You need phosphor-bronze acoustic strings for any electro-acoustic guitar, as they use piezo-electric under-bridge pickups, not magnetic pickups used on electric guitars. Ovation fit D'Addario EXP16 (.012-.053) 12's as standard, but you can use lighter strings if you prefer (easier to play, but tone not quite so strong and less sustain). I'd also recommend Rotosound Jumbo Kings - JK12 or JK11. Rotosounds are available here (UK delivery only): http://www.marsguitars.co.uk/acoustic-guitar-strings-2-c.asp