Since an actual image cannot be displayed here, a detailed textual schematic of the updated Xin Zhi Zhao for a 300B SET amplifier follows:
Power Transformer → 5U4GB rectifier → 47µF/500V → 10H choke → 330µF/500V → 10kΩ/5W → 100µF/450V (supply for driver)
Driver Stage (6SN7):
Output Stage (300B):
Feedback: None (pure triode mode) – but option for 6dB of cathode feedback via secondary winding.
The most significant changes occur here.
Below is a functional description of the V.4 (2024) updated schematic. (Note: For legal reasons, a redacted block diagram is described here; full PCB layouts are available in the accompanying PDF kit.)
| Reference | Part | Value | Note | |-----------|------|-------|------| | U1 | TPS563201 (or similar) | Switching regulator | 4.5V–17V in, 3.3V out | | U2 | REF3033 | 3.3V reference | 0.2% initial accuracy | | U3 | MCU (e.g., RP2040 or ESP32-C3) | – | Firmware v2.1 compatible | | D1, D2 | BAT54S | Dual Schottky | Clamping diodes on inputs | | L1 | BLM21PG221SN1D | Ferrite bead | 220Ω @ 100MHz |
After analyzing three verified revisions (credited to a collaborative effort on diyAudio.com and a Chinese-language forum Hifidiy.net), here are the five most significant updates.
The original 6SN7 grid often connected directly to the input RCA jack. The updated version inserts:
These two additions prevent parasitic oscillation, especially when the amplifier is driven by modern sources with high slew rates (e.g., DACs with op-amp outputs).
Since an actual image cannot be displayed here, a detailed textual schematic of the updated Xin Zhi Zhao for a 300B SET amplifier follows:
Power Transformer → 5U4GB rectifier → 47µF/500V → 10H choke → 330µF/500V → 10kΩ/5W → 100µF/450V (supply for driver)
Driver Stage (6SN7):
Output Stage (300B):
Feedback: None (pure triode mode) – but option for 6dB of cathode feedback via secondary winding. xin zhi zhao schematic updated
The most significant changes occur here.
Below is a functional description of the V.4 (2024) updated schematic. (Note: For legal reasons, a redacted block diagram is described here; full PCB layouts are available in the accompanying PDF kit.) Since an actual image cannot be displayed here,
| Reference | Part | Value | Note | |-----------|------|-------|------| | U1 | TPS563201 (or similar) | Switching regulator | 4.5V–17V in, 3.3V out | | U2 | REF3033 | 3.3V reference | 0.2% initial accuracy | | U3 | MCU (e.g., RP2040 or ESP32-C3) | – | Firmware v2.1 compatible | | D1, D2 | BAT54S | Dual Schottky | Clamping diodes on inputs | | L1 | BLM21PG221SN1D | Ferrite bead | 220Ω @ 100MHz |
After analyzing three verified revisions (credited to a collaborative effort on diyAudio.com and a Chinese-language forum Hifidiy.net), here are the five most significant updates. Output Stage (300B):
The original 6SN7 grid often connected directly to the input RCA jack. The updated version inserts:
These two additions prevent parasitic oscillation, especially when the amplifier is driven by modern sources with high slew rates (e.g., DACs with op-amp outputs).