A couple of years ago, as I was preparing a profile of the band for the venerable folk magazine Sing Out!, one member remarked to me in passing that the Crooked Jades are "Jeff Kazor's project." That member is gone, as are all the others from the lineup I met and interviewed -- except, of course, for Kazor. That is, allow me to clarify, from the current live performing ensemble. Banjoist/slide-guitarist Seth Folsom, from the incarnation I knew, is a regular presence on Shining Darkness. Rose Sinclair has since replaced him.

In any event, the Jades -- headquartered in San Francisco, where Kazor lives, though some other members reside or have resided on the East Coast -- manage to sound like the same group, if a musically evolving and deepening one, from album to album. Darkness is the fifth of them; there is also an EP released in 2004. (My reviews of two previous recordings, The Unfortunate Rake Vol. 2: Yellow Mercury [2003] and World's on Fire [2006], have appeared in this space.) Darkness marks the first of them to consist of all-original material, though in some ways this feels like detail and little else. Traditional music, here its resounding echo if not the thing itself, continues to define the soundscape.

In their approach the Jades conjure up the notion that they almost literally skipped the 20th century, leaving one foot stranded in the 19th and the other striding forward into the 21st. Even so, Kazor's instrumental composition "Shining Darkness Interlude" brings to mind -- I'm sure not his intention -- an outtake from the Incredible String Band's 1968 The Hangman's Beautiful Daughter. Kazor, interestingly, does not play on the cut.

Listening to the Jades has always been a curiously emotional experience for me, as if stirring sensations I could not have imagined "mere" music could touch. More prosaically, you could make the case, which as one called upon to render these judgments I am inclined to do, that no better neo-oldtime string band exists in America. There are some splendid competing bands out there (not least the other "crooked" one, the Massachusetts-based Crooked Still), with impressively inventive ways of restating tradition, and I mean to demean none of these admirable outfits. It occurs to me, however, that what Kazor, working with the extraordinary musicians he recruits, does is so distinctive as to create its own category of folk recreation.

There may be no way to state this except metaphorically, but while other modern folk bands strive to expand the tradition outward, Kazor and bandmates compress it inward until it feels like a black hole in which, you would swear, the world itself could collapse.

As I learned from my several hours with his company, Kazor is an ethnomusicologist in all but academic degree, a formidably intelligent, curious man with encyclopedia-level knowledge of world musics, not to mention keen musical skills himself. If the Jades sound is rooted, proximately anyway, in Appalachia and Delta, it yet absorbs notes, tunings and instruments (for example, the Vietnamese one-stringed box zither) from places improbably far afield. The results never come across as other than natural and unforced. In fact, they barely draw attention to themselves beyond generating the faint but growing sense, as one listens attentively or casually, that a piece doesn't sound quite as one expects it to sound. That realization is always a pleasurable one.

Yes, it's also scary and unsettling. Here, the roots are so long and deep that they give the impression, at moments, of having sunk through into another world. Shining Darkness is, no question, beautiful, but more than that, it is astounding.