ric8138 Posted September 19, 2022 Report Share Posted September 19, 2022 Recently ran into an issue with ultrasonic security system messing with Sennheiser G3’s. Does anyone make a low pass filter to go between mic and transmitter to avoid this issue? We got around it with a wired boom and 2 hardwired lavs, but it was not easy. Please don’t tell me to just buy “Lectro”, I know that’s the long range answer, but when working on micro budget indies, it’s just not practical. Quote Link to comment Share on other sites More sharing options...
Rick Reineke Posted September 19, 2022 Report Share Posted September 19, 2022 I have seen an in-line high or low pass filter for unbalanced lavs, (which most are). If the noise is getting in through the mic/wire connection,I would try another mic (and/or channel.. It would likely be the same feeding a Lectro (or whatever) if it's getting in through the cable . I have never encountered security system interference noise working on many ENG with the G series Sennheiser or others on thousands of ENG and docu shoots (prior to sound for movies),. Quote Link to comment Share on other sites More sharing options...
Patrick Farrell Posted September 19, 2022 Report Share Posted September 19, 2022 You could build an RC filter into an adapter cable to roll off everything above 20kHz. However, having a resistor in line could potentially affect the bias voltage that the mic sees so choose values carefully and test beforehand. Quote Link to comment Share on other sites More sharing options...
ric8138 Posted September 20, 2022 Author Report Share Posted September 20, 2022 11 hours ago, Rick Reineke said: I have seen an in-line high or low pass filter for unbalanced lavs, (which most are). If the noise is getting in through the mic/wire connection,I would try another mic (and/or channel.. It would likely be the same feeding a Lectro (or whatever) if it's getting in through the cable . I have never encountered security system interference noise working on many ENG with the G series Sennheiser or others on thousands of ENG and docu shoots (prior to sound for movies),. This was a new one on me, but apparently the motion detectors “chirp” in the 40k range. The mic picks it up and it messes with the compander circuit in the G3, causing a pumping volume sound. First time I’ve run into it in 30 years of sound. Quote Link to comment Share on other sites More sharing options...
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