Jill Scott's annus just keeps on getting more mirabilis. The soul singer from Philadelphia started the year by winning her third Grammy - for the song Daydreamin' recorded with the rap star Lupe Fiasco. She then made an auspicious breakthrough as an actor, playing the starring role of Precious Ramotswe in Anthony Minghella's film adaptation of The No 1 Ladies' Detection Agency, screened on BBC One in March. And last month, on stage at Carnegie Hall, New York, the 36-year-old divorcée announced her engagement to Jon Roberts, the drummer in her backing band.

At Brixton, Roberts and his kit were behind a cage of Perspex screens, a technical strategy that did nothing to improve a typically hopeless Academy sound mix that managed to be both muffled and booming at the same time. This was a shame, because Roberts performed with explosive authority and, like everyone else in the 11-piece band, was clearly a musician of exceptional ability.

Scott fared only marginally better. Her voice is an extraordinary instrument and when she sang He Loves Me (Lyzel in E Flat) with a gentle piano accompaniment, it took on an operatic quality as she soared and swooped around the contours of the melody. But for much of the show her presence within the overall sound mix was far too subdued and nowhere near commensurate with her commanding stage manner.

Scott has forged an emotional link with her audience during a solo career that has produced three studio albums, and her show was peppered with little homilies from the heart. She prefaced an impassioned performance of Hate On Me with some pretty explicit instructions on how to ignore hurtful criticism, prompting loud whoops of sympathy from the predominantly female, Saturday-night crowd. “You gotta do right by me/ It's mandatory,” she sang with an imperious toss of the head as she embarked on an epic rendition of the title track of her current album, The Real Thing.

The pace sagged and attention wandered during a sequence of slower, seduction songs including Come See Me and Imagination, but Scott saved her most heartfelt performance for the end, when she instructed the sound- man to “take off the reverb” and sang a new song, And I Heard. The audience took up the gospel-like refrain while the band formed a conga-line and danced their way off stage, a joyous end to a frustratingly muted show.

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