Moving From USA Overseas... Looking For Advice re: Electrical Service and Gear

Thanks for the additional info, Lucidear. Following is the text of the inquiry I sent to Acupwr via their website:

Regarding your autotransformers that can convert from 50 to 60 Hz and vice versa, and are indicated as being intended for use with refrigerators, freezers, and other such appliances:

1)Would you recommend that these autotransformers can be used to power a high quality stereo system?

2)Can you provide me with some indication as to how these devices convert frequency? As an electrical engineer I know that a transformer or autoformer by itself cannot do so.

3)Can you provide me with some indication of how greatly the resulting output differs from a pure sine wave. For example is it a stepped approximation of a sine wave, or a sawtooth waveform, or some other approximation of a sine wave having large amounts of distortion?

Thank you.

Shortly afterward I received a phone call from a fellow who described himself as being non-technical but who said he had spoken to one of their technical people. He said that the tech person told him the output is essentially a pure sine wave, but that they would only recommend these devices for use with motor-driven appliances, and would not recommend them for use with a stereo system. I asked why that would be the case if the output is essentially a pure sine wave, and he couldn’t provide an answer but thought it had something to do with the connected motor providing a "kick" of some sort to the transformer. I repeated question 2 to him and again he couldn’t answer. He said he would try to have the tech person contact me to provide further detail, but that hasn’t happened yet.

I’ll post back if and when the tech person provides further info. Meanwhile I can only speculate that the "kick" he refers to, that would be provided by a connected motor, might have something to do with a phenomenon called "inductive kickback." That is the principle by which the induction coil in a car generates the very high voltage pulse that is applied to the spark plugs, and is the reason that a tube amp having an output transformer (which is inductively based) should not be operated without a load.

The bottom line at this point: I would not take the chance of using these devices with valuable audio equipment. Also, as was indicated earlier in the thread there are many audio components that are designed such that they can be used at both frequencies, as long as the voltage is proper. That should be indicated on their nameplate and/or in their manual.

Best regards,

-- Al

No way I'd move such a nice system all that way.  Too risky.  Better to find someone local to take care of your system until you are stateside again.  ;-)

Al,

thanks for you consideration and contributions to this thread.  Acupwr also makes step down transformers that only effect the voltage - frequency remains unchanged.

i have confirmed that all of my gear will be fine on 50hz, so am only condiderig these units.  Do you share the same concerns about the voltage only autotransformers?

is there another step down transformer that you would recommend?

thanks again,
Scott

Al, what do you think will happen if a turntable AC synchronous motor is run on 120 V and 50 hz instead of 60 hz ?
Also, is the the frequency really always stable 60 hz here in the US ? Voltage is definitely not.

Acupwr also makes step down transformers that only effect the voltage - frequency remains unchanged. I have confirmed that all of my gear will be fine on 50hz, so am only considering these units.

Great! I see no reason to be concerned about functionality issues or damage occurring with the step-down transformers that don’t purport to convert frequency. I don’t have any feel, though, for whether or not they would compromise sonics to any degree. Although I’d expect the degree of any such compromise, if present at all, to be system dependent.

FWIW I once had occasion to use a much less expensive 120V to 100V step-down transformer I purchased from www.voltageconverters.com, in a relatively non-critical application in a second system. It worked fine in that application, with no perceivable sonic side-effects.

Inna, while as you say USA voltages can vary significantly, and are considered to be in spec as long as they are between 114 and 126 volts (i.e., 120V +/- 5%), my impression is that the 60 Hz frequency is very tightly controlled. And things I’ve read in the past have indicated that typically it is monitored such that if synchronous clocks accumulate very small errors over a period of say a few hours (perhaps even well under a second of error, although I’m not sure of the exact amount), the frequency is adjusted very slightly to gradually bring them back to the correct time.

Regarding turntables having synchronous motors, if a particular model does not provide a means by which it can be adjusted for 50 Hz operation, then, yes, I’d expect it to run slow.

Best regards,
-- Al