This update is recommended for all QSC K.2 Series active loudspeakers that use a firmware version prior to 1.2.0.x. The firmware contains important updates for improved protection of the amplifier power supply (in all models) and of the low-frequency driver (K10.2 model only).
K.2 firmware updater can be downloaded from the QSC website.
“Protect Mode 4” is a message that may show up after a successful firmware update of the K.2 Series speaker . This message is indicating that the amp module is sensing a performance issue on the low frequency driver. If this message appears, follow the listed instructions shown below.
THE MESSAGE: “PROTECT MODE 4” | “POSSIBLE SPEAKER DAMAGE DETECTED.” | “NEXT”
1. Press “NEXT” to navigate to the next step.
2. NEW MESSAGE = “PROTECT MODE 4” | “A 100HZ TONE WILL BE PLAYED” | “NEXT”
3. Press “NEXT” to engage the test tone.
4. NEW MESSAGE = “IS TONE CLEAR AND UNDISTORTED?” | “YES” or “NO”
5. Listen and confirm if the tone is clear:
•Press “YES” if the audio is clear and sounds like a pure sine wave.
•Press “NO” if the audio has distortion or is NOT CLEAR.
If “YES” is pressed, the LCD will display a new message:
•NEW MESSAGE = “PROTECT MODE 4” | “SPEAKER IS OKAY” | “EXIT”
•Press “EXIT” and the speaker will go back to the “Home” screen and resume normal operation.
If “NO” is pressed, the LCD will display a new message”
•NEW MESSAGE = “PROTECT MODE 4” | “PLEASE CONTACT A QSC SERVICE CENTER” 
•This indicates that there is already damage on the low frequency driver and that the speaker will need to be sent to a QSC Authorized Service Center for further inspection.
NOTE: If “NO” was pressed accidentally and the tone was in fact clear, cycle power on the speaker and the PROTECT MODE 4 messaging will start over again. Proceed through the test again to confirm that the tone is clear.
The PROTECT MODE 4 message can appear during operation. This indicates that the firmware has detected a potential issue. If this occurs, audio will stop and the listed procedure will be needed to clear the message.
If the message appears repeatedly during operation, the speaker will need to be sent to a QSC Authorized Service Center for evaluation.