"In Cobalt, there exists a very special substance that exhibits the best of both worlds; on one hand, there is incredibly high permeability, yet great power handling (high flux) - In other words, you have a material that is extremely sensitive, yet can handle anything it is called to do. The cobalt transformers essentially provide unrivaled low level detail and resolution, surpassing the best materials."
Lifted from http://www.magnequest.com/cobalts.htm
Mag Metals has all the lams/inch and lams/pound in their catalog.
As far as Silicon, your talking about M6, which is used in power applications (where you actually have some current flowing in the transformer, ac/dc etc.)
So it's used in pwr x-formers, output transformers with dc, parafeed chokes that handle some milliamps, etc.
Think of a transformer core as a vacuum tube.
Think of the coil as the source feeding the vacuum tube.
The source can either be high impedance (guitar pickup) or low impedance (Shure SM57)
The source will dictate how many turns are on the transformer.
The Core:
Core as a 12AU7: more current handling capabillity but less gain than a 12AX7. Probably less distortion. More headroom. This would be perhaps 49 percent Nickel.
Core as a 12AX7: more amplification factor, (more permeabillity means more inductance per turn) but lees current capibillity (saturates easier than a 12AU7) Less headroom. More distortion. This would be your mu metal, 80 percent Nickel, etc.
Core as a 6L6: Tons of current, low perm, low distortion, good in incremental inductors (DC in the core) This would be your M6.
Kind of a lame analogy, but what else is new!
Mu Metal is a patented blend. I do not know if the patent has expired, who is making it now, how many permutations it has evolved into. I tend to think of any 80 percent blend as some form of mu metal.
Yes you can judge nickel content sometimes by eye.
49 looks different than 80, etc.
Also look for grain orientation. Sometimes they roll it out differently to get the flux right at the corneres and other joints. The rerally old UTC's and WE's used non grain oriented.
:guinness:
