# The difference between a toroidal and I-E transformer in amps



## tonyvdb

So this discussion came up and I wanted to put some facts together about the differences between using the standard power supplies found in most amps/receivers and toroidal transformers.

A toroidal uses a Doughnut shaped core & is much slimmer than a conventional (E-I) transformer allowing for a smaller height footprint.

A toroidal transformer creates very low interference, since its magnetic field is contained within its self

It provides large peak currents, well beyond its rating, but it draws a huge current surge on switch on meaning it can dim lights when switched on or even worse trip breakers if circuit is overloaded.

Toroidals are more costly to make and take up more footprint space.

A conventional transformer of 25% to 40% higher capacity can be put in the equipment, for the same Budget. That Conventional transformer of higher capacity will put out even more juice than a toroidal transformer, of the same price

There are many companies of what I call cheap equipment that use them for example the Jamo AVR-693 uses one in it so just because they use one does not make it high end.

I do not believe that there is any real gain by using a Toroidal transformer over a standard I-E transformer. 

Thoughts?


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## Lumen

One advantage of toroidal over laminated is lower noise from hum/buzz. Air gaps between the plates of a laminated transformer can cause them to vibrate against each other. Transformer noise contributing to a room's noise-floor depends largely upon its design and materials. But transformer hum may be insignificant when compared to air duct noise.


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## tonyvdb

*Toroidal Transformer*










*EI transformer*


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## tonyvdb

BlueRockinLou said:


> One advantage of toroidal over laminated is lower noise from hum/buzz. Air gaps between the plates of a laminated transformer can cause them to vibrate against each other. Transformer noise contributing to a room's noise-floor depends largely upon its design and materials. But transformer hum may be insignificant when compared to air duct noise.


Yes, this can be an issue however if designed right there is no reason that the hum cant be inaudible. On my Onkyo 805 it has a huge transformer (the receiver weighs 54lbs) and Ive never heard any noise from it.

Also some will argue that the magnetic field the EI transformers generate can be problematic but again shielding can be placed to prevent this at minimal cost and this interference is an audible 60Hz hum.


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## Talley

tonyvdb said:


> Yes, this can be an issue however if designed right there is no reason that the hum cant be inaudible. On my Onkyo 805 it has a huge transformer (the receiver weighs 54lbs) and Ive never heard any noise from it.
> 
> Also some will argue that the magnetic field the EI transformers generate can be problematic but again shielding can be placed to prevent this at minimal cost and this interference is an audible 60Hz hum.


Although I'm an master electrician I'm not 100% fact about the various transformers in their capability. I do know the more expensive audio units will use a toriodal type.

Even for isolation you can get isolation transformers in the standard EI or the toriodal so who really nows the difference.

My understanding was the ability to handle surges better which help regulate the secondary side voltage keeping it more stable.


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## tonyvdb

Talley said:


> My understanding was the ability to handle surges better which help regulate the secondary side voltage keeping it more stable.


Correct however as I mentioned above all you have to do is increase the size of the EI transformer and this issue becomes mute. The added cost of a slightly larger EI transformer is still less expensive than a comparable toroidal trans.
The bigger issue is that many receivers particularly lower cost ones have far to small a power supply to meet theses demands and almost never have any pre outs to hook up external amps.


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## Lumen

tonyvdb said:


> It provides large peak currents, well beyond its rating, but it draws a huge current surge on switch on meaning it can dim lights when switched on or even worse trip breakers if circuit is overloaded.


Personally, I never became accustomed to dimming lights (and bogged-down appliance motors haha j/k) when my monoblocks "flame-on." It's almost as if the air gets sucked out of the room for an instant! Seriously though, I would think that large peak currents are what you want for realistic audio transients.



tonyvdb said:


> A conventional transformer of 25% to 40% higher capacity can be put in the equipment, for the same Budget. That Conventional transformer of higher capacity will put out even more juice than a toroidal transformer, of the same price.


I'm not sure what kind of capacity you mean.



tonyvdb said:


> Yes, this can be an issue however if designed right there is no reason that the hum cant be inaudible. On my Onkyo 805 it has a huge transformer (the receiver weighs 54lbs) and Ive never heard any noise from it.
> 
> Also some will argue that the magnetic field the EI transformers generate can be problematic but again shielding can be placed to prevent this at minimal cost and this interference is an audible 60Hz hum.


Agreed, and an IE xfrmr can be oriented in its chassis such that the lobes of its magnetic field are pointed away from sensitive circuitry. But in crowded AVR chassis of good design, I wouldn't be surprised to find a toroidal xfrmr instead, because of its controlled emissions. 

Some companies offer external power supplies (the so-called two-chassis component) to remove radiated emissions from the equation, but that introduces a whole new set of problems (e.g. umbilical & enclosure design, short circuit protection, etc.). Then again, some jump on the external supply bandwagon under the guise of an increase in perceived quality.


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## Talley

BlueRockinLou said:


> Agreed, and an IE xfrmr can be oriented in its chassis such that the lobes of its magnetic field are pointed away from sensitive circuitry. But in crowded AVR chassis of good design, I wouldn't be surprised to find a toroidal xfrmr instead, because of its controlled emissions.
> 
> Some companies offer external power supplies (the so-called two-chassis component) to remove radiated emissions from the equation, but that introduces a whole new set of problems (e.g. umbilical & enclosure design, short circuit protection, etc.). Then again, some jump on the external supply bandwagon under the guise of an increase in perceived quality.



Yup... this can be found in the "Whats the catch" part: http://www.soundstage.com/maxdb/maxdb071998.htm

talking about the magnetic field. Seems that the Toroidal offers the easiest construction to avoid this issue and can be placed right next to the amplifer sections

He also goes on stating that an EI can end up offering better audio properties if built right (and be alot larger)


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## tonyvdb

This is what the inside of the Onkyo 805 looks like. It is a beast









Well placed the power supply should not be an issue.

This is the inside of the Samson servo amp


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## Talley

tonyvdb said:


> This is what the inside of the Onkyo 805 looks like. It is a beast
> 
> 
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> 
> Well placed the power supply should not be an issue.
> 
> This is the inside of the Samson servo amp


That little thing?

Here's mine ... I thought it was a baby


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## nova

And then there is my favorite...


You guys need to add some capacitors to yours :whistling:


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## willis7469

nova said:


> And then there is my favorite...


 I can't see it. I hope it's a 572 bowtie with a pro-charger....oh wait wrong place.


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## lcaillo

nova said:


> And then there is my favorite...
> 
> 
> You guys need to add some capacitors to yours :whistling:


Looks like you have room for a bigger transformer in there Mark! lddude:


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## Talley

lcaillo said:


> Looks like you have room for a bigger transformer in there Mark! lddude:


haha


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## Blacklightning

Here you go... so large, no room for an amp. :yay:


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## Talley

Guys you joke... but seriously Torus uses the Piltron toroidals in their units and right now they one of if not the best units available to the market right now. 

Torus AVR2: http://www.toruspower.com/reviews/north-american-retail-avr2/

These things are mammoth, weigh a ton and all they do is balanced isolation with voltage regulation. Nice units but costly and they use GIANT toroidals... wish I could find an interior shot of their big 10,000va unit!


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## Talley

I already purchased one 1,000w isolation transformer and will order me this 2000w balanced isolation transformer also if I find the results of the 1,000w to be good: http://shop.plitron.com/shopexd.asp?id=332

I think it was about 330 shipped for a single unit which is a really good price for a 2kw. 

One 2kw for the amp
one 1kw for the preamp
one 500w for the projector
one 250w for the bluray

This is what I'm working on now.


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## Lumen

lcaillo said:


> Looks like you have room for a bigger transformer in there Mark! lddude:





Blacklightning said:


> Here you go... so large, no room for an amp. :yay:





Talley said:


> Guys you joke... but seriously Torus uses the Piltron toroidals in their units and right now they one of if not the best units available to the market right now. <snip>
> These things are mammoth, weigh a ton and all they do is balanced isolation with voltage regulation. Nice units but costly and they use GIANT toroidals... wish I could find an interior shot of their big 10,000va unit!


My monoblocks were modded with custom Plitrons by the amp's designer, but they're so puny (pics on request) compared to what I see here. I'm sooooooo ashamed :sob: 

But wait! The GREAT DEBATE says there are only slight differences between amps. That means my toroid is as big as your toroid :neener: :R


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## nova

lcaillo said:


> Looks like you have room for a bigger transformer in there Mark! lddude:


Sure, if you're a glass is half empty kinda guy.
I prefer to think if it as there is plenty of room to grow or,
My toroidal's not small, my chassis is big...


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## Glen B

Now this is a true beast in terms of transformer size or output power.










or this


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## fill35U

"Classy" amp, Glen! I love the look of the old SAE stuff, too! 

Here's another big toroid:


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## AegonTargareon

My understanding is that because a toroidal uses a donut core there is no imbalance of fields having to go around corners and therefore operate far more efficiently that the E-I core. 
I find I get more current from a toroidal than I ever did from an E-I and the efficiency is above 90% which the E-I gets close to 90% (design depending) but never above.


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