Introduced by Gibson in 1959, the Varitone 6-way tone control is a circuit that acts as a notch filter, reducing frequencies at set points along the frequency spectrum. Filtering is achieved by passing the signal through capacitors that effectively remove or reduce specific frequencies. As the Varitone knob is rotated from positions 1 to 6, the center frequency of the filter shifts from high frequencies to lower frequencies, producing unique tones at each setting. Probably the most notable use of a Varitone circuit in an electric guitar is B.B. King’s Lucille.
An example of the various settings and the tonal effect of a Varitone circuit:
- Position 1: Bypass (no effect)
- Position 2: -8.5dB at 1875Hz (or 1.875kHz )
- Position 3: -12dB at 1090 Hz (1.090 kHz)
- Position 4: -15dB at 650 Hz
- Position 5: -16dB at 350 Hz
- Position 6: -20dB at 130 Hz
The specific frequencies impacted by the Varitone will be dependent on the values of capacitors used.