LOOSE STRING FOR DOUBLE BASS Helicore Orchestra H613 The (A) 3/4 tension soft. Helicore orchestral strings for double bass are made with a core consisting of several braided steel strands, producing a moderate and warm tonal quality. The heart design makes the strings very easy to play under the left hand. The string's damping has been optimized to create a good balance between sustain in pizzicatos and response when playing with the bow, giving us great response in many different styles, from a symphonic style to jazz or bluegrass.