Found this on the 365 Days website. A fucking amazing track by The Greek Fountains.

365 Days - Contributed by: Strictly Kev

Here’s a one minute instrumental version of Neal Hefti’s Batman Theme recorded on a wet afternoon about four years ago. Me on bass, my brother Gerry on guitar, soulless robotic drum programme on drums.

There are five different bass tracks here, played in different positions on the neck and then doubled up, one in to each speaker to give it that weird sound. One of the bass tracks was distorted with an Electro-Harmonix Big Muff pedal, if memory serves.