Product Highlights: Mid-frequency richness, warm sound, elastic response, strong airiness, and long-lasting listening pleasure! Changing tubes from different brands yields noticeable differences in performance, making it ideal for novice DIY enthusiasts who enjoy experimenting.
The Charm of Vacuum Tubes: Vacuum tube amplifiers paired with digital audio sources (such as CD, VCD, DVD, etc.) use the "tube sound" to mellow or eliminate digital harshness, resulting in a warm, musically rich, and airy sound that delivers sweet, smooth musicality (often referred to as "tube warmth"). In contrast, standard transistor amplifiers can produce a sharp, fatiguing sound due to digital artifacts, commonly known as "transistor sound" or "solid-state harshness."
The 12AU7 is a classic low-frequency dual triode, distinct from high-frequency dual triodes (like the 6N3) and general-purpose dual triodes (such as the 6N1). Its key features include moderate amplification, low transconductance, and high plate dissipation and maximum plate voltage. Widely regarded for its rich sound and affordability, it is an excellent choice for voltage amplification. Additionally, its high grid bias makes it well-suited for dynamic signal sources like the McIntosh MCD301, which outputs up to 6V.
While many preamps use pentodes like the EF86 or 6AC7, their high internal resistance can hinder synergy with power stages. We believe that a two-stage amplification design is unnecessary for tube preamps; the key lies in increasing the plate voltage to extend the characteristic curve and enhance dynamic output. Thus, we adopted a single-tube, single-stage amplification circuit, achieving outstanding results post-assembly. The principle is as follows:
Reference circuit diagram; component values may vary—refer to the actual internal components.
Unit Components Overview:
◆ 36W pure copper wire power transformer (model 663508) and 10H 45mA high-inductance choke (48X20), crafted from high magnetic flux core for minimal leakage, low heat, and vibration-free operation.
◆ Two 6Z4 tubes for rectification (compatible with 6X4 imported rectifier tubes via adapter; custom orders for dual 6X4 units available—inquire for pricing). Filter circuit includes: 47UF Japanese Tokyo Electronics TE capacitor x1, 220UF Taiwanese TEAPO high-speed low-resistance capacitor x1, 0.1UF film safety capacitor x1, and 10H choke in a CLRC configuration for low ripple and silent background. Tube rectification offers finer highs and smoother sound compared to solid-state rectification.
◆ Dual 160V 120MA high-voltage supply; 12AU7 powered by 6.3V 1A AC, with two filament balance resistors grounded to effectively reduce noise. This filament wiring preserves the musical nuance of AC heating without hum. Both 6Z4 tubes use 6.3V AC supply at 2A current.
◆ No input coupling capacitor; output coupling uses Japanese Tokyo Electronics TE 2.2UF MKP high-end film capacitor in parallel with TE 0.1UF capacitor for excellent high and low-frequency performance.
◆ Renowned brand copper-pin metal film precision resistors combined with carbon film resistors for rich tube sound.
◆ Japanese ALPS 16-type potentiometer.
◆ Fully hand-wired point-to-point soldering with star grounding for minimal noise and easy component upgrades.
◆ Includes new Psvane 12AU7 and Shuguang 6Z4 x2 tubes as standard.
◆ Copper-pin silver-plated tube sockets.
◆ Pure gold-plated copper RCA jacks, durable and secure. Two input channels switchable via rear switch; one output channel.
◆ Sound Quality: Rich and full-bodied audio, extremely quiet background, and high dynamics.
◆ High-quality 1.2MM thick steel powder-coated chassis for effective electromagnetic shielding, styled in vintage Western Electric design. Transformer mounts feature British-style red Transformer copper-plated brackets.
◆ Dimensions: 110MM width, 220MM depth (including knobs and RCA jacks), 130MM height (from feet to top of 6Z4 rectifier tube).
◆ Weight: 2.35KG
◆ Chassis accessories include: ① Silver-contact toggle switch ② Three-pin US standard copper power socket ③ Solid aluminum knob with dial for excellent feel ④ Rubber feet
[Technical Parameters]
1. Input sensitivity: 200mV
2. Voltage output: 2V (RMS THD <0.03%) - 17V, voltage gain approximately 7x.
3. Signal-to-Noise Ratio (S/N Ratio): 97 dB
4. Frequency Response: 10Hz - 40kHz (-0.5 dB)
5. Input Impedance: 100 kohm
6. Output Impedance: 2 kohm
7. Channel Separation: 65 dB
