How PETER INFELD cello strings make a difference so you sound your best PETER INFELD strings for cello make you shine in many different ways. The strings are very reliable and help you sound great with minimal effort. The strings tremendous sound colors stay controllable at all times. They have a centered tonal core and sound especially powerful in the mids. These strings have been developed for remarkable balance and outstanding projection that lets your sound shine all the way to the farthest corner of the room.