A configured TYPE 121 pre amplifier coupled with a single ended driver and amplifier. Dissipation per channel is 2.2va@4r. Magnitude is sufficient to drive meter bridges, headsets, and loudspeakers that are 90dB/va or better. The unit employs a split 12AX7 and a pair of EL95 pentode connected valves that decouple through a PHILIPS TYPE A3 15412-1 PL 086 series output transformer or its equivalent with a nominal negative feedback of 1060r, with a nominal plate voltage of 260v. The 204 can be specified with electrolytic or polypropylene supplies. All coupling capacitors are polystyrene.