XLR Mic Mute Switch with LEDs – Proof of Concept

Mic mute switch with LED hacked and ready to road-test!


I play music on stage, and that usually means using amplification (PA) systems. The bands I play with (Frost and Fire, The Turning Stile+, and others) typically have a bunch of musicians playing a host of instruments, each with their own microphones. Consequently, we need a lot of mic mute switches. The enemy of sound is noise. The more open microphones you have on stage, the higher the noise floor gets, which is bad–so you need to be able to turn off mics when they’re not in use.

Several years ago, I bought some Rolls MS111 mic switches for this purpose, and they’ve been great–with one gripe: it’s pretty hard to see whether the mic is muted or not. You’re basically looking at a band of metal 1mm wide from about 7 feet away trying to see whether it’s 1mm or 2mm tall right now. Hard. I’ve wanted a mute switch with an LED status indicator for a while now.

The easy way to do this is to add a battery to the box, wire it into the unused side of the pushbutton switch, and use that to power the LEDs. Problem is, that would require carrying extra batteries (heavy and wasteful), modifying the case to be able to hold a 9v battery (impossible in this case), and, worst of all… knowing that the solution was inelegant.

I wanted the LEDs to be powered through the +48v phantom power that’s provided by the sound board.

an early prototype

I’ll detail how I did this in a future post (and provide the circuit schematic). I’ve had a lot of fun and a lot of frustration trying to figure this out, and I want to make it easier for future tinkerers. But for now, I’m typing this up and getting it out the door before I head out for a gig–and we’ll see how the mute switch does in the real world! There’s a video proof of concept at the end of the article.



Here’s a quick demo! Sorry for the camera shake–it was late and I was too tired to find the tripod).

Thanks for watching! I’ll post the schematic and further discussion soon. If you enjoyed this, please subscribe and give the video a thumbs-up!

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29 thoughts on “XLR Mic Mute Switch with LEDs – Proof of Concept

    1. Hi Kenny,

      Sorry about that–I’ve been busy with family stuff. I’m reworking the schematic because, although it works perfectly as a mute, there’s a possibility for power spikes to knock out the LEDs.

      1. Curious if you’ve had a chance to get back to this. It’s exactly what I’m going to need for the pulpit Mic at church. Right now it’s running through a pgx1 body pack, so can use mute switch on that, but as soon as I get some hardlines up front it’ll be phantom powered. Anyway if you could send what you have I could maybe help tweak it

  1. Thanks Hollis, just seeing this now :-O, but I also hope the project comes to fruition sometime this year. Got the Rolls with my DPA 4088 headset- all works fine, sure would be nice to have visual guidance.

  2. I have done something very similar, but instead of relying on phantom power from the mixer, I simply used a wall wart, 9-12 volt, DC to power the LED’s. Use a double throw switch, one side shorts the mic hot to ground, the other side closes (or opens) the circuit for the LED’s. (Open or close the LED circuit depending on if you want the LED to be lit, or off when the mic is shorted to ground. I usually use green LED’s, on, if the mic is not shorted, and working, or red LED’s, on , when the mic is shorted to ground, ie “off”.
    Very simple and cheap to build, no pops or added noise if you build it in a metal box and connect the box to ground.

  3. Hi,
    I also have some Mic mute boxes that I need to add a LED being powered from the 48V phantom power supply.

    I can manage to do that but I always have a click sound when switching.

    Do you have any clicks in your unit? could you please post the schematic of the circuit you used?

    Thank you so much

    1. Hi Frank, thanks for the link but that is not the same thing as this project here.
      In that one the LEDs are fed from a 9V battery.

      In this project, at least what the author said was that LEDs are powered through the +48v phantom power.


  4. There are a number of us that would still be interested in the schematic for this project and possibly a short build video pointing out where you tapped the MS111 circuit board. Thank you in advance for any assistance you can provide.

  5. Any idea on when your schematic will be posted? I built a simple noiseless mute switch for my condenser microphone. When i introduce an LED indicator using phantom power on audio pins 2&3, popping is heard when the mute switch is activated. I’m trying to find a way to isolate the LED power of the circuit from the audio to prevent popping when i mute the microphone.

  6. Anybody heard from Hollis yet ?? We “ALL” are definitely waiting….waiting ….waiting for even a rough Schems… anything , anything, anything, PLEASE Hollis , any help you could help us get the “Green LED” mod going on this Rolls Mic Mute unit , PLEASE…..

    – Dave

    (And All the kids playing in the Little League World Series EVERT YEAR are begging and waiting for this Schematic !!! NO MORE Pop on the Announcers Mic ! PLEASE HELP US ? )

  7. XLR Mic Mute Switch with LEDs – Proof of Concept
    September 30, 2017

    And in October 2023 still no schematic. Even a rough draft would be beneficial

  8. Hello Hollis…
    One more dude here asking for that long-postponed schematic. Perhaps we all forget to say: I’m going to pay for that sheet!

    Please, don’t make people wait a decade 🙂

  9. Hollis last reply was in 2018, so 5 years ago… Hollis is from from this for a long time doing something else completely different.
    Sorry guys but there will be never be a schematic from Hollis, or any word from him ever

  10. Hi friends,
    Thanks so much for your interest, and I’m sorry that it’s taken so long to reply. We had a lot of intense stuff happening in our family when I was last writing, and I’ve never gotten back around to drawing up a schematic that’s clearer than the scribbles in my lab notebook. Between starting a family, going back to grad school, starting a business, and all the rest, it seems like I never quite find the time to go digging. Thanks for your patience.

    That said, I do still want to do this! I really appreciate the interest, and I’m especially grateful to the folks who approach this with respect and generosity, rather than… something else. Your kindness is noted.

    If and when I get to it, I’ll post a link here. I’ll do my best to get there before the decade is up!

    Thanks, and let’s talk soon,

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