FloridaGull , It was made by luthier Bruce Taylor for Pete. Pete has gone through a number of them. Someone who didn't like his politics put his foot through one of them. Pete backed his car over another. Martin has made some patterned after Pete's 12-string. Here's a write-up on the Martin:
For more than 70 years, Seeger has embraced and championed traditional American music, as a member of the Almanac Singers in the 1940s, the Weavers in the 1950s and recently, as a solo artist. The 12-String J12SO! is inspired by Seeger's personal 12-string guitars, the first two of which were custom built by Liverpool luthier and engineer G. Stanley Francis; with later, evolved versions crafted by Connecticut luthier Bruce A. Taylor.
The J12SO! model has Martin's Grand Jumbo body style, built of solid woods. The top is built of Sitka spruce, East Indian rosewood on the back and sides, a genuine mahogany neck with unadorned black ebony fingerboard, and a polished East Indian rosewood headplate. The headplate includes the familiar gold C. F. Martin & Co. logo, as well as a banjo sketch drawn by Seeger and a replica of his signature inlaid in mother of pearl. The unique and distinctive triangular sound hole is surrounded by a black/white/black/white fine line rosette, and the top of the sound hole is encircled by bold herringbone purfling and grained ivoroid binding.
Both models are finished with a polished gloss lacquer finishes, with aging toner on the tops to enhance their vintage style and are protected in Vintage Series Geib-style hardshell cases.
-1962 Martin D-21 -1950 Gibson LG1 -1958 Goya M-26 -1974 Yamaha FG75 high strung -A number of banjos, mandolins, Autoharps, ukuleles, dulcimers, mouth harps, a Tele clone and various other stuff. -I own a fiddle, but only play it when Maggie and the cats are all out of the house.
Another moderately old thread but again, since I'm the newbie I'm probably going to dig up a few zombies.
I've played 12 strings on and off for quite a few years (and think that every guitarist should have one in her quiver - they are truely the grand pianos of the guitar world). There are a number of "standard" ways to tune a 12 and so called alternate tunings can be wonderful on them. But I'm sorry, that link is just wrong.
Part of the problem, I think, is that it appears to be focused on electric players - there's lots of talk about effects and pedals and such - it seems to be mostly the kind of lead playing that electric guys do (no strumming or finger picking) and frankly, in my book, lots of electric playing is just noise....
Most 12 strings are tuned in the same sequence as a sixer, eEaAdDgGbbee bottom to top. The first and second course are unison string, tuned the same (like a mandolin). The other four courses have a smaller string usually in the even (6, 8, 10, 12) position tuned one octave higher than the primary string. That is what gives a 12 its "shimmer" (or jangle) The pair of strings is played together (usually) however some people can pick just one of them at a time (Chris Proctor is a good example). With normal light gauge 12 string sets the tension is about 260 pounds total, which is maybe 150% of a sixer - not double as many folks think.
The first "altered" tuning for a 12 string is what the electric Rickenbackers do - reverse the primary and octave strings. On your pick downstroke you hit the primary first - it does give it the distinctive sound that we associate with Ric's. Its possible to experiment with this on an acoustic 12 but its a big hassle - new nut and possibly a saddle and bridge work.
Next altered tuning is to tune everything down one or two semi tones (D# to D# or D to D). This reduces the tension significantly (with the same string sets) and dramatically changes the sound. You loose a lot of the jangle and get more of a roar to the sound. If you sing or play with others you can simply throw on a capo at the first or second fret or transpose. If your 12 string is truly designed and braced for concert tuning and light gauge strings it might sound muddy when tuned down - it is often wise to bump the string gauges up a bit (0.010 to 0.012 on the first course). You'll see these branded as 'mediums'.
Lots of 12 strings were designed to be tuned even lower. The Taylor LKSM is designed for C# to C#). Pete Seegers Taylor (not the same taylor) and of course Huddie Ledbetters iconic Stella are all designed and braced to be tuned way down. At some point you need to go to longer scale lengths and phatter strings. As I recall Leadbelly strung 16 to 70 or something and tuned to A.
One other thing that Leadbelly did was to tune the third course in unison and actually tune the 12th strings two octaves higher than the 11th. I've experimented with this and ended up going back to standard stringing (but B to B on my long scale ladder braced 12).
Last, and far from least, a 12 string can be tuned to one of the "normal" altered tunings like dropped D (or its lower equivalents) or an open tuning (D, G, C... with any of them down a step or two or three). The Seeger example above, and of course the iconic Leo Kottke. An open tuning opens (no pun) all of the possibilities of slide on a 12 (Kottke, Paul Gerimia, me), but the important thing in this context is that the pairs of strings are still tuned to the same note, unlike the example.
I currently have three 12 strings, a pretty normal Martin D12-28 (24.9 scale) which is usually tuned one or two semi tones down, my OM sized 12 (25.4 scale) which is always down two and frequently some open tuning below that) and my 000 sized ladder braced Stella clone (26.5) which is strung with cables and tuned B to B or lower.
Note that the Stella clone is 12 fret, slot head and has a tailpiece. We can talk about that sometime....