Review of First Watt S5 Amplifier

Mar 16, 2025

Lecture Notes: Review of First Watt S5 SIT-5 Amplifier

Introduction

  • Speaker: Steve Guttenberg, audio reviewer with 25+ years experience.
  • Product Focus: First Watt S5 SIT-5 Amplifier, designed by Nelson Pass, manufactured in California.

First Watt S5 SIT-5 Overview

  • Design: Class A, single-ended design.
  • Output Transistor: SIT (Static Induction Transistor) made by Tonen, Japan.
  • Sound Quality: Unique sound not typical of solid state or other Class A amplifiers.

Companies by Nelson Pass

  • First Watt: Focuses on low-powered, Class A, single-ended amplifiers.
  • Pass Labs: Produces more powerful Class A amplifiers capable of driving a wider range of speakers.

Amplifier Specifications

  • Output Power: 35 watts into 8 ohms, 60 watts into 4 ohms.
  • Design: Zero feedback, single-ended.
  • Appearance: Comes with a silver or black face plate.
  • Inputs/Outputs:
    • Single RCA input.
    • Gold-plated binding post.
    • Power switch (located at the back).

Review System Setup

  • Speakers:
    • Pure Audio Project Duet 15
    • Klipsch OJZ
    • Magnan SMG Planar Magnetic Speakers
  • Comparison Amplifiers:
    • Pass Labs XA25
    • First Watt SIT-4
  • Other Equipment:
    • Linear Tube Audio MicroZOTL preamplifier
    • Mola Mola DAC
    • J's Audio CD Transport
    • Technics SL1200G Turntable
    • Ortofon Cadenza Blue Cartridge
    • Nordost Red Dawn Speaker Cables

Pricing

  • First Watt SIT-5: $11,000 per pair.
  • First Watt SIT-4: $5,000.
  • Pass Labs XA25: $5,150.

Sound Quality and Comparison

  • SIT-5 Characteristics:
    • Lush, romantic, full quality.
    • Described as having warmth, body, and beauty.
  • Comparison with XA25:
    • SIT-5: More lush, less focused.
    • XA25: More neutral, precise.
  • Comparison with SIT-4:
    • SIT-4: More immediate, connected sound.
    • SIT-5: More blooming, voluptuous sound.
  • Different Impressions with Different Speakers:
    • High sensitivity speakers enhance the SIT-5's qualities.
    • Low sensitivity Magnan SMG speakers showed SIT-5's capability to drive them effectively.

Personal Reflections

  • Listening Experience: Familiar music sounded different and more affecting.
  • Preference: SIT-5 seduces with its lush sound, although less neutral compared to XA25.

Recommendations

  • For Accurate Sound Seekers: Consider neutral amplifiers like NAD M23.
  • For Rich Sound: SIT-5 offers a unique, lush sound profile.

Conclusion

  • Steve's Personal Take: Finds SIT-5 to be extraordinary, challenging his reference XA25.
  • Nelson Pass's Genius: Recognized for creating amplifiers with beautiful sound.

Viewer System Highlight

  • Featured System: Grant from Quebec, Canada, with a variety of vintage and contemporary audio equipment.

Final Remarks

  • Steve emphasizes the joy and passion in discovering new dimensions in familiar music.
  • Encourages experimentation with setups for new audio experiences.