Converting imported 120V Amps to 240V Amps

[Wakefield Turntables]

I've been severly tempted to import several big "Yank" amps but always wondered how easy it would be to convert to 240V. I've been going to get a Sansui BA5000 numerous times but always had worries that the amp wouldn't be performing optimally. So I have a simple question. Is a small or large job to get most amps converted over from 120 to 240V, additionally what does it involve? Sorry if this is a stupid question but I think I'd like to get into a little box swapping as a new hobby. Thanks, Andy.

[walpurgis]

Not tried it myself, but I see problems with getting transformers of suitable physical dimensions and layout, not to mention spec. Also the value of the amp will be knocked down.

[Ali Tait]

Keep the amp as is and buy one of these-

http://www.airlinktransformers.com/american_voltage_converters/america_uk_voltage_converters/

[Light Dependant Resistor]

I've been severly tempted to import several big "Yank" amps but always wondered how easy it would be to convert to 240V. I've been going to get a Sansui BA5000 numerous times but always had worries that the amp wouldn't be performing optimally. So I have a simple question. Is a small or large job to get most amps converted over from 120 to 240V, additionally what does it involve? Sorry if this is a stupid question but I think I'd like to get into a little box swapping as a new hobby. Thanks, Andy.

Hi Andy
What I normally do with 120v equipment is use a step down transformer, and mark the 120v cable appropriately
so it is not at any time plugged into 240v. Here I have a Sony CD player and being 120v I use a step down
transformer works perfectly.

With power amps this requires step down transformers with suitable larger current rating. You can get these step down transformers 240 UK plug to 120v with USA type fittings , so you can't make error with plugs.

http://www.digikey.co.nz/Web%20Export/Supplier%20Content/thomas-research-1121/pdf/thomas-doi-choose-stepdown-transformer.pdf?redirected=1

FOR THE EXPERIENCED & PLEASE REFER TO FORUM Rules concerning SAFETY
Changing transformers is tricky as original sizing is difficult to match and secondary taps are hardly ever never the same.
and if voltages are different involve then converting or regulating DC rails so quite involved and challenging.
If attempting this harder way you will need a schematic for the amplifier - and then to assess its AC secondary
requirements. Toroidal transformers are available in many secondary tap voltages and currents. You also need
experience and many cautions with transformer taps fuses and primary AC mains voltages

So a suitably rated step down transformer is recommended, being a lot easier and safer to use.

Cheers / Chris

[awkwardbydesign]

Keep the amp as is and buy one of these-

http://www.airlinktransformers.com/american_voltage_converters/america_uk_voltage_converters/

That looks like a simple solution. Just get the biggest you can afford for future-proofing. I bought a 3kVA site transformer in a tin box for £10 and fitted sockets to it. It sometimes tripped out the mains circuit breaker when I turned it on!
BTW, on a related matter, if using 220v valve amps on our 240v supply, making up a bucking transformer works well. http://sound.westhost.com/articles/buck-xfmr.htm But not for 120v amps.

[Ali Tait]

I had to fit an NTC to my balanced power supply to stop it tripping the board.

[TheMooN]

It is worth bearing in mind that the transformers mentioned whilst converting the Voltage do not convert the Frequency of UK mains, ergo the mains Traffo in your import will be additionally temperature stressed by approximately 12% , local fluctuations dependent, this may induce an enhanced insulation breakdown over time leading to failure, especially with budget transformers, one may also experience induced hum due to the disparity in mains frequency.
All that said, large quality Mains transformers ( As with the OP's Sansui) are much less prone to the former scenario due to better quality insulation and winding topology, however they may still be susceptible to induced hum.

[Ali Tait]

Buy from Japan then. :-)