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Ron
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N_Cook wrote:
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N_Cook
Guest
Ron <ron@lunevalleyaudio.com> wrote in message
news:CPOdnaXSau0Hj7_WnZ2dnUVZ8uCdnZ2d@bt.com...
3 of them made on the same batch of tape and on the same machine but more
than 15 years ago. As they are all stored in the same environment they could
theoretically all have chemically degraded/stretched to the same degree. I'm
trying to find some process that gives an independent verification that does
not require a know good machine.
eg quartz controlled (so low tens ppm) f-meter coupled strobe fed to
rotating capstan if diameter/s of the spindles are manufactured to specific
dimensions of precisely known tolerances. Perhaps 1.9 +/- 0.002 mm and 2.4
+/- 0.002mm say, no such data found googling. I can only measure to +/-0.02
mm and no slip gauges for absolute calibration.
+/-2 in 200 or so, is not accurate enough
news:CPOdnaXSau0Hj7_WnZ2dnUVZ8uCdnZ2d@bt.com...
N_Cook wrote:
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.
So you are saying that you already have a test cassette?
3 of them made on the same batch of tape and on the same machine but more
than 15 years ago. As they are all stored in the same environment they could
theoretically all have chemically degraded/stretched to the same degree. I'm
trying to find some process that gives an independent verification that does
not require a know good machine.
eg quartz controlled (so low tens ppm) f-meter coupled strobe fed to
rotating capstan if diameter/s of the spindles are manufactured to specific
dimensions of precisely known tolerances. Perhaps 1.9 +/- 0.002 mm and 2.4
+/- 0.002mm say, no such data found googling. I can only measure to +/-0.02
mm and no slip gauges for absolute calibration.
+/-2 in 200 or so, is not accurate enough
B
bg
Guest
N_Cook wrote in message ...
playback frequency of the tape which gives you the tape speed. Obviuosly,
the accuracy of the test tape, the accuracy of the counter, etc all come
into play to add errors. The industry standard is to use a wow and flutter
meter in conjunction with a test tape. The test tape is recorded at 3000hz
on a reel to reel recorder and then loaded into a cassette shell because
there is no cassette recorder on earth that can produce a test tape with the
10x or 5x accuracy needed as a standard.
Wow and flutter meters are basically frequency meters. They are like guitar
tuners, but the output is weighted to breakup the frequency variations into
long and short term changes.
If you can find a calibrated wow and flutter meter with a test tape, I'm
sure the cost will far exceed what your client is willing to pay. The
technology is at least 20 years old, and there really isn't a market for
anyone to make this equipment available.
The bottom line -------- Even if you go through the time and expense to do
this right, what good is it if your client's tapes are not recorded at the
same precision? You and he will be better off if you add a front panel speed
control so that he can dial in the speed to match the tape being played
tape speed will be correct. The proper way to do this is to measure theArfa 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
You are assuming that if the capstan rotates at the correct RPM , that the
playback frequency of the tape which gives you the tape speed. Obviuosly,
the accuracy of the test tape, the accuracy of the counter, etc all come
into play to add errors. The industry standard is to use a wow and flutter
meter in conjunction with a test tape. The test tape is recorded at 3000hz
on a reel to reel recorder and then loaded into a cassette shell because
there is no cassette recorder on earth that can produce a test tape with the
10x or 5x accuracy needed as a standard.
Wow and flutter meters are basically frequency meters. They are like guitar
tuners, but the output is weighted to breakup the frequency variations into
long and short term changes.
If you can find a calibrated wow and flutter meter with a test tape, I'm
sure the cost will far exceed what your client is willing to pay. The
technology is at least 20 years old, and there really isn't a market for
anyone to make this equipment available.
The bottom line -------- Even if you go through the time and expense to do
this right, what good is it if your client's tapes are not recorded at the
same precision? You and he will be better off if you add a front panel speed
control so that he can dial in the speed to match the tape being played
B
bz
Guest
"N_Cook" <diverse@tcp.co.uk> wrote in
news:hft7vv$nsr$1@news.eternal-september.org:
Google for
guitar tuning meter
There are meters available for ~20 bux and even some 'on line' meters.
Record a known good 'string note' frequency and use it for your standard.
Should get you close enough for any audiophile's ears
--
bz 73 de N5BZ k
please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.
news:hft7vv$nsr$1@news.eternal-september.org:
Suggestion:3 of them made on the same batch of tape and on the same machine but
more than 15 years ago. As they are all stored in the same environment
they could theoretically all have chemically degraded/stretched to the
same degree. I'm trying to find some process that gives an independent
verification that does not require a know good machine.
eg quartz controlled (so low tens ppm) f-meter coupled strobe fed to
rotating capstan if diameter/s of the spindles are manufactured to
specific dimensions of precisely known tolerances. Perhaps 1.9 +/- 0.002
mm and 2.4 +/- 0.002mm say, no such data found googling. I can only
measure to +/-0.02 mm and no slip gauges for absolute calibration.
+/-2 in 200 or so, is not accurate enough
Google for
guitar tuning meter
There are meters available for ~20 bux and even some 'on line' meters.
Record a known good 'string note' frequency and use it for your standard.
Should get you close enough for any audiophile's ears
--
bz 73 de N5BZ k
please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.
N
N_Cook
Guest
bg <bg@nospam.com> wrote in message news:hftuf0$od4$1@news.xmission.com...
I found a large quantity of salvaged capstans+spindles.
26 off on my mike (rather than callipers before) measure 1.99 +/-0.01 of
reading accuracy and 2 nearer 2.00
5 off measure 1.79mm
1 at 2.19mm
9 measure 2.49mm
So I will give a few to my engineer mate and ask him what they measure and
the temperature at the time.
The machine in question uses 2.49.
Assuming it is actually 2.5mm then doing the maths and strobing with quartz
f-meter calibrated strobe then my test tapes are 0.4 percent out from
calculation via 15/8 ips etc.
spindle rotation speed of 6.05 rev per second with an error of about 0.4
percent , needs longer gate time or repeating more times to bring that
accuracy up (rounding errors? so probably longer gate time required than my
meter has).
If 2.49 diameter then 0.6 percent out
N_Cook wrote in message ...
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:wRYTm.105473$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
You are assuming that if the capstan rotates at the correct RPM , that the
tape speed will be correct. The proper way to do this is to measure the
playback frequency of the tape which gives you the tape speed. Obviuosly,
the accuracy of the test tape, the accuracy of the counter, etc all come
into play to add errors. The industry standard is to use a wow and flutter
meter in conjunction with a test tape. The test tape is recorded at 3000hz
on a reel to reel recorder and then loaded into a cassette shell because
there is no cassette recorder on earth that can produce a test tape with
the
10x or 5x accuracy needed as a standard.
Wow and flutter meters are basically frequency meters. They are like
guitar
tuners, but the output is weighted to breakup the frequency variations
into
long and short term changes.
If you can find a calibrated wow and flutter meter with a test tape, I'm
sure the cost will far exceed what your client is willing to pay. The
technology is at least 20 years old, and there really isn't a market for
anyone to make this equipment available.
The bottom line -------- Even if you go through the time and expense to do
this right, what good is it if your client's tapes are not recorded at the
same precision? You and he will be better off if you add a front panel
speed
control so that he can dial in the speed to match the tape being played
I found a large quantity of salvaged capstans+spindles.
26 off on my mike (rather than callipers before) measure 1.99 +/-0.01 of
reading accuracy and 2 nearer 2.00
5 off measure 1.79mm
1 at 2.19mm
9 measure 2.49mm
So I will give a few to my engineer mate and ask him what they measure and
the temperature at the time.
The machine in question uses 2.49.
Assuming it is actually 2.5mm then doing the maths and strobing with quartz
f-meter calibrated strobe then my test tapes are 0.4 percent out from
calculation via 15/8 ips etc.
spindle rotation speed of 6.05 rev per second with an error of about 0.4
percent , needs longer gate time or repeating more times to bring that
accuracy up (rounding errors? so probably longer gate time required than my
meter has).
If 2.49 diameter then 0.6 percent out
A
Arfa Daily
Guest
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hftvlm$nii$1@news.eternal-september.org...
not good enough for your very discerning customer with "perfect pitch", then
it is he who is at fault, for believing that the cassette medium is
sufficiently good to serve his needs, and you for allowing him to continue
believing this ...
Arfa
news:hftvlm$nii$1@news.eternal-september.org...
This is becoming bizarre ... Konig strobe test tape. Good enough. End of. Ifbg <bg@nospam.com> wrote in message news:hftuf0$od4$1@news.xmission.com...
N_Cook wrote in message ...
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:wRYTm.105473$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
You are assuming that if the capstan rotates at the correct RPM , that
the
tape speed will be correct. The proper way to do this is to measure the
playback frequency of the tape which gives you the tape speed. Obviuosly,
the accuracy of the test tape, the accuracy of the counter, etc all come
into play to add errors. The industry standard is to use a wow and
flutter
meter in conjunction with a test tape. The test tape is recorded at
3000hz
on a reel to reel recorder and then loaded into a cassette shell because
there is no cassette recorder on earth that can produce a test tape with
the
10x or 5x accuracy needed as a standard.
Wow and flutter meters are basically frequency meters. They are like
guitar
tuners, but the output is weighted to breakup the frequency variations
into
long and short term changes.
If you can find a calibrated wow and flutter meter with a test tape, I'm
sure the cost will far exceed what your client is willing to pay. The
technology is at least 20 years old, and there really isn't a market for
anyone to make this equipment available.
The bottom line -------- Even if you go through the time and expense to
do
this right, what good is it if your client's tapes are not recorded at
the
same precision? You and he will be better off if you add a front panel
speed
control so that he can dial in the speed to match the tape being played
I found a large quantity of salvaged capstans+spindles.
26 off on my mike (rather than callipers before) measure 1.99 +/-0.01 of
reading accuracy and 2 nearer 2.00
5 off measure 1.79mm
1 at 2.19mm
9 measure 2.49mm
So I will give a few to my engineer mate and ask him what they measure and
the temperature at the time.
The machine in question uses 2.49.
Assuming it is actually 2.5mm then doing the maths and strobing with
quartz
f-meter calibrated strobe then my test tapes are 0.4 percent out from
calculation via 15/8 ips etc.
spindle rotation speed of 6.05 rev per second with an error of about 0.4
percent , needs longer gate time or repeating more times to bring that
accuracy up (rounding errors? so probably longer gate time required than
my
meter has).
If 2.49 diameter then 0.6 percent out
not good enough for your very discerning customer with "perfect pitch", then
it is he who is at fault, for believing that the cassette medium is
sufficiently good to serve his needs, and you for allowing him to continue
believing this ...
Arfa
B
Bob Larter
Guest
On 10/12/2009 2:42 AM, N_Cook wrote:
capstan with one of those cheap digital verniers.
--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
You should be able to get a very accurate reading of the diameter of theRon<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$1@news.eternal-september.org...
Set up a sig genny and test him out
Much easier to say the test tape is stretched.
Perhaps perfect pitch testing would only work by playing the likes of JSB
Tocatta and Fugue in D major, not pure tones
How come I cannot google the rpm of an audio cassette capstan? A calibrated
strobe and tipex mark on the capstan periphery should give a definite answer
(assuming the spindle is clean and not worn).
It should be determinable from tape speed of 1 7/8 in per sec and spindle
diameter, that is about 1.9mm, but what should it be to 0.1 percent
accuracy?
capstan with one of those cheap digital verniers.
--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
B
Bob Larter
Guest
On 12/12/2009 3:31 AM, bz wrote:
--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
<nods> 440Hz is the usual reference tone."N_Cook"<diverse@tcp.co.uk> wrote in
news:hft7vv$nsr$1@news.eternal-september.org:
3 of them made on the same batch of tape and on the same machine but
more than 15 years ago. As they are all stored in the same environment
they could theoretically all have chemically degraded/stretched to the
same degree. I'm trying to find some process that gives an independent
verification that does not require a know good machine.
eg quartz controlled (so low tens ppm) f-meter coupled strobe fed to
rotating capstan if diameter/s of the spindles are manufactured to
specific dimensions of precisely known tolerances. Perhaps 1.9 +/- 0.002
mm and 2.4 +/- 0.002mm say, no such data found googling. I can only
measure to +/-0.02 mm and no slip gauges for absolute calibration.
+/-2 in 200 or so, is not accurate enough
Suggestion:
Google for
guitar tuning meter
There are meters available for ~20 bux and even some 'on line' meters.
Record a known good 'string note' frequency and use it for your standard.
Should get you close enough for any audiophile's ears
--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
N
N_Cook
Guest
Bob Larter <bobbylarter@gmail.com> wrote in message
news:hfv8rv$i4r$1@blackhelicopter.databasix.com...
The mechanical structure of a digital is the same as a vernier or DTI one .
With the same susceptibility for the plate-form arms to deflect from
unrelieved manufacturing stresses , let alone abuse. Compared to micrometers
which have a more rigid , less internally stressed, rod like basic
structure. Just because you can read to greater accuracy does not
necessarily mean better measurement in absolute terms
news:hfv8rv$i4r$1@blackhelicopter.databasix.com...
On 10/12/2009 2:42 AM, N_Cook wrote:
Ron<ron@lunevalleyaudio.com> wrote in message
news:vZCdnX7J1q8uL4LWnZ2dnUVZ7rVi4p2d@bt.com...
N_Cook wrote:
Ron<ron@lunevalleyaudio.com> wrote in message
news:0dednd3AmaG0B4LWnZ2dnUVZ7tqdnZ2d@bt.com...
N_Cook wrote:
Arfa Daily<arfa.daily@ntlworld.com> wrote in message
news:vbKTm.64350$Dl4.48926@newsfe08.ams2...
"N_Cook"<diverse@tcp.co.uk> wrote in message
news:hflv4c$p04$1@news.eternal-september.org...
Set up a sig genny and test him out
Much easier to say the test tape is stretched.
Perhaps perfect pitch testing would only work by playing the likes of
JSB
Tocatta and Fugue in D major, not pure tones
How come I cannot google the rpm of an audio cassette capstan? A
calibrated
strobe and tipex mark on the capstan periphery should give a definite
answer
(assuming the spindle is clean and not worn).
It should be determinable from tape speed of 1 7/8 in per sec and
spindle
diameter, that is about 1.9mm, but what should it be to 0.1 percent
accuracy?
You should be able to get a very accurate reading of the diameter of the
capstan with one of those cheap digital verniers.
--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
The mechanical structure of a digital is the same as a vernier or DTI one .
With the same susceptibility for the plate-form arms to deflect from
unrelieved manufacturing stresses , let alone abuse. Compared to micrometers
which have a more rigid , less internally stressed, rod like basic
structure. Just because you can read to greater accuracy does not
necessarily mean better measurement in absolute terms
B
Bob Larter
Guest
On 12/12/2009 8:01 PM, N_Cook wrote:
helps. And for your purpose one should be plenty accurate enough.
--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
Sure, but you can zero out a digital vernier each time you use it, whichBob Larter<bobbylarter@gmail.com> wrote in message
news:hfv8rv$i4r$1@blackhelicopter.databasix.com...
On 10/12/2009 2:42 AM, N_Cook wrote:
Ron<ron@lunevalleyaudio.com> wrote in message
news:vZCdnX7J1q8uL4LWnZ2dnUVZ7rVi4p2d@bt.com...
N_Cook wrote:
Ron<ron@lunevalleyaudio.com> wrote in message
news:0dednd3AmaG0B4LWnZ2dnUVZ7tqdnZ2d@bt.com...
N_Cook wrote:
Arfa Daily<arfa.daily@ntlworld.com> wrote in message
news:vbKTm.64350$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
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?
You should be able to get a very accurate reading of the diameter of the
capstan with one of those cheap digital verniers.
The mechanical structure of a digital is the same as a vernier or DTI one .
With the same susceptibility for the plate-form arms to deflect from
unrelieved manufacturing stresses , let alone abuse. Compared to micrometers
which have a more rigid , less internally stressed, rod like basic
structure. Just because you can read to greater accuracy does not
necessarily mean better measurement in absolute terms
helps. And for your purpose one should be plenty accurate enough.
--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
N
N_Cook
Guest
N_Cook <diverse@tcp.co.uk> wrote in message news:...
from the
mechanical engineer.
1.99 +/-0.01 of
reading accuracy (measured at 62 degree c) and 2 nearer 2.00
5 off measure 1.79mm
1 at 2.19mm
9 measure 2.49mm
Either spindles or bearings would have to
be an off-size for free movement, so presumably sintered metal bearings
are (easier?) made round number size and spindles made 0.01mm smaller
diameter and
speed of rotation adjusted just as easily to that as any other speed.
--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://diverse.4mg.com/index.htm
A rather belated follow up, just got the representative measurements backbg <bg@nospam.com> wrote in message news:hftuf0$od4$1@news.xmission.com...
N_Cook wrote in message ...
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
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"N_Cook" <diverse@tcp.co.uk> wrote in message
news:hfoghs$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
You are assuming that if the capstan rotates at the correct RPM , that
the
tape speed will be correct. The proper way to do this is to measure the
playback frequency of the tape which gives you the tape speed.
Obviuosly,
the accuracy of the test tape, the accuracy of the counter, etc all come
into play to add errors. The industry standard is to use a wow and
flutter
meter in conjunction with a test tape. The test tape is recorded at
3000hz
on a reel to reel recorder and then loaded into a cassette shell because
there is no cassette recorder on earth that can produce a test tape with
the
10x or 5x accuracy needed as a standard.
Wow and flutter meters are basically frequency meters. They are like
guitar
tuners, but the output is weighted to breakup the frequency variations
into
long and short term changes.
If you can find a calibrated wow and flutter meter with a test tape, I'm
sure the cost will far exceed what your client is willing to pay. The
technology is at least 20 years old, and there really isn't a market for
anyone to make this equipment available.
The bottom line -------- Even if you go through the time and expense to
do
this right, what good is it if your client's tapes are not recorded at
the
same precision? You and he will be better off if you add a front panel
speed
control so that he can dial in the speed to match the tape being played
I found a large quantity of salvaged capstans+spindles.
26 off on my mike (rather than callipers before) measure 1.99 +/-0.01 of
reading accuracy and 2 nearer 2.00
5 off measure 1.79mm
1 at 2.19mm
9 measure 2.49mm
So I will give a few to my engineer mate and ask him what they measure and
the temperature at the time.
The machine in question uses 2.49.
Assuming it is actually 2.5mm then doing the maths and strobing with
quartz
f-meter calibrated strobe then my test tapes are 0.4 percent out from
calculation via 15/8 ips etc.
spindle rotation speed of 6.05 rev per second with an error of about 0.4
percent , needs longer gate time or repeating more times to bring that
accuracy up (rounding errors? so probably longer gate time required than
my
meter has).
If 2.49 diameter then 0.6 percent out
from the
mechanical engineer.
1.99 +/-0.01 of
reading accuracy (measured at 62 degree c) and 2 nearer 2.00
5 off measure 1.79mm
1 at 2.19mm
9 measure 2.49mm
Either spindles or bearings would have to
be an off-size for free movement, so presumably sintered metal bearings
are (easier?) made round number size and spindles made 0.01mm smaller
diameter and
speed of rotation adjusted just as easily to that as any other speed.
--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://diverse.4mg.com/index.htm