So-called reality is warped on Bamako Moon, as Dan Harper, otherwise known as Invisible System, reconfigures core material from his two recent ‘overground’ album releases, Bamako Sessions (World Music Network) and Dance to the Full Moon (ARC Music). He removes the vocals from the first, and adds voices to the second, transforming instrumental and song-based originals into their opposite numbers, remixing and dubbing in the process. Harper also adds some completely fresh material.

It's a conceptually confusing process, as the preceding two albums already enjoy a frisson of reinterpretation and relocation. Add to this the integral concept of Frome-resident Harper travelling around Mali and beyond, recording local players, then fusing their talents with his own production skills, and we have a joyous miasma of ethnographic groove-collaging. On the one hand he risks diluting the impact of the two core albums, but on the other he's justified by the sheer quality of the actual music, in all of its incarnations.

As Harper is in full control here, perhaps he views Bamako Moon as representing the ideal shape of this material. The opening run involves an acoustic tilt, with singer Sambou Kouyaté dominating, partnered by guitars, ngoni, kora, balafon and percussion. ‘Diabate’ and ‘Kidou’ are early highlights. The new ‘Echo Rock’ is gritty and driving, with choppy fuzz and reverb guitars, placed just at the point where the acoustic tips over into dance-floor instrumentals for the album's second part. Sometimes there's a ghostly minimalism, heard to best effect on ‘Le Rap De Penzy’.

The four hours of Ambiences in Mali is even more specialised, passing from collaboration, through field recording, into a realm of uneventful 30-minute tracks where Harper left his microphone rolling interminably. An environmental feeling is embraced, as musical outbreaks come and go, but the results are way too sparse for even the most open-minded of minimalists.