Discontinued. The VAC 23 features volume, treble, bass, tone, and master controls. The pull treble control boosts upper mids and gain. The Tone switch has 3 positions: brighter/thinner, normal, and darker/thicker. The pull gain switch, on the volume control, bypasses treble and bass for a hot tweed tone.  V.A.C. presets are: 23, 18, 11, 5, and 3 watts.