Yamamoto Sound Craft A-08S-205D single stereo amplifier

is a very good amplifier, but its output is only about strong. Therefore, the speaker used is limited. High-performance speakers such as Altic, JBL, and Rauser fit. These speakers have high conversion efficiency and high efficiency, so the amplifier output is small. But on the other hand, the noise of the amplifier also grows accordingly.

In general, the noise level is fairly low even with AC ignition, but variations in vacuum tubes and other reasons seem to cause variations in the output noise in WE205D ignition. Therefore, the company changed the ignition method of the WE205D to the DC ignition method using the Schottky diode by double wave rectification, which obtained a favorable result in the A-09. To simplify the circuit, the constant voltage circuit was not adopted, and only diodes and capacitors were used. This allowed the residual noise to be 0.4-0.6mV low. The voltage supplied to the WE205D was slightly increased, and the maximum output was about 1.3W. The rectifier has changed to 80, which is clearer than 5U4G. In addition, the DC ignition of the front-stage circuit, the adoption of the capacitor enclosed in the ebony case of the company, the improvement of the output transformer, etc., we adopted the highest quality parts in each component.

In addition, a current meter is placed on the chassis so that the current of the output tube can be checked at all times. Valuable WE205D vacuum tube operation status can be confirmed, and the approximate life of the vacuum tube can be determined by this current meter.
These improvements made the sound more dynamic and powerful. When asked about our large 3-way speaker system and ALTEC605A, we got a much stronger and clearer sound than 300B.

WE-205D operating conditions

• Plate Voltage: 380V

• Plate Current: 25mA

• Plate loss: about 9.5W

• Rp: 5k ohm

• Rk: 1.25k ohms

• Drive method: CR coupled self-bias method