Step down transformers detrimental to SQ?

Hello, does anyone know if step down (or up) transformers have adverse effects on sound quality? I'm looking to pickup a 100V amp and use a step down here in US. 

not sure about effect on SQ but would assume no problem unless in too close proximity to other transformer.......and would you not need a step UP transformer here with a 100V amplfier?
You won't need a transformer. Not if you're talking about line voltage. Line voltage is nominal, as in uncalibrated, as in it varies. What is called 110 here in the US can turn out to measure lower. (Occasionally even quite a bit lower, in what is called a brown-out.) Which, strangely enough, voltage running a little low like that turns out to be a much bigger problem than voltage that runs high.

This is because, first thing your amp does is run the incoming AC through its power supply. The power supply converts the AC to DC. Everything actually runs on this DC power supply. CD player, turntable, DAC, your laptop for that matter. It all runs on DC. As such it is all pretty darn near immune to AC voltage- unless said voltage drops too low. Damage from high voltage however only happens when voltage spikes crazy high. Think lightning. Some tens of volts though is nothing. I travel, and have plugged in many times to 200-220v, none of my 110v gear was ever harmed in the least.
@bsmg I was under impression that I need a step down because the voltage from my wall is higher than the amp spec. So it takes 120V down to 100V for amp intake? I could be wrong though. I've never used a transformer.

@millercarbon Are you sure I can operate a 100V amp in US? This overseas dealer has specifically told me it would kill the amp if I plugged it into 120V w/o transformer?
If your overseas dealer told you that then he's as electrically misinformed as, well as pretty much everyone else. You're talking to a guy who has wired a whole house, recently installed a panel, and has a whole system personally custom wired to run on a dedicated line that goes from 220v coming out the service panel to a custom solid silver step-down transformer that does drop the 220 to 110 just under my listening room. Not to mention built a 200 watt amp, modified lots of electronics. And yes I am sure.

But hey, don't take my word for it. Go try and find yourself a step-down transformer designed to go from 110 to 100. Good luck! They don't make one. For the simple reason there is no market for one. Because nobody needs one. Because it just doesn't make any difference.
Incidentally, and this is probably nothing, but I am curious to know if this is an older vintage type amp? And where was it made?

Again, there's no problem with higher voltage. Its lower that tends to cause problems. And since if you go back to say early 1900's America (or 'modern' day California) you were much more likely to encounter low voltage situations, its possible they were designing (and labeling) electronics for those somewhat lower voltages.

Either that, or it was made somewhere with substandard (by modern standards) electricity (like, you know, California) or maybe even somewhere foreign. Like.... all together now.... California.

Kidding. California would get the label right.

But seriously: vintage? Country?
@bsmg I was under impression that I need a step down because the voltage from my wall is higher than the amp spec.

Sorry; you’re correct. I misunderstood what you were asking.

Don’t know where millercarbon is but my power conditioner shows a digital voltage readout when it’s on and I’ve never seen it drop below 121V and most of the time it reads 123V,,,,,,in northeast TN hard by the VA border.

And you're lucky with that 220V stuff......I once plugged in a 110V blow dryer in Manila; it ran real fast for about 2 seconds and died.
Sounds like you bought a Luxman on Ebay. :)

Yeah, just get acupwr and you should be fine. I heard good things about them, I would not save a few dollars on this device.
As for sound quality..shouldn't make things better, I'd say. You will want a very good low gauge power cord for amp, anyway.
Step down transformers detrimental to SQ?

Just make sure the amperage rating is at least two times higher than the mains fuse on the amp this should keep the core from saturating even a little.
Also step down transformers can actually be better for mains born noise getting into the amp.

Cheers George
I heard some crazy Japanese audiophiles do double conversion, up and down, and claim it improves the sound. I should try it one day. But before that I should try to run my Nak deck on 220V - it has custom dual voltage transformer.
Thanks for the acupwr link.

And @erik_squires yes well I haven't purchased yet but eyeing a Luxman from Japan off eBay.. good guess! :)
Excel Audio has 505's for $2,600

Line voltage is nominal, as in uncalibrated, as in it varies. What is called 110 here in the US can turn out to measure lower ...
This is mistaken. Nominal voltage in the US is 120VAC and is regulated by state agencies, such as a Board of Public Utilities. Typically, a tolerance of ±5 percent is allowed.

I wouldn't recommend using any device designed for 100VAC on a 120VAC line.
I heard some crazy Japanese audiophiles do double conversion, up and down, and claim it improves the sound.

Not quite but close, there is a bit of a fad at the moment over there, to use 1:1 isolation transformers, which are 100v in 100v out they are doubling up on these.
I’ve used a 2amp one now for 20 years now for my source equipment only, and will always do so.

here is a US made one, I’m sure there are others.

Here are some eBay ones.

Cheers George

I ran a Luxman Class A amp 100v with a step down and found it wonderful. You do need a step down as the extra 10-20v in NA can cause issues.

 If you are concerned think of it this way there is a huge step down transformer out in front of your house or very close to it taking the 20'000ish VAC down to your house voltage so we all have a (many)transformer(s) in our circuit weather we want to admit it or not, well unless your running off batteries. Also there is always one inside your amp so another one really isn't a concern just make sure its big enough to handle turn on surge and power delivery.

Look on the back of your unit for power usage and triple it for a good measure. I ran a 1kw step down with my 50wpc Class A amp with no issues and room to spare.

interesting Georgehifi on the 1:1 that may be useful for DC blocking. DC on the line can cause transformer mechanical hum.

  Excel Audio has 505's for $2,600

I ordered one last week, arriving today.
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Its also possible to step down the AC voltage by doing an old DIYer trick which is to buck the AC line voltage.

This is done with a smaller transformer that has a secondary rated for the current you need (50% more than the fuse rating is good) and the difference in voltage. Since most homes are at 120Volts these days, that's a transformer with a 20Volt output at however many amps your amp needs.
The primary of the transformer runs off of regular wall voltage. The secondary is put in series with the AC line going to the amp. You have to try the secondary hookup both ways- one way will buck the voltage up 20 volts (adds to the line voltage) the other way will subtract 20 volts which is what you want.

The result is a much smaller and less expensive transformer can be used but you have to know more about how to use it. There are always tradeoffs...
interesting Georgehifi on the 1:1 that may be useful for DC blocking. DC on the line can cause transformer mechanical hum.
Yes also RF as well.

Cheers George
+1 atmasphere, I have used a bucking transformer and it's a very clean solution to the problem, but if I recall mine only dropped the voltage around 14V, not 20V.
What about the difference in cycles per second? 50 v 60 hz....
A web search turns up ONE country on Earth running 100v, Japan. The world being a big place rendered tiny by the internet, where anything and everything can be found (a German man looking for people willing to be killed and eaten had several applicants) and knowing how people love to prove others wrong even if it means missing the whole point, saying there aren't any was a bad idea. I stand corrected.

But, calibrated (what I said) and regulated (what I never said) are two completely different things. Seriously. You could look it up. The 5% regulatory variance allows the NOMINAL (means, you could look it up, in name only) 120v to vary as low as 114v. Whatever. The question was, do stepdown transformers affect SQ. The answer is yes. And do I even need one? To go from 120 to 100? To avoid damage? The answer is no.


Your spreading some ignorant nonsense.  Most places in the US have close to 120VAC - and if running an apparatus with a 100VAC primary winding you will end up with 20% over voltage on the input to all  internal DC regulators in it.   This can be a serious issue because the regulators now will have to dissipate an additional 20% of heat and if marginally heat sinked,  this is trouble.

Most definitely use a step-down transformer, even better if you can find one with isolation as well - this will produce cleaner AC power to your amplifier thus resulting in higher SQ.

Good Listening


An equally important concern is if it is 50Hz or 60Hz current.  Running a 50 Hz unit on our 60Hz can cause overheating. (If it’s 50/60Hz rated, you are okay as far as current goes)
NC fan

Actually it is easier for a transformer to run on 60Hz than 50Hz so that would be a non issue.

Good Listening 


@erik_squires Thanks for the tip that is an amazing price...

Thanks all this has been informative.
You can get a bucking transformer for less than $50.00 that would do the job with many amplifiers. You might have to spend $100 for a really big amp.
+1 on the Accupower.

I bought one and am pleased with it.  In the event you purchase one, I suggest you opt for one which allows for future growth.