I'd look at contacting the contractor about that hum. I assume the input you've been using is a pair of RCA jacks. If using them is creating a hum with the wireless receiver, odds are it will create hum anytime you plug in anything that isn't battery powered. To me, that would be grounds for making a FIR request to have it fixed.drepouille wrote: Tue Aug 05, 2025 8:34 am I will try using the crab box to isolate the receiver. I will also try using an XLR cable instead of the mono audio cable.
Ground loop noise 2nd hour
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russellhltn
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Re: Ground loop noise 2nd hour
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dave.swartz
- Member
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- Joined: Wed Apr 01, 2020 8:07 am
Re: Ground loop noise 2nd hour
1) The standard wireless mic receiver used by the church has an XLR mic jack on it. Just plug it into the chapel mic jack. The XLR jack is balanced audio which is better than unbalanced audio for eliminating noise.
2) The RCA audio input jack I have seen in many chapels converts the unbalanced stereo audio to balanced mono audio right at the jack with a transformer. This jack is our principle method of injecting audio from a presentation ( extracting audio from the projector ) into the sound system.
3) We had horrible hum once when the XLR connector in the pulpit was touching conduit. The conduit gave an alternative ground path. Moving the connector from the conduit fixed it. So ask yourself what is the alternative ground path of the receiver? Perhaps do a test with the mic powered by a battery. Most wireless mics I have seen have a power supply with only 2 conductors.
4). Reach out to FMG for a solution. The church standard wireless mic is the Audio Technica System 10. It uses 2.4 GHz spread spectrum digital transmission. There is only one mic for each receiver. Works great and there is both XLR and unbalanced audio jacks.
5) One final observation just to be through. We have an old FM based audiotechnica wireless mic. It came with two mics. A hand mic and a lavilier mic both mics are on the same frequency. You cannot use both at the same time. If you do it will sound horrible since you will have two transmitters doubling on the same frequency. I only ask since you said one receiver and two mics and I have never seen a chapel with two unbalanced audio jacks, which begs the question how do you plug it in?
2) The RCA audio input jack I have seen in many chapels converts the unbalanced stereo audio to balanced mono audio right at the jack with a transformer. This jack is our principle method of injecting audio from a presentation ( extracting audio from the projector ) into the sound system.
3) We had horrible hum once when the XLR connector in the pulpit was touching conduit. The conduit gave an alternative ground path. Moving the connector from the conduit fixed it. So ask yourself what is the alternative ground path of the receiver? Perhaps do a test with the mic powered by a battery. Most wireless mics I have seen have a power supply with only 2 conductors.
4). Reach out to FMG for a solution. The church standard wireless mic is the Audio Technica System 10. It uses 2.4 GHz spread spectrum digital transmission. There is only one mic for each receiver. Works great and there is both XLR and unbalanced audio jacks.
5) One final observation just to be through. We have an old FM based audiotechnica wireless mic. It came with two mics. A hand mic and a lavilier mic both mics are on the same frequency. You cannot use both at the same time. If you do it will sound horrible since you will have two transmitters doubling on the same frequency. I only ask since you said one receiver and two mics and I have never seen a chapel with two unbalanced audio jacks, which begs the question how do you plug it in?