USB DAC design based on CT7601SR (based on "filtering capacitor" solution)

Modified based on the filter capacitor https://oshwhub.com/xyzdiy/ct7601-usb-dac V1 version, and also referred to the V2 version.
 2023.6.3
    MAX97220 indicators are underestimated. The MAX97220 noise of 7uV was measured with two 20kΩ resistors selected, so the index of the max97220 should be better, here it should be 4uV (within 20khz). The indicators should be similar to those of the Meizu Pro decoder amp.
 2023.5.10
    The LPF circuit was changed to the SABRE9601K circuit, and the op amp is still the MAX97220. Reasons: 1. The max97220 indicator is also good, the noise is 7uV, which is enough. 2.max97220 is cheap and can be replaced by domestic pin to pin.
   Modify the output level. R34-R37 can use 0Ω, 470Ω, and 806Ω, and the output corresponds to 2.16Vrms, 1.4Vrms, and 1Vrms. This is the simulation result. You can change it according to your own headphones. 1Vrms is suitable for most headphones. If it is too high, it is difficult to adjust the volume. If the sound is too loud, it is not good for the ears.
    Optimize the power supply of es9018k2m. The most worthy of optimization here is that in the original version, es9018k2m VCCA, AVCCR, and AVCCL share a power supply, and the indicators are greatly affected. VCCA, AVCCR, and AVCCL are powered by three LP5907s separately. For the remaining LDOs, just choose a cheap and convenient one, choose 6206.
 
   Change the crystal oscillator and use an audio crystal oscillator with low phase noise. Calculate 192*192=36.864MHz. The minimum clock frequency for the 192KHz sampling rate is 36.864MHz. A higher frequency consumes more power and causes greater electromagnetic radiation, so choose 45.1584MHz or 49.152MHz. Depending on what you usually use, 44.1KHz or 48KHz, choose accordingly. 45.1584MHz or 49.152MHz.
 
  Divided the land. The grounds of the es9018k2m and the charge pump of the max97220 are separated.
 
  Signal chain resistors and capacitors. The resistance of the op amp is a thin film resistor with an accuracy of 0.1%, the signal chain capacitor is c0g, and the decoupling is x5r. The BOM has been changed.
 
 
   The effect is okay, and it’s a good game to play. Like the similar ones from Meizu, it sounds like the indicators are a bit worse. Not much value for money.
Original address: https://oshwhub.com/xyzdiy/ct7601-usb-dac.
 
   After welding, I blew it a few more times and repaired the welding a few more times to achieve the Iraqi quality.