Amorphous and nanocrystalline cores are fine materials, but there's no value added for a tube audio amplifier.
You can do it, if you want a very slightly smaller OPT, and you want to pay about 10x on OPT cost, due to the core alone.
The benefits only show up when very low losses are needed, or high mu (small signal and pulse transformer applications; it's comparable to (su-)permalloy), or high power density, medium frequency applications (where the size can be smaller than ferrite, for the same losses, in the 1-50kHz range).
If you're of the belief that more money equals better sound, then by all means, it's a fine way to go. 8)
Tim
You can do it, if you want a very slightly smaller OPT, and you want to pay about 10x on OPT cost, due to the core alone.
The benefits only show up when very low losses are needed, or high mu (small signal and pulse transformer applications; it's comparable to (su-)permalloy), or high power density, medium frequency applications (where the size can be smaller than ferrite, for the same losses, in the 1-50kHz range).
If you're of the belief that more money equals better sound, then by all means, it's a fine way to go. 8)
Tim
I use amorphous cored transformers in most of my latest projects and have generally observed better linearity across the board and better HF extension/detail.
The cost differential is probably less than 50% IMLE.
MM is offering both metglas and a more generic amorphous core. Lundahl offers their cut amorphous core in a number of SUTs and line level transformers. I've found them superior in resolution and HF response to similar alternatives in M6 or similar materials.
Enough so that other than power transformers I don't use anything else now.. I'm not a big fan of spending money unnecessarily, but perhaps am also subject to all of the human failings of irrationality and bias. I'm comfortable with it.
The cost differential is probably less than 50% IMLE.
MM is offering both metglas and a more generic amorphous core. Lundahl offers their cut amorphous core in a number of SUTs and line level transformers. I've found them superior in resolution and HF response to similar alternatives in M6 or similar materials.
Enough so that other than power transformers I don't use anything else now.. I'm not a big fan of spending money unnecessarily, but perhaps am also subject to all of the human failings of irrationality and bias. I'm comfortable with it.
This post is stuffed with nonsense
Transformers wound on amorphous or nanocrystalline cores are superior in transparency and reproducing detail.
Amorphous core transformers need some more core mass compared to high quality (HiB) silicon steel and nanocrystalline core transformers to compensate lower permeability.
When manufacturers charge 10x the price for transformers wound on amorphous or nanocrystalline cores you are fooled.
To give an idea, here is a simple price comparison for the different high quality core materials, all c-cores:
When a HiB c-core, 0.23mm lamination, would cost 15 euro, an iron based amorphous c-core would cost some 20 euro, and a nanocrystalline c-core some 25 euro. All cores the same dimension.
For one typical 300B single ended output transformer cost price for the cores would be 60, 80 and 100 euro for respectively HiB, amorphous and nanocrystalline (I use four cores for one transformer in a stacked double c-core configuration). Then the cost of labour for winding, assembling and so on, which is more than the cost price of materials (cores, magnet wire and assembling materials).
So, an output transformer with the more expensive core materials is in the end not necessarily more than 10% (amorphous) or 20% (nanocrystalline) more expensive than the HiB silicon steel core transformer.
These comparisons are based on what I, as a winder, pay for the cores. Maybe other winders pay more for the cores, or they have a different price policy.
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Yes, the monolith would be better because of the better design, not specially by the amorphous core. Just look at the dcR for the Lundahl, 1000 Ohms!
From technical point of view it is a fact but if somebody find a sound difference it may be due to the winding resistance or/and the capacitance between turns and layers?
Maximum core excitation for HiB silicon steel, iron based amorphous and nanocrystalline c-cores is 2T, 1,56T and 1,25T respectively.
A good transformer will be designed to stay well under 1T at maximum primary voltage swing at 20 Hz, so this is not the most important factor.
At least as important is to keep DC resistances low, and therefore bigger cores are needed in order to minimize the number of windings and to have ample winding space.
It's all striving for the best set of compromises.
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The nice thing when using c-cores is that, using the same wound bobbin, you can easily swap cores when dimensions are the same, and this way you can listen what the different core materials do with the sound.
That's why I use HiB silicon steel for standard transformers now, and Finemet for best quality (instead of amorphous).
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I found a nice site with some information about a Tribute finemet transformer and very nice photo of a lundahl transformer:
DIYTRIODE. Dla melomanów i budowniczych DIY Audio: 25.11.2014 - Interstage kontratakuje! Saga w odcinkach.
DIYTRIODE. Dla melomanów i budowniczych DIY Audio: 25.11.2014 - Interstage kontratakuje! Saga w odcinkach.
400 ohms versus 1K, and the amplifier never runs in A2, so not very relevant. There was > 10dB improvement in driver stage linearity with the MM transformer. (And flat down to 20Hz)
I dont understand very well. For SE xformer if you calculate the air gap for the quiescent curent at 1 or 0.9 T it will be very near the saturation for sheet with saturation at 1.25T? With HiB or ZDKH we have a minimum of 0.6T margin it seems more safe?
Best regards
Another nice thing when using c-cores is that changing the air gap is easy if necessary.
This thread however is about how amorphous core material would perform in a (huge PP) output transformer, and there is quite some information to be found on this forum about other subjects which play a role in audio transformers.
This thread however is about how amorphous core material would perform in a (huge PP) output transformer, and there is quite some information to be found on this forum about other subjects which play a role in audio transformers.
This post is stuffed with nonsense
Transformers wound on amorphous or nanocrystalline cores are superior in transparency and reproducing detail.
If you can show me how to measure those quantities, I'll be glad to show you by how many decibels you are correct.
Or, if you can show that you are -- as the proceeding post put it,
and restate your above as a personal opinion, that would be gracious too.
Either I've been wasting a huge percentage of money, or we're talking very, very different materials.
It's possible the Metglas materials are worse, and cheaper.
The last time I priced a Vacuumschmelze core large enough for reasonable VAs at mains frequency, it was over $200. Not to mention the sales rep had a hell of a time trying to locate the damn thing..
If the material you've been using is a much poorer grade, that might account for a lot on price, too.
I don't know that any cheap Chinese producers have gotten into the amorphous metals market, but I haven't been watching that closely in the last years.
Tim
That's fine, but that wouldn't be due to the core -- GOSS (nearly) and permalloy are just as good on mu, only lacking the low eddy current and hysteresis losses that nanocrystalline offers.
In other words, if you simply use heavier wire, and add more insulating tape between layers and windings, to the point where you are using the next size larger core, then you'll have reduced the capacitance and resistance by the same margin that a fancier core would offer you.
And again, this only applies to small signal transformers: power transformers (OPTs and mains) are limited by Bmax, which is similar (1-1.8T ballpark) for both materials.
Tim
If you can show me how to measure those quantities, I'll be glad to show you by how many decibels you are correct.
Or, if you can show that you are -- as the proceeding post put it,
and restate your above as a personal opinion, that would be gracious too.
Either I've been wasting a huge percentage of money, or we're talking very, very different materials.
It's possible the Metglas materials are worse, and cheaper.
The last time I priced a Vacuumschmelze core large enough for reasonable VAs at mains frequency, it was over $200. Not to mention the sales rep had a hell of a time trying to locate the damn thing..
If the material you've been using is a much poorer grade, that might account for a lot on price, too.
I don't know that any cheap Chinese producers have gotten into the amorphous metals market, but I haven't been watching that closely in the last years.
Tim
Hi Tim,
Even if I would be able to prove the better sound quality of amorphous and nanocrystalline materials because of their magnetic properties (which would require a scientific approach), quite some people would not accept it simply because we are dealing with audio with all it's subjectivism and "my .... is longer than yours" attitudes.
My statement is not a single personal opinion, but based on quite a number of personal opinions from others as well. Maybe the statement becomes a bit less subjective then
.The last time you got a price for a Vacuumschmelze core must be quite a while ago.
Vacuumschmelze ceased production of goss c-cores maybe already ten years ago because production of c-cores, being bulk material, has become too expensive in western countries. Vacuumschmelze is now active in socalled "special products"; their magnetic products are based on amorphous and nanocrystalline alloys. Maybe they still do some permalloy stuff too.
Your sales rep apparently had a hell of a time to locate some old stock?
The material I use is not poorer grade.
HiB cores come from a Japanese manufacturer with a plant in China; quality is at least on par with the best I've seen from Vacuumschmelze, Waasner and others.
Amorphous material is an American development but, when I am right, the production of cores has been mostly in India.
The Chinese also offer amorphous and nanocrystalline stuff but the problem is that the quality of the finished product is not constant.
Nanocrystalline (Finemet) is a Hitachi development; several Asian manufacturers (and even Vacuumschmelze) are licensed to make products based on Finemet tape.
When for buying this stuff you are dependent on your local sales rep then yes, you pay the price, but to cut cost price as much as possible you have to look for better sources
.
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Maybe people think Vacuumschmelze stopped making SiFe iron materials but they didn't.
You can buy them from the Germany distributor Sekels if you wish.
TRAFOPERM<sup>®</sup>
You can buy them from the Germany distributor Sekels if you wish.
TRAFOPERM<sup>®</sup>
My statement is not a single personal opinion, but based on quite a number of personal opinions from others as well. Maybe the statement becomes a bit less subjective then
Hmm...
Excuse me, but have you perhaps heard the saying?
"The plural of 'anecdote' is 'anecdotes', not 'data'."
To paraphrase:
"The plural of 'subjective' is not 'objective'."
Just because someone attends weekly Flat Earth Society meetings, and has never entertained a single soul of a different opinion, does not mean that they are, in any objective sense, or even a wider subjective sense, "right"...
Not to say you are a Flat Earther, but it sounds like you are well aware of some of the more, ahh, shall we say, "Curved Speaker Cone Society" types?
Just because "they" say something, does not make it universally true.It was Vitroperm something or other (probably the 450 grade, I forget), and as far as I know, the unusual properties were its large size (Ae ~ 300mm^2 I think), and its type, a cut core (whereas they seem to prefer stripwound toroid shapes, which are even available from Mouser, with prices consistent with what I recall).
Which is also why I find mains-frequency transformers a bit... suspect. I remember reading articles about it, that they were going to 'revolutionize' power transmission and save a few watts here and there on core loss in the pole transformers. And I can believe that the high cost would be justified over the long service life (easily 50 years, with absolutely zero service -- not something very many people can claim of their amplifiers!
). But from what I've seen (not having seen your sources, and what grades of material are offered), those should be in the kilobuck range!Nanocrystalline (Finemet) is a Hitachi development; several Asian manufacturers (and even Vacuumschmelze) are licensed to make products based on Finemet tape.
When for buying this stuff you are dependent on your local sales rep then yes, you pay the price, but to cut cost price as much as possible you have to look for better sources
It's interesting actually, as there was some coincidence when the sales rep came by:
I was working at an industrial company. We called in the sales rep because we're building transformers (obviously enough), and I wanted to get an idea of the power, size, weight and loss tradeoff for these materials. (In the end, we chose 3F3 ferrite, big ol' 100mm rings.) We were discussing one of the power supplies under development, and one of the shop guys overheard who we were talking to.
As it happens, he had used their products before, and HMG/Finemet. His background is industrial brazing applications -- which like soldering, involves a filler metal, but unlike hand soldering, this is done quickly, with direct electric heating. VAC and HMG used to make amorphous and strip alloys for this market, so he had used them before.
Same old technology, different application. In fact, we had even looked into using some core halves to concentrate the flux, for induction heating. Amorphous alloys going from the fryer, back into the frying pan, I guess you could say..
Tim
I just called Sekels to verify.
Trafoperm n3 is now trafoperm n4.
Sekels confirmed that Vacuumschmelze stopped production of goss tape for their c-cores some 20 years ago....
The goss products on offer by Sekels come from Asian suppliers I was told.
Martin, you are enjoying your fourth account now on this forum; the former three banned.
Instead of spreading noise again, try to contribute in a more positive manner
You can call me John.
Then Sekels should update there recently renewed side i gues if that is truth what you say.
Werkstoffe für Kernbleche und Blechpakete
Then Sekels should update there recently renewed side i gues if that is truth what you say.
Werkstoffe für Kernbleche und Blechpakete
I just called Sekels to verify.
Trafoperm n3 is now trafoperm n4.
Sekels confirmed that Vacuumschmelze stopped production of goss tape for their c-cores some 20 years ago....
The goss products on offer by Sekels come from Asian suppliers I was told.
Martin, you are enjoying your fourth account now on this forum; the former three banned.
Instead of spreading noise again, try to contribute in a more positive manner
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