My understanding is they use ultra pure copper alloyed with rare earth elements but why not just read what they say on their website - http://www.masterbuiltaudio.com/technology
Generally speaking in regards to your comments about the relevance of CERN & aerospace applications etc., being an engineer like you, I can appreciate that the deep experience the MB folks gained in designing cables for ultra low reactance and very low noise & distortion (shielding), would be directly applicable to designing cables for audio. I've never heard or read (through VSA or the new MB website) that they use the same cable formulations for audio as they did for those other applications - simply that they gained a lot of insight into the constituent elements of cable/shielding design for very demanding applications and applied that knowledge to their designs of audio cables.
As you'll note on their website, they applied their scientific approach specifically to the design of their audio cables but also augmented this with blind ABX testing and feedback from folks in the industry using their cables with various equipment and speakers.
While I appreciate a scientific view and skepticism, I think perhaps folks are taking some of the (mostly anecdotal) information too literally - I've personally tried to get details about the construction and alloys used in these cables but the MB folks are not disclosing this as it is highly proprietary information (as anyone can appreciate). The other factor with MB is that they have access to test equipment that can measure extremely low levels of reactance and distortion - I don't know for a fact, but I would guess that most other cable manufacturers out there don't have access to the same test equipment as the cost of these is not justified if you are just building audio cables. This is another bleed-over form their work in the aerospace industry.
Cheers, Joe
Yes, I've read the Technology section, and that's how it all started last week. Moreover, I found the source of Amir's quote, plus a little more information about this aerospace connection - see http://dimfshifi.com/index.php/master-built/
Master-Built cables are designed and fabricated by a subsidiary of Delphi Aerospace. These cable use lab-grade Single-Crystal laboratory-grade copper solid core wire with aerospace shielding, Pat. Pend noise reduction technology; and German or Japanese made hi-purity plugs. The Standard and Signature cables use Teflon shielding for super clean high frequency response.
The new Ultra Extreme alloy was developed during a contract with CERN to provide a “super conductivity” cable with close-to-zero resistance and/or signal loss; this alloy was used in the Large Hadron Collider. The new S-C alloy is available as speaker or interconnects only and will be available until the current supply of alloy runs out.
The last highlighted sentence - "to provide a super conductivity cable" - is simply absurd. FWIW, you can guess how much respect I have left for those making these claims. At least they put "super conductivity" in quotes, but wow, what a claim.