XLR A/B Switcher with Mute

[elbert013]

Hello All, I am a novice when it comes to building circuits so please go easy on the grade-school-looking drawing.

I am trying to build an A/B switcher that has a mute function. You would think this has been done but I have searched for hours trying to find one and have come up short. I did see a lot of forums for just an A/B switcher so I adopted some info from that. I just want someone to take a look at this schematic I drew up to see if it looks right.

The other image is basically what I want but made with 1/4 inch inputs. Again, I have seen this idea used on 1/4 inch but it is important in this case that it is XLR.

Thanks!

[Rodgre]

On first glance that looks good, as far as the switching is concerned but there are two other things to consider.

I was looking into something similar recently, just for the task of muting a mic when I wasn't singing.

There may be a need to put some sort of tie-down resistors to keep from "popping" when switching, but I am not sure what value or where it needs to go because I don't have the brain function to think about it just yet.

To that end, there is also the issue of whether you are passing phantom power (or need to).

Sorry I don't have an explanation for how to implement this at the moment, but if no one else responds with a better explanation, I will post a better reply later.

Good luck!
Roger

[Kevin Mitchell]

There may be a need to put some sort of tie-down resistors to keep from "popping" when switching, but I am not sure what value or where it needs to go because I don't have the brain function to think about it just yet.

Agreed. 1M on the inputs should do it.

I would change the mute switch so that ground is on the center lugs so you're not grounding out the live signal at any time - the output will be 0v instead of floating. But I'm not sure if there's a common rule of thumb on this, just how I'd swing it.

Don't forget the negative lead of the mute LED.
Use a single resistor for each LED to power. With a shared supply as you've drawn you'll likely notice the brightness change when a 2nd LED is kicked on.

[elbert013]

Okay, good to know I'm on the right track. Thank you for the reply.

I won't be using a mic that requires phantom power with this setup so that's not really a worry

Agreed. 1M on the inputs should do it.
[/quote] in my case

Kevin, in this case are you refering to a 1m resistor or building in a 1ms delay circuit. Thanks!

[Kevin Mitchell]

I was expanding on what Rodgre had suggested - placing a 1M resistor from the input signals to ground.
If you don't give current a place to go any capacitors on the source signals are left to hold a charge and they'll hold as much as they're warranted. When you instantly give that charge a place to go makes an audible popping. With a pulldown resistor it'll always have a place to go.