6S4S-3A5

The 6S4S-3A5 is an exclusive SE (Single Ended) Class A stereo tube amplifier, handcrafted in Latvia. It combines the highest-quality craftsmanship, classic audiophile components, and refined design. The point-to-point wiring method eliminates unnecessary interference and ensures maximum signal purity. This technique, used only in high-end tube amplifier construction, highlights the precision of each stage and the artisan’s craftsmanship. It is a one-of-a-kind creation, available in a single copy, making this amplifier a true collector’s piece.

Construction

• Chassis: Made from solid wood, giving natural warmth and elegance. The metal details are crafted from stainless steel, ensuring durability and a visual contrast with the wood texture. Each element has been carefully finished to achieve not only superior sound quality but also an aesthetically harmonious appearance.

• Capacitors: Paper capacitors are used. They are based on layers of paper impregnated with special insulating oil, wax, or resin, and placed between metal foil layers. This construction provides relatively high capacitance and stable operation at high voltages.  Advantages of paper capacitors:

  1. Warm and musical sound

  Paper capacitors are considered highly musical – they give the sound a soft, natural timbre and a harmonious warmth, making them especially suitable for vocals and acoustic instruments.

  2. Smooth high-frequency reproduction
     Unlike many modern plastic or ceramic capacitors, paper capacitors do not emphasize harshness in the sound; instead, they soften it and make the highs more natural. This is often appreciated in vintage and Hi-End tube amplifiers.

  3. High operating voltage
     Paper capacitors were traditionally designed to handle high DC voltages (often 400–1000 V), which makes them ideal for tube equipment where such voltages are standard.

  4. Wide frequency range

  They can operate across a wide frequency spectrum, maintaining good signal transmission without distortion.

  5. Longevity (when properly stored)
     Hermetically sealed and impregnated paper capacitors can last for decades. That is why many vintage amplifiers are still functioning with their original capacitors.

• Tubes

  • Power stage: Two 6C4C tubes – renowned for their musical character, revealing music with both delicacy and strength. The 6C4C is a Soviet-designed and manufactured directly heated triode (DHT). It was created as an analogue of the Western 2A3 tube, one of the most iconic audio triodes. Production ran in the USSR from the mid-20th century (around the 1950s) until the 1980s, primarily in factories in Moscow and other Soviet republics. The 6S4S–3A5 amplifier uses rare military-grade tubes from 1958.
    Today, the 6C4C is highly valued by audiophiles worldwide as one of the classic tubes for building high-quality audio amplifiers (Comparison of Power Triodes AD1, Ed, and 6S4S).

  • Preamplifier: Two RCA 3A5 tubes – providing a detailed, transparent, and naturally flowing soundstage. The 3A5 is a directly heated double triode (DHD), developed in the 1940s by RCA (Radio Corporation of America). Thanks to its compact size, low filament voltage, and reliability, the 3A5 found wide application, especially in the United States, and was later highly valued in audio equipment. In high-end SE (Single Ended) Class A amplifiers, the 3A5 is often used as an input/driver tube, as its smooth and musical character perfectly complements higher-power triodes such as the 2A3, 6S4S, or 300B. Among audiophiles, the 3A5 is considered one of the most musical low-power triodes, capable of delivering very high-quality signal processing when used in the right circuit.

  • Power supply: BO188 rectifier tube, delivering a traditional tube power supply character with unique dynamics and harmonic richness.

Technical Specifications

Sound Quality

The sound signature of this amplifier is distinctly musical, rich in nuances and emotional depth. It creates a wide, three-dimensional soundstage where every instrument takes its place with a natural timbre. The sound is smooth yet powerful enough to highlight dynamic passages while maintaining calm and lyrical moments.

This tube is not designed for raw power or aggressive tones – instead, it reveals the subtle details and emotional essence of music. It is ideally suited for classical, acoustic, and vocal music, while jazz and instrumental music lovers will also appreciate its natural, refined, and detailed presentation.

Overall Impression

The 6S4S – 3A5 amplifier is not only a high-end audio device but also a work of art that unites functionality with aesthetic pleasure. It is a choice for those who value:

• authentic analog sound,
• handcrafted individuality,
• high-quality materials and unique design,
• and the exclusivity of owning an unrepeatable piece of audio equipment.

This amplifier is created for people for whom sound is not just background, but a lifestyle and a passion.

Key Specifications