Tone Merchants Concentric Jazz Bass Control PlateTone Merchants Concentric Jazz Bass Control Plate Concentric Jazz Bass Control Plate was made by Fender for a very short period of time, 1960 1962 but has had a lasting effect with an almost mythical feel about it. In fact these Concentric Jazz Basses from 60 62 are now highly sought after by collectors and tone junkies. Concentric controls for bass give you a wide range of tone options. Being able to contour the volume and tone of each pickup