VOX AC30 6TB

British VOX. Three channels, each with two inputs. About 1961 the "Top Boost" (or "Brilliance") feature was Vox's optional addition of a rear panel-mounted circuit that introduced an extra gain stage and tone controls for bass and treble (as opposed to the single "tone" control of early AC30s). The unit became so popular that its features were soon implemented to newer AC30/6 models, and the controls moved from the rear panel to the control panel. Vox AC30/6 amplifiers from around 1963 had already implemented the top boost, and therefore had 3 tone controls. People began to refer to these amplifiers as AC30TBs.