Stepdown transformer 240v - 220v

Hi Guys
I have a integrated amplifier that is set for 220v European and i need to use it on a 240v outlet here in Australia , the amplfier transformer is rated at 500va and the amp is 100wpc into 8ohm
what size stepdown transformer would i need ?
i have seen a stepdown that is rated at 600w - 2.7 amps
and a 1000w - 4.5amps .
I wish to maintain the best sound from the amp and don't want to restrict its power supply .
sorry but i am a bit of a nuff with electronics.

Thanks for your help


These are the bomb, will do 240 or 220 at the push of a button on the front panel and regulate voltage. I have one , good stuff.
Some further info on the amplifier :

2x100W @8ohm and a 2x220W @2ohm output power with a 50 A (!!!) current peak.
Another peculiarity of this amplifier is that it works in class A up to 2x5 Watts @8ohm.
Minimum I would recommend for ANY amp is 2KVA. Maybe 1.5 KVA for an autoformer but I would rather have the isolation of secondaries.

2000W / 240V = 8.33A

These have got to be autoformers/converters. Real transformers with primary and secondary windings would be a lot heavier.

The following are transformers but don't have an enclosure and require proper wiring/outlets.
Hi Ng
Thanks for the link to the Tortech site
What is th difference between a autoformer/converters and say a Real transformer ? as stated in your post .
They have a 2400v - 11 amps unit as well for around $20.00 more.
Any real advantage with the 2400-11amps over the 2000w -9amp
I have read that stepdown transformers can degrade the sound of a amplifier so just don't want to make a mistake with a purchase.
In general my outlet reads between 235v & 245v depending on the day and different times , one day i checked and it was 225v ,came back 30 minutes later and it was back up to 241v
We have a power pole transformer 2 doors up on the road side.

Here is a little blurbabout the difference between and autoformer and transformer.
It may help:

Thanks for the link Elizabeth
starting to get my head around the workings of stepdowns
my main concern is getting a stepdown unit that will not bring a audible reduction in dynamics hence my confusion as to what size to buy , I am not much of a electronics man
just a enjoy the music kinda guy :)

Tasmania . Aus
"What is the difference...?"

Between the Tortech and the Signal SU/DU at 2000 watts, about 20 kg and several hundred dollars.

An autotransformer only has one winding and offers no isolation and no filtration. They are more efficient per weight and cost. If you want a packaged unit, that may be the only option available.

The mass of bigger core with dual/quad windings does give it some magnetic stability, if I'm using that term properly.

Bandwidth is not an issue for power transformers, unlike audio. They only have to provide 50 or 60 Hz. In fact, the narrower the better.

As far as degradation, there are various opinions and experiences and I can't account for each implementation although I've seen some that were just wrong. I've got several oversized isolation and center-tapped (don't ask) transformers and haven't heard any degradation, just a bit less noise. Not a big proponent of using them for amps because of the way a class AB amp draws power in spikes, but as long they're sufficiently oversized, it shouldn't hurt.

Be aware too that transformers can have a mechanical hum that can be unpredictable to each installation and environment.

Thanks Ng
Will look to purchase a Tortech unit
as they are local here in Australia and at around $200
affordable .

How old is the amp ? Europe has been 230V, not 220V, for the past 15 years. If it works with 230V, it will have absolutely no problem working with 240V (hey, I measure 236V at my AC outlet most of the time).
Hi Elberoth
The amp is from the mid 90s , 1996 i believe ,
it has 220v stamped on the back , this is a review link to the amp in question.
The amp is Italian -A.M.Audio PA-100.


I wouldn't worry too much about that. There are thousands of amps on the market in Europe, that were made with 220V in mind. Now we have 230V (which means that allowable voltage is deviation is 207-242V, according to the +5%/-10% rule) and you do not hear about the older stuff suddenly breaking.

Measure the voltage across your AC lines, and if it is less than 240V, I wouldn't worry one bit.
Hi Elberoth
Been away on travels
checked the mains and it is a constant 244v - 245v
i have noticed that A.m audio's current amplifiers still have 220v stamped on the back ,

Does 220v with a squiggly line behind it and nothing else
imply it is 220v only ? as i have seen 220/240v on other equipment.
Received a response from the manufacturer and was informed

Nominal supply 220 VAC

Power transformer from 245 to 220 VAC minimum 1000VA.