Uncovering the hidden gems
　of Golden Tube 300B

The audio note 300B power amplifier has been reborn with the latest knowledge on traditional circuits.

Features

New Generation original OPT for optimized 300B bass extension and vocal fidelity
Improvements over classic 300B amplification circuit plus modern features
Dual GZ34 rectification and strengthened power supply design
New flagship silver signal capacitors and parts (applied also to Kagura, G-1000 and GE-10)

Circuit Configuration

Input stage is plate follower and direct connection cathode follower by 6072. Classic type phase inverter circuit is chosen for good balance of naturalness. 300B power tubes are fully driven with low impedance by 6CG7 in parallel configuration.
By suppressing overall NFB to only 2 dB, a new level of dynamic and low distortion is achieved. Sound quality is also improved through adding high quality resistors in combination with the VR of hum balancing circuit. 300B output stage is self-biasing circuit. This help owner to replace various kind of vintage 300B without stress.
Smart modular design and shortest wiring set good foundation for Gakuoh II's long durability with good sound.

Ideal Power Supply

High sound purity is obtained through independent rectification circuits for both amplification stage and output stage. Decoupling capacitors are installed close to each ripple filters to form clean signal loops. This design strongly reduced the inter-stage interference to minimum.
Using 2 pieces of rectifier tubes in parallel raise instantaneous current performance of the output stage. The rectifier tube is chosen with sound quality as prime concern. Independent power transformers are used to source clean high current to the heaters of the rectifier tubes.

High Grade Parts

Based on a full copper chassis, all premium grade parts are employed through listening tests. New design silver output transformers using in-house winding technique, Kagura generation silver signal capacitors, silver lead resistors, internal silver wiring materials SSW (silk silver wire), Ls-41 flagship interconnect, low vibration molded power transformer are all applied. All parts, including C and R, are placed at their optimized position.

Power Cable

ACz-AVOCADO

Specifications


Product	300B Push-Pull Monaural PowerAmplifier

Model	Gakuoh II

Rated power	20W @1kHz, 5% THD

Frequency response	10Hz ～ 40kHz (+0dB, -3dB @1W)

Input / Impedance	RCA, XLR (unbalanced) / 70kΩ

Output	4Ω, 8Ω, 16Ω (2 outputs factory preset)

Noise	Less than 1mV

Vacuum tube	300B x2, 6CG7 x2, 6072 x1, GZ34 x2

Power consumption	120W

Dimension	294mm(W) 284mm(H) 485mm(D) (excluding protrusions)

Weight	32kg