Now in its 16th year, the Southbank Centre's Meltdown festival has netted a wide range of curators, from John Peel to David Bowie, Massive Attack to Morrissey. This year's choice (it's also a bit of a coup), the saxophonist, composer and musical visionary Ornette Coleman, must count among the most fruitful.
For one thing, he is the first sole black curator, and I've never seen so many black faces in a Royal Festival Hall crowd as at the opening night's main event, the Roots. The Philadelphia hip-hop band's MC, Black Thought, takes the stage to loud cheers, followed by drummer Ahmir "Questlove" Thompson. The latter, eventually joined by the rest of the band, kicks up a storm as the MC raps, non-stop, for half an hour without breaking sweat; an astonishing performance, and the crowd, on their feet since the first minute, are dancing in their places all night.
There are plenty of other shades in the band's palette. Living Colour guitarist Vernon Reid produces jangling arpeggios, followed by Frank Zappa-esque solos. Jazz sounds abound amid the beats, and towards the end the group are joined by Ornette Coleman with tenor saxophonists David Murray and the 91-year-old Andy Hamilton. Murray's solos tear through the music, hard blasts building to high screeching and skronking. Coleman is something else, his lilting alto starting on a high wail and descending through different scales - straight blues, free jazz which veers into classical; it defies categorisation and is undeniably beautiful, possibly the essence of what he terms "harmolodics", his philosophy of music.
The next night plays host to Yoko Ono and a band that includes her son Sean Lennon, Mark Ronson on bass and members of Japanese experimental pop band Cornelius. Ono is a bounding sprite, a pint-size packet of energy, amazing for her 76 years. She bowls about the stage warbling and yodelling on tracks such as vintage opener "Why?" Her relationship with son Sean is sweet, and you can't help warming to them both; his guitar is impressive, often veering into Magic Band or My Bloody Valentine territory. Coleman appears tonight, too, as does the singer Antony Hegarty, a huge presence next to the tiny Yoko. Their duet on new track "I'm Going Away Smiling" is touching, with an amazing, elastic, cello-like solo on theremin from Pamelia Kurstin.
Senegalese singer-guitarist Baaba Maal and his band are great. Starting slowly with "Tindo", Maal hits his first high note two minutes in; it resonates around the hall, and we're away. What a voice; those hard, high notes, alternating with falsetto and tumbling scales. The full band come on for the title track of new album Television, and are joined by guests. VV Brown duets sweetly on the lovely "Djarabi", while London rappers Kano and Bashy come on for "A Song for Women". The energy is astounding, especially when talking drum player Massamba Diop trades licks with the other two percussionists, Bahkane Seck and Mamadou Sarr.
Over in the Queen Elizabeth Hall I catch James Blood Ulmer, a disciple of Coleman, who takes the stage solo and sings to an open tuning on his electric guitar. It's rough blues interspersed with tightly packed runs of fast jazz figures, and his themes are often biblical, though two songs about Hurricane Katrina and one about his ornery grandfather stand out.
Patti Smith is one of the most anticipated gigs of the week, and the audience the most vocal. Montreal post-rockers the Silver Mt Zion Memorial Orchestra are her backing band but she takes the stage solo for the signature "Piss Factory" and is then joined by SMZ leader Efrim Menuck on drums and Portishead's Adrian Utley, who attacks a guitar with a paintbrush to spooky effect. Smith's daughter Jesse plays piano on a couple of numbers, one a nautical tribute to her late husband Fred "Sonic" Smith, before Red Hot Chili Pepper Flea takes the stage, backing her beatnik verse with a high bass loop over which he improvises.
I'm delighted when the Master Musicians of Jajouka, who have played every afternoon for free, come on to blast us with their ancient pagan ritual music - wailing riffs from ghaita reed horns and hypnotic drumming; Smith salutes them in a poem and joins in with squealing clarinet. The full band produce an amazing sound, electric guitars fusing with the string section in a warm, wild noise. Smith draws an intense performance from the pit of her soul on the first encore, "Pissing in a River", and is dazed by the end.
A rich mix then, and it's a sign of the esteem in which Coleman is held that so many fine musicians felt so clearly honoured to be part of his Meltdown.
• The Observer is Meltdown's media partner
