As the Congotronics albums from Kinshasa demonstrate, one sound of young urban Africa is the shrill squeak of an antique Casio keyboard. This troupe from the 'burbs of Tanzania's Dar es Salaam (nicknamed "Bongo") combine distorted electronics with galloping rhythms hammered out on a battery of homemade drums and plastic pipes. Dubbed "mchiriku", it's crazed, urgent stuff with an incendiary live show – "We are the fighter plane," goes the boast – but the vocals are rich and tuneful and the lyrics full of homilies about respecting fellow citizens, the search for love and the timeless truth that "water does not flow uphill".