Amorphous cores have been around for a while, from the Lundahl site>
"Old News July 2004
Amorphous core OPTs.
The LL1620, LL1623, LL1627, LL9202 and LL1679 are now available with Amorphous C-cores. (Sorry, no data sheet is yet available. I expect most data to be unchanged, except max signal/power level)
If these transformers are received well, we plan to get cores also for the LL1660 size transformers.
LL1688
is a new BIG tube output transformer designed for 845 applications.
The transformer weights 4 kg and is the biggest transformer we can presently manufacture.
LL1689
is a new tube preamp output transformer based on the LL1660, but with turns ratio 9+9:1+1+1+1.
LL1922
is a high level line input stepup transformer (turns ration 1+1 : 4+4) similar to the UTC-LS10. "
these cores have to be bigger than the steel cores because there is a bigger air gap between the layers, so for the same volume, you have less core with the amorphous stuff.
but some audiophile people like the sound, probably because of the increased frequency response of the core which can mean less distortion and phase shift at the high end.
Kevin at K and K audio , back in N. Carolina can tell you about the differences, he has actually done listening tests on a lot of these fancy transformers,
here is their website with some cool projects,
http://www.kandkaudio.com/
if you go to this link and enter "amorphous" into the serch text box, you will get many threads having to do with amorphous cores.
http://www.audioasylum.com/forums/KandK/bbs.html
it looks like the power companies are starting to build big amorphous power transformers, >
"More than ever, electric utilities and industries today are searching for technologies that will reduce their operating costs and improve energy savings throughout their systems. New transmission and distribution (T&D) technologies are now available to help utilities meet these goals.
With a new generation of Metglas® amorphous metal distribution transformers (AMDTs) -- with up to 80% lower core loss than conventional transformers -- Metglas, Inc. is helping utilities worldwide to achieve their efficiency objectives. When you consider that 10% of all electricity generated by utilities is lost in the transmission & distribution process, the potential savings through reductions in core loss can be significant."
looks like tons of companies are starting to use amorphous, global warming being one of the motivating factors,
some more on low level stuff:
"Amorphous magnetic cores allow smaller, lighter and more energy efficient designs in many high frequency applications for Invertors, UPS, ASD (Adjustable speed drives), and Power supplies (SMPS). Amorphous metals are produced in using a rapid solidification technology where molten metal is cast into thin solid ribbons by cooling at a rate of one million°C/second. Amorphous magnetic metal has high permeability due to no crystalline magnetic anisotropy.
Amorphous magnetic cores have superior magnetic characteristics, such as lower core loss, when compared with conventional crystalline magnetic materials."
ok, now on the grain question,
not all cool audio transformers use grain oriented lams,
there are some old western electric models that use regular "barn roof" non grain oriented lams,
but most non grain lams are used for low cost power transformers or motors, etc
there are two main advantages to using non grain,
the first is that it is dirt cheap, about 1/2 to 1/3 the price of microsil.
and the second is that there is very little magnetic aging with the non grain stuff.
when you align the grains in a lamination, they eventually become disordered again,
this is due to heat and stress and maybe a few other things, so the property of the grain orient tends toward the non grain,
where as the non grain is already where it is going to be in thirty years, which is non grain.
so you might lose a little perm and thus bass with a grain orient that is really old.