Step down Transformers do they work well?

[Anthony Goldie]

 

 

I've been looking into importing some American power amplifiers which run at 110v rather than the 240v here I was wondering if anyone has used step down transformers to power any gear from the US and how did it go?

[muon*]

Tortech in Sydney make good step downs

[rockeater]

3 hours ago, Anthony Goldie said:

I was wondering if anyone has used step down transformers to power any gear from the US and how did it go?

I have and I am using one to power my Wadia 861 player.

But powering a CD player which uses 20W of steady power is one thing, supplying current to a power amp is another.

Power amps which are not Class A, use "power on demand" which varies a lot depending on gain and music material.

If you want to have any kind of decent slam, I would advise you against it.

 

Or, pick one which has an international version and in which you can switch it to 230V AC.

[Warren Jones]

I also used a 240-100V step down to run my Technics SP10 for a couple of years before I built a Victor TT-71 for a mate and passed the set down onto him.

 

Stepping down the voltage steps the current up, so as long as the TX is sized correctly you should have no issues. Just make sure any step down you do buy is approved for use in Australia, if it's not then you could have insurance issues if your (god forbid) your house burns down.

[Monkeyboi]

I've used them.  Things to consider -

 

• Beware of auto-transformers that don't have a separate and isolated secondary winding.  Not recommended.  Steer clear of any transformer with dubious or incomplete specifications and ensure the transformer complies with Australian electrical safety standards.
• Cheap transformers can buzz and hum even when under no or low load.  This can be very annoying if audible.  
• Power amplifiers unless they have a soft start circuit can draw very large currents at switch on.  Something to consider when selecting a suitable transformer.  You don't want to be blowing the transformer's protection fuse.   
• As @muon* said.  Tortech make good units.  Worth checking them out.
• as @rockeater said.  Constant power consumption devices are easy to power via a transformer as long as the transformer matches or exceeds the VA rating of your device.  With your typical power amplifier (not Class A) if you must use a transformer buy one which greatly exceeds the VA (maximum power consumption) of the amplifier you intend to use otherwise you might run into voltage droop issues when pumping up the volume.
• as per what was said by and IMHO @Warren Jones

[xlr8or]

When using a 240v to 110v US stepdown one thing that is often overlooked is US versus AU AC mains frequency - i. e., 60Hz versus 50Hz. It's important to check if the US power amps can accommodate both 50 and 60Hz for their power transformer ratings.

[Plasmod3]

On 02/09/2022 at 5:07 PM, xlr8or said:

When using a 240v to 110v US stepdown one thing that is often overlooked is US versus AU AC mains frequency - i. e., 60Hz versus 50Hz. It's important to check if the US power amps can accommodate both 50 and 60Hz for their power transformer ratings.

I understand 50 vs 60hz affects mostly motors rather than electronics isnt that right?

[Monkeyboi]

3 hours ago, Plasmod3 said:

I understand 50 vs 60hz affects mostly motors rather than electronics isnt that right?

 

There's a bit more than that if you delve a bit deeper into transformer theory, but the frequency of the supply matters if the device relies on the frequency of the mains power to operate correctly.  Examples are synchronous turntable motors not controlled by a separate frequency generating circuit, some digital clocks not using their own crystal oscillator and some voltage regulation equipment designed specifically designed to operate at a specific frequency.

 

Some other possible issues might be using a transformer designed for 50Hz / 60Hz operation on aircraft which typically use a 400Hz a.c. supply.

 

For most applications any well designed transformer will (if suitably rated) perform adequately on either 50 or 60Hz.

[Plasmod3]

8 hours ago, Monkeyboi said:

 

There's a bit more than that if you delve a bit deeper into transformer theory, but the frequency of the supply matters if the device relies on the frequency of the mains power to operate correctly.  Examples are synchronous turntable motors not controlled by a separate frequency generating circuit, some digital clocks not using their own crystal oscillator and some voltage regulation equipment designed specifically designed to operate at a specific frequency.

 

Some other possible issues might be using a transformer designed for 50Hz / 60Hz operation on aircraft which typically use a 400Hz a.c. supply.

 

For most applications any well designed transformer will (if suitably rated) perform adequately on either 50 or 60Hz.

Ahhh, got it... I can see how the Hz affects clocks in the components as well

[andyr]

8 hours ago, Monkeyboi said:

For most applications any well designed transformer will (if suitably rated) perform adequately on either 50 or 60Hz.

 

AIUI, Alan ... transformers designed for 60Hz use (ie. USA) get hot when used with 50Hz mains (ie. in Oz).

 

Sure you might say that these transformers therefore are not "well designed" - whereas I would say ... mfrs do not generally over-spec their products ... as this makes their mfr cost higher than it could be ... and mfring cost control is one of the key factors in corporate longevity.  So US mfrs use traffos designed for 60Hz operation - which have less iron in their cores than we would use in Oz, for 50Hz operation.

 

[Monkeyboi]

1 hour ago, andyr said:

 

AIUI, Alan ... transformers designed for 60Hz use (ie. USA) get hot when used with 50Hz mains (ie. in Oz).

 

Sure you might say that these transformers therefore are not "well designed" - whereas I would say ... mfrs do not generally over-spec their products ... as this makes their mfr cost higher than it could be ... and mfring cost control is one of the key factors in corporate longevity.  So US mfrs use traffos designed for 60Hz operation - which have less iron in their cores than we would use in Oz, for 50Hz operation.

 

 

As I already said "There's a bit more than that if you delve a bit deeper into transformer theory,...."

If the equipment states 50Hz / 60Hz operation on it or in the user manual then the core contains enough magnetic material to cope with safe operation on either frequency.  If it says 60Hz only then that's what it must be used on.

[BATMAQN]

So before you get lost in the techo mumbo jumbo that the more intelligent members on here go on about no offence boys it's just above a lot of the people heads on here.

I would recommend the Tortech gear every time I've been using Tortech to run my Japanese voltage Sansui amps record players for years without any issues, can't see why it would be any different for US voltage. 

[rantan]

Just now, BATMAQN said:

I would recommend the Tortech gear every time I've been using Tortech to run my Japanese voltage Sansui amps record players for years without any issues, can't see why it would be any different for US voltage. 

 

Definitely.

I have a Tortech isolated for my 100V Pioneer PL 50 vintage DD 'table for years with zero issues.

I pretty much forget it is actually there and working.

One of the best buys I have ever made.

[rockeater]

27 minutes ago, rantan said:

I have a Tortech isolated for my 100V Pioneer PL 50 vintage DD 'table for years with zero issues.

Any TT, DAC, CD player or even pre-amp will work fine when the voltage is reduced by a trafo.

But a performance of a high power, current current power amp will not be improved upon by using the step down in front of it.

Particularly, if you are hard core audiophile who worries about cables and the like accessories.

[rantan]

38 minutes ago, rockeater said:

But a performance of a high power, current current power amp will not be improved upon by using the step down in front of it

 

I never claimed it would . It is a cases of what suits the particular situation and certainly I don't think anyone would say that a step down actually improves sound quality.

You either need one or you don't.

[pretender]

On 2/9/2022 at 12:04 PM, Monkeyboi said:

I've used them.  Things to consider -

 

• Beware of auto-transformers that don't have a separate and isolated secondary winding.  Not recommended.  Steer clear of any transformer with dubious or incomplete specifications and ensure the transformer complies with Australian electrical safety standards.
• Cheap transformers can buzz and hum even when under no or low load.  This can be very annoying if audible.  
• Power amplifiers unless they have a soft start circuit can draw very large currents at switch on.  Something to consider when selecting a suitable transformer.  You don't want to be blowing the transformer's protection fuse.   
• As @muon* said.  Tortech make good units.  Worth checking them out.
• as @rockeater said.  Constant power consumption devices are easy to power via a transformer as long as the transformer matches or exceeds the VA rating of your device.  With your typical power amplifier (not Class A) if you must use a transformer buy one which greatly exceeds the VA (maximum power consumption) of the amplifier you intend to use otherwise you might run into voltage droop issues when pumping up the volume.
• as per what was said by and IMHO @Warren Jones

So if the amp say is specified at say 400w max, what would be a good enough margin for the power of the transfotmer?

[BATMAQN]

A 500w will do the job fine however I found getting the 1000w gave a bit of flexibility if you need to run two things in the future.

 

Tortech 

Edited March 9, 2023 by BATMAQN

[Monkeyboi]

1 hour ago, pretender said:

So if the amp say is specified at say 400w max, what would be a good enough margin for the power of the transfotmer?

 

It depends on the power factor and Class of operation of the amplifier.  Power transformers aren't rated by Watts, rather Volt-Amps (VA).  As the power factor (PF) of the load on the secondary affects the phase relationship between the voltage and the current rating a transformer in Watts would not be appropriate unless the PF was = to 1.  With most amplifiers using a linear or a switch0mode power supply the PF is rarely 1.0 unless the design incorporates PF correction circuitry which most don't.

 

A typical Class A amplifier draws the same amount of power no matter if it amplifying silence or operating at full output power.  So a Class A amplifier that draws 400 watts would need a transformer capable of delivering in excess of 400VA continuously depending on its PF rating.  If, however the amplifier is a typical Class AB or a Class D, then as long as the transformer can deliver up to the rated power intermittently it should work just fine.  Remember music is dynamic and the power drawn by a typical Class AB or Class D amplifier will depend on the power of the signal delivered to your speakers.  The louder the volume the more power your Class AB or Class D amplifier consumes.

 

Transformer design and specifications in terms of choice is a complex subject that's too extensive to answer simply in the scope of this quick and dirty explanation.  In short, buy a transformer that has a VA rating well in excess of your needs and that should be a safe bet.  That strategy will also give you some wriggle room should you add extra components to your system that will be operating through the same transformer.

 

[BATMAQN]

Maybe ring Tortech I found them quite helpful and knowledgeable about this subject.

[Rrobot]

I'm another happy tortech transformer customer too. Although it took me a couple of tries in all honesty. I wasn't satisfied with the hum/buzz from the standard 1010w isolation step down and so I returned it and they sent me an audio grade one with an interwinding earth screen which is a fair bit quieter (but much more expensive).  Maybe my dirty WA power is full of DC and I needed a conditioner not an over specced step-down. Dunno, but none of my other transformers were as noisy... A 1000w trafo has a fairly big core so it's hard to avoid it humming to some extent at least. If your room is very quiet or you're very sensitive to hum it's perhaps a consideration. 

Edited March 9, 2023 by Rrobot

[Rorza]

Okay so what would happen if you used a 100va rated tortech transformer, outputting 110v 50hz to power an amplifier that needs 250W 120v 60hz?

[Rorza]

23 minutes ago, Rorza said:

Okay so what would happen if you used a 100va rated tortech transformer, outputting 110v 50hz to power an amplifier that needs 250W 120v 60hz?

It appears a blew the fuse on the Tortech, although the LED still works. Found the right Tortech 500w to buy now. Is it likely I also damaged the amp?

[andyr]

On 09/03/2023 at 9:29 PM, Rrobot said:

A 1000w trafo has a fairly big core so it's hard to avoid it humming to some extent at least. If your room is very quiet or you're very sensitive to hum it's perhaps a consideration. 

 

It is indeed (a large core).  I have a 500VA step-down which doesn't hum - so maybe I just don't have any DC on the mains.

 

If you do ... maybe try a "DC blocker" in front of it?

 

[Rrobot]

35 minutes ago, andyr said:

 

It is indeed (a large core).  I have a 500VA step-down which doesn't hum - so maybe I just don't have any DC on the mains.

 

Thats good news!  If I recall my 500VA step down was/is pretty quiet also...the 1000 watt is probably overkill for my use tbh. 

[theophile]

Chiming in on this topic.

 

It's fashionable to have prejudices about topics nowadays. Why should this one be any different...

 

All that is needed is plenty of headroom. On the rear compliance plate of all components is displayed the total power consumption. Add up all the totals of the equipment to be powered through the step down. My rule of thumb is to have to transformer capacity at 4 times the total needed. Which means that the power available is exponential to the power required.

 

After that I never worry about the transformer. I got a cutom made 2KVa 240 to 100V step down made for the many Japan Domestic devices I own. Does anybody seriously think that it can't handle hifi gear?

Edited March 18 by theophile