V-TBA – is a 250KΩ volume potentiometer with a special P taper characteristic enlarging the effective zone of a rotation when volume adjusting.
The extra feature of this potentiometer is an adjustable paralel treble bleed circuit.
In pictures below there are two axamples of 3 jumper switches in OFF position meaning there is just a basic capacitor acting on treble bleed control.
In third picture all of the 3 jumper switches are ON resulting in the maximum capacitance acting in the paralel treble bleed circuit.
Trimmer potentiometer – (see arrow), adjustable with a simple screw-driver, effects on a resistance value of the treble bleed circuit.
The combination of jumper switches and setting of the trimmer offers almost infinite values of treble bleed impact on the volume control.