Topic: Surplus amps

[av_phile1]

Whether toroids are cheaper or not to manufacturer is entirely beside the point.   The commerce behind it from greedy manufacturers, if at all,  will not change the fact one bit.   

[aHobbit]

... will not change the fact one bit.   

... truly puzzling!        -  am still at a loss at what the fact is all about ...     

excerpts from
http://www.pearl-hifi.com/06_Lit_Archive/07_Misc_Downloads/Toroidal_Trans_Myths.pdf

I’ve been lucky enough to speak to a variety of high-end manufacturers about AC power, transformers,
and component design. Conversations with Richard Vandersteen, Mike VansEvers and Emil Rotar (Warner Imaging) have been most illuminating. Years ago, I never really gave power transformers much thought. The assumption was that because so many high-end manufacturers were using toroidal power transformers, toroids must be demonstrably superior. Imagine my surprise when I started noticing that many of the best sounding components I’ve experienced in my system have all had EI-frame transformers. Coincidence? I might have thought so before finding out so more about power and transformers. Now  I’m convinced that cleverly done EI-frame transformers could/should give us better sounding high-end audio components.

...Doug Blackburn
[email protected]

[av_phile1]

Well if you can't get it, that's really not my problem.    Feel free to believe what you want.  (Though facts are totally below the purview of beliefs.)  But who knows, the sun just might rise from the west. 

[aHobbit]

Well if you can't get it, that's really not my problem.    Feel free to believe what you want.  (Though facts are totally below the purview of beliefs.)  But who knows, the sun just might rise from the west. 

oh well ... just got the feeling na ... pinasakay mo lang kami eh ... may consent ka ba sa UP para idamay professors mo?     


Ano nga ulit point mo? Torroids' SUPERIOR efficiency?     

sa Audio Lies and Myth thread ba ang bagsak niyan? 

JD ... na-validate ko na yung mga signatures ng initiative na ito ... it has my vote!         

[rascal101]

What are we discussing about? Torroids are better than E-Is as far as effeciency. What efficiency? If we are talking about power then ...

Efficiency = Output Power /( Input Power x PF)

To help you guys out, the mere fact that you have high leakage capacitance and inductance on torroids already shows who is more superior. However, it isn't that simple. Based on my experience with switching PSU, we only use torroids due to size constraints - you get higher permeabilities kasi on torroids vs standard E-I cores. Unfortunately higher permeabilities also translates to higher tolerance in inductance.

So whether you use torroids or E-I cores is entirely based on your application. If you have size constraints go for toroids otherwise go E-I.

[av_phile1]

HIGH EFFICIENCY

The key to all toroidal transformer advantages is its efficiency. And the key to its efficiency is the core. The core is a continuous strip of grain oriented silicon steel, wound like a clock spring, under tension. It is annealed to relax the molecular structure which ensures that all grains are in the magnetic direction (unlike the old standard EI, with about 40% in the wrong direction). There is no air gap, resulting in a stacking factor of 97.5% of its weight. Since all the windings are symmetrically spread over the entire round, gapless core, a higher flux density is possible (toroidal transformers operate at flux densities of 16 to 18 kilogauss, while traditional EI transformers operate at 12 to 14 kilogauss). The magnetic flux is in the same direction as the grain oriented silicon steel core, thus achieving very high electrical efficiencies. Typical efficiency figures for toroidal transformers are 95% (e.g. 18kVA at 98% efficiency).

Other advantages:

LOW Mechanical HUM

Toroidal transformers are also acoustically quieter than EI transformers. The absence of an air gap typically provides an 8:1 reduction of acoustic noise. In addition the windings tightly envelope the entire core, effectively reducing magnetostriction - the main source of the familiar mechanical hum found in standard vertically laminated EI transformers. Compared to EI transformers, toroids are silent.

Low Magnetic Field.

Another type of noise is magnetic. Toroidal transformers radiate about 1/10 the magnetic field of EI transformers; this is, again, because of the inherent efficiency and unique construction. The windings which cover the core act as a shield. The magnetic field is contained doing what it should, transforming energy from primary to secondary. This may eliminate the need for special shielding and makes toroidal transformers especially suitable for applications in sensitive electronic equipment, such as: low level amplifiers, medical equipment, and near CRTs.

Low Offload Losses

It takes a lot less energy to maintain the magnetic field in a toroidal core. This is known as excitation or quiescent power. Toroids require about 1/16 the excitation power of conventional transformers. That's 1/16 the electricity required by EI transformers in standby mode. This can translate into big savings in large transformer applications such as industrial controls


http://www.plitron.com/pages/advantag.htm

[av_phile1]

Toroidal transformers are more efficient (around 95%) than the cheaper laminated EI types. Other advantages, compared to EI types, include smaller size (about half), lower weight (about half), less mechanical hum (making them superior in audio amplifiers), lower exterior magnetic field (about one tenth), low off-load losses (making them more efficient in standby circuits), single-bolt mounting, and more choice of shapes. This last point means that, for a given power output, either a wide, flat toroid or a tall, narrow one with the same electrical properties can be chosen, depending on the space available. The main disadvantage is higher cost.

A drawback of toroidal transformer construction is the higher cost of windings. As a consequence, toroidal transformers are uncommon above ratings of a few kVA. Small distribution transformers may achieve some of the benefits of a toroidal core by splitting it and forcing it open, then inserting a bobbin containing primary and secondary windings.

http://en.wikipedia.org/wiki/Transformer

[av_phile1]

Light Weight

Because they are more efficient, toroids are generally up to 50% lighter than conventional E-I type transformers.

Small Size

A toroid's compact dimensions are always less than E-I type transformers. Furthermore, the height to diameter relationships can be adjusted by design.

Low Stray Magnetic Field

Because toroids have no air gaps and the field is enclosed by the windings, they emit very low radiated magnetic fields. Primary and secondary circuits are uniformly wound around the entire core.

Flexible Mounting

Several mounting options make toroids easier and faster to install than conventional E-I type transformers.

Low Mechanical Hum

Because the core material is tightly wound, welded, and insulated, very low noise is experienced as compared to conventional E-I units.

Flexible Dimensions

In the design phase, the height and diameter can be varied around any constant power requirements. This benefit is significant to any design requiring a slim line or low profile.

Reduced No-Load Losses

Where stand-by modes constitute a large portion of the operating cycle, toroids can save significant energy. These savings alone can justify the use of toroidal transformers.

http://www.nictec.com/custom_magnetic_products/custom_toroidal_magnetics.asp

[av_phile1]

The Toroidal Core

At the heart of the toroidal is a highly efficient donut shaped core. To construct the core, grain-oriented silicon-iron is slit to form a ribbon of steel which is then wound, like a very tight clock spring. The result is a core in which all of the molecules are aligned with the direction of flux. Molecules not aligned with the flux direction increase a core's reluctance (the capacity for opposing magnetic induction), degrading performance to the level of common steel when the molecules are 90 degrees out of phase. EI laminated cores, which are stamped from grain-oriented Si-Fe, may have as much as 40% of the total core area perpendicular to the ideal grain direction, with another 40% acting only as a return flux path. This more efficient use of the core material in a toroidal can result in a size and weight reduction of up to 50% (depending on power rating), allowing the design engineer to innovate by exploiting the toroidal's small size, low weight, ease of mounting, and flexible dimensions.

Efficiency

Since toroidal cores are constructed of a continuously wound ribbon, there is virtually no air gap. The windings are evenly wrapped over the entire core allowing the transformer to operate at a higher flux density than in standard transformers. Toroidal transformers can operate at 1.6 to 1.8 Tesla (16,000 to 18,000 Gauss) while EI cores are limited to 1.2 to 1.4 Tesla (12,000 to 14,000 Gauss). The magnetic flux of the windings is oriented in the same direction as the grain-oriented core, thus achieving very high electrical efficiencies. Efficiency is a measure of a transformer's ability to deliver the input power to the load.

http://www.tabtronics.com/TECHNOLOGY/ElectromagneticBasics/ToroidalTransformerBasics/tabid/112/Default.aspx

[rascal101]

It has higher magnetic flux densities but generally the distribution is non-homogenous that is why the play on the inductance is higher. I would not argue on efficiency with you because there are ways to compensate for magnetic losses. Anyway these losses would not be as significant as semiconductor losses anyway. Also, magnetic losses are not easy to compute. Apart from copper losses other losses are not that apparent. In fact in our loss budgets, we don't even consider magnetic losses. The only thing we consider on magnetics is

1. Saturation
2. Thermals

Now whether using torroids translates to higher efficiencies should be taken in the context of design topology, board space and customer requirement.

[av_phile1]

Toroidal P ower T ransformers

Toroidal power transformers are used to convert power level voltages from one level to another.Toroidal power transformers have the following advantages

Toroidal transformers are noiseless and highly efficient in operation. They have dismal stray magnetic fields. Toroidal transformers are suitable for applications that necessitate tiny size and lesser weight.


The Toroidal Core

This high efficient core is placed at the center of the toroidal.To construct the core, the grain-oriented silicon-iron will slit to make a ribbon of steel that isvery tightly wound.The result delivers a core with all of its molecules aligned with the flux direction. The molecules that are not aligned with the flux directionen hancethe reluctance of the core. This causes the performance to be reduced such that it is equivalent to that of common steel, especially when the molecules are out of phase by 90 degrees.

Stray Magnetic F ields

The main reason for the flux leakage from any transformer occurs due to the presence of the air gap. An ideal magnetic circuit is free of air gap. In EI transformers, the air gap present at the junction of ‘I’ and ‘E’ is the main cause for the flux leakage. This flux moves around the surroundings because of the high reluctance of the air and the flux concentration in the laminations. Mounting holes and grooves found in the laminations result in aminimal quantityof flux leakage. A continuous ribbon of steel is being used to wound toroidal cores;hence,stray fields from air gaps are eliminated .

In addition, the copper core is uniformly encased by the windings of the toroidal transformer. Magnetostriction isthemain source of acoustic noise in the transformers which is reduced in the toroidal transformers by covering the solid ring cores with the windings.Audible noise will be reduced to a good extent by varnish impregnating the toroidal core and the copper windings.

http://www.reedlink.com/ProductInfo~Productid~39378~ProductName~Toroidal-Transformers.html

[rascal101]

Just to add ...

Our competitor on an 800W and 1.2KW psu is using EI core but we are using torroidal core. Our topology is way better than them - full bridge ZVS (zero voltage switching) but they are getting 1 - 2% better efficiency. BTW, they are using 2 FET forward interleaved transformer topology which is a rather old topology if you ask me. And by the books alone should get you about 3 - 5% lower in efficiency vs full bridge ZVS.

[av_phile1]

It has higher magnetic flux densities but generally the distribution is non-homogenous that is why the play on the inductance is higher. I would not argue on efficiency with you because there are ways to compensate for magnetic losses. Anyway these losses would not be as significant as semiconductor losses anyway. Also, magnetic losses are not easy to compute. Apart from copper losses other losses are not that apparent. In fact in our loss budgets, we don't even consider magnetic losses. The only thing we consider on magnetics is

1. Saturation
2. Thermals

Now whether using torroids translates to higher efficiencies should be taken in the context of design topology, board space and customer requirement.

Ofcourse there are ways to  compensate for the inefficiencies of the EI types.  I am just presenting the points about the inherent superioity of the toroid as a transformer discussed in these sites which I recall sounded just like what I read in textbooks and what my professors said.  I am sure modern circuit topologies can compensate for any weaknesses in a component.    The fact that you have to compensate clearly indicates what it is compared with toroid.   The choice of which configuration to use is often dicatated by economics and practicality, rather than component superiorty. (Same with speakers, compromises are often made)   DIYers know how difficult it is to wind on those doughnut cores.  So if expediency is the way, as in many production faclities, it may be a lot faster and easier to use EI and compensate electronically than use a toroid that have yet to be wound. 

And just because you can achieve high efficiency ratings in the OVERALL circuit topology where the EI sits won't change the fact that,  taken on its own, outside any circuit topology, the toroid, done right,  has a higher efficiency by its very geometry and construction.  

[rascal101]

We use EI or torroids based on requirement, existing topology and technology. To me it doesn't matter if its EI or torroid, I will use what works best for my application. 

[rascal101]

I hope that someday I can can tour you in our facility and we can visit our Magnetics dept. There are some things that aren't discussed on the internet.

[av_phile1]

I have no problem with that.   Electrical and electronic components works as a TEAM to achieve an end.  While its weakiest link often determine how it will operate, other components in that circuit topology can be so designed to compensate or correct for whatever weakness a component has that by sheer economics must be in it.  In the same way that speaker makers often have to address the resonance of a speaker driver by notching out such resonances in the dividing networks, rather than using a more expensive driver without those particualr resonances in order to make the price user-friendly..   Used in the context of the right topology and application, I would tend to think that a well constructed EI can do the job, as they already do in many applications.   But that is no argument to debunk the already well-known fact that toroids are inherently more efficient, for the reasons indicated in those sites I pasted.   Such a fact is very well utilized by Bryston, Krell, Aragon and other brands in their power amps.   Again, arguably little to do with better sound quality, but I can see the advantage of using toroid in amplifier applications.  There may be exceptions, but you don't make rules based on exceptions.  

[Signal2Noise]

Whether torroid or EI, basta ako ang alam ko...Less heat ang torroid xformer, pero sa audiophile application...EI ang mas madalas gamitin.  Depende kung sino at papaano ginawa.  Kahit torroid pa 'yan kung mga pipitsugin anywhere-in-china galing, walang binesa (no say).  Pero kung EI at Made in USA or Germany naman ito mas maganda...same thing in vice-versa.

Sa history ng amplification, legend na iyong TO300 na xformer as the best in terms of efficiency and drive.  Halos lahat ng modern xformers na lumabas ay nag-patterned sa dynamics nito.  Pero hindi ito torroid?

In fairness sa mga dounut-shaped xformers(torroid & super-ring), OK ito kase less lahat (heat, vibration..etc), but it doesn't make it superior. 

Again, practicality lang, wala nang masyadong complexity...I challenge anybody here...Tell me kung ano ang pinakamagandang brand & klase ng TRANSFORMER sa buong mundo, iyong wala nang tatalo sa design & dynamics nito...Ika nga ay Super & Ultimate Transformer (torroid, super-ring or EI)?

[JojoD818]

I was upgrading a cdp with a torroid tranny, the owner said that for it's price (the cdp), it's already a bargain. When I saw the current discussion here I remembered what he said...

"Jo!, ano sa palagay mo? Ok na talaga ang presyo nitong cdp ko ano? Mura na naka-torroid pa!"

It seems like the concensus among "consumer" knowledge is that torroids are superior to EIs.

Or is it?

[Eggballs]

The discussions is very meaty indeed!!!

It seems like the concensus among "consumer" knowledge is that torroids are superior to EIs.

Or is it?

Commercially yes... due to hype. These people from giant nanufacturers must convince the consumers that torroids is superior than EIs, otherwise they will suffer heavy losses.

Technically no. Both have efficiency greater than 93% or better.

The deciding factors will be its application, the available space, the appearance (he he he) and the bigger factor... the belief (true or not) in the head of its user 

[ATJr.]

see guys, i told you that this is a debateable topic didn't i?

i have built lots of amps using ei's with none of the supposed issues that are associated with it such as noise and stray fields. i have built just one torroid amp with the torroid of my own fabrication and i can not tell the difference is acoustics, only that the torroid has lower magnetizing current.

[av_phile1]

The discussions is very meaty indeed!!!

It seems like the concensus among "consumer" knowledge is that torroids are superior to EIs.

Read the sites I pasted, the consensus is also among professionals.

Toroids are not just used in high end audio where its efficiency provides better weight to flux density ratios and size to power ratios especially in powerful amps that can benefit best in weight reduction (like humans  ).   Check the Bryston and Aragon amps, among others.   The obvious fact that for the same electrical input and output KVA requirement, toroids provide a smaller footprint, wire turns and weight is evidence of their inherent efficiency.

Toroids are also extensively used in aerospace-grade gears where efficiency allowing the same better weight to flux density ratios are required.  In all the aircraft navigational avionics instruments I've worked with as an aircraft instrument specialist in my first job, none use EI.  Their manuals are unanimous in declaring the high efficiency of toroids over EI for use in sensitive avionics gears.  They confirmed exactlly what I learned in UP.  I read they are also used/preferred  in senstiive medical gears, but I have no experience there.

I can understand the aversion of many DIY people with toroids.  They are difficult to assemble, and often expensive to source. Anybody can wind an EI.  But Toroids require a lot of patience.  The resulting sonic difference may not even exist for all the trouble.  There is where the debate on many forums are - whether toroids produce better sonics.  But I won't go there. It's better efficency is a given.  Efficiency however does not necessarily equate to better sonics.   But that doesn't change the fact that toroids are more inherently efficient because of its geometry and construction.  The sites I referred to are very clear on that.  Better still, just pick any engineering textbook about transformers and the same conclusions can be found. 

[av_phile1]

see guys, i told you that this is a debateable topic didn't i?

i have built lots of amps using ei's with none of the supposed issues that are associated with it such as noise and stray fields. i have built just one torroid amp with the torroid of my own fabrication and i can not tell the difference is acoustics, only that the torroid has lower magnetizing current.

The debatable issue is on whether toroids provide better sonics. Those debates are everywhere in many forums I've visited and joined.  But not about efficiency.  That's already a given.  Efficiency in transformer operation has nothing to do with accoustic qualities.    And you can be efficient in providing lousy quality.     But there are also pundits who would argue that toroids have performance qualities outside of efficiency that improves on the sound quality. I would go for that as well.  But that's another topic.

[oweidah]

sirs,
just wondering lang po. what if, nauna "nadiskubre" and torroids kesa sa EI core tranny? eh di nasanay na ang mga tao sa torroids at nang dumating ang EI core- uy! mas ok yata ang kwadrado kesa sa donut?! "di kaya hype" and getting into the consumer psyche lang yan? how many times have we heard, maybe even nobel-prize awarded people na dinoktor lang ang mga scientific data etc, pwede at kayang-kaya din doktorin ng mga audio amplifier manufacturers ang mga datus nila?
di kaya ang mas importante eh mahalaga ang suma-total ng produkto (amplifier) kesa kung ano ang ginamit- torroid man o EI? 

just my mamera 

[bumblebee]

Makiki-OT ako.

Ano ibig sabihin ng 2x0-25V secondaries? Meaning the tranny can output 0V to 25V? So kung kailangan ko ng 22V pwede kong gamitin ito?

[JojoD818]

Makiki-OT ako.

Ano ibig sabihin ng 2x0-25V secondaries? Meaning the tranny can output 0V to 25V? So kung kailangan ko ng 22V pwede kong gamitin ito?

It means your tranny has two 25V windings. it's the same as saying 0-25V, 0-25V. the output is fixed at 25V, not from 0 to 25V.

depends if the 22V is AC or DC.

[bumblebee]

22V AC ata. Papuntang rectifier circuit. So, given this situation, what does one do? Voltage divider?

[JojoD818]

I can understand the aversion of many DIY people with toroids.  They are difficult to assemble, and often expensive to source. Anybody can wind an EI.  But Toroids require a lot of patience.

Hi,

DIYers don't think like that. It is, most of the time, the DIYers who builds the most difficult projects to assemble - even those projects that everyone else doesn't want to build. DIYers do try and find ways to source out parts, no matter how much it costs. With the prices of copper nowadays, shipping a torroid would be the only expense that may be overboard. 

I also agree about the needed patience since I have wound a torroid myself. fortunately, any serious DIYer shouldn't have any patience problem because he/she must be full of it before DIY'ing.

 

[JojoD818]

22V AC ata. Papuntang rectifier circuit. So, given this situation, what does one do? Voltage divider?

what does one do? go find a 2x0-22V tranny for a full-wave or a 0-22V with a full-wave bridge.

voltage dividers don't work here, especially if the current demand fluctuates.

[bumblebee]

Thanks again, Master JojoD

[ATJr.]

sirs,
just wondering lang po. what if, nauna "nadiskubre" and torroids kesa sa EI core tranny? eh di nasanay na ang mga tao sa torroids at nang dumating ang EI core- uy! mas ok yata ang kwadrado kesa sa donut?! "di kaya hype" and getting into the consumer psyche lang yan? how many times have we heard, maybe even nobel-prize awarded people na dinoktor lang ang mga scientific data etc, pwede at kayang-kaya din doktorin ng mga audio amplifier manufacturers ang mga datus nila?
di kaya ang mas importante eh mahalaga ang suma-total ng produkto (amplifier) kesa kung ano ang ginamit- torroid man o EI? 

just my mamera 

fyi, torroids came just about the same time as ei's, torroids are not new...