 The first widely produced Princeton, the 1948 tweed-covered "TV front," used one 6SL7 or 6SC7 dual-triode tube to provide two stages of RC-coupled voltage amplification in the preamplifier section; the power amplifier section used a single cathode-biased 6V6 beam power tetrode necessarily in Class A operation.The amplifier had a single volume control and a simple low-pass tone control to control treble response.The Princeton circuits up through 5C2 differed from the Fender Champ in having two versus one preamp stage (6SC7 dual-triode vs 6SJ7 pentode) and added the tone control that was absent in the Champs; the 12AX7-based Princeton models 5D2 through 5F2-A were essentially the Champ circuits 5D1 through 5F1 with a tone control and a somewhat larger output transformer.