October 2024: Fractal Audio's VP4 Virtual Pedalboard has been added to the wiki.
Humbuster
Contents
About Humbuster
Humbuster is Fractal Audio's electronics design for reducing unwanted noise that is caused by ground loops.
It requires the use of Humbuster cables with Humbuster-compatible output ports on Fractal Audio devices. All 1/4" outputs on the Axe-Fx II, III, FM3, FM9, FX8 and AX8 are Humbuster-compatible. Read this: Connections and levels.
"Won't do anything for pickup hum. It just fights ground loops." [1]
"Humbuster cables do not eliminate noise. Humbuster cables in conjunction with Humbuster outputs can significantly reduce hum due to ground loops. The outputs of Fractal Audio products have a special circuit that, in conjunction with a Humbuster cable, senses the difference in ground potential between the devices and cancels the difference thereby reducing hum. It's certainly not snake oil and you can find numerous testimonials on our forum that speak for the effectiveness." [2]
Humbuster cable
A Humbuster cable has a TRS end and a TS end. The TRS end ("stereo" plug) goes into the Fractal Audio device. The TS end ("mono" plug) connects to the other side, probably an amp.
"The Humbuster outputs sense the ground noise at the far end of the cable and cancel it out. Remember there is no such thing as a wire with zero impedance." [3]
"If you pull the cable out halfway it will get twice as loud. This is due to the humbuster output design. Don't pull the cable out halfway." [4]
"The 1/4" outputs have a "remote ground sense" feature. You take a TRS cable and on one end you put a TRS plug and on the other end you put a regular TS plug. On the TS end you tie the ring conductor to ground. Plug the TRS end into the Axe-Fx II. The ground noise of the attached equipment is sensed and added to the output signal thereby cancelling the common-mode noise (hum). This is especially useful when doing the 4CM since that's when you usually get the worst ground loops."
"A Humbuster cable is grounded at both ends. It's a three-wire configuration. The third conductor samples the ground potential at the receiving end and sends that back to the transmitter where it is used to cancel the ground noise. The manual even shows you how to make your own."
You can buy Humbuster cables from:
WARNING: When connecting a Humbuster output to a balanced TRS 1/4" input on another device, use a standard shielded 1/4" TS to 1/4" TS instrument cable (patch cable). Do NOT use a Humbuster cable. Do NOT use a balanced 1/4" TRS to 1/4" TRS cable. [5]
