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RE: Outfitting AC to 220V in USA

I live in Hawaii and have the opportunity to purchase an ASR Emitter I amplifier (220V version) for bi-amping. My AC is currently at 120V but my electrician tells me he can run a dedicated 220V line from my dedicated audio circuit breaker to power the 220V amplifier. The amplifier's power cord has a standard 15 amp IEC and has what I believe to be a German Shuko two prong plug.

I contacted a business that specializes in selling European wall outlets, transformers, and outlets. The representative recommended that I pick-up a transformer to convert 220V to 120V to power the 220V amplifier.

I would prefer not to purchase a transformer and would rather (if possible) have an electrician install a dedicated 220V line and install a Shuko wall outlet, that will enable me to use the amplifier's power cord and go directly to the wall outlet. Is this possible? If so, does the standard German AC power line or shuko power cord have two positives, one neutral and one gorund OR two positives and one ground OR two positives and a floating ground?

If a transformer is the only alternative, can you provide me with a brief explanation why. I do not know if I will have phase problems.

I would appreciate your thoughts to my questions. Thank you in advance for your assistance.
hawaiikid
tobias
1,534 posts
 
I suspect you may wind up going the transformer route. If you do, the amp may be starved for current on peaks if the transformer core is too small. To avoid this, get a tranny that is larger than the load seems to require. Two or three times larger is not excessive. In exchange, the extra isolation the transformer provides will help to quiet the background and enlarge the soundstage.
jea48
4,453 posts
 
An update ....... A technician who sells European plugs and outlets informed me that I should purchase a transformer to convert from 220V to 120V. I was told European or overseas power has only one phase as opposed to USA with 3 phases.
>>

Huh?

Houses in the USA are fed from a utility power transformer with a single phase, split phase, secondary winding. 120/240 volt nominal grounded ac system.

The 240 volt is single phase that being 2 hot conductors. Have you heard of balanced power, 60V - 0V - 60V, isolation transformer systems? The secondary of the balanced isolation transformer is a split phase winding. The secondary winding is center tapped in the middle of the winding, thus split phase. The center tap is connected to earth ground. Well that is exactly what is done with houses in the USA. 120V - 0V - 120V, the center tap is connected to earth ground and becomes the grounded conductor the neutral.
....Hot.............Grounded...........Hot....
.....L1..............Neutral.................L2......
...120V.............0V..................120V.....

....^------------240V-------------^

Most European homes electrical power is single phase 240 volt nominal grounded system. One hot ungrounded conductor and one grounded conductor the neutral.
hawaiikid OP
107 posts
 
Jea48 ......... Thank you very much for your explanation. You are the first person to really explain this to me and I appreciate the time you took.
ngjockey
1,042 posts
 
There are rare pieces of audio gear that don't like split phase. Most have no compatibilty issues and European gear would be even less likely to have problems than American because of international standards.

All electric stoves and dryers use 240V (+120/0/-120) in US/Canada. The two hots are 90 degrees out of phase (inverse sine wave) and cumulative. Oddly, this is still, most often, called single-phase. The neutral only carries the difference ("garbage" for a single load) between the hots. 3 phase is used in industrial/commercial motors where three hot 115V, or more, at 60 degrees phase add up to 208V, or more. 3 phase has no neutral and, sometimes, no ground.

An adequately sized transformer would isolate and filter AC and often sounds better. They're not that expensive, if you know what you're looking for. It only has to reproduce a very narrow 60 Hz bandwidth. Converting from 60 Hz to 50Hz is usually not necessary for audio gear.
jea48
4,453 posts
 
Hawaiikid, you will notice I did not give a position one way or the other what you should do. As for Hawaii I only assume your ac power system is like what we have here in the lower 48. You stated the equipment you were interested in is 220V. What is your Line to Line, L1 to L2, voltage in your residence? You will notice for the voltage readings I gave for my examples I used 120V and 240V "nominal". My L1 to L2 measures 247V, Line to neutral 123.5V, in the evening hours.

If you decide to install a 240V branch circuit you will need check the actual L1 to L2 voltage before doing so. What is the voltage tolerance of the 220V equipment? + or - ?

If you decide to buy a transformer make sure it is large enough as others have posted here.

You have two choices to make for a transformer,
A step up autotransformer 120V to 220V nominal. The cheaper way to go. In this case no isolation from the Main Line power.
Or a step up isolation transformer 120V to 220V nominal. Best way to go but a lot more money.
Jim
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