Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Radio Man
 
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Default Converting A Cassette Recorder?

Can a cassette recorder be converted for
variable speed playback?


  #2   Report Post  
 
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generally yes, most dc motors used in cassette decks have a speed pot
which you could tap into.
-Ben

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TCS
 
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On Tue, 11 Jan 2005 12:14:42 GMT, Radio Man wrote:
Can a cassette recorder be converted for
variable speed playback?


Generaly not, unless ripping out the motors and replacing them with ones
you can control is your idea of fun.
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Sam Goldwasser
 
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TCS writes:

On Tue, 11 Jan 2005 12:14:42 GMT, Radio Man wrote:
Can a cassette recorder be converted for
variable speed playback?


Generaly not, unless ripping out the motors and replacing them with ones
you can control is your idea of fun.


Depends on how the motor speed is regulated. It may be internal or
external. However, even if you can vary the speed, don't expect
decent fidelity over a wide range of speeds. Correcting for semitone
of pitch error should be possible.

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mike
 
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Radio Man wrote:
Can a cassette recorder be converted for
variable speed playback?



The first one I converted about 35 years ago had a centrifugal
speed regulator. Had to mess with the weights inside the motor.
Not variable.

Next one was also a centrifugal one, but just made a power supply
with negative output resistance that matched the load curve of the
motor. Worked way better than I expected over a wide speed range for
recording voice. I needed LONG record times. Would be unsatisfactory
for music.

If you expect the pitch to stay constant with changes in speed, you need
an electronic solution.

You said "playback", not record. Depending on what you're doing, you
might have better luck with preprocessing on a computer and spitting it
back out on your PDA, if you need portability...like an audio book
application.
mike

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NSM
 
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"mike" wrote in message
...

| You said "playback", not record. Depending on what you're doing, you
| might have better luck with preprocessing on a computer and spitting it
| back out on your PDA, if you need portability...like an audio book
| application.

Some software will let you do this - speed up or slow down up to 2.0 times.

N


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JURB6006
 
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Interesting. I hate to jump in like this, but you mentioned changing the speed
but not pitch.

Brings me back to the first time, one of the high end Sony BETA models had 2X
playback with sound. Because it simply altered the head switching the pitch
didn't change. It sounded a bit chopped up, but it was intelligible.

The second time was I think a JVC, BUT IT WASN'T HIFI ! It used BBDs to chop
so many microseconds out of every second. It sounded alot smoother chopping at
higher than 60Hz.

About a year ago, a buddy at work showed me a program that could manipulate the
speed of music without affecting the pitch, and he told me it could also change
the pitch without affecting the speed.

We have a machine shop and can install any motor you want to drive that
cassette mechanism, but these days it's better to manipulate it in the digital
domain. At least for speed and pitch, there are no viable options, for
equalization analog is better, at least a good one is. I have an old
Soundcraftsman I'd like to use, but it needs a power transformer. I'll fix it
one of these days. My stereo sounds good enough, but it would be nice to have
it running. I haven't found a decent software EQ yet, and actually I'm having a
hard time finding a good enough soundcard. The hiss is not in my amp and I know
that for sure.

Rolling back the rates to pre-inflationary levels, that is my two cents worth.

JURB

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WEBPA
 
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Missed the early parts of the thread but:

In the early 1970's someone (Analog Devices? Signetics? ) introduced a
single-chip analog device called VSC - "Variable Speech Control" intended for
"speed listening." It permitted continuous speed adjustments of a tape
recorder or record player ... without pitch changes. I still have (somewhere) a
demo recording bound in Electronics magazine (NOT the consumer "Electronics",
but the EE journal version that preceded it). It was normal and speeded-up
version of a very boring lecture (didn't get more intersting at any of the
increased or decreased speeds.)

As far as I know, Sony was the only manufacturer that used this chip. I still
have a purse-size cassette recorder that has VSC, a V8 deck (EV-C1) that has 2X
playback with sound (same as your BII machine).

PC Software that can change an audio file's speed without changing pitch (or
pitch without speed change) is very common. I've used CoolEdit for years to
stretch/shrink sound to fit ill-formed *.avi and *.mpg files.

p a w e b e r 0 2 @ a o l . c o m

Interesting. I hate to jump in like this, but you mentioned changing the
speed
but not pitch.

Brings me back to the first time, one of the high end Sony BETA models had 2X
playback with sound. Because it simply altered the head switching the pitch
didn't change. It sounded a bit chopped up, but it was intelligible.

The second time was I think a JVC, BUT IT WASN'T HIFI ! It used BBDs to chop
so many microseconds out of every second. It sounded alot smoother chopping
at
higher than 60Hz.

About a year ago, a buddy at work showed me a program that could manipulate
the
speed of music without affecting the pitch, and he told me it could also
change
the pitch without affecting the speed.

We have a machine shop and can install any motor you want to drive that
cassette mechanism, but these days it's better to manipulate it in the
digital
domain. At least for speed and pitch, there are no viable options, for
equalization analog is better, at least a good one is. I have an old
Soundcraftsman I'd like to use, but it needs a power transformer. I'll fix it
one of these days. My stereo sounds good enough, but it would be nice to have
it running. I haven't found a decent software EQ yet, and actually I'm having
a
hard time finding a good enough soundcard. The hiss is not in my amp and I
know
that for sure.

Rolling back the rates to pre-inflationary levels, that is my two cents
worth.

JURB





webpa

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Asimov
 
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"WEBPA" bravely wrote to "All" (05 Feb 05 00:44:27)
--- on the heady topic of " Converting A Cassette Recorder?"

WE From: (WEBPA)
WE Xref: aeinews sci.electronics.repair:9483

WE Missed the early parts of the thread but:

WE In the early 1970's someone (Analog Devices? Signetics? ) introduced a
WE single-chip analog device called VSC - "Variable Speech Control"
WE intended for "speed listening." It permitted continuous speed
WE adjustments of a tape recorder or record player ... without pitch
WE changes. I still have (somewhere) a demo recording bound in Electronics
WE magazine (NOT the consumer "Electronics", but the EE journal version
WE that preceded it). It was normal and speeded-up version of a very
WE boring lecture (didn't get more intersting at any of the increased or
WE decreased speeds.)
WE As far as I know, Sony was the only manufacturer that used this chip.
WE I still have a purse-size cassette recorder that has VSC, a V8 deck
WE (EV-C1) that has 2X playback with sound (same as your BII machine).

WE PC Software that can change an audio file's speed without changing
WE pitch (or pitch without speed change) is very common. I've used
WE CoolEdit for years to stretch/shrink sound to fit ill-formed *.avi and
WE *.mpg files.
WE p a w e b e r 0 2 @ a o l . c o m

Hi,

I've heard talk before on this group of a machine with a rotating
audio head that could vary the speed of the recording without altering
the pitch. Apparently it would vary the head's rotation speed in sync
with the tape speed so that the pitch stayed constant. I suppose it
was an early form of analog over-sampling...

A*s*i*m*o*v

.... A stereo system is the altar to the god of music.



  #11   Report Post  
WEBPA
 
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These machines were used for radio & TV station program logging (used to be an
FCC requirement), and for law-enforcement telephone logging. The ones I've
seen used 1 or 2 inch tape running at 15/16 ips or less (recording) and could
record a dozen or so separate, parallel channels via a nightmare-ish rotating
head assembly. You could play back at 2x or 3x and usually hear intelligible
voice. You turned up the speed then dialed down the pitch. Not real sure about
the physics, but I suspect it was a hetrodyne system of some kind.

Hi,

I've heard talk before on this group of a machine with a rotating
audio head that could vary the speed of the recording without altering
the pitch. Apparently it would vary the head's rotation speed in sync
with the tape speed so that the pitch stayed constant. I suppose it
was an early form of analog over-sampling...

A*s*i*m*o*v

... A stereo system is the altar to the god of music.



webpa

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