Completed to re-design my old D1V3.3 or D1 clone pcb as below: Name it D1V2 + Zen I/V. Please write to me if you are interested in the PCB. No kit offer! Full assembly Boards with limited supply only.
Totally I have made 3 versions of boards for testing – V17, V28 and V30. The photos of each version is as below in sequence.
The board can use DAC – PCM63, PCM1702 and PCM1704. Note PCM170x need to use a converter board as in second picture. For digital filter, it can use SM5842, SM5843, SM5813, DF1700, PMD100, DF1704, DF1706 etc… Digital receiver is WM8804 with excellent jitter performance. More details in the reference manual below.
Compare to D1V33, it is much better in sound stage, imaging, resolution and details. It still remain the analogy sound of smoothness and best vocal DAC when PCM63 is used. When DF1704 and PCM1704 is used, the input is set to 16-24 bit digital input mode and output of DF is set to 24 bit mode. The resolution is found better than PCM63 a bit but remain the smoothness of R-2R DAC sound.
Two versions if Zen IV are tested – J/K and K/K. Here is the summary of measured results : IV resistors & capacitors and Rail comparison table_v30
Conclusion is to use the KK IV + KK Buffer – 2SK369 or 2SK363 is the optimum design choice using 20V rails. Nelson Pass original Zen IV using JK IV is having too weak output level at 30V rails. Also J74 is not available easily with reasonable cost.
Reference Manuals:
Digital filter setting table (apply to all Version boards): DIGITAL FILTER PIN CROSS REFERENCE SM5842_V30.4