Blast from my past – In 2012 I reviewed FirstWatt's SIT1 [$10K/pr], a 10/8W into 8/4Ω monaural amplifier from Nelson Pass exploiting a silicon-carbide based static induction transistor he had commissioned from US supplier SemiSouth. Whilst the SIT1 and its two direct descendants have long discontinued, the use of transistors with bona-fide triode curves continues in today's SIT4 stereo and SIT5 mono amps. Those use a far more powerful industrial part from Japan's Tokin. Yet the SIT1 started this particular micro branch on the class A amplifier tree to demonstrate the effectiveness of a very simple single-stage zero NFB circuit wherein one output device generated both voltage and current gain. We might say that in Nelson's implementations, these transistors operate like triodes without output iron. It makes them single-ended transistor amps so SET of different stripes. The SIT1 even sported 4Ω output impedance for the low damping factor high-efficiency speakers suitable for such low power prefer. I still have my pair and draft it into service whenever review speakers like Voxativ's Hagen2, Lindemann's Move/Move Mini or Cube's Lotus 10 knock on my door. Discovering Nelson's exotic SIT range was another nail in my personal tube-amp coffin to enjoy less noise, lower distortion and more bandwidth than direct-heated triodes offer.
