Anyone use 100v or 220v gear with a transformer?

Is there a downside to using a 100v or 220v amplifier with a step-down or step-up transformer to convert to 120v?
NO issue if you use a big enough transformer. Extremely high power 220 V devices may draw too much current for some 110v household circuits since the current will be doubled into the step up transformer.

Note that many very old devices, turntables and motors are designed to work on 50 Hz (use zero crossings or frequency for timing) and will not work properly at 60 Hz without modification. Nowadays most electronics use crystal oscillators and don't care about line frequency...although power supplies and motor windings are normally adapted to frequency too - anything with a motor may not perform in an optimal manner.

(Note that a step up transoformer does nothing to change the frequency)
I was considering a Japanese unit (100v), and was thinking of using a Japan Voltage converter.
Thanks, Shadorne. I am specifically interested in a tube amplifier that draws 195w maximum according to the manufacturer's spec sheet.

The step-down transformer manufacturers suggest a maximum load of no higher than 90% of the transformer's rated wattage. So, if I use a step-down transformer rated for 300w I should be fine, yes?
300w is going to be too small. It will 'work', but you'll probably find the amp sounding constrained. Any transformer with a 1KVA rating should do.


05-13-07: Pauly
300w is going to be too small. It will 'work', but you'll probably find the amp sounding constrained. Any transformer with a 1KVA rating should do.
According to the electrical conversion formulas on this page, 1 kVa would equal 1000 watts.

If the maximum draw of the amplifier is 195 watts, how will providing 1000 watts be more beneficial than providing 500 watts (or more than double the maximum draw of the appliance)?

Also, the amplifier uses a 5a fuse, so 100v X 5a = 500 watts. The amp's fuse blows at 500 watts, so supplying more than 500 watts seems superfluous, yes?

What amp or preamp are you looking at?
I would think that the smaller x-former would heat up significantly. Depending on the windings, hot coil wire could change the resistive load, thus leading to slight voltage fluctuations. Yes? No? Opinions?

You will probably have to change you main fuses, especially if going from 220v to 110v.
This would involve a small step down from 110-120v to 100v.
Electrically it'll work. Sonically it will not. I can't beleive nobody hears the degradation using a step up/down transformer causes. Its not subtle. I'd try to find a 120v unit instead.
Your power company uses step down transformers themselves. I use a tranformer with my Japanese laserdisc player which is 100v and have not had a problem in the five or six years I have used it. It sounds wonderful by the way. It really makes DVDs sound anemic in general.
A transformer is best when it doesn't approach it's limits. For that reason, I suggest using at least double the draw. So I agree that 500 VA to 1 KVA would be better.

Also, a transformer can have a mechanical hum, espescially when overworked or supplied dirty power. The benefits of a transformer are elimination of DC offset and roughly 12 dB noise reduction (toroids being half that but less likely to hum and more compact). Good for ground loops too. There is some draw at idle but they are efficient enough to not worry about leaving powered.

Signal Transformers has a DU series that is shielded, Q-rated and steps down to 104V. These are not in boxes and do not include plugs.

I have never experienced any drawback using power transformers aside from one (of several) humming but that one was scavenged from industrial equipment. I have used them for isolation and to convert to balanced AC and in all cases, the sound was improved. Sometimes subtle, sometimes amazing.
+++ If the maximum draw of the amplifier is 195 watts, how will providing 1000 watts be more beneficial than providing 500 watts (or more than double the maximum draw of the appliance)? +++

Easy, transformers are reactive by nature and distortion/reactance goes up the closer a trans get to its rated output. The bigger the trans the better. A 1 to 5 ratio will yield about the best performance per buck.

If you were running a 200watt heater or refrigerator I'd say use a 300watt trans. A 300watt (or 500watt) trans will not let your amp do its best. .

As usual bad advice reigns supreme. Not that I think anyone here is purposely being misleading... they just must not be capable of hearing it. I suppose that makes them lucky. Regardless- a transformer will absolutely diminish performance. But 117v gear for a 117v country.
But 117v gear for a 117v country.
Specifically what equipment have you heard while using a step-down transformer, and what was the voltage conversion used?

BTW, welcome to Audiogon. Thanks for posting your first two answers in this thread.
I've heard several pieces with transformers over the years. I recently had a Reimyo CD player and a Airtight preamp that was 100V. Both were sold after I heard my friends 117v Airtight in comparison. Both had the same tubes and it was in the same system. The dynamics in particular were much better without the transformer. The transformer was a 2000 watt unit which had won out in comparison to a few others I tried. Its not a small difference. Why do you think manufacturers go through so much trouble to design a power transformer?
Thanks for the welcome. I don't normally post but this topic was fresh in my experience.
I'm often amazed how much time people devote to forum posting rather than music listening. Tonight I'm forced to keep my system off- my girlfriend is studying.
As usual those who disagree can't hear well enough to know the difference. I guess we are all very lucky not to afflicted with golden ears. There are many sound improving devices available that use transformers for isolation. The more filtering from the power company, the better. We use such devices all of the time with portable CD players and telephones and many like devices.
+++ a transformer will absolutely diminish performance +++

That is patently untrue. Given the correct isolation transformer, it will dramatically improve your sound, especially if you live in apartment complex where the mains are very dirty. Isolation transformers can drop noise floor by 6 to 12 db.

Folks like BPT don't have thriving business because their products detract from sound.

I guess you are the lucky one – enjoy your iPod.

Interesting and informative answers from everyone. Most agree (including the manufacturer's Japanese representative) that a step down transformer can be used without problem.

The issue of sonics is the quagmire. Other than the mention of degraded sonics here, the only other mention of this has been from a US dealer. Clearly, there could be an agenda with the dealer, but I also am not willing to dismiss the possibility of degradation.

I have decided to forego purchasing the Japanese unit.
I have decided to forego purchasing the Japanese unit.

Sorry to hear you have been frightened away from your plan. I agree with Pauly that bigger is better. Most Transformer cores saturate when used close to their rated power and that is when you get annoying humming from DC offsets and potential degradation in the quality of the power.

I am actually quite surprised that the Japanese unit will not function with 120 Volts if it is rated at 100. I would have expected the Japanese device would tolerate the slightly higher voltage. (Nominal power is allowed to vary about 5% from your utility and devices are normally designed to function properly a further 3% to 5% outside this range (due to further voltage drop in the home). I would expect a similar kind of tolerance for Japanese equipment.

Signal degradation is very unlikely.
The ability of the 100v unit to function on 110-120v either straight to the wall or with a step-down transformer was not the issue. Sonic degradation was an issue, as was safety and warranty service, which would have required shipping the unit to Japan for service if it was required.

I spoke with someone today who is intimately involved with tube gear, and who has no agenda whatsoever, and his advice was to buy the 120v USA version.

I'll have to admit, it was difficult passing up the opportunity to buy the Japanese model for 45% less than the US version with 120v transformers (and nothing else different), and because of the large price differential I will likely explore other integrated amplifiers.
If you run a 100v unit on the 120v USA standard, don't expect your unit to last too long...and forget about your warranty! The USA standard is 120v +/- 5% [or 114v to 126v]. So at best, you'll be running at a 14% over-voltage; at worse, a 26% over-voltage...OUCH!
Point made.

Moving on...