What's with Toroids?

[Seth=L]

I see toroidal power supplies in two divisions of audio, real cheap stuff or salty stuff.

I have seen toroids in the Insignia receivers, Dual brand HTIAB systems, PC speakers, and I saw one just the other day in a cheap Philips HTIAB at a pawn shop.

Then you also see toroids in NAD, Outlaw, and many other manufacturers that produce "superlative" or esoteric equipement.

As for the in between stuff, like Mid-level Yamaha, Denon, Onkyo, Integra, and H/K they use Iron Core power supplies, WTF?

 

[Ampdog]

One thing it might say, is that they are on the whole neither convincingly better or convincingly worse that other types!

Toroids generally have lower loss, are simpler to wind, have mostly less stray magnetic field and are somewhat smaller than the classic E-I types. In between there are also C-cores: Also lower loss but more expensive to make since it has the winding complexity of a layer wound transformer but cores are more expensive. Toroids can be somewhat more expensive (at least locally) - the winding machine costs capital layout. But it also depends on the production run.

The main (and true) advantage is lower stray magnetic field. But whether this is a practical factor will also bepend on the layout of the rest of the equipment. To my mind there is not a single outstanding advantage. I have seen application in all kinds of equipment, not necessarily price-related. It might be economy-related for a particular firm. Let us see what greater experts have to say.

 

[Seth=L]

One thing it might say, is that they are on the whole neither convincingly better or convincingly worse that other types!

Toroids generally have lower loss, are simpler to wind, have mostly less stray magnetic field and are somewhat smaller than the classic E-I types. In between there are also C-cores: Also lower loss but more expensive to make since it has the winding complexity of a layer wound transformer but cores are more expensive. Toroids can be somewhat more expensive (at least locally) - the winding machine costs capital layout. But it also depends on the production run.

The main (and true) advantage is lower stray magnetic field. But whether this is a practical factor will also bepend on the layout of the rest of the equipment. To my mind there is not a single outstanding advantage. I have seen application in all kinds of equipment, not necessarily price-related. It might be economy-related for a particular firm. Let us see what greater experts have to say.

But you are the expert, you design amplifiers! We are all gonna die without you man.

Sorry, I am just so happy right now I could make up a completely new word................Vertastado....see I have lost my mind. I just got a new receiver and I am just so tickled to death.

 

[yettitheman]

Seth, when you get some more money, let me make you a cdp with this transport
http://www.daisy-laser.com/products/CD/modules/CDPro2/cdpro2.htm

 

[Ampdog]

But you are the expert, you design amplifiers! We are all gonna die without you man.

Sorry, I am just so happy right now I could make up a completely new word................Vertastado....see I have lost my mind. I just got a new receiver and I am just so tickled to death.

Seth, er....

1. Well, rather you die without me than because of me.

2. But you say that you have lost your mind. Should I then interpret your kind comment from that angle??

But thanks. I have just never used toroids, for no distinct negative reason. I use C-core transformers, but they have one disadvantage. They can hum - mechanically, I mean, and then there is nothing you can do about it. As you know the core is wound from grain-oriented steel like a coil, and the layers can sometimes separate just enough to vibrate. Lately I have requested the winder to smear each core end (of the 4 "C"s) just before assembly with the laquer that he pots them in. Still have to use those, though.

So, still, I would like to see comments from those who regularly use toroids, why they do.

 

[Seth=L]

The only reason for such careless comments was I had just gotten a new Yamaha receiver and I was enjoying it quite a lot. I am still enjoying quite a lot.

Are you saying that C-core transformers hum or Toroids?

 

[stratman]

Torroids are more efficient than hemorrhoids.

 

[Ampdog]

Are you saying that C-core transformers hum or Toroids?

C-cores can hum (mechanically, meaning the "laminations" vibrate). There was perhaps confusion because toroids are also wound cores. But they stay intact. Perhaps you know that C-cores are "wound" like toroids, only in a rectangular way. Then each loop is cut and the faces ground so that they fit together as perfectly as possible after being fitted over the windings. It is here that the steel layers at the ends can separate slightly. Some winders are reluctant to use them at all because of the difficulty to gaurantee moiseless operation.

Efficiency? Toroids are more efficient, the core being uncut and in closer proximity to the windings, but in low powers (including most amplifiers) I do not believe that is going to be significant.

 

[Seth=L]

Thank you for the info Ampdog, very much appreciated. I don't know much about transformers so to speak, like for instance how they are rated.

Which reminds me, how are transformers rated?

 

[Ampdog]

Not sure that I fully understand what you want to know, Seth=L.

For smaller power transformers (say up to 300W) I think "full load" is calculated on the basis of 5 - 10% power loss, usually equally divided between copper (winding) losses and iron (core) losses. That is the background for one way of estimating a power transformer's wattage. If one presumes 5% total copper (winding resistance) loss, which is supposed to be equally divided again between primary and all secondaries, then one measures the primary winding's wire resistance. Say this is 14 ohms for a 230V primary. The wire loss voltage drop can then be assumed to be 2,5% or 5,75V. That over 14 ohms gives 410mA maximum primary current, or a transformer of 230 x 0,41 = 94W. This is approximate as the standards of transformer companies vary, but it will serve to illustrate. (One measures the primary winding resistance, because the secondary resistance with semiconductor power supply transformers may be too low to measure accurately with an ordinary DVM.)

Also there is a difference in the iron loss between normal E/I core, C-core and toroids. The latter is smaller, giving a smaller core area for the same power, thus shorter total winding lengths, less copper loss and so on round the circle.

This comes from my general experience; others may be able to reply (and perhaps amend) in greater detail.

 

[Seth=L]

Not sure that I fully understand what you want to know, Seth=L.

For smaller power transformers (say up to 300W) I think "full load" is calculated on the basis of 5 - 10% power loss, usually equally divided between copper (winding) losses and iron (core) losses. That is the background for one way of estimating a power transformer's wattage. If one presumes 5% total copper (winding resistance) loss, which is supposed to be equally divided again between primary and all secondaries, then one measures the primary winding's wire resistance. Say this is 14 ohms for a 230V primary. The wire loss voltage drop can then be assumed to be 2,5% or 5,75V. That over 14 ohms gives 410mA maximum primary current, or a transformer of 230 x 0,41 = 94W. This is approximate as the standards of transformer companies vary, but it will serve to illustrate. (One measures the primary winding resistance, because the secondary resistance with semiconductor power supply transformers may be too low to measure accurately with an ordinary DVM.)

Also there is a difference in the iron loss between normal E/I core, C-core and toroids. The latter is smaller, giving a smaller core area for the same power, thus shorter total winding lengths, less copper loss and so on round the circle.

This comes from my general experience; others may be able to reply (and perhaps amend) in greater detail.

Well you have alread went over my head.

I just wanted to know how to tell is one power supply is more powerfull than another. If there isn't a simple way to tell I will have to research more on it I guess.

Thanks for the info I may be able to understand it once I do some reading.