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\Granma\ Dave Schein II, CSO
 
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Default HELP: 1/4" RtR Tape Speed Problem

I am converting a 3" 1/4" 4-track reel-tape to CD. Trouble is, the
beginning is playing back fast and high-pitched (hand-in-hand), but the tail
is slow and low-pitched. This implies to me it is a section from a larger
reel of tape, but on a small reel. I am currently capturing at 3.75ips.

Is there a way of balancing out the speed errors?

I tried using a small-spool reel for takeup, but to no avail.

Should I try transferring the tape to a larger spool, to simulate the
suppossed former reel, or am I way off on that one? My thought about that
is that it may have been from a larger, 7.5ips reel

Any ideas?

Thanks,

Dave Schein II


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Steve King
 
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""Granma" Dave Schein II, CSO" wrote in message
news:26%te.393$al.359@trnddc07...
I am converting a 3" 1/4" 4-track reel-tape to CD. Trouble is, the
beginning is playing back fast and high-pitched (hand-in-hand), but the
tail
is slow and low-pitched. This implies to me it is a section from a larger
reel of tape, but on a small reel. I am currently capturing at 3.75ips.

Is there a way of balancing out the speed errors?

I tried using a small-spool reel for takeup, but to no avail.

Should I try transferring the tape to a larger spool, to simulate the
suppossed former reel, or am I way off on that one? My thought about that
is that it may have been from a larger, 7.5ips reel

Yes. Transfer the tape to a reel with a larger hub. For the tape you have
I would probably reach for a large hub seven inch reel. On all but some
dictation machines and perhaps some older, small, portable, battery
operated, tape decks the tape is driven at a constant speed from one end of
the tape to another. If the hold-back and take-up tensions on the feed reel
and take up reel are too high, the tape will slip between the steel capstan
and the rubber idler causing speed variation. That sounds like your
problem.

Steve King


  #3   Report Post  
Stephen Worth
 
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In article 26%te.393$al.359@trnddc07, \"Granma\" Dave Schein II, CSO
wrote:

I am converting a 3" 1/4" 4-track reel-tape to CD. Trouble is, the
beginning is playing back fast and high-pitched (hand-in-hand), but the tail
is slow and low-pitched. This implies to me it is a section from a larger
reel of tape, but on a small reel. I am currently capturing at 3.75ips.


Reel to reel tapes should maintain a consistent speed all the way
through, regardless of the size of the reel. Are you sure your deck is
working properly?

If the tape is somehow recorded with a gradual speed change, it's
possible that if you figured out the correct pitch for each end, you
could find a program for you computer that would make the correction
from head to tail. I used Peak, but I've never tried to do anything
like that before.

See ya
Steve

--
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Scott Dorsey
 
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\"Granma\" Dave Schein II, CSO wrote:
I am converting a 3" 1/4" 4-track reel-tape to CD. Trouble is, the
beginning is playing back fast and high-pitched (hand-in-hand), but the tail
is slow and low-pitched. This implies to me it is a section from a larger
reel of tape, but on a small reel. I am currently capturing at 3.75ips.


No, you have a tape that was made on one of the Japanese 3" recorders
that drove the reel at constant speed rather than using a capstan. These
were popular for dictation applications in the early seventies. The speed
is not constant; the rate of rotation of the take-up reel is. These things
have a lot of flutter but that was fine for the application. Most of them
are half-track.

Is there a way of balancing out the speed errors?


Yes, you can use a piece of equipment that I designed and used to sell,
which connects to the varispeed input on the ATR-100 and allows you to
ramp speed up or down in a controlled fashion.

Or you can try and find one of the Concord or Sony recorders that the
tape was recorded on.

I tried using a small-spool reel for takeup, but to no avail.


Right.

Should I try transferring the tape to a larger spool, to simulate the
suppossed former reel, or am I way off on that one? My thought about that
is that it may have been from a larger, 7.5ips reel


No, the reel size will not change the speed. On a conventional tape
machine, the tape is driven at constant speed by a capstan and so the
tape speed is independant of reel size.

Any ideas?


Easiest thing might be to write some code to do this in software once
you have acquired the signal. Do your playback with the NAB EQ bypassed,
do the varispeed in software, then equalize it in software again.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #5   Report Post  
William Sommerwerck
 
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I am converting a 3" 1/4" 4-track reel-tape to CD. Trouble is, the
beginning is playing back fast and high-pitched (hand-in-hand), but the

tail
is slow and low-pitched. This implies to me it is a section from a larger
reel of tape, but on a small reel. I am currently capturing at 3.75ips.


Is there a way of balancing out the speed errors?


I tried using a small-spool reel for takeup, but to no avail.


Should I try transferring the tape to a larger spool, to simulate the
suppossed former reel, or am I way off on that one?



Way, way off. The reel size has nothing whatever to do with the tape speed.
Open-reel tape is constant-speed.

However...

What you have is a tape made on a rim-drive machine. These were fairly
common in the earliest days of transistor portable tape recorders, because
capstan drive was much too expensive.

Instead of a capstan and pinch roller moving the tape at a steady speed, the
take-up reel turns at a constant rate. The tape speeds up as the diameter of
the tape on the reel increases -- hence, fast at the beginning and slow at
the end, when played back at constant speed.

The only thing I can think of is to copy the recording to a minicassette
(NOT microcassette) dictation machine such as a Lanier (which are also
rim-drive), and use the recorder's variable-speed playback to adjust.




  #6   Report Post  
Paul Stamler
 
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"Scott Dorsey" wrote in message
...
\"Granma\" Dave Schein II, CSO wrote:
I am converting a 3" 1/4" 4-track reel-tape to CD. Trouble is, the
beginning is playing back fast and high-pitched (hand-in-hand), but the

tail
is slow and low-pitched. This implies to me it is a section from a

larger
reel of tape, but on a small reel. I am currently capturing at 3.75ips.


No, you have a tape that was made on one of the Japanese 3" recorders
that drove the reel at constant speed rather than using a capstan. These
were popular for dictation applications in the early seventies. The speed
is not constant; the rate of rotation of the take-up reel is. These

things
have a lot of flutter but that was fine for the application. Most of them
are half-track.

Is there a way of balancing out the speed errors?


Yes, you can use a piece of equipment that I designed and used to sell,
which connects to the varispeed input on the ATR-100 and allows you to
ramp speed up or down in a controlled fashion.

Or you can try and find one of the Concord or Sony recorders that the
tape was recorded on.

I tried using a small-spool reel for takeup, but to no avail.


Right.

Should I try transferring the tape to a larger spool, to simulate the
suppossed former reel, or am I way off on that one? My thought about

that
is that it may have been from a larger, 7.5ips reel


No, the reel size will not change the speed. On a conventional tape
machine, the tape is driven at constant speed by a capstan and so the
tape speed is independant of reel size.

Any ideas?


Easiest thing might be to write some code to do this in software once
you have acquired the signal. Do your playback with the NAB EQ bypassed,
do the varispeed in software, then equalize it in software again.


Not really necessary to write your own varispeed code; DC-SIX has a function
that will do it quite handily. I use it often for correcting 78s that are
off-pitch. You can set the beginning of the file to a different setting than
the end,. and the software will ramp between the two settings.

Peace,
Paul


  #7   Report Post  
Arny Krueger
 
Posts: n/a
Default

"Granma" Dave Schein II, CSO wrote:

I am converting a 3" 1/4" 4-track reel-tape to CD.

Trouble is, the
beginning is playing back fast and high-pitched

(hand-in-hand), but
the tail is slow and low-pitched. This implies to me it

is a section
from a larger reel of tape, but on a small reel. I am

currently
capturing at 3.75ips.


Is there a way of balancing out the speed errors?


This can be done in the digital domain by working with the
pitch-changing features of common computer audio editing
software such as Audition/CE.


  #8   Report Post  
Adrian Tuddenham
 
Posts: n/a
Default

William Sommerwerck wrote:

I am converting a 3" 1/4" 4-track reel-tape to CD. Trouble is, the
beginning is playing back fast and high-pitched (hand-in-hand), but the

tail
is slow and low-pitched. This implies to me it is a section from a larger
reel of tape, but on a small reel. I am currently capturing at 3.75ips.


Is there a way of balancing out the speed errors?


I tried using a small-spool reel for takeup, but to no avail.


Should I try transferring the tape to a larger spool, to simulate the
suppossed former reel, or am I way off on that one?



Way, way off. The reel size has nothing whatever to do with the tape speed.
Open-reel tape is constant-speed.

However...

What you have is a tape made on a rim-drive machine. These were fairly
common in the earliest days of transistor portable tape recorders, because
capstan drive was much too expensive.

Instead of a capstan and pinch roller moving the tape at a steady speed, the
take-up reel turns at a constant rate. The tape speeds up as the diameter of
the tape on the reel increases -- hence, fast at the beginning and slow at
the end, when played back at constant speed.

The only thing I can think of is to copy the recording to a minicassette
(NOT microcassette) dictation machine such as a Lanier (which are also
rim-drive), and use the recorder's variable-speed playback to adjust.


Other methods (if you are sure it really was recorded on a spool-drive
machine as opposed to a capstan-drive one):


Method 1)

Place the approprite sized take-up spool on a variable-speed turntable
and use it to draw the tape through the playback machine.

I have done this successfully using a Lenco turntable and a Ferograph 7,
which has an open deck layout, allowing the tape to be easily threaded
so as to by-pass the capstan. The two units must be fairly close
together (or the span of tape must be supported) to prevent the loose
tape from fluttering around.

If you start off with an empty 'cine' take-up spool and find the speed
change from end to end is too great, it means the core diameter of the
spool is smaller than the one the tape was recorded on. Try partially
pre-filling the take-up spool with a pile of scrap tape, then lace your
tape on top of it. After a few attempts, you will find the size of pile
needed to give you roughly the correct starting diameter. After that,
you can use the turntable speed for fine adjustment.



Method 2) ...entirely at your own risk.

If the tape playback machine has a synchronous or semi-synchronous
motor, feed it with variable frequency 'mains'. Only consider this
method if you are electrically qualified and experienced.

Use a signal generator at around 40 - 80 c/s to drive public address
amplifiers giving 100 volt line output. In the UK, two amplifiers in
series (or a step-up transformer) are needed, but in the US it should be
possible to use only one amplifier.

Connect the output of the amplifiers to the mains input of the tape
playback machine and adjust the frequency to get the required playback
speed. This works over only a limited range of frequency and a lot will
depend on the design of the tape machine and ampifier, whether they are
robust enough to take this kind of mal-treatment.

Keep your wits about you and continually check for the signs or smells
of overheating components. If the amplifier has a tendency to oscillate
or generate strong harmonics under overload conditions, it will burn out
the resistors in any switch-suppressor networks of the tape machine.

I have used this method with a pair of Quad 50E amplifiers in series to
get 200 volts to operate a Ferrograph 7 and an assortment of small
dictating machines for various formats.
http://www.poppyrecords.co.uk/other/mandela/dictabelts.htm


If you have to alter the mains input adjuster to get the machine to
operate on the reduced voltage, don't forget to put it back to normal
mains voltage afterwards!




--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk
  #9   Report Post  
\Granma\ Dave Schein II, CSO
 
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Default

Word!

Thank you for the input. I am using an AKAI 1722-II, which I believe to be
capstan drive. The recording was made some years ago on a GE recorder, that
may well be spool-driven. Thank you for all the information. I'll take a
look at that DC-SIX thing.

-gran


"Paul Stamler" wrote in message
...
"Scott Dorsey" wrote in message
...
\"Granma\" Dave Schein II, CSO wrote:
I am converting a 3" 1/4" 4-track reel-tape to CD. Trouble is, the
beginning is playing back fast and high-pitched (hand-in-hand), but the

tail
is slow and low-pitched. This implies to me it is a section from a

larger
reel of tape, but on a small reel. I am currently capturing at

3.75ips.

No, you have a tape that was made on one of the Japanese 3" recorders
that drove the reel at constant speed rather than using a capstan.

These
were popular for dictation applications in the early seventies. The

speed
is not constant; the rate of rotation of the take-up reel is. These

things
have a lot of flutter but that was fine for the application. Most of

them
are half-track.

Is there a way of balancing out the speed errors?


Yes, you can use a piece of equipment that I designed and used to sell,
which connects to the varispeed input on the ATR-100 and allows you to
ramp speed up or down in a controlled fashion.

Or you can try and find one of the Concord or Sony recorders that the
tape was recorded on.

I tried using a small-spool reel for takeup, but to no avail.


Right.

Should I try transferring the tape to a larger spool, to simulate the
suppossed former reel, or am I way off on that one? My thought about

that
is that it may have been from a larger, 7.5ips reel


No, the reel size will not change the speed. On a conventional tape
machine, the tape is driven at constant speed by a capstan and so the
tape speed is independant of reel size.

Any ideas?


Easiest thing might be to write some code to do this in software once
you have acquired the signal. Do your playback with the NAB EQ

bypassed,
do the varispeed in software, then equalize it in software again.


Not really necessary to write your own varispeed code; DC-SIX has a

function
that will do it quite handily. I use it often for correcting 78s that are
off-pitch. You can set the beginning of the file to a different setting

than
the end,. and the software will ramp between the two settings.

Peace,
Paul




  #10   Report Post  
Paul Stamler
 
Posts: n/a
Default


""Granma" Dave Schein II, CSO" wrote in message
news:0lfue.4456$Uj.1511@trnddc08...
Word!

Thank you for the input. I am using an AKAI 1722-II, which I believe to

be
capstan drive. The recording was made some years ago on a GE recorder,

that
may well be spool-driven. Thank you for all the information. I'll take a
look at that DC-SIX thing.


It's a useful program for editing and cleaning up audio if you use it with
restraint and taste. The interface is kinda clunky and at least on my
machine it crashes more than I'd like, but it does the job well for the
price.

Peace,
Paul




  #11   Report Post  
\Granma\ Dave Schein II, CSO
 
Posts: n/a
Default

yeah, i just took a look at their site. For my temporary purposes, I don't
know that it's worth the $200 for this $30 job, but I will keep it in mind
for the future. I use SoundForge for the other stuff, for the most part. I
should really put that $200 toward the upgrade for that, I believe.

Thank you for the help, Paul,

Dave



"Paul Stamler" wrote in message
...

""Granma" Dave Schein II, CSO" wrote in message
news:0lfue.4456$Uj.1511@trnddc08...
Word!

Thank you for the input. I am using an AKAI 1722-II, which I believe to

be
capstan drive. The recording was made some years ago on a GE recorder,

that
may well be spool-driven. Thank you for all the information. I'll take

a
look at that DC-SIX thing.


It's a useful program for editing and cleaning up audio if you use it with
restraint and taste. The interface is kinda clunky and at least on my
machine it crashes more than I'd like, but it does the job well for the
price.

Peace,
Paul




  #12   Report Post  
Richard Crowley
 
Posts: n/a
Default

""Granma" Dave Schein II, CSO" wrote ...
I am converting a 3" 1/4" 4-track reel-tape to CD. Trouble is, the
beginning is playing back fast and high-pitched (hand-in-hand), but
the tail
is slow and low-pitched. This implies to me it is a section from a
larger
reel of tape, but on a small reel. I am currently capturing at
3.75ips.


You didn't state *how much* of a pitch change. If it is slight, it may
have been due to reel/hub size and tension issues, but if large, maybe
from an old hub-drive recorder?

Is there a way of balancing out the speed errors?


I'd capture it using CoolEdit/Audition and use the "Pitch Bender"
function where you can set the beginning and ending factor and
apply the change over the entire length of the capture. It even
shows you a graph of change vs. time so you can set up a non-
linear change if necessary.

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