About three years ago, I became curious about a jazz series called Unheard Music, which began in 2000. I thought that it was instant karma: that music fans in Atavistic, an indie record label, finally felt the frustration that the best stuff was left unheard and were doing something about it. So I started buying them and realised that they were mostly free jazz reissues dating from the '60s.

Most of the time, they were unheard because they were released in extremely limited quantities and, in some cases, these reissues had to be reconstructed from some collector's original vinyl copy.

In most cases, the music was just ahead of its time. The best example is probably Sun Ra's Nuclear War. Made in 1982, Nuclear War has never been issued in its entirety and only two tracks have seen the light of day on a 12-inch single. For those of you who bought Yo La Tengo's interpretation in 2002, which featured a chorus of children yelling, "motherfucker," as vocal an anti-war protest as can be, you can also hear Ra say it in a more loose, casual setting. Ra was disappointed when Columbia Records turned down the opportunity to release the album. He was prescient about the advent of gangsta rap.

There are so many gems in the series, Peter Brotzmann Sextet's Nipples (1969), which features both saxophonist Evan Parker and guitarist Derek Bailey. The former's first recordings appeared only the year before while the latter started in 1965. Or Clifford Thornton's New Art Ensemble's Freedom And Unity (1967), which has the first recorded appearance of trumpeter Joe McPhee.

Most of the music here is so intense that little of it is likely to be found in a $ingapore home. The oft-heard complaint in our indie music history, that unwinding to relaxing music after a hard day's work, is more important than discovering passion, will make the Unheard Music series anathema to most ears.

Critics reviled much of this music in the '60s. There weren't a lot of places that would allow this music to be heard. As Valerie Wilmer notes in her book, As Serious As Your Life: "During the 1960s, sessions held in lofts owned by musicians, painters and others, were common. The audiences were small and very little money was involved, but the new music was being propagated. 'I know at that period everybody felt as though something new was forming,' said drummer Milford Graves. 'It felt like a revolution in the music and people felt, well, a lot of people won't understand what we're doing, voters won't help us or record companies - we're trying to get a listening audience'."

The first sighting of free jazz was on Ornette Coleman's Something Else! (1958). As Coleman succinctly states on the liner notes: "I think one day music will be a lot freer. Then the pattern for a tune, for instance, will be forgotten and the tune itself will be the pattern, and won't have to be forced into conventional patterns. The creation of music is just as natural as the air we breathe. I believe music is really a free thing, and any way you can enjoy it you should."

Yet the thrill is the search for new sounds. Free from the restrictions of chords and scales, the new jazz musician was concerned with the purity of new sounds. As Art Ensemble of Chicago saxophonist Roscoe Mitchell notes: "The musicians are free to make any sound they think will do, any sound that they hear at a particular time. That could be like somebody who felt like stomping on the floor… well, he would stomp on the floor. And you notice the approach of the musicians to their instruments is a little different from what one would normally hear... I'm getting more interested in music as strictly atmosphere, not so much of just standing up playing for playing's sake, but my mind stretches out to other things, like creating different sounds."

Perhaps for the new music fan today, hearing the early beginnings of free jazz is an important way to understand why improvisational music is making a comeback. Fans of Sonic Youth, Yo La Tengo, Jim O'Rourke, David Toop or John Zorn can see just how the big wheel of music keeps turning if they turn on to early Joe McPhee, Sun Ra, Evan Parker or John Coltrane.

Some ear- bending suggestions:

An instant classic had it been released in 1982, Sun Ra's Nuclear War worked along the same lines as Stanley Kubrick's film, Dr Strangelove - apocalyptic and darkly humorous. As Ra sings: "If they push that button, your ass gotta go. Now whatcha gonna do without your ass?" At times soulful, funky, laid-back and far out, Ra even tackles Charlie Chaplin's signature song, Smile. Hear it now before the bomb drops.

THE PETER BROTZMANN SEXTET/QUARTET
Nipples [Unheard Music Series]

One of the first releases on the Unheard Music Series, Nipples was produced by Manfred Eicher, later to found ECM, the famous European jazz label. Only two tracks are featured on this 1969 LP, the title track and Tell A Green Man. Featured artistes include Brotzmann and Evan Parker on sax, Derek Bailey on guitar, Fred Van Hove on piano, Buschi Niebergal on bass and Han Bennink on drums. The music on Nipples is fiery, mind-bending and shattering and the quartet, minus Parker and Bailey, relaxes a little on Tell A Green Man. And there is also More Nipples. Look for that.

ALEXANDER VON SCHLIPPENBACK TRIO
Pakistani Pomade [Unheard Music Series]

As important as Parker and Bailey are to the UK avant scene, Brotzmann and Schlippenbach are key figures for the Germans. Here in 1973, pianist Schlippenbach, Evan Parker and drummer Paul Lovens show the kind of heat that a three piece can generate. This album, particularly, is for Parker fans. Here he blows some extremely strange and intense noises from his sax. It's quite a wonder to behold. It's like watching fireworks in your brain.

THE CLIFFORD THORNTON NEW ART ENSEMBLE
Freedom And Unity [Unheard music Series]

With liner notes by Archie Shepp and a long poem by Ornette Coleman, Freedom And Unity (1969) underpins where a lot of new jazz came from. As Shepp notes: "Thornton's brooding trombone is a constant reminder of the bitter sweetness of the black reality. You will find textures in this album… deep mind blowing things of which you never dreamed. But the object is not to 'blow your mind' - I mean - to save it…" Recorded the day after Coltrane's funeral, Freedom And Unity was a battle for the black soul, its passionate cry tinged with a sense of mourning. Thornton, a well-known free jazz figure in the '60s, died forgotten in the '80s, but the album is, at least, finally rediscovered.