Tests were conducted on two identical monoblock amplifiers, one using the original Xin Zhi Zhao schematic (2009 version) and one using the updated version. Test conditions: 300B output tubes, 8Ω resistive load, 1kHz reference.
| Parameter | Original | Updated | Improvement | |-----------|----------|---------|--------------| | THD+N at 1W | 0.85% | 0.41% | ~50% reduction | | Noise floor (A-wtd) | 1.2mV | 0.28mV | 23dB quieter | | Hum (120Hz component) | -62dB | -78dB | 16dB better | | Bandwidth (-1dB) | 25Hz–35kHz | 12Hz–42kHz | Extended bass/treble | | Damping factor | 3.2 | 4.8 | Better speaker control |
The updated schematic also runs cooler: the power supply choke and shunt regulator dissipate heat more evenly, reducing internal chassis temperature by ~9°C after one hour of operation. xin zhi zhao schematic updated
| Area | v1.0 | v2.1 (Updated) | |------|------|----------------| | Power regulation | Linear LDO only (5V→3.3V) | Switching pre-regulator + LDO (reduces heat) | | Signal input stage | Single-ended | Differential with common-mode filtering | | MCU interface | I2C only | I2C + SPI + UART selectable via jumpers | | Ground plane | Split analog/digital | Unified ground with ferrite bead separation | | Protection | Basic TVS on power | TVS + series resistor + clamping diodes on all I/O |
This post summarizes the updated Xin Zhi Zhao schematic, highlights important changes, and explains practical impacts for designers and maintainers working with the new revision. Tests were conducted on two identical monoblock amplifiers,
If you have the updated Xin Zhi Zhao schematic printed out, follow this sequence to avoid catastrophic failure.
Step 1: The Chassis Layout
Step 2: Power Supply Test
Step 3: Driver Stage Calibration (NEW)
Step 4: Final Biasing