Q&A: QSC K12.2 Powered Speaker Deeper Dive

…Why is my speaker cutting out? To answer this question I had to do a bit of digging around on some audio forums and it seems like this is a pretty well known issue among repair techs that work on QSC products.

From what I could surmise there was some sort of manufacturing defect with the amplifier module that occurred in a large number of speakers made around 2020 and 2021. The issue clearly wasn’t discovered during any quality control checks and is present in enough speakers that folks would send in brand new speakers with the issue, and continue to get back different brand new speakers with the defect.

In 2020, QSC released its first firmware update, 1.2.0, to the K.2 Series since its launch in 2017 that adds a function called Protect Mode 4 (PM4). Protect Mode 4 is a safety measure designed to protect QSC K.2 loudspeakers and amplifiers from critical thermal failure. It will become active when the unit detects that it is being driven at dangerously high levels, causing overheating or distortion. When Protect Mode 4 is triggered, the speaker will shut down automatically in order to avoid further damage.

So instead of your speaker dying and turning off, it will now turn off so it doesn’t die.

This can be incredibly frustrating while playing a live gig as the issue may not become apparent until the middle of the performance and you have no way to know if the speaker will continue functioning correctly.This problem was specifically worse in the K12.2 as a lot of you commented. At the time, QSC would try to blame other gear/cables/user error before admitting to a defect. This was until April of 2022 when firmware 1.4.1 became available.

Firmware 1.4.1 was for only the K12.2 and was to fix two specific problems: PM4 False Trigger and PM4 Perpetual State. Let’s read the blurb from the PM4 Perpetual State notes:

“some K12.2 loudspeakers might enter a state of “perpetual” Protect Mode 4 (PM4) in which this error message would appear on the rear screen and the loudspeaker would mute. This mode would persist even after power cycling the unit and therefore making the loudspeaker unusable in any capacity.”- Firmware Updates Log

For nearly two years the speaker could false trigger that could lead to your speaking becoming a brick.

So where does this leave us today? As of September 2022, QSC updated the chipset in the K.2 line of speakers. Speakers made after the September date have a different firmware version, 1.5.5, installed in the factory. So here's to hoping that the plague of problems has concluded.

To avoid these problems, or at least make them a little better, here are tasks that you can do:

- Make sure your speaker is updated to the latest firmware version

- When you buy your speaker, consider getting a warranty on it.

- If it does get a negative PM4, register your speaker and open a case with QSC.