Hybrids Are Hot
"Recent advances in solid-state output devices and other components have opened up design possibilities never previously available," Audio Research's Terry Dorn explained. "And that led to our developing the Hybrid Drive HD220 stereo power amplifier ($8995)."
A JFET input feeds a 6922 dual-triode gain stage, which, in turn, feeds a 6H30 dual-triode cathode follower. That signal goes through ARC's proprietary coupling caps to the amplifier's 24 Thermal Trak bipolar output devices (12 per channel), achieving 220Wpc. Thermal Trak output devices automatically adjust their internal bias in response to their operating temperature, which, Dorn assured us, delivers "extremely consistent" performance no matter how hard you push the amp.
A short demo suggested that the HD220 might be a monster—especially in the bottom end.