the tube rectifiers of AC30s were replaced by [ame="http://en.wikipedia.org/wiki/Silicon"]silicon[/ame] rectifiers, which became standard on later AC30TB models. In the late 1970’s Vox also introduced a solid-state AC30 (AC30SS), which is the AC30 model that was used by [ame="http://en.wikipedia.org/wiki/Status_Quo"]Status Quo[/ame]. A tube AC30TB with spring reverb feature was reintroduced in 1978. In