Common Mode Noise Filter – Coax Bargain Basement Store / Bargain Basement Switchcraft 12B Stereo 1/4 Jack - 3 Conductor, panel mount, Vintage Mic Chassis Jack Switchcraft 12B Stereo 1/4 Jack - 3 Conductor, panel mount, Vintage Mic Chassis Jack SKU SW12B-1 $1.95 Buy Now Typical user comment: The filter was quite effective. Was surprised that it actually reduced the noise level more than the signal so S+N/N improved by 1.9 S units. Bill