Yamamoto Sound Craft A-08S WE101D/104D Single Stereo Amplifier WE101D ST Tube Included Used Item
Product code: 101d-5Yamamoto Sound Craft A-08S WE101D/104D Single Stereo Amplifier WE101D ST Tube Included Used Item
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Dedicated power amplifier for WE101D/104D
A-08S Western Electric 101D/104D Version
Yamamoto Sound CraftThis is a listening device that was installed in the listening room. Since it was used for listening by the manufacturer, maintenance is perfect. It is an extremely sharp unit. As it was a listening device within the manufacturer's headquarters, usage was quite limited, and the included WE101D ST vacuum tube has very little usage time. It will be shipped after manufacturer maintenance. It comes with a 6-month manufacturer warranty, including the output vacuum tube.
This is a sister model of A-08S dedicated to WE101D and WE104D. Although the output is less than 1W, the sound quality is excellent, comparable to WE205D, and it was commercialized because the sound quality and output exceeded expectations during the prototype stage, making it sufficiently practical.
The low output of about 0.25W for WE101D is achieved by applying a plate voltage of about 250V and flowing 13.5mA, resulting in a power consumption of about 3.5W. The load impedance at this time is set to 5k ohms, yielding an output of about 0.6W. On the other hand, for WE104D, the maximum output according to the specifications is about 0.8W at a plate voltage of 190V, so the same condition is adopted. For both types, the plate current value is fine-tuned by adjusting the cathode resistance to find the optimal value, achieving an output of about 0.8W as per the specifications. Additionally, both vacuum tubes can be used simply by switching the cathode resistance.
| Used Vacuum Tubes | WE-101D/104D*, C3m,80 |
|---|---|
| Maximum Output | WE101D: About 0.6W/8Ω WE104D: About 0.8W/8Ω |
| Frequency Characteristics | 22Hz-28kHz (-3dB) |
| Output Transformer Impedance | Primary Side 5kΩ, Secondary Side: 8Ω |
| Residual Noise | 0.4-0.8mV |
| Drive Method | CR Coupling, Self-Bias Method |
| Size | 400(W)294(D)204(H)m |
| Weight | 14.3 kg |
It's sensational to the point of being hard to believe!!
The 101D is far superior to the 300B. It is the best amplifier I have ever used.
My impression of the amplifier using the WE101D is that it has the most dynamic and clear sound among all the amplifiers from the same company, including the WE205D, 45, and 300B, except when played at high volumes. This seems to be greatly influenced by the non-choke power supply of this amplifier. Normally, amplifiers use choke coils to eliminate ripple in the B power supply of the output stage, but this amplifier does not use choke coils due to its low current draw and instead forms a filter with only CR to supply the B voltage.
The output stage's cathode bypass capacitor uses a polypropylene capacitor with a lug terminal from the American Dearborn company, which is sealed in a high-strength epoxy resin case similar to Bakelite, contributing significantly to the sound quality. Additionally, this unit uses a Siemens C3m vacuum tube as the driver tube, with the shield case removed. The C3m is a relatively new design pentode released around 1968, known for its excellent characteristics, producing a clean sound with minimal noise.
Both the WE101D and WE104D were tested with ST and tennis ball types, with the ST type providing a tight and well-defined sound, while the tennis ball type offered a more relaxed and spacious sound. The tennis ball type is visually interesting and enjoyable to look at, but it is expensive, so I feel that the ST type is sufficient if choosing based on sound quality. The speaker terminals only have an 8Ω output, but using 4Ω or 16Ω speakers poses no issues. However, in either case, the maximum output will decrease. With a maximum output of 8W, the output will be around 4-6W.
