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?
On 04 Mar 2004 02:32:03 GMT, email@example.com (NoParlez) Gave us:
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.
On Fri, 5 Mar 2004 00:19:41 -0000, "steve h" Gave us:
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.
On Thu, 04 Mar 2004 21:21:26 -0800 DarkMatter wrote: | On Fri, 5 Mar 2004 00:19:41 -0000, "steve h" Gave | us: | |>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.
If you pitch them really close together, you can have 5 marks pass by in a strobe cycle at 60 Hz, or 6 marks pass by in a strobe cycle at 50 Hz. It would only be good if the speed is in the right ballpark, but once there this would let you fine tune it to the line frequency. So for 33+1/3 RPM,
1080 marks, at 1/3 degree each, around the circle should do it. For 45 RPM that would be 800 marks. I don't know how you would do it for 78 RPM.
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.
Donald L. Phillips, Jr., P.E. Worthington Engineering, Inc.
145 Greenglade Avenue Worthington, OH 43085-2264
snipped-for-privacy@worthingtonNSengineering.com (remove NS to use the address)
On Sat, 06 Mar 2004 01:27:19 GMT, "Don Phillips" Gave us:
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.