D/A build in the human vocal 4 times frequency gain tuning module

Original dac top view.
After tuning couple capacitor sound color change other capacitor.
For more space to fit x4 frequency gain tuning module.


After modify the system block.



3.5k-8.5k 高次偶次諧波 band pass filter simulation profile.



Estimate more space for filter inductor.


Fine tune PCB top dimension.


Fix band pass filter inductor.


Fix pcb board  on aluminum plate.


Finish circuit and assembly all plate together.


Put module into DAC and finish wire connection.


Fix volume knob.


Finish wire connection on volume knob.


Finish side view.
今調整...幾乎無法再調回去.
聲音的寫真程度改變幅度很大.
音符好像快從喇叭跳躍出來一樣.
...

 CD也可以有類似LP的聽感
真的是蠻神奇的.