| Feature | CX31993 (Fixed) | Apple A2049 (C100) | Realtek ALC5686 | | :--- | :--- | :--- | :--- | | | 32-bit | 24-bit | 32-bit | | Max Sample Rate | 384kHz | 48kHz (locked) | 384kHz | | Output Impedance | ~2Ω (very good) | ~0.9Ω (better) | ~10Ω (worse) | | Power Draw | 35mA (fixed) | 25mA | 45mA |
Always pull I²C lines high (2.2kΩ to 3.3V) even if you don’t use it. The chip floats otherwise.
If software tweaks do not yield the "better" sound you seek, the issue may be the hardware design. The stock CX31993 chip, on its own, has a specific analog output stage. Many premium dongles pair the CX31993 with an or SGM8262 op-amp. cx31993 datasheet fix better
(most needed):
// Example of the "Fix" found in Linux Kernel Source (patch_cirrus.c) // This sequence was not in the original datasheet 0x11, AC_VERB_SET_COEF_INDEX, 0x0020 , // Unlock the secret register 0x11, AC_VERB_SET_PROC_COEF, 0x0001 , // Enable the specific output path | Feature | CX31993 (Fixed) | Apple A2049
The datasheet omits the soft-start sequence. Implement this GPIO sequence via MCU or CPLD:
For advanced users, several techniques can be employed to further optimize the CX31993 datasheet performance: The stock CX31993 chip, on its own, has
If you are trying to implement this chip or fix a driver: