Many years ago, when I was attending a Midwestern state university, I worked the night shift in the student union as a janitor to help pay tuition. I worked with a crew of genial older guys for whom this was their full-time job. Around 2 a.m. we'd take a break for a sandwich and coffee. They'd turn on the radio, and their tastes ran to hard-core country music as played on a station out of Waterloo, Iowa. As I recall, the station must have sold slots of its late-night/early-morning air time to sponsors. I recall that this sponsor -- I believe in retrospect that it must have been Uncle Jim O'Neal -- was pitching the tough mountain music of an outfit I'd never heard of, J.E. Mainer's Mountaineers.

I didn't know it at the time, but Mainer (along with his brother Wade) was a longtime performer of what I learned Southerners call "old-time music." (Or, as Mike Seeger would quip, "Old-time music is what the folk call folk music.") I had never heard music like that before, or for that matter music of that wild intensity. It would not be long before it would become an enduring obsession. Even now, hardly a day goes by that I don't hear some of it.

I'd never heard of Rural Rhythm Records, either, but it was courtesy of them that Mainer, a North Carolina fiddler who would die in 1971, was sounding out of that radio. A year later, acting on a tip from a passing acquaintance, I bought a New Lost City Ramblers album and began my education in traditional, pre-bluegrass Appalachian music. I already knew a little about bluegrass via Flatt & Scruggs's Columbia records, but I was soon to know a whole lot more. In due course I heard about Rural Rhythm and through that knowledge something about Jim O'Neal.

A Californian with Southern roots, O'Neal ran a mail-order operation that catered to a largely rural audience whose tastes ran to no-longer-quite-mainstream music of all kinds. But his first love was bluegrass and old-time, based in his youthful exposure to folk songs, hymns and sentimental 19th-century parlor ballads. He wanted to preserve that body of songs for future generations, and with that philosophy in mind he founded Rural Rhythm in the 1960s.

A typical Rural Rhythm LP carried 20 cuts. On most, the average cut was in the vicinity of two minutes long. The songs were recorded with no extras; unless the cut itself was an instrumental, there were unlikely to be anything but the briefest fiddle, banjo or mandolin breaks. The songs were overwhelmingly in the public domain, so they not only were vintage songs but required no overhead-expanding royalty payments. Nothing fancy, and the packaging was little more than functional clip art. It was also, you might argue, some of the most compelling traditional Southern music ever recorded.

O'Neal put together an amazing roster of bluegrass and old-time artists. Some were well known in their little corner of the musical world (Mainer, Mac Wiseman, Don Reno, Red Smiley). Others, also first-rate artists (Earl Taylor, Jim McCall, Hylo Brown, Bobby Smith, Raymond Fairchild), weren't famous for one reason or another. But a Rural Rhythm album assured you of no-nonsense hard-driving mountain music that could cure anybody's blues. They've certainly cured mine on many an occasion.

O'Neal died in 1982, and in 1987 Sam Passamano II, who had worked for O'Neal when he was a college student, purchased the label and attendant businesses. Passamano went on to modernize Rural Rhythm. In recent decades it has signed a range of younger and more modern (albeit still mostly at least neo-traditional) acts. The CDs are packaged attractively, the production qualities are top-notch and the music is solid. No bluegrass fan has anything to complain about Rural Rhythm in 2013.

The label also works on a second track, devoted to the preservation of the music O'Neal recorded. It regularly issues 20- to 25-cut reissues in varying formats and at close to half the price of a regular CD. The two CDs listed at the head are current examples. You may have even seen them, or their antecedents under a range of titles, last time you were in a store that still markets recorded music. Possibly, you thought they were just another example of cheap department-store collections, something thrown together with a metaphorical shovel by record-company hacks with no engagement with the music. If so, you would have been wrong.

Accumulate enough O'Neal-era reissues, and you won't have every old Southern song -- that well may not be bottomless, but it always seems so -- but you'll have most of the good ones. For a few random examples: "Foggy Mountain Top," "Nine Pound Hammer," "Ground Hog," "Red Rockin' Chair," "Worried Man Blues," "Wreck of the Old 97," "Handsome Molly," "Girl I Left in Sunny Tennessee," "Shady Grove." And more. Much more. If you don't know those songs, it's an instant education. And if you do, they sound great in the hands of by some of the finest bluegrass bands of the 1960s and '70s, when the genre was still close to its origins in ballad singing, string bands and country churches.

Besides the continually repackaged anthologies, Rural Rhythm keeps recordings devoted to individual acts in print. O'Neal knew how to pick 'em. A particular favorite of mine is The Best of Mac Wiseman. Wiseman, still alive, was there in the late 1940s, at the beginning of bluegrass. Like O'Neal, he favored venerable folk and heart songs in his repertoire, and I doubt anybody has ever sung them better. Wiseman's rich, expressive baritone, matched with his taste for strong, enduring melodies and sometimes arcane songs ("Little Mohee," "Little Blossom"), will take the listener directly to hillbilly heaven. His version of "Picture from Life's Other Side," composed in the latter 1800s, is even more darkly beautiful -- it's also more textually complete -- than Hank Williams's classic reading. In both the technical and larger sense, there may have never been a finer bluegrass vocalist in bluegrass than Wiseman in his prime, as he is here. Bluegrass fans know that, of course, but people who don't know the genre ought to know the name and the work.

Mama Likes Bluegrass Music, by Raymond Fairchild & the Frosty Mountain Boys, was a revelation to me when I first heard it not long ago. Knowledgeable bluegrassers usually point to Earl Scruggs and Don Reno as the leading banjo innovators, but a case can be made for the less celebrated Fairchild, too. His distinctive style is instantly discernible even to a non-musician's ear. You won't mistake it for anybody else's. He and his band give new life even to such well-worn stuff as "Dixie," "Casey Jones" and "Cripple Creek." Their version of the old Ferlin Husky hit "Wings of a Dove" is riveting.

I have probably two dozen Rural Rhythm reissues in my CD collection, and space prevents me from mentioning them all. Lately, though, I've been listening to two retrospectives of Earl Taylor & Jim McCall (one each representing their 1960s and 1970s sides), Hylo Brown (The Best Of), Don Reno & Bill Harrell (With the Tennessee Cut-Ups) and, yes, J.E. Mainer & His Mountaineers (Old Time Mountain Music & More Old Time Mountain Music) -- a double-disc set of Mainer at his rawest and wildest. There also two more releases in the Power Picks series, one of instrumental bluegrass, the other of bluegrass gospel. It's all to be marveled at, and so are the prices.