lighting and related control equipment, particularly at the budget / DJ end of the market. However, using three-pin XLR connectors for DMX512 is specifically prohibited by section 7.1.2 of the DMX512 standard. Use of the three-pin XLR in this context firstly presents a risk of damage to the lighting equipment should an audio cable carrying 48-volt phantom power be accidentally connected. Four-pin (XLR4) Four-pin XLR connectors are used in a variety of applications. They are the standard connector for intercom headsets, such as systems made by Clear-Com and Telex. Two pins are used for the mono headphone signal and two pins for the unbalanced microphone signal. Another common use is for DC power connections for professional film and video cameras and related equipment. Some desk microphones with LEDs use them. The fourth pin is used to power the LED indicating that the microphone is on. Other uses for the four-pin XLR include some scrollers (colour-changing devices for stage lighting), AMX analog lighting control (now obsolete) and some pyrotechnic equipment. Four-pin XLR is used for balanced headphone connections, from a balanced amplifier, where there is no common earth between the two channels. Connection diagram: 1 - left channel + phase; 2 - left channel - phase; 3 - right channel + phase; 4 - right channel - phase. Five-pin (XLR5) Five-pin XLR connectors are the standard for DMX512 digital lighting control. Other common uses are for dual-element or stereo microphones (two balanced audio signals with a common ground) and stereo intercom headset (three pins for the stereo headphone signal - left, right, and ground, and two pins for the unbalanced microphone signal). Additionally, five-pin XLR is commonly used for DC power in audio equipment. Six-pin (XLR6) Six-pin XLR connectors are used for dual channel intercom systems and stage lighting control applications. Another common use is professional stereo headset with balanced microphone (headphone left-pin 4, headphone right-pin 5, headphone common-pin 3, mic high-pin 2, mic low-pin 1, mic ground-pin 6). Seven-pin (XLR7) Seven-pin XLR connectors are used to connect some valve (tube) condenser microphones to their power supplies (carrying signal, polarisation voltage, heater and HT). Used by several models of Le Maitre and Ultratec fog machines for remote control. An obsolete use for seven-pin XLR connectors was analogue lighting control signals, as well as for wired intercom in broadcast studios, specifically with Ward-Beck intercoms. PDN The loudspeaker Cannon (known as a PDN