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 |
First Watt: The First Watt Philosophy and Purist Class-A Architecture
First Watt represents a visionary project created in 1998 by legendary audio engineer Nelson Pass, dedicated to exploring the boundaries of purist amplification outside mainstream commercial constraints. The brand is built upon Dick Olsher’s famous statement that "the first watt is the most important watt." If an amplifier fails to deliver texture and natural nuance at one watt, massive output capabilities become irrelevant. First Watt specializes exclusively in low-power Class-A amplifiers rated up to 25 watts, utilizing elegantly simple circuit topologies with minimal or zero global feedback.
By embracing minimal component count and prioritizing the performance of individual active gain devices, First Watt amplifiers deliver extraordinary micro-dynamics, captivating detail, and a fluid naturalness often compared to the finest tube designs, backed by solid-state reliability. Each design released by Nelson Pass represents a distinct sonic approach, incorporating specialized JFET and SIT power transistors or zero-feedback current-source topologes. First Watt amplifiers are engineered specifically for audiophiles utilizing high-efficiency loudspeakers who prioritize subjective musical performance, absolute transparency, and pure emotion over raw power. At Dream Audio, we proudly present these iconic masterpieces of conceptual high-end engineering.
Manufacturer information (GPSR)
Manufacturer
Pass Laboratories
13395 New Airport Road, Ste G Auburn, CA 95602 (530) 878 5350 USA
info@passlabs.com