60Hz/50Hz

[Den Murray]

Group:

A little education for me please!

I've got a direct drive record deck (240V/50Hz), if I run it through a
step-up transformer (120V/240V) on a 120V/60Hz supply what will the effect
on the motor be? I asusme that the speed will be increased by 20% (i.e. a
factor of 60/50). Will there be any other effects?

Cheers

 

[DarkMatter]

Yeh, all your records will sound like Alvin and the Chipmonks

Den wrote

That would depend on the type of drive motor. Some are tractored by
the line frequency, and some are DC driven, and tractored by a control
board. I would say that most are of the second type. Using the line
freq for something like audio streaming is bad cause we HEAR it.

What will be off is the line excited neon that will flicker at 120
Hz, as opposed to 100Hz, making the speed setting ticks along the
platter edge incorrect for setting the speed. I think there are some
you can print out, and tape on though that will allow proper setting
at 60Hz.

If it is an old cheapy turntable with no speed setting, you would be
at the mercy of the internal circuits or line frequency, whichever is
relevant in your case.

 

[steve h]

If the deck has a pitch control it is most likely dc or uses a pulse
generator to drive the motor, few direct drive decks are powered by a
synchronous mains motor.

Steve H

 

[sQuick]

That would depend on the type of drive motor. Some are tractored by
the line frequency, and some are DC driven, and tractored by a control
board. I would say that most are of the second type. Using the line
freq for something like audio streaming is bad cause we HEAR it.

What will be off is the line excited neon that will flicker at 120
Hz, as opposed to 100Hz, making the speed setting ticks along the
platter edge incorrect for setting the speed. I think there are some
you can print out, and tape on though that will allow proper setting
at 60Hz.

If it is an old cheapy turntable with no speed setting, you would be
at the mercy of the internal circuits or line frequency, whichever is
relevant in your case.

I would have to agree with DarkMatter here,
most drives owned & opened up are DC motors.
There are usually a couple of pots inside to tweak
the 45 or 33 1/3 speed.

so 50hz or 60hz, shouldn't change the rpm, but would
have an effect on any timing strobes on the deck.

sQuick..

 

[DarkMatter]

If the deck has a pitch control it is most likely dc or uses a pulse
generator to drive the motor, few direct drive decks are powered by a
synchronous mains motor.

The problem results when the 60Hz strobe is used on the 50 Hz lands
on the platter edge for speed control. It results in nearly a 17%
change in speed, if "used" as if correct. Many platters I am aware of
had both 50, and 60 Hz lands on them. If not, they are downloadable
somewhere, I'm sure. They can also be calculated, and a custom
template be drafted.

 

[DarkMatter]

I have a 50/60HZ, 120/240V Technics turntable I bought at the base exchange
in Germany in 1982 that automatically adjusts for frequency. You do have to
remember to switch the voltage though.

When I first move to Germany in 1979, the old 60 HZ turntable did not like
50 HZ. I had a reel-to-reel and cassette recorder (back in the day, you
recorded your record onto tape to "save" it from the wear of the needle) so
I would play the record at 78 rpm and record it at 15 fpm but play back at
7.5 fpm to dub it to my cassette. The 78 rpm setting spun at 65 rpm (5/6 of
78) and by halving the playback speed, I was able to record my records at
32.5 rpm instead of 33-1/3 rpm. Sounds was a little off but not enough to
bother me into buying a new turntable right away.

The things cheapskates do to get by.


Sincerely,


Donald L. Phillips, Jr., P.E.

My uncle recorded hundreds of thousands of old 78s onto tape, right
after buying the new disc usually. His collection is now in the
historical archives in Cincinnati. They were every type of music,
IIRC. I was but a kid. I sure wish I had that collection now though.