Joining violinist Magnus Johnston, cellists Marie Macleod and Calum Cook, and viola exponent Benjamin Errington is double bass player Tim Gibbs, the first ever to reach this stage.
Deciding who will go through to Sunday's concert final are three distinguished string players - Stephanie Gonley, Moray Welsh and Robin McGee. Hosted by Stephanie Hughes.
(The brass final is tomorrow evening at 6.40pm) (Stereo)