CHUBAN Reference-Grade FM711 Core Circuitry: High-End HiFi Class A Pure Power Amplifier (150W/8 ohms, 300W/4 ohms)

FM711 Original Specifications and Core Circuitry

Independent 2-channel pure power amplifier design, allowing for more flexible preamp pairing and less interference.

Layout surpassing the original, resulting in super-stable operation with zero noise.

16 brand new gold-sealed 2N3440/5416 tubes for testing and pairing. 2000 tubes are tested per cycle.

20 original Toshiba 5200 output tubes per test pair (made in Japan). Selected from thousands of tubes.

Each tube is connected in parallel with a Wima capacitor and decoupling capacitor.

800W high-quality Nippon Steel core transformer with independent windings for left and right channels.

80000uF ELNA AUDIO high-reliability capacitors.

Soft start and comprehensive speaker protection circuitry.

CNC precision machined all-aluminum chassis, 430*130*315mm.

AC110V or AC220V, Black or Silver.

Weight: 16KG

AP Test Data All specifications are very high; see test results below.

Output Power: 150W/8 ohms, 300W/4 ohms RMS power, stable full-power output over extended periods.

Output Midpoint: 1mV

Output Noise: 0.05mV, extremely low, the lowest among our amplifiers.

Signal-to-Noise Ratio: 120dB

Dynamic Range: 121dB

Distortion: 0.005%

Channel Separation: 100dB

Bandwidth: 5-50kHz

Quality Assurance

To ensure quality, every unit undergoes comprehensive AP testing to ensure it meets design specifications.

Tests include: bandwidth, noise (signal-to-noise ratio), dynamic range, distortion, intermodulation distortion, channel separation, amplification, etc.

72-hour stress test on the entire unit, 1-hour stress test at full 8-ohm load on the amplifier, and over 1 hour of listening practice. CNC precision machined all-aluminum chassis.

This machine has ultra-low distortion. Every machine is tested. When outputting 32.8V (with 8 ohm load, outputting 135W), the distortion is 0.003%.

Each large tube is connected in parallel with a decoupling non-polar capacitor and a decoupling electrolytic capacitor:

Output power: (with 8 ohm load), it can output RMS 36.7v undistorted voltage, 8 ohms 150w, see the figure below:

Precision matched tubes in groups of 20

Power tubes made in Japan

Brand new, original, recently produced gold-sealed tube

F7 (FM711) AP was tested by “L7Audiolab” L7 Audio Laboratory, the results are as follows: