xlr microphone mute

[newperson]

Hi,

I am looking to make some microphone mutes for stage use. Something to turn off the signal when the trumpets are not playing.

From some brief research it seems that shorting pins 2 and 3 of an xlr connector should work. If a spst switch is used and the signal goes nowhere will this be fine without popping?

Are there any other solutions out there?  I read the GEO mute article and see there are a few pedals on the market.

[GibsonGM]

Look at this: http://www.procosound.com/download/datasheets/Old%20Version%20of%20Cough%20Drop.pdf

[newperson]

Thanks for the link.  Are the resistor and cap there to have some sort of load for an amp? 
That link does look like it confirms which pins need to be lifted.

...Thank you...

[GibsonGM]

Looks like it gives a path for discharge, to avoid the *pop* you speak of....to "slow it down"...at least to my eye, that is.

[PRR]

> shorting pins 2 and 3 of an xlr connector should work.

That usually works. That IS the classic cough-switch.

The classic name is "cough switch" because if mike must be muted for more than a cough there is a Board Engineer to do that. Obviously you do not employ a board-op. And the "cough" switch works as long as the contacts are closed; only difference is you want a toggle/slide contraption instead of a momentary push-to-cough mechanism.

The situation you describe, at modern gear prices: you could set up a small mixer just for the horns, near the horns (or the conductor), with a mute/fade control. Control the whole section, not each mike. Muting at higher level tends to pop less. Of course this requires a few dolars and some space, and some responsibility for working the mute at the proper times.

> some sort of load for an amp?

No.

In some cases there is a small DC voltage between pin 2 and 3. This would mostly be with Phantom Power condenser mikes-- 1% unbalance between two Phantom supply resistors could be up to a half-Volt of DC (but usually much less). Since a half volt (even a part of a half of a volt) is BIG by microphone standards, sudden go-away of this DC is equivalent to a huge POP.

Battery-power mikes (often electret) may also leak some DC to the output.

The 47K+100uFd lets the 100uFd charge to the DC voltage, and hold it while the switch changes. Pop will be far less.

Try just the switch. If that isn't annoying, you are good to go.

If in *your* setup it POPs, try the R-C network. Ideally the cap is non-polar, but for a test you can use standard polar electrolytic. (The polar may decay over a period of months, but not in an evening's test.) The value of the cap is always a compromise, and large changes don't make a lot of difference, so use what is handy. 50uFd will leak more bass (not from trumpets, but you have drum rumble on stage). 200uFd is large physically. The resistor is even more flexible: 2K "might" change the mike sound, 200K might not pass a full charge to a leaky cap, but anything in your 10K-100K drawer is fine. Power is infinitesimal so any resistor you can see will handle the heat.

[PRR]

Apologies for ALL ITALIC. I misformatted, then the server dumped (my fault?), and I could not get back in to fix it.

[newperson]

Thank you for the detailed information.  I am just now getting back to this.  I noticed that the caps pole is not marked and you said that a non polar cap would be suggested.  I have never used non polar cap at the higher 100uf value range.  Since I only have the more common type which way would the (-) side point to?  

Or would I need to try two 200uf in series to "make" a non polar 100uf cap?

Also voltage wise for the cap, I would guess anything over 5 volts would be fine?  Is there a need for a 25v-50v cap?



http://i.imgur.com/LoHBRvw.jpg

[newperson]

I found a couple 100uf bipolars in my parts (I guess I have used them before) and wired as the diagram shows.  No pop on my amp.  I will pass them along to my uncle's band to see if they work nicely in their set up. 

Thanks again for the information. 

[PRR]

100uFd NP can be found for "crossovers".

Two plain e-caps back-to-back will also work.

[mck]

Thank you for all this usefull information.

In the Shure circuit here, http://www.shure.com/americas/support/find-an-answer/mute-switch-with-phantom-power
the cap used is 1000uF or 2200uF.
In this topic, it is about 100uF...

What could explain this difference of values ? What would you give for advice ?

I'm also wondering these same questions :

• ... polar cap : which way would the (-) side point to? 

• Also voltage wise for the cap, I would guess anything over 5 volts would be fine?  Is there a need for a 25v-50v cap?