Pilot Tone
Pilot tone, let me try to explain…
All Evolution Wireless mic generations since G2 have used Pilot Tone squelch. When Pilot tone is enabled on the receiver it “looks” for 32.768kHz tone as well as the RF strength being above the Squelch threshold before it un-mutes.
When Pilot tone is enabled on any G2, G3, G4 or 2000 series Mic transmitter a low level of 32.768kHz tone is added to the transmitted audio. If Pilot is active on the TX and the Mute switch is activated then the Pilot tone is turned off in the TX so the RX will (should) Mute as well. All Stereo analogue IEM transmitters (not just Sennheiser ones) send a 19kHz “Pilot” tone when operating in Stereo mode. (Search Zenith GE Stereo Multiplex system for why) When transmitting in Mono mode IEM transmitters do not transmit any Pilot tone at all.
So, wireless mic receivers will not (should not) in-mute if Pilot is enabled and the TX is an IEM tx because there will either be the wrong Pilot tone - RX is looking for 32kHz not 19kHz - or no Pilot tone. The wireless mic RX needs to have Pilot disabled. The TX setting is irrelevant. The wireless mic RX will only ever be Mono. If the IEM TX is operating in Stereo mode and being fed a stereo signal the wireless mic RX will output a Mono Sum signal.
Equally, IEM receivers are expecting either 19kHz Pilot tone which tells them it’s a Stereo Multiplex encoded signal, or no Pilot tone at which point they will assume it is a Mono signal. An added complication is the option of a Pilot tone Mute option on G2 and later IEM receivers. This stops the RX working in the presence of a Mono signal 🤦♂️ When you do an IR Sync to an IEM Tx that is set to Mono mode the software automatically disables Pilot tone on the IEM RX, but you can do it manually of course. The IEM RX does not care at all whether a wireless mic TX has Pilot enabled; it will completely ignore the 32kHz tone if it is there, so the setting on the wireless mic TX is irrelevant when using an IEM RX.
You just need to disable Pilot detection on the RX whenever there is a mismatch of IEM/Mic tx/RX. This probably needs a table really. I might make one. Can’t promise.
The EK 1038 & EK 1039 though outwardly (and inwardly tbh) the same as IEM rxs are Mono only and do not have any Stereo multiplex decoding capability.
Source: Andrew Lillywhite