Better !free! - Cx31993 Datasheet Fix

Place the 1nF closest to the pin. This reduces hiss by ~12dB on sensitive IEMs.

| Feature | CX31993 | ALC5686 | | :--- | :--- | :--- | | | Neutral-to-slightly-bright, clean, analytical | Warmer, more analog-sounding, often described as "musical" | | Best For | Critical listening, technical ability. | Casual listening, genre-flexible. | | Price Point | $5–$15 | $10–$20 | | Availability | Very high, particularly in low-cost dongles. | High, but generally in slightly more expensive dongles. |

If you are designing a board or modifying a commercial dongle to eliminate background hiss:

Enable Developer Options and disable "Disable USB audio routing." Use USB Audio Player Pro (UAPP) for bypassing Android's internal SRC (Sample Rate Conversion). Fix C: "Muddy" Sound or Lack of Bass cx31993 datasheet fix better

Most "datasheet fixes" do not involve hardware; they involve eliminating logical conflicts in the host operating system. Since the CX31993 uses the standard USB Audio Class 2.0 driver, Windows often misidentifies it or applies the wrong power plan.

The CX31993 is often paired with an independent amplifier chip, such as the

A common issue with this chip is audible popping or static when the system suspends the codec to save power. Place the 1nF closest to the pin

This reduces ultrasonic noise from the Σ-Δ modulator, dropping THD+N to <0.003% (20Hz–20kHz).

If you’d like, I can draft a single-sheet consolidated “quick-start” datasheet or generate a lab bring-up checklist tailored to your board’s schematic and chosen clock/power topology.

: Plug a high-impedance adapter or leave the headphone plug "open" (partially inserted) when first connecting the dongle to your device. Once the device recognizes the DAC, fully plug in your actual headphones to bypass the auto-gain limitation and potentially double the output power. 3. Clicking or "Circuit Ticking" | Casual listening, genre-flexible

: Approximately 0.0003% (-95dB), ensuring minimal harmonic distortion.

Use a 12.5pF crystal (e.g., ECS-.327-12.5-13) with 15pF caps to ground. Avoid 6pF or 9pF types—they cause startup failures or excessive jitter.