Yamamoto Sound Craft A-08S-205D Single Stereo Amplifier

The WE205D is a very good amplifier, but its output is only about 1W. Therefore, there are only a few speakers to use. Suitable for high-efficiency speakers such as Altic, JBL, and Rouser. These speakers have high conversion efficiency and efficiency, so the amplifier output is small. However, on the other hand, the amplifier noise also increases accordingly.

Generally, the WE205D can have a much smaller noise level when igniting AC, but due to variations in vacuum tubes and other reasons, it seems that variations in the output noise often occur when igniting AC. Therefore, the company has changed the ignition method of the WE205D to a DC ignition method using Schottky diodes using double-wave rectification, which achieved good results with the A-09. To simplify the circuit, no constant voltage circuit was used, only diodes and capacitors were used. This allowed us to keep the residual noise low at 0.4-0.6mV. The voltage supplied to the WE205D has also been increased slightly, bringing the maximum output to approximately 1.3W. The rectifier tube has been changed to 80, which has a clearer sound than 5U4G. In addition, we have adopted the highest quality parts for each component, including DC ignition of the front circuit, adopting a capacitor enclosed in the company's special ebony case, and improving the output transformer.

In addition, an ammeter is placed on the chassis so that the current in the output tube can be checked at all times. You can check the operating status of the valuable WE205D vacuum tube, and the approximate life of the vacuum tube can be determined using this ammeter.
These improvements make the sound more dynamic and powerful. When I listened to our large 3-way speaker system and the ALTEC605A, I got a much more powerful and clear sound than the 300B.

Operating conditions for WE-205D

• Plate Voltage: 380V

• Plate Current: 25mA

• Plate Loss: Approx. 9.5W

• Rp: 5k ohms

• Rk: 1.25k ohms

• Drive method: CR-coupled self-bias method