25 years ago I had access to a professional audio-visual studio and managed
to record a couple of tapes with crystal derived 1KHz sine tones on a
calibrated cassette deck. Since then I've mangled one and only one remains
so reluctant to use it, maybe stretched for all I know, no accesss to known
good player these days.

Decided instead to use a strobe LED and f-counter coupled sig gen shone
directly on the capstan (x4 speed for easier use , seeing the strobing image
at x1 LED pulsing is very difficult). Also now knowing that spindles come in
sizes like 1.99mm ... 2.49 mm never seemingly 1.95mm , always ending with a
9 so no great accuracy required to measure the spindles , often with
restricted access for mic/calipers
Then maths for tape speed for 1 7/8 inches per second.
This worked fine for 2.29mm spindle and for a hyper-critical musician.

I repeat this technique this week for a much more basic machine which has a
1.69mm spindle and scaling for that, adjusting motor speed and even I could
tell ,playing a familiar music tape ,that the tempo was wrong.
Placing 1KHz test tape in and checking beats with a f-counter coupled sig
gen and it was 1 and 1/3 semitones too fast. So what have I not taken into
account in the linear scaling, influence of tape thickness ? tape curl
around a tighter spindle? different rubber formulation of the pinch wheel?

In the same vein what is the piece of Wagner music that has something like
39 bars of the same note played from the beginning , Tristan & Isolde ? .
What other piece of music commercially recorded onto cassette tape, to look
out for, containing a sustained single note it might be possible to use as a
test tape. ?

Anyone use a tape with any old constant tone recorded on it but small
magnet
erased start and stop points of 100 seconds say by measured length of 1.875
x 100 inches ( by pulling out of the cassette and then rewinding back in )?
Would be slow but would be a last back stop I suppose for cross-comparison

In case my math/s is wrong the strobe frequency (capstan speed 1/4 of this)
for 1.69 mm I made 35.9 Hz but for 1KHz test tape and 1Hz beats required
backing off to 33.1 Hz when strobed

"N_Cook" wrote:
25 years ago I had access to a professional audio-visual studio and managed
to record a couple of tapes with crystal derived 1KHz sine tones on a
calibrated cassette deck. Since then I've mangled one and only one remains
so reluctant to use it, maybe stretched for all I know, no accesss to known
good player these days.

Decided instead to use a strobe LED and f-counter coupled sig gen shone
directly on the capstan (x4 speed for easier use , seeing the strobing image
at x1 LED pulsing is very difficult). Also now knowing that spindles come in
sizes like 1.99mm ... 2.49 mm never seemingly 1.95mm , always ending with a
9 so no great accuracy required to measure the spindles , often with
restricted access for mic/calipers
Then maths for tape speed for 1 7/8 inches per second.
This worked fine for 2.29mm spindle and for a hyper-critical musician.

I repeat this technique this week for a much more basic machine which has a
1.69mm spindle and scaling for that, adjusting motor speed and even I could
tell ,playing a familiar music tape ,that the tempo was wrong.
Placing 1KHz test tape in and checking beats with a f-counter coupled sig
gen and it was 1 and 1/3 semitones too fast. So what have I not taken into
account in the linear scaling, influence of tape thickness ? tape curl
around a tighter spindle? different rubber formulation of the pinch wheel?

In the same vein what is the piece of Wagner music that has something like
39 bars of the same note played from the beginning , Tristan & Isolde ? .
What other piece of music commercially recorded onto cassette tape, to look
out for, containing a sustained single note it might be possible to use as a
test tape. ?

Anyone use a tape with any old constant tone recorded on it but small
magnet
erased start and stop points of 100 seconds say by measured length of 1.875
x 100 inches ( by pulling out of the cassette and then rewinding back in )?
Would be slow but would be a last back stop I suppose for cross-comparison

A flat screwdriver tip touched at ten second intervals. Thirty seconds
should get it very accurate.

Greg

"N_Cook" wrote:
25 years ago I had access to a professional audio-visual studio and managed
to record a couple of tapes with crystal derived 1KHz sine tones on a
calibrated cassette deck. Since then I've mangled one and only one remains
so reluctant to use it, maybe stretched for all I know, no accesss to known
good player these days.

Decided instead to use a strobe LED and f-counter coupled sig gen shone
directly on the capstan (x4 speed for easier use , seeing the strobing image
at x1 LED pulsing is very difficult). Also now knowing that spindles come in
sizes like 1.99mm ... 2.49 mm never seemingly 1.95mm , always ending with a
9 so no great accuracy required to measure the spindles , often with
restricted access for mic/calipers
Then maths for tape speed for 1 7/8 inches per second.
This worked fine for 2.29mm spindle and for a hyper-critical musician.

I repeat this technique this week for a much more basic machine which has a
1.69mm spindle and scaling for that, adjusting motor speed and even I could
tell ,playing a familiar music tape ,that the tempo was wrong.
Placing 1KHz test tape in and checking beats with a f-counter coupled sig
gen and it was 1 and 1/3 semitones too fast. So what have I not taken into
account in the linear scaling, influence of tape thickness ? tape curl
around a tighter spindle? different rubber formulation of the pinch wheel?

In the same vein what is the piece of Wagner music that has something like
39 bars of the same note played from the beginning , Tristan & Isolde ? .
What other piece of music commercially recorded onto cassette tape, to look
out for, containing a sustained single note it might be possible to use as a
test tape. ?

Anyone use a tape with any old constant tone recorded on it but small
magnet
erased start and stop points of 100 seconds say by measured length of 1.875
x 100 inches ( by pulling out of the cassette and then rewinding back in )?
Would be slow but would be a last back stop I suppose for cross-comparison

I have made a tape measuring marks, and touching each mark with something
slightly magnetic. They don't have to close together.

Greg

gregz wrote in message
.
...
"N_Cook" wrote:
25 years ago I had access to a professional audio-visual studio and
managed
to record a couple of tapes with crystal derived 1KHz sine tones on a
calibrated cassette deck. Since then I've mangled one and only one
remains
so reluctant to use it, maybe stretched for all I know, no accesss to
known
good player these days.

Decided instead to use a strobe LED and f-counter coupled sig gen shone
directly on the capstan (x4 speed for easier use , seeing the strobing
image
at x1 LED pulsing is very difficult). Also now knowing that spindles
come in
sizes like 1.99mm ... 2.49 mm never seemingly 1.95mm , always ending
with a
9 so no great accuracy required to measure the spindles , often with
restricted access for mic/calipers
Then maths for tape speed for 1 7/8 inches per second.
This worked fine for 2.29mm spindle and for a hyper-critical musician.

I repeat this technique this week for a much more basic machine which
has a
1.69mm spindle and scaling for that, adjusting motor speed and even I
could
tell ,playing a familiar music tape ,that the tempo was wrong.
Placing 1KHz test tape in and checking beats with a f-counter coupled
sig
gen and it was 1 and 1/3 semitones too fast. So what have I not taken
into
account in the linear scaling, influence of tape thickness ? tape curl
around a tighter spindle? different rubber formulation of the pinch
wheel?

In the same vein what is the piece of Wagner music that has something
like
39 bars of the same note played from the beginning , Tristan & Isolde ?
..
What other piece of music commercially recorded onto cassette tape, to
look
out for, containing a sustained single note it might be possible to use
as a
test tape. ?

Anyone use a tape with any old constant tone recorded on it but small
magnet
erased start and stop points of 100 seconds say by measured length of
1.875
x 100 inches ( by pulling out of the cassette and then rewinding back
in )?
Would be slow but would be a last back stop I suppose for
cross-comparison

I have made a tape measuring marks, and touching each mark with something
slightly magnetic. They don't have to close together.

Greg

"They don't have to close together." ----- They don't have to be close
together.?


I was forgetting whatever your reaction time is, then the same for start and
stop mark so 100 seconds is excessive.
When I have some time I will dig out a deck and try cross-comparing this
measured length, 1KHz tape of old and strobing ,

Another thought . Anyone know what effect, for an otherwise good deck and
same pinchwheel contact force , would swapping the pinch wheel for a harder
rubber composistion have and a softer one.

"N_Cook" wrote:
gregz wrote in message
.
..
"N_Cook" wrote:
25 years ago I had access to a professional audio-visual studio and
managed
to record a couple of tapes with crystal derived 1KHz sine tones on a
calibrated cassette deck. Since then I've mangled one and only one
remains
so reluctant to use it, maybe stretched for all I know, no accesss to
known
good player these days.

Decided instead to use a strobe LED and f-counter coupled sig gen shone
directly on the capstan (x4 speed for easier use , seeing the strobing
image
at x1 LED pulsing is very difficult). Also now knowing that spindles
come in
sizes like 1.99mm ... 2.49 mm never seemingly 1.95mm , always ending
with a
9 so no great accuracy required to measure the spindles , often with
restricted access for mic/calipers
Then maths for tape speed for 1 7/8 inches per second.
This worked fine for 2.29mm spindle and for a hyper-critical musician.

I repeat this technique this week for a much more basic machine which
has a
1.69mm spindle and scaling for that, adjusting motor speed and even I
could
tell ,playing a familiar music tape ,that the tempo was wrong.
Placing 1KHz test tape in and checking beats with a f-counter coupled
sig
gen and it was 1 and 1/3 semitones too fast. So what have I not taken
into
account in the linear scaling, influence of tape thickness ? tape curl
around a tighter spindle? different rubber formulation of the pinch
wheel?

In the same vein what is the piece of Wagner music that has something
like
39 bars of the same note played from the beginning , Tristan & Isolde ?
.
What other piece of music commercially recorded onto cassette tape, to
look
out for, containing a sustained single note it might be possible to use
as a
test tape. ?

Anyone use a tape with any old constant tone recorded on it but small
magnet
erased start and stop points of 100 seconds say by measured length of
1.875
x 100 inches ( by pulling out of the cassette and then rewinding back
in )?
Would be slow but would be a last back stop I suppose for
cross-comparison

I have made a tape measuring marks, and touching each mark with something
slightly magnetic. They don't have to close together.

Greg

"They don't have to close together." ----- They don't have to be close
together.?



Right ! One way is to use a stopwatch for start stop.


I was forgetting whatever your reaction time is, then the same for start and
stop mark so 100 seconds is excessive.
When I have some time I will dig out a deck and try cross-comparing this
measured length, 1KHz tape of old and strobing ,

Another thought . Anyone know what effect, for an otherwise good deck and
same pinchwheel contact force , would swapping the pinch wheel for a harder
rubber composistion have and a softer one.

should have little effect, but inches per second will tell.

Greg

Use the references provided. Get a cassette tape of high quality,
prerecorded, and the CD of the exact same album.

Play them both, almost in sync, you know what I mean. A five minute
song ending well within a second of each other is pretty damn
accurate. I'd actually record a few one minute bursts of 1,000 Hz or
something and leave the original information on the tape, just don't
erase it. That way it can be played in a reference deck and if the
song doesn't end on time you know the tape is stretched.

When you use the same tape and deck you lay down the 1,000 Hz you have
established the accuracy as per a prerecorded cassette. If it hasn't
been played, that is about as close as you're going to get.

About the laying down anything on that tape, like mechanically, that
stuff stretches so anything like this can only be really accurate if
the tape is actually running through a machine. Stringing out 18 ¾ "
of tape on the diningroom table isn't quite going to do the trick.

The best bet for regular decks would be to just put a sensor on the
flywheel and either put in a servo or a strobe type indicator and a
pitch control. That capstan direct is the best indicator. It could
just be a few magnets or something on the flywheel and a little coil,
or better yet optic because it's a tape deck. Either way, your
reference is quartz, so unless the tape actually slips on the capstan,
it will be about as accurate as a cassette can be.

I know what you mean about some people being hypersensitive to certain
things. If they have perfect pitch they need to make sure their toilet
is in tune. I don't mean that mean, some would just laugh themselves.
Others cannot stand wow and flutter and might even claim to hear it in
CDs. I can't stand ****ty bass. I mean if it is boomy I want out of
there, but my **** rocks the rocks. I also can't stand speakers out of
phase, can anyone else tell or what ? LOL

For a guy who is super sensitive to speed, any deck he has you should
modify. Put some reflective tapes on the flywheel(s) and a little
sensor and LED or something. Just to act as a tachometer. Eight tapes,
eight pulses. Put your motor in. Don't be whining, it has a shaft,
give it a shaft. Now electronically YOU take over that motor. Divide
down some frequency to where one eighth of the rotation of the capstan
equals 0.234375" along it's circumference.

Think of being able to excel in the industry, get respect and...... oh
****it, think of the bill you can write for this.

1. Installed new motor and servo
2. Calibrated same
3. You don't want to know the rest, but the Mossad was involved -
briefely

You gotta have a good time at this.

On Feb 28, 1:25*am, Jeff Urban wrote:
Use the references provided. Get a cassette tape of high quality,
prerecorded, and the CD of the exact same album.

Play them both, almost in sync, you know what I mean. A five minute
song ending well within a second of each other is pretty damn
accurate. I'd actually record a few one minute bursts of 1,000 Hz or
something and leave the original information on the tape, just don't
erase it. That way it can be played in a reference deck and if the
song doesn't end on time you know the tape is stretched.

When you use the same tape and deck you lay down the 1,000 Hz you have
established the accuracy as per a prerecorded cassette. If it hasn't
been played, that is about as close as you're going to get.

About the laying down anything on that tape, like mechanically, that
stuff stretches so anything like this can only be really accurate if
the tape is actually running through a machine. Stringing out 18 ¾ "
of tape on the diningroom table isn't quite going to do the trick.

The best bet for regular decks would be to just put a sensor on the
flywheel and either put in a servo or a strobe type indicator and a
pitch control. That capstan direct is the best indicator. It could
just be a few magnets or something on the flywheel and a little coil,
or better yet optic because it's a tape deck. Either way, your
reference is quartz, so unless the tape actually slips on the capstan,
it will be about as accurate as a cassette can be.

I know what you mean about some people being hypersensitive to certain
things. If they have perfect pitch they need to make sure their toilet
is in tune. I don't mean that mean, some would just laugh themselves.
Others cannot stand wow and flutter and might even claim to hear it in
CDs. I can't stand ****ty bass. I mean if it is boomy I want out of
there, but my **** rocks the rocks. I also can't stand speakers out of
phase, can anyone else tell or what ? LOL

For a guy who is super sensitive to speed, any deck he has you should
modify. Put some reflective tapes on the flywheel(s) and a little
sensor and LED or something. Just to act as a tachometer. Eight tapes,
eight pulses. Put your motor in. Don't be whining, it has a shaft,
give it a shaft. Now electronically YOU take over that motor. Divide
down some frequency to where one eighth of the rotation of the capstan
equals 0.234375" along it's circumference.

Think of being able to excel in the industry, get respect and...... oh
****it, think of the bill you can write for this.

1. Installed new motor and servo
2. Calibrated same
3. You don't want to know the rest, but the Mossad was involved -
briefely

You gotta have a good time at this.

I had been listening to tapes slightly off speed in my truck for
months. It wasn't really bad, just enough to annoy me. I finally got
the ambition, while on vacation at the lake two Summers ago to pull
the deck and adjust the motor speed. The unit is a 1990 Delco in dash
radio/cassette player. Yes it's old but Delco equipment has always
been nicely made, and this one is in good condition. The capstan motor
has a small hole in the back to access a pot for speed adjustment. I
found a tape of an 8 minute song that had the exact time of the song
marked on the cassette. I timed the capstan motor by repeatedly
playing the tape and creeping up, (or down) on the speed while timing
the song on my phone, until the song ended at the right place. It's
not lab precision but I think I got pretty close, and I am no longer
annoyed by incorrect pitch. I like your idea about using a CD though.
I would think that that method would be as close to lab standard as
could be attained. Lenny