The 1960s Vox amplifiers had as much to do with the distinctive “British Invasion” sound as did the horde of bands that released singles and albums on these shores. Vox amps had a distinctively bright, “chimey” sound, and for U.S. groups unable to afford the British amp imports, Vox built a compact treble-boost unit (the V806), which plugged into any domestic amplifier to impart that extra-glossy sheen that was so popular. The chrome-plated unit had a 1/4-inch jack on one end, with an on/off switch and a 1/4-inch input jack along one edge. Most guitarists just plugged them in, turned them on, and left them on. By the late 1960s, as music evolved to include psychedelic sounds and raw blues tones, some guitarists discovered that the treble boosters produced a nice gain boost, as well. By turning the treble way down on the amp, then plugging in a Vox (or other brand) treble booster, guitarists quickly found out that boost would add a nice overdrive effect. Today, Queen’s Brian May uses a homemade treble booster plugged into a wall of Vox AC30s (with the treble rolled off) to achieve his signature sound. Other guitarists (like the late Rory Gallagher) used somewhat similar setups. Most modern treble boosters are designed to add even more boost to the output while adding a level control.