The First Watt SIT-4 is a single-ended Class A power amplifier designed by Nelson Pass, representing the fourth generation of First Watt amplifiers to utilize Static Induction Transistors (SITs / VFETs) as power amplifying devices. Utilizing a single SIT device in a Common-Source configuration without negative feedback, the SIT-4 operates similarly to a single-ended triode (SET) tube amplifier but directly drives loudspeaker impedances without requiring an output transformer. Supported by a MOSFET "mu follower" current source and buffered at the input by a NOS Toshiba 2SK170 JFET, the SIT-4 delivers tube-like harmonic warmth with superior bandwidth (extending up to 80 kHz at -3 dB) and lower distortion. Optimized primarily for high-efficiency loudspeakers such as Altec, Klipsch, JBL, and Lowther, it produces clean, musical power with an open, highly detailed soundstage.
| Frequency response | 4 Hz až 80 kHz (-3 dB) |
|---|---|
| Input impedance | 4 Ω |
| Power consumption | 200 Watts |
| Fuse | Typ 3AG pomalá (2,5 A pre 120 V AC / 1,25 A pre 240 V AC) |
| Gain | 20 dB |
| Noise | 75 µV nevážený, 20 Hz – 20 kHz |
| Distortion @ 1 Watt | 0,6 % |
| Output Power @ 8 Ω | 10 Watts @ 2 % THD |
The First Watt brand represents a unique, visionary project by the legendary audio engineer Nelson Pass, founded in 1998 with the aim of exploring the boundaries of purist amplification without the compromises of the commercial market. The brand builds on Dick Olscher’s famous idea that it is precisely the first watt of power that is most important for overall musicality. If an amplifier does not sound natural and detailed at the very first watt, enormous power output in the hundreds of watts loses its meaning. First Watt specialises exclusively in low-power amplifiers operating in pure Class A with an output of up to 25 watts, which utilise exceptionally simple circuit designs with minimal or zero negative feedback.
Thanks to their simple circuitry and an emphasis on the top-quality of individual transistors, First Watt amplifiers deliver exceptional micro-dynamicsdynamics, captivating detail and a silky naturalness that is often compared to the finest valve designs, yet with the absolute reliability of solid-state technology. Each model from Nelson Pass’s workshop represents a unique concept, whether it involves the use of special JFET and SIT transistors or a current-source circuit without negative feedback. First Watt amplifiers are designed for discerning audiophiles with highly sensitive loudspeakers who seek subjective perfection, absolute fidelity and uncompromising musicality.
Manufacturer information (GPSR)
Manufacturer
Pass Laboratories
13395 New Airport Road, Ste G Auburn, CA 95602 (530) 878 5350 USA