Headline: Technical Update: Xin Zhi Zhao Schematic Revised
We have finalized the updates to the Xin Zhi Zhao schematic. This revision addresses [mention specific improvement, e.g., power delivery optimization / signal integrity / component placement].
Key Changes:
The latest version (v[Version Number]) is now available. Please ensure you are referencing the most recent file for your builds or analysis.
#ElectronicsDesign #Engineering #Schematic #PCBDesign #XinZhiZhao #TechUpdate xin zhi zhao schematic updated
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.
| 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 | Headline: Technical Update: Xin Zhi Zhao Schematic Revised
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
Note: These files are for reference only. Validate all connections before powering up.
Since the first release of the updated schematic in late 2023, over 200 documented builds have appeared across English and Chinese DIY forums. Common feedback includes:
“The updated power supply killed 99% of the hum I’d tolerated for years. My 300B now competes with solid-state noise floors.” — user TriodeLover, diyAudio.com The latest version (v[Version Number]) is now available
“I was skeptical about the shunt regulator on the driver, but the soundstage widened noticeably. Less ‘glare’ on high vocals.” — user Audiophile_Zhang, Hifidiy.net
No major safety issues have been reported, though a small number of builders initially blew the shunt regulator by omitting the heatsink (see mistake 5.4 above).