100V to 230V - Japanese Vintage Amps

[Robbi3And]

I'm wanting to get a few vintage power amplifiers like Marantz 140, 300, MA6100 and Sansui BA-2000. Trouble is they are worth an arm and a leg down here in Oztralia. I've found a pretty good Japanese auction site where beasts such as these go for a fraction of what they do downunder here and even with shipping a very attractive price-wise. Trouble is they are all 100V units and as everyone knows the standard here is 230V.

 

QUESTIONS:

1. Do most amps come with power transformers that have multi-taps that can be modified reasonably easily (all these units were sold in 240/230 volts markets)?
2. If YES to Q1 are they easily modified?
3. If NO, what difference/influence does a 240V → 110V step-down transformer have on their sound?
    

Thanks in advance for any advice.

Edited September 24, 2018 by Robbi3And

[Eddierukiddingvarese]

Just get a 240V → 110V tranny converter, not a prob

[Bronal]

19 minutes ago, Eddierukiddingvarese said:

Just get a 240V → 110V tranny converter, not a prob

Japanese voltage is 100V.

 

But remember that many Japanese amps of this period use two-pin mains plugs and are not earthed.  My inclination would be to have an amp earthed, but you run the risk of creating a ground loop (or whatever it's called).

[Gryffles]

No issues with a step down transformer.

 

Go for it!

[Monkeyboi]

Preference would be to use a stepdown isolation transformer (not an auto transformer) with a secondary output of 100 volts. Although you might get away with a 110 volt model I personally wouldn't recommend it as this voltage can go higher if your mains input (240v) goes higher.  In some gear there may not be enough margin not to cause a fault and / or shorten the life of the components.  Remember at 110 volts compared to 100 volts you are already 10% over-voltage.

 

Ensure the stepdown transformer has a high enough power (VA) rating to handle the load.

 

In the case of the Sansui BA-2000 power amplifier, the export and EU models have tapped transformers to set the mains supply voltage from 100, 120, 220 and 240 volts 50/60Hz and can be easily adjusted.  The US model is fixed voltage.

 

Cheers,

Alan R.

Edited September 24, 2018 by Monkeyboi
added info

[Robbi3And]

20 hours ago, Monkeyboi said:

Preference would be to use a stepdown isolation transformer (not an auto transformer) with a secondary output of 100 volts. Although you might get away with a 110 volt model I personally wouldn't recommend it as this voltage can go higher if your mains input (240v) goes higher.  In some gear there may not be enough margin not to cause a fault and / or shorten the life of the components.  Remember at 110 volts compared to 100 volts you are already 10% over-voltage.

 

Ensure the stepdown transformer has a high enough power (VA) rating to handle the load.

 

In the case of the Sansui BA-2000 power amplifier, the export and EU models have tapped transformers to set the mains supply voltage from 100, 120, 220 and 240 volts 50/60Hz and can be easily adjusted.  The US model is fixed voltage.

 

Cheers,

Alan R.

Thanks Alan, The 110 volts was a typo on my part - I would use a 240 to 100 volt unit. But would dearly love to convert them to use 230 straight out of the wall.

[Zaphod Beeblebrox]

On 24/09/2018 at 11:08 AM, Robbi3And said:

I'm wanting to get a few vintage power amplifiers like Marantz 140, 300, MA6100 and Sansui BA-2000. Trouble is they are worth an arm and a leg down here in Oztralia. I've found a pretty good Japanese auction site where beasts such as these go for a fraction of what they do downunder here and even with shipping a very attractive price-wise. Trouble is they are all 100V units and as everyone knows the standard here is 230V.

 

QUESTIONS:

1. Do most amps come with power transformers that have multi-taps that can be modified reasonably easily (all these units were sold in 240/230 volts markets)?

No. The Japanese  (100VAC) and US/Canada (117VAC) markets are so large that most large manufacturers build models specific to those markets (so they can save about $5.00), hence power transformers will be non-tapped types.

On 24/09/2018 at 11:08 AM, Robbi3And said:

1. If YES to Q1 are they easily modified?

IF the amps are European/Australian designated ones, then modification involves changing transformer taps.

 

On 24/09/2018 at 11:08 AM, Robbi3And said:

1. If NO, what difference/influence does a 240V → 110V step-down transformer have on their sound?

If the transformer is suitably rated, then no.

 

On 24/09/2018 at 11:08 AM, Robbi3And said:

Thanks in advance for any advice.

 

[Spinnergeoff]

I've used transformers without any problems, even on a power amplifier, but quite a few older japanese hifi components had variable voltage switches in them - they were very export oriented and made it easy. I think you'll find Accuphase still do that, but inside the amp not on the back panel! 

[silex]

I have a Nakamichi 730 receiver and accompanying 588 cassette deck, both pretty mint external condition. Both probably need work but a worthwhile proposition. Pm if interested

[The Fez]

No issues with stepdown tranny, IMO. I've run power amps from Japan up to power ratings of 250watts (Denon POA-3000ZR) RMS per channel - that's max rated power output not current draw but some had pretty decent draw. You need 100volt, not 110volt. I do use a large tranny, an isolated 1.5KW from Tortech, with twin power outlets. This allows me to run both my Yamaha B-3 in monoblock mode, amongst other amps, preamps or TT's.

 

I have had no issues. As mentioned here before, I've run identical Japanese amps -- Export 230v from the mains and 100V Japanese domestic and me and others cannot tell any difference in sound. If anything the isolated power transformer may be a better power source for the amp. I dunno. I think the 1.5KW tranny costs me around $450 some years ago, expect to pay more today..  

Edited November 7, 2018 by The Fez