MusicMan® StingRay®, StingRay®5, Classic Sabre, Sterling®, and Sterling®5 Basses have a pickup selector switch connected to a 3-band EQ. It is very common to upgrade the system to a Bartolini HR-2.5AP Pre-Wired Harness.

The HR-2.5AP harness connects to the existing switch and provides a Volume with a push-pull switch to select active or passive mode. When in passive mode, the EQ is bypassed so the switch and volume remain functional even if the battery is dead.In active mode, the 3-Band EQ provides ultra-low noise boost and cut for Treble, Mid, and Bass.The Mid knob also has a push-pull switch to select 250Hz or 800Hz as the mid frequency to allow you to define your voice in a mix of instruments. The harness also has an adjustable gain trimmer so you can boost your output by up to 12dB.