Cassette tape speed adjustment

[N_Cook]

Assuming my test tape is stretched (I doubt it , as it would have to be even
stretch the whole length).
I normally test speed monaurally so the beats are unmistakable. That is 1KHz
test tape output and floating accurate 1KHz sine signal both fed into one
headphone cup. Easily gives 0.1 percent resolution (assuming test tape is
ok).

If I record accurate 1KHz tone onto a blank tape for exactly ( to human
reaction time accuracy) 100 seconds. Then replay for beats of 1Hz or so and
output lasts for 100 seconds +/- reaction time then is the speed correct? I
suspect that repeating this process with the speed regulator changed , say 5
percent, would also give "correct" speed, that time also


Does anyone know how much effect types and thickness (play duration C30 to
C90) have on replay speed perhaps in conjunction with too soft or too hard
pinch wheel rubber ?

 

[AZ Nomad]

On Tue, 8 Dec 2009 16:32:52 -0000, N_Cook <diverse@tcp.co.uk> wrote:

Assuming my test tape is stretched (I doubt it , as it would have to be even
stretch the whole length).
I normally test speed monaurally so the beats are unmistakable. That is 1KHz
test tape output and floating accurate 1KHz sine signal both fed into one
headphone cup. Easily gives 0.1 percent resolution (assuming test tape is
ok).

If I record accurate 1KHz tone onto a blank tape for exactly ( to human
reaction time accuracy) 100 seconds. Then replay for beats of 1Hz or so and
output lasts for 100 seconds +/- reaction time then is the speed correct? I
suspect that repeating this process with the speed regulator changed , say 5
percent, would also give "correct" speed, that time also

Does anyone know how much effect types and thickness (play duration C30 to
C90) have on replay speed perhaps in conjunction with too soft or too hard
pinch wheel rubber ?

none at all.

 

[Ron]

AZ Nomad wrote:

On Tue, 8 Dec 2009 16:32:52 -0000, N_Cook <diverse@tcp.co.uk> wrote:
Assuming my test tape is stretched (I doubt it , as it would have to be even
stretch the whole length).
I normally test speed monaurally so the beats are unmistakable. That is 1KHz
test tape output and floating accurate 1KHz sine signal both fed into one
headphone cup. Easily gives 0.1 percent resolution (assuming test tape is
ok).

If I record accurate 1KHz tone onto a blank tape for exactly ( to human
reaction time accuracy) 100 seconds. Then replay for beats of 1Hz or so and
output lasts for 100 seconds +/- reaction time then is the speed correct? I
suspect that repeating this process with the speed regulator changed , say 5
percent, would also give "correct" speed, that time also


Does anyone know how much effect types and thickness (play duration C30 to
C90) have on replay speed perhaps in conjunction with too soft or too hard
pinch wheel rubber ?


none at all.

Tape speed depends on the rotational speed and diameter of the capstan.
On a properly maintained deck all other factors are irrelevant.

Ron(UK)

 

[Meat Plow]

On Tue, 8 Dec 2009 16:32:52 -0000, "N_Cook" <diverse@tcp.co.uk>wrote:

Assuming my test tape is stretched (I doubt it , as it would have to be even
stretch the whole length).
I normally test speed monaurally so the beats are unmistakable. That is 1KHz
test tape output and floating accurate 1KHz sine signal both fed into one
headphone cup. Easily gives 0.1 percent resolution (assuming test tape is
ok).

If I record accurate 1KHz tone onto a blank tape for exactly ( to human
reaction time accuracy) 100 seconds. Then replay for beats of 1Hz or so and
output lasts for 100 seconds +/- reaction time then is the speed correct? I
suspect that repeating this process with the speed regulator changed , say 5
percent, would also give "correct" speed, that time also


Does anyone know how much effect types and thickness (play duration C30 to
C90) have on replay speed perhaps in conjunction with too soft or too hard
pinch wheel rubber ?

Excessive take up reel torque can result in unacceptable wow and
flutter. Same with the supply reel. I don't think the thickness of the
tape has much to do with anything.

 

[Arfa Daily]

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hflv4c$p04$1@news.eternal-september.org...

Assuming my test tape is stretched (I doubt it , as it would have to be
even
stretch the whole length).
I normally test speed monaurally so the beats are unmistakable. That is
1KHz
test tape output and floating accurate 1KHz sine signal both fed into one
headphone cup. Easily gives 0.1 percent resolution (assuming test tape is
ok).

If I record accurate 1KHz tone onto a blank tape for exactly ( to human
reaction time accuracy) 100 seconds. Then replay for beats of 1Hz or so
and
output lasts for 100 seconds +/- reaction time then is the speed correct?
I
suspect that repeating this process with the speed regulator changed , say
5
percent, would also give "correct" speed, that time also


Does anyone know how much effect types and thickness (play duration C30 to
C90) have on replay speed perhaps in conjunction with too soft or too
hard
pinch wheel rubber ?

I just use a speed test tape from Konig. It has a strobe wheel behind what
would normally be the tape viewing window. Very easy to see an accurate
setting for the speed, and virtually instant comparison between forward and
reverse. Also easy to see any cyclic variations in speed, or long term
drift.

Arfa

 

[N_Cook]

Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:vbKTm.64350$Dl4.48926@newsfe08.ams2...

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hflv4c$p04$1@news.eternal-september.org...
Assuming my test tape is stretched (I doubt it , as it would have to be
even
stretch the whole length).
I normally test speed monaurally so the beats are unmistakable. That is
1KHz
test tape output and floating accurate 1KHz sine signal both fed into
one
headphone cup. Easily gives 0.1 percent resolution (assuming test tape
is
ok).

If I record accurate 1KHz tone onto a blank tape for exactly ( to human
reaction time accuracy) 100 seconds. Then replay for beats of 1Hz or so
and
output lasts for 100 seconds +/- reaction time then is the speed
correct?
I
suspect that repeating this process with the speed regulator changed ,
say
5
percent, would also give "correct" speed, that time also


Does anyone know how much effect types and thickness (play duration C30
to
C90) have on replay speed perhaps in conjunction with too soft or too
hard
pinch wheel rubber ?



I just use a speed test tape from Konig. It has a strobe wheel behind what
would normally be the tape viewing window. Very easy to see an accurate
setting for the speed, and virtually instant comparison between forward
and
reverse. Also easy to see any cyclic variations in speed, or long term
drift.

Arfa

Strobing of what rotational part against what reference?
How do you know if the tape is stretched?

 

[Ron]

N_Cook wrote:

Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:vbKTm.64350$Dl4.48926@newsfe08.ams2...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hflv4c$p04$1@news.eternal-september.org...
Assuming my test tape is stretched (I doubt it , as it would have to be
even
stretch the whole length).
I normally test speed monaurally so the beats are unmistakable. That is
1KHz
test tape output and floating accurate 1KHz sine signal both fed into
one
headphone cup. Easily gives 0.1 percent resolution (assuming test tape
is
ok).

If I record accurate 1KHz tone onto a blank tape for exactly ( to human
reaction time accuracy) 100 seconds. Then replay for beats of 1Hz or so
and
output lasts for 100 seconds +/- reaction time then is the speed
correct?
I
suspect that repeating this process with the speed regulator changed ,
say
5
percent, would also give "correct" speed, that time also


Does anyone know how much effect types and thickness (play duration C30
to
C90) have on replay speed perhaps in conjunction with too soft or too
hard
pinch wheel rubber ?


I just use a speed test tape from Konig. It has a strobe wheel behind what
would normally be the tape viewing window. Very easy to see an accurate
setting for the speed, and virtually instant comparison between forward
and
reverse. Also easy to see any cyclic variations in speed, or long term
drift.

Arfa




Strobing of what rotational part against what reference?
How do you know if the tape is stretched?

It doesn't matter if the tape is stretched, the tape speed is governed
by the rotational speed of the capstan.
If the tape were stretched you would have to adjust the capstan speed to
get the right playback pitch on that particular tape tho I doubt it
would be very noticable.
Somewhere I still have a cassette with 100 hz on one side and 8k on the
other, plus a strobe disk visible through the window on the 100 hz side.
You set the capstan speed by measuring the 100 hz on playback. The 8k is
for head alignment. The strobe disk is driven by the capstan.

Quite often the playback speed would be adjusted to be correct, followed
by complaints from the customer that all his tapes now seem to play at
the wrong speed!

Ron(UK)

 

[N_Cook]

Ron <ron@lunevalleyaudio.com> wrote in message
news:0dednd3AmaG0B4LWnZ2dnUVZ7tqdnZ2d@bt.com...

N_Cook wrote:
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:vbKTm.64350$Dl4.48926@newsfe08.ams2...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hflv4c$p04$1@news.eternal-september.org...
Assuming my test tape is stretched (I doubt it , as it would have to
be
even
stretch the whole length).
I normally test speed monaurally so the beats are unmistakable. That
is
1KHz
test tape output and floating accurate 1KHz sine signal both fed into
one
headphone cup. Easily gives 0.1 percent resolution (assuming test tape
is
ok).

If I record accurate 1KHz tone onto a blank tape for exactly ( to
human
reaction time accuracy) 100 seconds. Then replay for beats of 1Hz or
so
and
output lasts for 100 seconds +/- reaction time then is the speed
correct?
I
suspect that repeating this process with the speed regulator changed ,
say
5
percent, would also give "correct" speed, that time also


Does anyone know how much effect types and thickness (play duration
C30
to
C90) have on replay speed perhaps in conjunction with too soft or too
hard
pinch wheel rubber ?


I just use a speed test tape from Konig. It has a strobe wheel behind
what
would normally be the tape viewing window. Very easy to see an accurate
setting for the speed, and virtually instant comparison between forward
and
reverse. Also easy to see any cyclic variations in speed, or long term
drift.

Arfa




Strobing of what rotational part against what reference?
How do you know if the tape is stretched?



It doesn't matter if the tape is stretched, the tape speed is governed
by the rotational speed of the capstan.
If the tape were stretched you would have to adjust the capstan speed to
get the right playback pitch on that particular tape tho I doubt it
would be very noticable.
Somewhere I still have a cassette with 100 hz on one side and 8k on the
other, plus a strobe disk visible through the window on the 100 hz side.
You set the capstan speed by measuring the 100 hz on playback. The 8k is
for head alignment. The strobe disk is driven by the capstan.

Quite often the playback speed would be adjusted to be correct, followed
by complaints from the customer that all his tapes now seem to play at
the wrong speed!

Ron(UK)

Whatever touches the capstan spindle could wear and if the reference source
for stobing is a mains lamp, that is only set for (UK) 50x60x60 cycles per
hour (for synchronous clocks) and short term only +/-0.5 percent targetted
frequency.

I have the related problem of someone who says he has perfect pitch.

 

[Ron]

N_Cook wrote:

Ron <ron@lunevalleyaudio.com> wrote in message
news:0dednd3AmaG0B4LWnZ2dnUVZ7tqdnZ2d@bt.com...
N_Cook wrote:
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:vbKTm.64350$Dl4.48926@newsfe08.ams2...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hflv4c$p04$1@news.eternal-september.org...
Assuming my test tape is stretched (I doubt it , as it would have to
be
even
stretch the whole length).
I normally test speed monaurally so the beats are unmistakable. That
is
1KHz
test tape output and floating accurate 1KHz sine signal both fed into
one
headphone cup. Easily gives 0.1 percent resolution (assuming test tape
is
ok).

If I record accurate 1KHz tone onto a blank tape for exactly ( to
human
reaction time accuracy) 100 seconds. Then replay for beats of 1Hz or
so
and
output lasts for 100 seconds +/- reaction time then is the speed
correct?
I
suspect that repeating this process with the speed regulator changed ,
say
5
percent, would also give "correct" speed, that time also


Does anyone know how much effect types and thickness (play duration
C30
to
C90) have on replay speed perhaps in conjunction with too soft or too
hard
pinch wheel rubber ?


I just use a speed test tape from Konig. It has a strobe wheel behind
what
would normally be the tape viewing window. Very easy to see an accurate
setting for the speed, and virtually instant comparison between forward
and
reverse. Also easy to see any cyclic variations in speed, or long term
drift.

Arfa



Strobing of what rotational part against what reference?
How do you know if the tape is stretched?


It doesn't matter if the tape is stretched, the tape speed is governed
by the rotational speed of the capstan.
If the tape were stretched you would have to adjust the capstan speed to
get the right playback pitch on that particular tape tho I doubt it
would be very noticable.
Somewhere I still have a cassette with 100 hz on one side and 8k on the
other, plus a strobe disk visible through the window on the 100 hz side.
You set the capstan speed by measuring the 100 hz on playback. The 8k is
for head alignment. The strobe disk is driven by the capstan.

Quite often the playback speed would be adjusted to be correct, followed
by complaints from the customer that all his tapes now seem to play at
the wrong speed!

Ron(UK)


Whatever touches the capstan spindle could wear and if the reference source
for stobing is a mains lamp, that is only set for (UK) 50x60x60 cycles per
hour (for synchronous clocks) and short term only +/-0.5 percent targetted
frequency.

I have the related problem of someone who says he has perfect pitch.

Set up a sig genny and test him out

 

[N_Cook]

Ron <ron@lunevalleyaudio.com> wrote in message
news:vZCdnX7J1q8uL4LWnZ2dnUVZ7rVi4p2d@bt.com...

N_Cook wrote:
Ron <ron@lunevalleyaudio.com> wrote in message
news:0dednd3AmaG0B4LWnZ2dnUVZ7tqdnZ2d@bt.com...
N_Cook wrote:
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:vbKTm.64350$Dl4.48926@newsfe08.ams2...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hflv4c$p04$1@news.eternal-september.org...


Set up a sig genny and test him out

Much easier to say the test tape is stretched.
Perhaps perfect pitch testing would only work by playing the likes of JSB
Tocatta and Fugue in D major, not pure tones

How come I cannot google the rpm of an audio cassette capstan? A calibrated
strobe and tipex mark on the capstan periphery should give a definite answer
(assuming the spindle is clean and not worn).
It should be determinable from tape speed of 1 7/8 in per sec and spindle
diameter, that is about 1.9mm, but what should it be to 0.1 percent
accuracy?

 

[AZ Nomad]

On Wed, 9 Dec 2009 15:42:00 -0000, N_Cook <diverse@tcp.co.uk> wrote:

Ron <ron@lunevalleyaudio.com> wrote in message
news:vZCdnX7J1q8uL4LWnZ2dnUVZ7rVi4p2d@bt.com...
N_Cook wrote:
Ron <ron@lunevalleyaudio.com> wrote in message
news:0dednd3AmaG0B4LWnZ2dnUVZ7tqdnZ2d@bt.com...
N_Cook wrote:
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:vbKTm.64350$Dl4.48926@newsfe08.ams2...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hflv4c$p04$1@news.eternal-september.org...


Set up a sig genny and test him out

Much easier to say the test tape is stretched.
Perhaps perfect pitch testing would only work by playing the likes of JSB
Tocatta and Fugue in D major, not pure tones

Has anyone ever heard of a tape stretching enough to be detectable?
I find that very hard to believe. Far more likely that the motor's
speed control is off.

Do you have another deck you can use? Record 5 minutes on the reference
deck and then compare the time to play the same on the test deck.
I've used a CD recording and then played the CD at the same time as
playing the tape on the test deck. If they fall out of sync then the
test deck is running at a rate different than the reference deck.

 

[Ian Jackson]

In message <slrnhhvj3n.kj1.aznomad.3@ip70-176-155-130.ph.ph.cox.net>, AZ
Nomad <aznomad.3@PremoveOBthisOX.COM> writes

On Wed, 9 Dec 2009 15:42:00 -0000, N_Cook <diverse@tcp.co.uk> wrote:
Ron <ron@lunevalleyaudio.com> wrote in message
news:vZCdnX7J1q8uL4LWnZ2dnUVZ7rVi4p2d@bt.com...
N_Cook wrote:
Ron <ron@lunevalleyaudio.com> wrote in message
news:0dednd3AmaG0B4LWnZ2dnUVZ7tqdnZ2d@bt.com...
N_Cook wrote:
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:vbKTm.64350$Dl4.48926@newsfe08.ams2...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hflv4c$p04$1@news.eternal-september.org...


Set up a sig genny and test him out


Much easier to say the test tape is stretched.
Perhaps perfect pitch testing would only work by playing the likes of JSB
Tocatta and Fugue in D major, not pure tones

Has anyone ever heard of a tape stretching enough to be detectable?
I find that very hard to believe. Far more likely that the motor's
speed control is off.

Do you have another deck you can use? Record 5 minutes on the reference
deck and then compare the time to play the same on the test deck.
I've used a CD recording and then played the CD at the same time as
playing the tape on the test deck. If they fall out of sync then the
test deck is running at a rate different than the reference deck.

That's exactly the way I have (occasionally) adjusted the speed of a
tape deck.

Record a CD track on a known (or hopefully) good deck, and play it back
on the suspect deck, while simultaneously re-playing the CD. A bit of
skilful nudging of the tape deck 'pause' and 'fast-forward' buttons will
be needed to get the audio adequately synchronised.

As you tweak the tape speed control, you will may get the two tracks in
almost perfect synchronism (producing a pleasant echo effect!). However,
this condition will probably hold for maybe only 10 or 20 seconds, after
which the tape audio will start to creep either 'early' or 'late', and
may even wander between the two.

At the end of a typical 3 minute track, the audio may be a a few seconds
out, and no matter hard you try, you are never going to do better. But
not even the most ardent audiophile with perfect pitch could ever detect
that the speed was incorrect.
--
Ian

 

[Ron]

Ian Jackson wrote:

In message <slrnhhvj3n.kj1.aznomad.3@ip70-176-155-130.ph.ph.cox.net>, AZ
Nomad <aznomad.3@PremoveOBthisOX.COM> writes
On Wed, 9 Dec 2009 15:42:00 -0000, N_Cook <diverse@tcp.co.uk> wrote:
Ron <ron@lunevalleyaudio.com> wrote in message
news:vZCdnX7J1q8uL4LWnZ2dnUVZ7rVi4p2d@bt.com...
N_Cook wrote:
Ron <ron@lunevalleyaudio.com> wrote in message
news:0dednd3AmaG0B4LWnZ2dnUVZ7tqdnZ2d@bt.com...
N_Cook wrote:
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:vbKTm.64350$Dl4.48926@newsfe08.ams2...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hflv4c$p04$1@news.eternal-september.org...


Set up a sig genny and test him out


Much easier to say the test tape is stretched.
Perhaps perfect pitch testing would only work by playing the likes of
JSB
Tocatta and Fugue in D major, not pure tones

Has anyone ever heard of a tape stretching enough to be detectable?
I find that very hard to believe. Far more likely that the motor's
speed control is off.

Do you have another deck you can use? Record 5 minutes on the reference
deck and then compare the time to play the same on the test deck.
I've used a CD recording and then played the CD at the same time as
playing the tape on the test deck. If they fall out of sync then the
test deck is running at a rate different than the reference deck.

That's exactly the way I have (occasionally) adjusted the speed of a
tape deck.

Record a CD track on a known (or hopefully) good deck, and play it back
on the suspect deck, while simultaneously re-playing the CD. A bit of
skilful nudging of the tape deck 'pause' and 'fast-forward' buttons will
be needed to get the audio adequately synchronised.

As you tweak the tape speed control, you will may get the two tracks in
almost perfect synchronism (producing a pleasant echo effect!). However,
this condition will probably hold for maybe only 10 or 20 seconds, after
which the tape audio will start to creep either 'early' or 'late', and
may even wander between the two.

At the end of a typical 3 minute track, the audio may be a a few seconds
out, and no matter hard you try, you are never going to do better. But
not even the most ardent audiophile with perfect pitch could ever detect
that the speed was incorrect.

You underestimate audiophiles sir!

 

[bg]

N_Cook wrote in message ...

Ron <ron@lunevalleyaudio.com> wrote in message
news:vZCdnX7J1q8uL4LWnZ2dnUVZ7rVi4p2d@bt.com...
N_Cook wrote:
Ron <ron@lunevalleyaudio.com> wrote in message
news:0dednd3AmaG0B4LWnZ2dnUVZ7tqdnZ2d@bt.com...
N_Cook wrote:
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:vbKTm.64350$Dl4.48926@newsfe08.ams2...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hflv4c$p04$1@news.eternal-september.org...


Set up a sig genny and test him out


Much easier to say the test tape is stretched.
Perhaps perfect pitch testing would only work by playing the likes of JSB
Tocatta and Fugue in D major, not pure tones

How come I cannot google the rpm of an audio cassette capstan? A calibrated
strobe and tipex mark on the capstan periphery should give a definite
answer
(assuming the spindle is clean and not worn).
It should be determinable from tape speed of 1 7/8 in per sec and spindle
diameter, that is about 1.9mm, but what should it be to 0.1 percent
accuracy?



pi times diameter gives the circumference of the capstan.

1 7/8 ips divided by circumference gives the required revolutions per
second.
You can measure the RPS of the flywheel, but that does not guarantee that
the tape is traveling at 1 and 7/8.
The bottom line is that you need a calibration tape and a frequency counter.
You can measure the frequency at several spots on the tape to see if the
tape pack and such, has any effect on speed.
BASF used to make an excellent calibration tape. I do not know if they are
still available, and they are not cheap.

 

[Arfa Daily]

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hfoghs$f07$1@news.eternal-september.org...

Ron <ron@lunevalleyaudio.com> wrote in message
news:vZCdnX7J1q8uL4LWnZ2dnUVZ7rVi4p2d@bt.com...
N_Cook wrote:
Ron <ron@lunevalleyaudio.com> wrote in message
news:0dednd3AmaG0B4LWnZ2dnUVZ7tqdnZ2d@bt.com...
N_Cook wrote:
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:vbKTm.64350$Dl4.48926@newsfe08.ams2...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hflv4c$p04$1@news.eternal-september.org...


Set up a sig genny and test him out


Much easier to say the test tape is stretched.
Perhaps perfect pitch testing would only work by playing the likes of JSB
Tocatta and Fugue in D major, not pure tones

How come I cannot google the rpm of an audio cassette capstan? A
calibrated
strobe and tipex mark on the capstan periphery should give a definite
answer
(assuming the spindle is clean and not worn).
It should be determinable from tape speed of 1 7/8 in per sec and spindle
diameter, that is about 1.9mm, but what should it be to 0.1 percent
accuracy?

The rotational speed of a cassette capstan is not a fixed given. The
diameter of capstans vary from machine to machine, and the correct speed of
tape transport is then a function of how fast you drive the capstan round.
The reference in my strobe tape, is indeed the mains. I have been using this
tape for many many years, and I have //never// had anyone complain that the
speed of their machine is off, after I have used it to set one up. Konig
must think that the mains is a good enough reference, otherwise, there would
be no point in them marketing the tape for the purpose of setting up speed.
Exception to this. As Ron said, very occasionally, when an owner has
recorded tapes when the machine was running at the 'wrong' speed ...

Arfa

Arfa

 

[N_Cook]

Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:wRYTm.105473$iT5.66666@newsfe12.ams2...

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hfoghs$f07$1@news.eternal-september.org...
Ron <ron@lunevalleyaudio.com> wrote in message
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N_Cook wrote:
Ron <ron@lunevalleyaudio.com> wrote in message
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N_Cook wrote:
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
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"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hflv4c$p04$1@news.eternal-september.org...


Set up a sig genny and test him out


Much easier to say the test tape is stretched.
Perhaps perfect pitch testing would only work by playing the likes of
JSB
Tocatta and Fugue in D major, not pure tones

How come I cannot google the rpm of an audio cassette capstan? A
calibrated
strobe and tipex mark on the capstan periphery should give a definite
answer
(assuming the spindle is clean and not worn).
It should be determinable from tape speed of 1 7/8 in per sec and
spindle
diameter, that is about 1.9mm, but what should it be to 0.1 percent
accuracy?



The rotational speed of a cassette capstan is not a fixed given. The
diameter of capstans vary from machine to machine, and the correct speed
of
tape transport is then a function of how fast you drive the capstan round.
The reference in my strobe tape, is indeed the mains. I have been using
this
tape for many many years, and I have file://never// had anyone complain
that the
speed of their machine is off, after I have used it to set one up. Konig
must think that the mains is a good enough reference, otherwise, there
would
be no point in them marketing the tape for the purpose of setting up
speed.
Exception to this. As Ron said, very occasionally, when an owner has
recorded tapes when the machine was running at the 'wrong' speed ...

Arfa

Arfa

http://www.dynamicdemand.co.uk/grid.htm
Wokingham, Surrey, UK monitored mains frequency,
is instructive, try it in the middle of a national televised football match
or similar


spindle consistency
Not from my random sample of 8 audio cassette capstan spindles, all were
1.9mm or a bit lower say 1.89, with no cleaning etc, just as found.
If 1.9mm then rotational speed of 478.72 rpm and if the specified diameter
(cannot even find that) is 0.075 inches (bit less than 1.9mm) then speed is
477.46 rpm for 15/7 ips.
Googling including "478" or "477" throws up nothing, googling on rev/sec not
possible in like manner


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[Ron]

N_Cook wrote:

Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:wRYTm.105473$iT5.66666@newsfe12.ams2...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hfoghs$f07$1@news.eternal-september.org...
Ron <ron@lunevalleyaudio.com> wrote in message
news:vZCdnX7J1q8uL4LWnZ2dnUVZ7rVi4p2d@bt.com...
N_Cook wrote:
Ron <ron@lunevalleyaudio.com> wrote in message
news:0dednd3AmaG0B4LWnZ2dnUVZ7tqdnZ2d@bt.com...
N_Cook wrote:
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:vbKTm.64350$Dl4.48926@newsfe08.ams2...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hflv4c$p04$1@news.eternal-september.org...
Set up a sig genny and test him out

Much easier to say the test tape is stretched.
Perhaps perfect pitch testing would only work by playing the likes of
JSB
Tocatta and Fugue in D major, not pure tones

How come I cannot google the rpm of an audio cassette capstan? A
calibrated
strobe and tipex mark on the capstan periphery should give a definite
answer
(assuming the spindle is clean and not worn).
It should be determinable from tape speed of 1 7/8 in per sec and
spindle
diameter, that is about 1.9mm, but what should it be to 0.1 percent
accuracy?


The rotational speed of a cassette capstan is not a fixed given. The
diameter of capstans vary from machine to machine, and the correct speed
of
tape transport is then a function of how fast you drive the capstan round.
The reference in my strobe tape, is indeed the mains. I have been using
this
tape for many many years, and I have file://never// had anyone complain
that the
speed of their machine is off, after I have used it to set one up. Konig
must think that the mains is a good enough reference, otherwise, there
would
be no point in them marketing the tape for the purpose of setting up
speed.
Exception to this. As Ron said, very occasionally, when an owner has
recorded tapes when the machine was running at the 'wrong' speed ...

Arfa

Arfa




http://www.dynamicdemand.co.uk/grid.htm
Wokingham, Surrey, UK monitored mains frequency,
is instructive, try it in the middle of a national televised football match
or similar


spindle consistency
Not from my random sample of 8 audio cassette capstan spindles, all were
1.9mm or a bit lower say 1.89, with no cleaning etc, just as found.
If 1.9mm then rotational speed of 478.72 rpm and if the specified diameter
(cannot even find that) is 0.075 inches (bit less than 1.9mm) then speed is
477.46 rpm for 15/7 ips.
Googling including "478" or "477" throws up nothing, googling on rev/sec not
possible in like manner

But compact cassette was never intended to be a precise method of
recording, almost everything about the system is inexact - the recording
medium itself is hardly a precision piece of engineering. The whole
system was designed for convenience over performance. Admittedly, there
are/were some very very good machines available which I`m sure way
outstripped the original design specs.

Cassette machines intended for 'homestudio' quality recording generally
run the tape at a faster speed and have a facility for varying that
speed. they still tend to use a crappy brushed dc motor and rubber belt
drives though.

Ron

 

[N_Cook]

Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:wRYTm.105473$iT5.66666@newsfe12.ams2...

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hfoghs$f07$1@news.eternal-september.org...
Ron <ron@lunevalleyaudio.com> wrote in message
news:vZCdnX7J1q8uL4LWnZ2dnUVZ7rVi4p2d@bt.com...
N_Cook wrote:
Ron <ron@lunevalleyaudio.com> wrote in message
news:0dednd3AmaG0B4LWnZ2dnUVZ7tqdnZ2d@bt.com...
N_Cook wrote:
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:vbKTm.64350$Dl4.48926@newsfe08.ams2...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hflv4c$p04$1@news.eternal-september.org...


Set up a sig genny and test him out


Much easier to say the test tape is stretched.
Perhaps perfect pitch testing would only work by playing the likes of
JSB
Tocatta and Fugue in D major, not pure tones

How come I cannot google the rpm of an audio cassette capstan? A
calibrated
strobe and tipex mark on the capstan periphery should give a definite
answer
(assuming the spindle is clean and not worn).
It should be determinable from tape speed of 1 7/8 in per sec and
spindle
diameter, that is about 1.9mm, but what should it be to 0.1 percent
accuracy?



The rotational speed of a cassette capstan is not a fixed given. The
diameter of capstans vary from machine to machine, and the correct speed
of
tape transport is then a function of how fast you drive the capstan round.
The reference in my strobe tape, is indeed the mains. I have been using
this
tape for many many years, and I have file://never// had anyone complain
that the
speed of their machine is off, after I have used it to set one up. Konig
must think that the mains is a good enough reference, otherwise, there
would
be no point in them marketing the tape for the purpose of setting up
speed.
Exception to this. As Ron said, very occasionally, when an owner has
recorded tapes when the machine was running at the 'wrong' speed ...

Arfa

Arfa

I've since found 2 capstan spindles of 2.4mm diameterm so no fixed
specification for cassette tape dynamics.

Another possibility as a test tape - record some constant tone, any f, on a
few minutes of tape, pull out a long length and pass a magnet over two parts
a measured distance apart. retract, and then time the interval between dips
in play mode

 

[Ron]

N_Cook wrote:

Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:wRYTm.105473$iT5.66666@newsfe12.ams2...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hfoghs$f07$1@news.eternal-september.org...
Ron <ron@lunevalleyaudio.com> wrote in message
news:vZCdnX7J1q8uL4LWnZ2dnUVZ7rVi4p2d@bt.com...
N_Cook wrote:
Ron <ron@lunevalleyaudio.com> wrote in message
news:0dednd3AmaG0B4LWnZ2dnUVZ7tqdnZ2d@bt.com...
N_Cook wrote:
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:vbKTm.64350$Dl4.48926@newsfe08.ams2...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hflv4c$p04$1@news.eternal-september.org...
Set up a sig genny and test him out

Much easier to say the test tape is stretched.
Perhaps perfect pitch testing would only work by playing the likes of
JSB
Tocatta and Fugue in D major, not pure tones

How come I cannot google the rpm of an audio cassette capstan? A
calibrated
strobe and tipex mark on the capstan periphery should give a definite
answer
(assuming the spindle is clean and not worn).
It should be determinable from tape speed of 1 7/8 in per sec and
spindle
diameter, that is about 1.9mm, but what should it be to 0.1 percent
accuracy?


The rotational speed of a cassette capstan is not a fixed given. The
diameter of capstans vary from machine to machine, and the correct speed
of
tape transport is then a function of how fast you drive the capstan round.
The reference in my strobe tape, is indeed the mains. I have been using
this
tape for many many years, and I have file://never// had anyone complain
that the
speed of their machine is off, after I have used it to set one up. Konig
must think that the mains is a good enough reference, otherwise, there
would
be no point in them marketing the tape for the purpose of setting up
speed.
Exception to this. As Ron said, very occasionally, when an owner has
recorded tapes when the machine was running at the 'wrong' speed ...

Arfa

Arfa



I've since found 2 capstan spindles of 2.4mm diameterm so no fixed
specification for cassette tape dynamics.

Another possibility as a test tape - record some constant tone, any f, on a
few minutes of tape, pull out a long length and pass a magnet over two parts
a measured distance apart. retract, and then time the interval between dips
in play mode


Far simpler, find a known good machine - your chum with perfect pitch

will help here - record a known frequency on a tape which you know to be
good. Play said tape back on customers machine with freq counter hooked
up to the headphone socket and adjust for same frequency - sorted.


My test tape is 100hz, I spose the higher the frequency, the better
accuracy you can get. Don't expect miracles.

 

[N_Cook]

Ron <ron@lunevalleyaudio.com> wrote in message
news:79mdnU8QxrtKk7_WnZ2dnUVZ8u-dnZ2d@bt.com...

N_Cook wrote:
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:wRYTm.105473$iT5.66666@newsfe12.ams2...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hfoghs$f07$1@news.eternal-september.org...
Ron <ron@lunevalleyaudio.com> wrote in message
news:vZCdnX7J1q8uL4LWnZ2dnUVZ7rVi4p2d@bt.com...
N_Cook wrote:
Ron <ron@lunevalleyaudio.com> wrote in message
news:0dednd3AmaG0B4LWnZ2dnUVZ7tqdnZ2d@bt.com...
N_Cook wrote:
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:vbKTm.64350$Dl4.48926@newsfe08.ams2...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hflv4c$p04$1@news.eternal-september.org...
Set up a sig genny and test him out

Much easier to say the test tape is stretched.
Perhaps perfect pitch testing would only work by playing the likes of
JSB
Tocatta and Fugue in D major, not pure tones

How come I cannot google the rpm of an audio cassette capstan? A
calibrated
strobe and tipex mark on the capstan periphery should give a definite
answer
(assuming the spindle is clean and not worn).
It should be determinable from tape speed of 1 7/8 in per sec and
spindle
diameter, that is about 1.9mm, but what should it be to 0.1 percent
accuracy?


The rotational speed of a cassette capstan is not a fixed given. The
diameter of capstans vary from machine to machine, and the correct
speed
of
tape transport is then a function of how fast you drive the capstan
round.
The reference in my strobe tape, is indeed the mains. I have been using
this
tape for many many years, and I have file://never// had anyone complain
that the
speed of their machine is off, after I have used it to set one up.
Konig
must think that the mains is a good enough reference, otherwise, there
would
be no point in them marketing the tape for the purpose of setting up
speed.
Exception to this. As Ron said, very occasionally, when an owner has
recorded tapes when the machine was running at the 'wrong' speed ...

Arfa

Arfa



I've since found 2 capstan spindles of 2.4mm diameterm so no fixed
specification for cassette tape dynamics.

Another possibility as a test tape - record some constant tone, any f,
on a
few minutes of tape, pull out a long length and pass a magnet over two
parts
a measured distance apart. retract, and then time the interval between
dips
in play mode


Far simpler, find a known good machine - your chum with perfect pitch
will help here - record a known frequency on a tape which you know to be
good. Play said tape back on customers machine with freq counter hooked
up to the headphone socket and adjust for same frequency - sorted.


My test tape is 100hz, I spose the higher the frequency, the better
accuracy you can get. Don't expect miracles.

Things counldn't be easier with a "known good machine " .
My 3 test tapes were created on what was supposed to be such a machine in a
pro AV studio.
One tape got knackered at one point but rest of tape agrees with the second
one. The third remains unused while first 2 agree with one another, using
any old speed consistent machine for cross-comparison, in relative rather
than absolute terms.