I’m Ben from Cambridge Audio. We’re known for making a brilliant range of hi-fi products including the amazing CX Series. I’m here today to tell you about our CAP5 protection system. To protect your amp and speakers, we’ve invented a unique amp protection system called CAP5 Cambridge Audio Protection consists of five different protection methods. DC Detection protects the speakers if the output of an amplifier goes to a high constant voltage, or DC because of some internal amp fault. This is rare, but detecting it could just save those expensive loudspeakers. CAP5 constantly monitors the heat created by your amp. Over temperature detection can be caused by excessively high volume levels, poor ventilation or if the impedance of the speakers is too low, making the amp work much harder and get too hot. If this happens, CAP5 will just switch off the amp to let it cool down. V/I or voltage/current protection monitors and protects the amp. It’s triggered when the volume is suddenly turned too high and the amp becomes overloaded. Again, CAP5 will just switch off the amp, so you can turn it back on at a lower volume. Every time the amp is switched on, CAP5 checks the speaker terminals for any ‘shorts’ which could have been accidentally made by badly connected speakers, or a stray strand of speaker cable. If a short is detected, the amp will stay in Standby mode so you can check the speaker connections and correct the problem. Clipping can damage your speakers and happens at very high volume levels when the output signal tries to go outside the maximum voltage that the amp can provide. CAP5 will detect when the amplifier starts to clip and automatically nudges the volume down until an undistorted output is reached again. We use CAP5 protection in the 851 and CX Series stereo amps, as well as many of our previous models such as the 640A, 650A, 651A and 840A. To tell you which CAP5 protection method has been triggered, on the CX amps the Direct, Speaker A/B and Mute lights on the front all flash together in the following sequences: Singular flashes. Flashes in bursts of two. Flashes in bursts of three. Flashes in bursts of four. On the 851 series amp’s the front panel display actually reads out the protection method that has been triggered. Thanks to the CAP5 protection system, you can enjoy your music for years to come with the peace of mind that your amp and speakers are protected.