[rockthecatbox]

I am considering buying a Yamaha Amplifier that is rated for 110/220Volts.  Based on the manual this is the "general" power supply version rather than the US 120V version.  The current owner (who brought it from Japan) says it's safe to use in the US.  Anyways I have my doubts.  I've sought out the answer but the more I read about it the more uncertain and nuanced the answer seems.  If you have any experience I would appreciate your input.  Thank you.

The amplifier is a Yamaha MX-800

[kd4ylq]

I've used Japanese market power amps (110v) without any problems here in the US. If you only want to run it as intended, you can buy a Variac (variable autoformer) and dial up 110v for the output voltage, or anything else "nearby" for that matter. The nicer, i.e. more expensive ones have built in metering for voltage and current draw - but they aren't exactly cheap.

[I.Greyhound Fan]

I own a Luxman DAC that I bought direct from Japan and it is 110v.  I use a step down converter and it sounds great.

I use something like this-

https://www.amazon.com/OLTEANP-Converter-Transformer-Universal-Protection/dp/B0CZQNMNY8/ref=sr_1_19?crid=3G6TPX097MYBQ&dib=eyJ2IjoiMSJ9.nLSKbNCSifZMdQnJmAcvM-C9oR6-QYtB1fjHRydnYsQPhkXu-DyxXkkBfEZUvWEwPFKzaXYTSwslLuxezBIHo_6Jk7sT2V1lIdgFzUOQHNz0nGDtP3yI3xMq0RZWa38yX0VgH9PCslIcEeUddK676rHdwmy2CIw4uW05ZtXpzMEDK8rzjPgpz2KD1EOyGNAI5RCvwUz1HheYVyyrjav92pOrBURSMQ00kycU3emR1rg.ii_ZpfMrANejETy4_ktSsW4Hsh_iNYQntFSnaMuoBfw&dib_tag=se&keywords=120v+to+110v+transformer&qid=1721919854&sprefix=120v+to+110v%2Caps%2C126&sr=8-19

[Speedskater]

A person with electrician skills, could make a 'Buck/Boost' transformer.

Bucking (And Boosting) Transformers
Copyright © 2010 - Rod Elliott (ESP)

https://sound-au.com/articles/buck-xfmr.htm

[toocool4]

Most equipment are designed to handle +/- 10%, the frequency is a different matter.

Me personally would not buy what is intended for my location. 

Years ago when I bought NuForce mono amps Ref 9se V2 from New York to take to UK, it was designed to work from 100v - 250v

[John Tulett]

According to the Yamaha MX-800 service manual, it describes 4 versions of this amplifier's power supply voltage.
- A. Australian model.  Set to 240 V.
- B and G. British and European models, respectively.  Switch selectable to 220 or 240 V.
- C and U. Canadian and USA models, respectively.  Set to 120 V.
- R. General model.  Switch selectable to one of 110/120/220/240 V.

It wasn't clear which power supply version from the wording in the original post.
- "Based on the manual this is the "general" power supply version rather than the US 120V version."  If it's the General model the service manual implies this version is selectable to any of 110/120/220/240 V.
- "The amplifier is a Yamaha MX-800u".  If it's a U model the service manual implies this version is set to 120 V.

There may be more to it than this and I may have missed something, but in any case, please find an extract of the Yamaha MX-800 power supply circuit diagram showing all 4 versions A, B/G, C/U and R - hopefully this can help make sense of things.
 
Thanks,
John

[rockthecatbox]

Many thanks - I think I am mistaken about the "U" and it is the MX-800.  I will know shortly and your information is helpful in any case. Cheers.

[Stercom]

Use a step down converter (120 down to 110). They are cheap and work well. Really doesn't make sense to chance a failure. Years ago, I had a "discussion" with a dealer who was selling stereo equipment in the US that was designed for the Japanese market. He claimed no step down was needed but, of course, he finally admitted the manufacturer's warranty "may" not apply if the wrong voltage was used! Anyway, just buy a step down!

[Doublej]

Look at the back of the unit. As shown in the picture below, to the left of the power cord you should be able to determine what voltages the unit will work with.

https://cdn11.bigcommerce.com/s-6naz0isypk/images/stencil/2048x2048/products/12586/81005/5588130-7466-7__18687.1510824357.jpg?c=2

[rotarius]

There is no need to step down from 120 to 110v.  That is crazy.  If your amp was 100v for Japan, then yes.  110v-120v is just fine.  It has to be designed within a range and 10% variation is allowed if not more.

[FullRangeMan]

How much is the tension in your wall outlet?

[I.Greyhound Fan]

I bought my Luxman DAC direct from Japan and it is 110V.  I bought a step down converter like these and it works great.

https://www.amazon.com/s?k=120v+to+110v+step+down&crid=3027WYVDCBFU&sprefix=120v++to+110v%2Caps%2C129&ref=nb_sb_ss_ts-doa-p_3_12

Just make sure you buy one with appropriate watts.

[Bill Baker]

What is the voltage at you outlet. It ranges quite a hit in the US. I’ve had customers with everything from 110-140VAC. You may not be that far off to make a difference.