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60 Hz Yamaha C-80 vintage preamplifier in 50 Hz country

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Does core saturation or related problems matter if my hi-fi preamplifier from the US only has a 30 W rating, and I want to use it in my 50 Hz country with a NEDIS 230 V to 110 V AC converter?

I have read the section called "Operation at Frequencies Lower than Normal" here:

I have read on hi-fi forums, but people often don't know about electronics engineering there.

The service manual is also online with schematics.

It depends on how much iron is in the core of the power transformer. Any 50Hz transformer will work fine on 60Hz but a 60Hz transformer may start to saturate on 50Hz. If it isn't labeled as such then the easiest way is probably to power it up while monitoring the current, if you hear an unusually loud buzzing or the current draw is excessive then you'll need to drop the voltage a bit to prevent saturation. If it all seems normal then let it run for a while and see if the transformer gets unusually hot.

Another idea would be to reduce the line voltage.  Look at the nameplate to see what the highest 60 Hz mains voltage rating is and then make sure the source is no more than 5/6 of that voltage.

Having said that, there is still the issue of filtering; it will have more power supply ripple.  In addition, if there is a clock in the unit, it may run slow, depending on its time standard.  Further, the maximum output audio power will be lower.

It's a preamplifier so output power should not be an issue, and I really doubt it contains a clock. The filtering is unlikely to be a problem either as there is typically plenty of margin.

You might want to check that the transformer really can accept 50hz or not. Often times a transformer was used that could do 50hz or 60hz despite the label saying only one or the other, especially if it can be wired to output either 110v or 220v. Sometimes the transformer really is specific to a frequency as well as a voltage.


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