Diagnosis
The humming noise you are experiencing with your Kefeya G2 screen extender is almost certainly caused by an electrical phenomenon known as a "ground loop." This occurs when there is a difference in electrical potential between your laptop's power source and the extender's power input. Because the G2 draws power through a combination of USB-C (DisplayPort Alt Mode) and often an auxiliary power cable, the audio circuit picks up electromagnetic interference (EMI) from the power delivery system. Specifically, the humming is the result of 50Hz or 60Hz AC interference leaking into the analog audio path of the built-in speakers. This is most common when the laptop is plugged into a wall charger while the G2 is simultaneously connected to a separate power brick. To confirm this is a ground loop, unplug your laptop's AC adapter and run both the laptop and the G2 on battery power. If the humming disappears instantly, the issue is external electrical noise rather than a hardware failure of the G2's internal amplifier.
FIX
To eliminate the humming noise and stabilize the audio signal, follow these precise steps to isolate the power delivery:- Isolate the Power Source: Disconnect the auxiliary power cable from the G2 extender. Attempt to power the unit solely via the USB-C cable connected to your laptop's Thunderbolt or USB-C 3.1 Gen 2 port.
- Change USB Ports: If your laptop has multiple USB-C ports, move the G2 to a port that is not adjacent to the laptop's primary charging port. This reduces the proximity of high-voltage current to the data/audio lines.
- Adjust Audio Gain: Lower the volume on the G2's physical hardware buttons to roughly 50% and instead increase the volume through the Windows or macOS system mixer. This reduces the "gain" on the noisy analog circuit, effectively lowering the audible hum.
- Verify Cable Seating: Ensure the USB-C cable is pushed firmly into the G2 port until you feel a distinct click. A loose connection can cause intermittent power fluctuations that manifest as a buzzing or humming sound.
- Disable "Audio Enhancements": In Windows, go to Settings > System > Sound > More sound settings. Right-click the G2 Speaker output, select Properties, go to the Enhancements tab, and check "Disable all enhancements." This removes software processing that can amplify the noise floor.
If That Didn't Work
- Use a Ground Loop Isolator: If you are using an external 3.5mm audio cable to route sound to the G2, install a 3.5mm Ground Loop Isolator (a small transformer-based device) between the laptop and the extender. This physically breaks the electrical connection while allowing the audio signal to pass through.
- Switch to a Powered USB Hub: Instead of plugging the G2 directly into the laptop, use a high-quality, externally powered USB-C hub with its own dedicated power supply. This creates a "buffer" between the laptop's motherboard and the extender, often cleaning up the electrical noise.
- Test with a Different Power Brick: If you are using the auxiliary power port, swap the USB-C power adapter for one with a higher quality ferrite bead (the small plastic cylinder on the cable). Cheap, non-branded power bricks often lack the filtering capacitors needed to prevent AC hum.
- Update Audio Drivers: Perform a clean install of your Realtek or Intel Smart Sound drivers. In some cases, an outdated driver fails to manage the power state of the USB audio interface, leading to electrical "leakage" in the form of noise.
Heads Up
- Avoid Daisy-Chaining: Do not plug the G2 into an unpowered USB hub; this creates unstable voltage drops that can cause both the humming noise and screen flickering.
- Cable Management: Keep the G2's power and data cables separated from high-voltage AC power strips. Crossing cables can induce EMI into the audio lines.
- Port Wear: Be gentle with the USB-C ports on the G2. Frequent plugging and unplugging can loosen the internal solder joints, which may turn a simple hum into a loud crackling sound.
- Firmware Check: Periodically check the manufacturer's support page for firmware updates that may optimize the power delivery handshake between the screen and your specific laptop model.