the sound card peaks at about -3 dB and
looking at the digital waveform in CoolEdit (25 years old, but I find
it easier to use than Audacity) there is no evidence of clipping.

44KHz??? How are we supposed to hear it? Do you mean 4KHz?

I meant a sampling rate of 44.1 kHz (441000 samples per second per
channel). In other words, CD quality. I used to know how the precise
figure of 44.1 kHz was derived - I remember it was something to do with
the line rates of PAL and NTSC video, because early CDs were mastered
onto videotape and they needed a value that "worked" for both systems.

Have you tried cleaning the heads, pinch wheel face and drive shaft with
a cotton bud soaked in meths? If any are dirty it will show up.

Is meths OK for cleaning tape heads etc? I wasn't sure whether the dye
and the impurities that are added to make it undrinkable might leave
residue. Not having any meths or isopropyl alcohol readily to hand, I
was tempted to try a few drops of gin ;-) But that would definitely
suffer from impurities!

It really is obnoxious distortion. I imagine it is physical (dirty heads
or tape transport) and would need some fiendishly complicated analogue
circuit or digital transform if (for some weird reason) one wanted to
achieve it in electronics or software ;-)

The other problem that can cause this is is the felt friction pad under
the tape spool carrier. That is a remove and replace job but thankfully
you don't need a manufacturer spare (at 25 years + not much chance
anyway!) Such felt can be bought at sewing shops etc.

I might just admit defeat and use my wife's all-in-one tape/CD/radio for playing the rest of the cassettes, as I did for the good version in the
sample I posted earlier. I was aware of a much more subtle "grittiness"
on some of the tapes I've copied so far using my Technics deck, so I
might go back and do one on her player and see if there is a difference.

--- SoupGate-Win32 v1.05
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On 16/09/2024 23:23, NY wrote:

Is meths OK for cleaning tape heads etc? I wasn't sure whether the dye
and the impurities that are added to make it undrinkable might leave
residue. Not having any meths or isopropyl alcohol readily to hand, I
was tempted to try a few drops of gin ;-) But that would definitely
suffer from impurities!

Instead of Gin, use vodka.

Meths will clean the heads, but isopropyl alcohol (IPA) is better. In
theory, the colouring used in meths can leave a deposit on the heads.

It really is obnoxious distortion. I imagine it is physical (dirty heads
or tape transport) and would need some fiendishly complicated analogue circuit or digital transform if (for some weird reason) one wanted to
achieve it in electronics or software ;-)

Old cassettes are always a pain to transcribe to digital. The format was originally intended for voice use only, and most cassettes and decks
were made with cheapness as a major feature.

Before starting you need to fully service the cassette deck you will be
using, changing all the belts if they are more than a year or two old,
and cleaning all the rubber components inside the transport. IPA is
best, as it will not harm the rubber.

Then, fast wind the cassette all the way in both directions and check
the felt pad for softness and lack of damage.

Clean the head after every tape you transcribe.

If you use Winamp (You need a version prior to version 50), there is a
plugin which can clean up a lot of the problems, such as phase
differences between stereo tracks, remove any last remaining trace of
the AC bias in the signal, and it can even be used to correct for
incorrect Dolby settings if that has been used. Your DAW can be used to
correct any pitch variations.


--
Tciao for Now!

John.

--- SoupGate-Win32 v1.05
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On Mon 16/09/2024 23:23, NY wrote:

On 16/09/2024 22:48, Woody wrote:

On Mon 16/09/2024 22:13, NY wrote:

On 16/09/2024 22:09, NY wrote:

I'm digitising selections from my archive of cassette tapes, so I've
dug out my trusty Technics cassette deck.

It has two cassette drives - one has just developed a fault with the
take-up spool not working (but only when playing; REW or FF is fine)
and the other has an intriguing and intermittent distortion on some
tapes - sometimes only affecting one side of a tape and not the other. >>>>
The decks are capable of auto-reverse, so they have two lots of
heads covering the two directions, and can play the tape in either
direction.

https://jmp.sh/s/rXY8XwaTOxtWuoELJnQQ (hosted on Jumpshare)

is a link to a 44 kHz WAV file (60 seconds) played on the deck with
the distortion.

I forgot to add. The problem is not clipping at the sound card. I've
adjusted the analogue level so the sound card peaks at about -3 dB
and looking at the digital waveform in CoolEdit (25 years old, but I
find it easier to use than Audacity) there is no evidence of clipping.

44KHz??? How are we supposed to hear it? Do you mean 4KHz?

I meant a sampling rate of 44.1 kHz (441000 samples per second per
channel). In other words, CD quality. I used to know how the precise
figure of 44.1 kHz was derived - I remember it was something to do with
the line rates of PAL and NTSC video, because early CDs were mastered
onto videotape and they needed a value that "worked" for both systems.

Have you tried cleaning the heads, pinch wheel face and drive shaft
with a cotton bud soaked in meths? If any are dirty it will show up.

Is meths OK for cleaning tape heads etc? I wasn't sure whether the dye
and the impurities that are added to make it undrinkable might leave
residue. Not having any meths or isopropyl alcohol readily to hand, I
was tempted to try a few drops of gin ;-) But that would definitely
suffer from impurities!

It really is obnoxious distortion. I imagine it is physical (dirty heads
or tape transport) and would need some fiendishly complicated analogue circuit or digital transform if (for some weird reason) one wanted to
achieve it in electronics or software ;-)

The other problem that can cause this is is the felt friction pad
under the tape spool carrier. That is a remove and replace job but
thankfully you don't need a manufacturer spare (at 25 years + not much
chance anyway!) Such felt can be bought at sewing shops etc.

I might just admit defeat and use my wife's all-in-one tape/CD/radio for playing the rest of the cassettes, as I did for the good version in the sample I posted earlier. I was aware of a much more subtle "grittiness"
on some of the tapes I've copied so far using my Technics deck, so I
might go back and do one on her player and see if there is a difference.

If you cannot obtain Isopropyl alcohol you could try lighter fuel which
will do just as well.

--- SoupGate-Win32 v1.05
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On Mon, 16 Sep 2024 22:09:50 +0100, NY <me@privacy.net> wrote:

<snip>

I had some very old cassette tapes that would not play consistently
and a friend of mine kindly fixed the problem for me.

Firstly he put the tapes into a quality case with decent rollers etc.

He then put the tapes in the oven. Yes, oven. The tapes would stick
and that was causing the problem. Low temperature for a few hours
IIRC and with a warning that it could only be done a couple of times.

I can't quickly find details on t'internet but https://arstechnica.com/science/2020/04/the-chemistry-of-why-baking-degraded-reel-to-reel-tapes-can-reverse-damage/

might give you some ammunition for further searches.

Anyway as a result I was able to recover tapes of my granddaughters'
great great grandfather (maternal, not my line) recorded in the late
'60s.



--
AnthonyL

Why ever wait to finish a job before starting the next?

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On 17/09/2024 20:26, AnthonyL wrote:

Anyway as a result I was able to recover tapes of my granddaughters'
great great grandfather (maternal, not my line) recorded in the late
'60s.

Family history tapes are priceless. In the mid 70s my dad recorded a conversation with my grandpa and my great grandma (grandpa's mother)
talking about life in the late 1800s and first few decades of the 1900s.
I digitised that tape ages ago - probably when I first got a PC with a
sound card. Ironically that tape is the one of two that I cannot find
now - but it doesn't matter because it's on my PC and on audio CD. I
also transcribed it and annotated with with cross-references to maps etc
when places were mentioned or when obsolete technology (eg a lime light
and an arc light in a theatre) was mentioned, in case my nephews ever
take an interest in later life.

I even found copies of photographs of a tram crash that grandpa and
great grandma mentioned witnessing from a distance of a few feet when he
was a young lad. The tram's brakes failed and it overshot the terminus
and skidded across the cobbles of the market place and half-demolished a
hotel while they were waiting to catch the tram on its return journey.

It's a matter of hearing *how* people spoke as much as the words they
said. I was rather shocked when I played the recording recently to count
just how many cigarettes my grandpa got through during the two hours of
the recording - the match-striking noise was a dead giveaway ;-)

--- SoupGate-Win32 v1.05
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NY wrote:

In the mid 70s my dad recorded a conversation with my grandpa and my
great grandma

The only reel-to-reel recording I remember of my family is an aunt
attempting to deny she was drunk, this was generally dragged out and
replayed at christmas ...

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

In article <lksuvoF4n5dU1@mid.individual.net>, John Williamson <johnwilliamson@btinternet.com> scribeth thus

On 16/09/2024 23:23, NY wrote:

Is meths OK for cleaning tape heads etc? I wasn't sure whether the dye
and the impurities that are added to make it undrinkable might leave
residue. Not having any meths or isopropyl alcohol readily to hand, I
was tempted to try a few drops of gin ;-) But that would definitely
suffer from impurities!

Instead of Gin, use vodka.

Meths will clean the heads, but isopropyl alcohol (IPA) is better. In
theory, the colouring used in meths can leave a deposit on the heads.

It really is obnoxious distortion. I imagine it is physical (dirty heads
or tape transport) and would need some fiendishly complicated analogue
circuit or digital transform if (for some weird reason) one wanted to
achieve it in electronics or software ;-)

Old cassettes are always a pain to transcribe to digital. The format was >originally intended for voice use only, and most cassettes and decks
were made with cheapness as a major feature.

Indeed but i do remember hearing some audio recorded by Angus McKenzie
waay back Nakamichi Deck and was it Dolby A ?>

Sounded bloody good:)...

Before starting you need to fully service the cassette deck you will be >using, changing all the belts if they are more than a year or two old,
and cleaning all the rubber components inside the transport. IPA is
best, as it will not harm the rubber.

Then, fast wind the cassette all the way in both directions and check
the felt pad for softness and lack of damage.

Clean the head after every tape you transcribe.

If you use Winamp (You need a version prior to version 50), there is a
plugin which can clean up a lot of the problems, such as phase
differences between stereo tracks, remove any last remaining trace of
the AC bias in the signal, and it can even be used to correct for
incorrect Dolby settings if that has been used. Your DAW can be used to >correct any pitch variations.

--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On 18/09/2024 14:36, tony sayer wrote:

In article <lksuvoF4n5dU1@mid.individual.net>, John Williamson <johnwilliamson@btinternet.com> scribeth thus

Old cassettes are always a pain to transcribe to digital. The format was
originally intended for voice use only, and most cassettes and decks
were made with cheapness as a major feature.

Indeed but i do remember hearing some audio recorded by Angus McKenzie
waay back Nakamichi Deck and was it Dolby A ?>

Sounded bloody good:)...

Use top quality type 2 or type 4 tape in a good recorder, and it sound
a;mpst as good as a 256 kb/s MP3 file...

Very few cassettes were recorded using Dolby A, and commercial ones were
always Dolby B




--
Tciao for Now!

John.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On 18/09/2024 14:55, John Williamson wrote:

Very few cassettes were recorded using Dolby A, and commercial ones were always Dolby B

The worst thing is when a tape is recorded with Dolby C but played back
without it (or vice versa) because that involves companding and
noise-gating in addition to altering the frequency response.

When ITV sold copies of "Inspector Morse" to ITV3 for repeats, someone
must have got the Dolby C switch in the wrong position before
duplicating the master to make ITV3's copy - and then ITV3 never seem to rectify this before transmission. It leads to pulsating throbbing levels
of noise, and speech which is almost painful to listen to: you hear
complete silence as two characters walk towards the camera, then one of
them speaks and you suddenly hear traffic noise in the background which disappears again as soon as they stop speaking.

--- SoupGate-Win32 v1.05
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