[Gopher]

I have my eye on a particular amplifier I really want that happens to be made in China.  I have found a source for it that will sell it for approximately 50% of what a US dealer would, but due to their contract with the manufacturer they can only sell  220V, 230V and 240V versions. 

Even buying direct from China, we're talking about $3k...   

Would trying it be a poor idea?  I imagine a step down transformer between my uberbuss and the Gran Corona power cable I want to use would negate their benefits...

Any thoughts?

[avahifi]

IF the unit in question has a power transformer with dual primary taps then rewiring it for 120V is not all that hard. See if you can find information about that.

In general, with dual primaries, they will be wired in series for 240V, or in parallel for 120V. Of course there is always the catch of what to do with any illumination aspects of the unit if they are run from the main 240V AC.  They then will be way too dim if connected to 120V.

If you decide to go with a 240V to 120V step down transformer, get one with at least double the current rating of the amplifier or it will apt to buzz and hum and run really really hot.

Regards,

Frank Van Alstine

[Gopher]

I inquired from the distributor about the dual primary taps, but was informed: "ACCORDING TO FACTORY INFORMATION IT IS NOT. VERY SORRY."

I guess a step down transformer would be the only option which isn't very appealing to me...

[Ericus Rex]

Is changing the power tranny an option in a case like this?  Assuming it's still cost effective to do so?

[Speedskater]

Almost all US homes have 240 Volts available at the main breaker box.  But it would require an electrician to get it to your listening room.

[Gopher]

Is changing the power tranny an option in a case like this?  Assuming it's still cost effective to do so?

it is possible, but I was surprised to get a shipping quote of $617 to the US...  That coupled with the pain in the ass factor makes me more inclined to spend a couple hundred more and just by a US model demo unit and rationalize the extra expense with a future resale value.

[Jazz and Baroque]

You might also consider that most electrical power outside the US is at 50 Hz, not the USA standard 60 Hz.  You can't change this with a step-down transformer.  Considering how well-tuned a power supply has to be, a change in the system freq could easily make a difference.  In a 50 Hz country, the filter would be tuned to remove 50, 100, 150, etc. rather than the US filters that would be tuned to 60, 120, 180.  Maybe, maybe not. 

YMMV,
Mike

[Ericus Rex]

it is possible, but I was surprised to get a shipping quote of $617 to the US...  That coupled with the pain in the ass factor makes me more inclined to spend a couple hundred more and just by a US model demo unit and rationalize the extra expense with a future resale value.

Maybe an equivalent tranny can be special-made in the US or, fingers crossed, be an off-the-shelf unit.  Worth the phone calls to a couple of transformer manufacturers if it can be had for under $200.

[Speedskater]

Except for units that have motors that need to operate at a certain RPM (like turntables) almost all 50 Hz units will be fine operating on 60 Hz power.  However the reverse is not true.  Units designed fo 60 Hz will be unhappy with 50 Hz power.

[avahifi]

Don't even think about running your amp on US 240V AC!  It is not safe.

European single phase 240V is simply that a hot 240V feed and a ground return.

US 240V is done by summing two 120V feeds and while this is handled safely on large appliances designed for this (electric stove for example) trying to do this with your power amp most certainly will put one of the 120V feeds hot on the chassis of your amp!  BIG TIME ZAPP FRY!

Regards,

Frank Van Alstine

[Speedskater]

Thanks Frank for pointing out that it's very possible for a unit to be wired for un-balanced 240V rather than balanced!

Jim Brown touches on the subject (pages 39 to 41), but all in all International wiring is very confusing!
http://www.audiosystemsgroup.com/SurgeXPowerGround.pdf

I think that US power is center-tapped 240V.

[Occam]

Don't even think about running your amp on US 240V AC!  It is not safe.

European single phase 240V is simply that a hot 240V feed and a ground return.

US 240V is done by summing two 120V feeds and while this is handled safely on large appliances designed for this (electric stove for example) trying to do this with your power amp most certainly will put one of the 120V feeds hot on the chassis of your amp!  BIG TIME ZAPP FRY!

Regards,

Frank Van Alstine

Frank,

I don't follow your assertion. I don't understand how running a component configured for single ended 120vac primaries on the power transformer off split phase balanced/technical 60-0-60vac is any different from running a component with power transformer primary wired for 240vac on North American split phase 240vac. I'm not discussing the merits of balanced power, but trying to understand the danger in a non-fault condition.
Certainly, stereo components running off split phase power, whether net 120 or 240vac should be GFCI protected as a component's power switch might not switch both poles (this is a Code requirement in the US for balanced/technical power, the requisite GFCI receptacle of any Code compliant external balanced transformer will also check and break for ground/neutral leakage). For a purpose run North American 240vac split phase circuit, one would simply use an appropriate GFCI breaker (properly adjusted and tested!).

This does beg the question, is a component configured so that the neutral wire is bonded to the chassis, which is an obvious danger for any split phase power. For the last 35 years, the answer is NO!, as UL and any ETL does not consider reversed hot and neutral a fault, and therefore such an 'appliance' is automatically defective. I believe, but would not swear to the fact that European and Japanese have similar standards.(I've no knowledge of PRC standards).

I actually remember from 35+ years ago 'AC/DC All American 5' radios as well as some very fine tube amps with neutral bonded to chassis. But time has marched forward. No modern component should ever bond neutral to chassis. While I don't currently run balanced/technical power, I used to, and I'm old, so I try to remember to check anything coming into my home for proper power input and chassis continuity & DIS-continuity, as appropriate.

If one receives a non-vintage component that bonds neutral to either chassis or safety ground, it is faulty and should be returned, and if not returned, thrown out. YMWNV

FWIW,
Paul

[Occam]

Gopher,

If you'd like, you're welcome to a 3kW+ isolation transformer, in a chassis, gratis. For some odd reason, SWMBO doesn't find it as aesthetically pleasing as I do. You'll need to change the plug and receptacles as they're locking.
But you've gotta come in from L.I. to Brooklyn and hump it out yourself.
You can rewire it to step up, single ended or split phase. Its currently wired for 1:1 isolation.
I think you're better off with properly configured 120vac primary components, but depending, it may be easier  and less costly to use a step up isolation transformer rather than run a 240vac line. I have far too many transformers laying about. PM me if you'd like a hernia....

Regards,
Paul

[Doublej]

it is possible, but I was surprised to get a shipping quote of $617 to the US...  That coupled with the pain in the ass factor makes me more inclined to spend a couple hundred more and just by a US model demo unit and rationalize the extra expense with a future resale value.

That's what I would do. Will it also come with a different more useful warranty? Shipping a unit back to China for repair doesn't seem feasible to me.

[Wayner]

I think Frank's point may have been missed here. The said amp, designed to run on 240volt with the usual hot and neutral will have the hot line fused. Does everyone agree with that?

Now, if we hook this amp up to our 240 volt system that we all have in our houses, the amp will now have one leg fused, the other, not.

Perhaps this is why Occam made his point about GFCI. So, to my thinking anyway, there is a wiring issue here. Obviously, there is going to have to be 240 volt outlet installed somewhere. The amp will not have the Neutral connected, but should have the ground connected.

I would install another fuse on the unprotect side of the supply, that matches the existing one.

The other avenue to take is to purchase a step-up transformer (120-240) and plug your amp into that.



Get it from here: http://www.parts-express.com/pe/showdetl.cfm?Partnumber=120-825&FTR=120-825

The simple and safe way around this problem....

Wayner