This really depends on the condensor mic. Is it balanced out, is it an electret or "true" condensor etc. If you could post a schematic of what you have it would help enormously.

Use the NC contacts on the switch to short pins 2 and 2 on the XLR connector. Doing that will mute the mic and should not affect the phantom power.

Thanks for the replies.
To be exact, the mic is an Audio Technica Pro 49Q gooseneck style, balanced condensor.
I wasn't sure if there was an effect on the phantom by shorting pins 2 to 3, but I tried it anyway. Again, it's going to be shorted continuously until the button is pushed momentarily. At any rate, there were still pops when I pushed the button. Sometimes quite loud. I'll try to get a schematic posted later tonight. If I can get the shorted pin 2 & 3 version to be quiet, I'd be happy to do it that way.

You are not going to be able to effectively mute a condenser microphone at the front end of your preamp. You must keep the microphone energized with phantom power 100% of the time. This phantom power cannot be shorted out even post breakout resisters. You can however mute the microphone from within the preamp. There is no sane reason to try to enable a push to talk at the output of a condenser microphone. Sure, you can do it if you are not using phantom power but, something like an electret self polarized condenser microphone. These frequently only require a 1 1/2 V battery for operation. But the desire is still rather dumb. And what are you plugging this microphone into? You can mute the output of a preamp silently. You generally can't mute the output of a microphone silently if it's a condenser microphone. If you can make more sense we can be more help.

I want to be able to smoke my cigarettes while filling my gas tank without any popping sound. How do I do that?
Mx. Remy Ann David

Shorting pin 2 and 3 mutes any mic before preamp without producing any pop even with a phatom power. Both pins are at the same voltage.

Laurend, post: 350682 wrote: Shorting pin 2 and 3 mutes any mic before preamp without producing any pop even with a phatom power. Both pins are at the same voltage.

That is absolutely incorrect. If you interrupt the Phantom power to the microphone and then reapply it, it'll cause a huge noise. That was blatantly bad information above. You want to mute the microphone post-preamp not pre-preamp. This is not a dynamic mic and cannot be treated as such.

Geez and French yet
Mx. Remy Ann David

RemyRAD, post: 350688 wrote: That is absolutely incorrect. If you interrupt the Phantom power to the microphone and then reapply it, it'll cause a huge noise. That was blatantly bad information above. You want to mute the microphone post-preamp not pre-preamp. This is not a dynamic mic and cannot be treated as such.

I've used this trick for years to allow clients censorship when I was sound engineer for a convention center. Nobody never noticed any huge noise in the 10 KW PA system. With that solution the mic preamp is still powered. Only the audio is muted. For sure it's not the best way to operate from a technical point of view. Controling the pre-amp is the correct solution. But we're in a push-to-talk design which must stay simple and effective. Shorting pins 2 and 3 (not 1) is simple and effective.

RemyRAD, post: 350688 wrote: That is absolutely incorrect. If you interrupt the Phantom power to the microphone and then reapply it, it'll cause a huge noise. That was blatantly bad information above. You want to mute the microphone post-preamp not pre-preamp. This is not a dynamic mic and cannot be treated as such.

Geez and French yet
Mx. Remy Ann David

Sorry, Remy, the information is absolutely correct. XLR pins 2 and 3 of a mic that has a true balanced output are at the same d.c. potential whatever the state of the phantom power, so shorting them together has no effect on the powering. I suggested this method in my post above out of experience with using an XLR M-F adaptor with a shorting switch I made many years ago, and it works fine as a mute for all the mics I have tried, both phantom-powered and not.

What I think is happening with the Audio Technica Pro 49Q is that it may not have a true balanced output. Some electret mics that use PP (or an internal battery) to power the FET buffer just drive the +ve output (pin 2) and decouple pin 3 directly to a.c. ground. The current for powering the buffer is taken from pin 2 via that pin's 6K8 resistor, causing the expected potential drop and therefore a d.c. imbalance with pin 3. A configuration of this sort will indeed cause clicks and pops when used with the shorting switch, but the signal will nevertheless be muted and the phantom power unaffected. Without taking one apart, it's not easy to tell if this is how the 49Q is configured, but for the switch to work silently, it would need some experimentation with load resistors from pin 3 to ground (around 33K - 47K) to balance the potentials at pins 2 and 3.

Boswell, post: 350699 wrote: Sorry, Remy, the information is absolutely correct. XLR pins 2 and 3 of a mic that has a true balanced output are at the same d.c. potential whatever the state of the phantom power, so shorting them together has no effect on the powering. I suggested this method in my post above out of experience with using an XLR M-F adaptor with a shorting switch I made many years ago, and it works fine as a mute for all the mics I have tried, both phantom-powered and not.

What I think is happening with the Audio Technica Pro 49Q is that it may not have a true balanced output. Some electret mics that use PP (or an internal battery) to power the FET buffer just drive the +ve output (pin 2) and decouple pin 3 directly to a.c. ground. The current for powering the buffer is taken from pin 2 via that pin's 6K8 resistor, causing the expected potential drop and therefore a d.c. imbalance with pin 3. A configuration of this sort will indeed cause clicks and pops when used with the shorting switch, but the signal will nevertheless be muted and the phantom power unaffected. Without taking one apart, it's not easy to tell if this is how the 49Q is configured, but for the switch to work silently, it would need some experimentation with load resistors from pin 3 to ground (around 33K - 47K) to balance the potentials at pins 2 and 3.

I'm sorry I must vehemently disagree with you. While this might be fine for line level sources, it certainly isn't for phantom powering a microphone. If you short terminals 2 & 3 the microphone preamp might make a quiet exit. However on reapplying phantom power to any condenser microphone especially those that require a true 48 V polarization voltage, the microphone will turn itself back on with an ugly thump. So I'm really surprised at you Boswell? This is a highly unprofessional question solved by a highly unprofessional solution. You don't mute condenser microphones by shorting out their power. Maybe you can with the cheap condenser microphones you've all used? But not with ones such as U 87's 414 and the like. I've never heard one of these microphones turn on quietly before, ever.

You might consider keeping the phantom, leaving the Phantom power applied to said microphone and interrupting the secondary of the transformer it is loaded into. That makes much more sense. That way the microphone is always powered on & always loaded into a source of stable impedance. The original question is just clueless foolishness and that's why this proper answer was rebutted numerous times. If you're going to screw up, you might as well screw up the correct way.

Push to scream!
Mx. Remy Ann David

Reminder for RemyRAD:
- pin 1: ground 0V
- pin 2: signal + and + 48V phantom power supply
- pin 3: signal - and + 48V phantom power supply
So shorting 2 and 3 doesn't short the power supply. So the pre-amp built in the mic is still powered. So there is no ugly thump. so...
The only situation where the shorting can't be applied is for T phantom power which doesn't exist anymore for serious microphones.

While I'm sure RemyRAD will spot her error when she reads the previous post I doubt very much that this will solve the original problem. When the OP first mentioned a goose neck condensor mic I was immediately wary that it might well be an electret mic and also not have a true balanced output. I would suggest that the OP reads Boswells suggestion as I fully expect he is correct that the mic in use has a pseudo balanced out. That is really why I asked for details in the first place!

While you may be able to balance the voltages on pins 2 and 3 in this case by doing as Boswell suggested, you may also need to fit a small trimmer to the pull down to fine tune the output. As the output signal will be at a low level any tiny imbalance will present a POP to the pre-amp input when using a simple shorting switch and the trimmer should give you the best chance of success. No guarantee though!

In this case RemyRAD may well be ultimately correct in that a mod to the internal mic or pre-amp circuit may be needed.

I want to thank all who replied to my question... except one.

Yes I understand that what I'm attempting falls under the "quick and cheap fix" category. And yes, I was hoping for a quick and cheap solution. Yet there is a method to the seeming madness. I appreciate those of you who gave me useful and knowledgeable answers, minus the editorial comments.

Boswell, you are probably right on. I will certainly try a little more experimentation with the load resisters. As mentioned before, I have used the shorting method before with perfect results. This is a different situation.

To Ms. RemyRAD, I have to say: nice way to welcome a new voice to the community! Really, "clueless foolishness?" Sorry to have wasted your time, but no one forced you to reply. I've always heard there is no such thing as stupid questions, just stupid answers. Ms. Remy, you have proved that to be correct.

You know, we are not all beginners here except for maybe one? There is no problem shorting out phantom power. There is a problem with reapplying the Phantom power to the microphone. The preamp in the microphone has to recharge. The process of reapplying the power will cause you a thump. But maybe you just need a few thumps on the head to understand this?

If on the other hand you can keep the Phantom power applied to the microphone and keep it loaded with 1200 ohms, then you can short the microphone input tube preamp without shorting out the power to the microphone. This will require at least a 2 PDT switch. Then since it will be obnoxious sounding with ambience on followed by ambience off, that could also be obnoxious sounding. A better technique would be what I created for NBC radio. Yes it involves a relay. Yes it involves 2 optical devices similar to what's found in optical compressors. One to softly lower the volume and the other to softly raise the volume. Along with timing capacitors to work out the proper fade in fade out points. Then you have an effective soft switch.

Greet a newcomer newbie who likes to correct people with over 40 years experience. Well you must be the smarter one?? You came here for free advice and have obtained such. Correcting us just proves your inexperience. Many professionals have numerous different ways of obtaining the same outcome. You didn't like my answer because it wasn't the answer you wanted. You know better. So why even ask the question?

Happy thumping
Mx. Remy Ann David

I'm sorry Remy but it's clear the penny hasn't dropped for you when you keep harping on about shorting out the phantom power! Not one post has suggested shorting the phantom power..... there is absolutely no issue with re-applying power when it has never been removed!

The suggestions so far are quite correct as shorting pins 2 and 3 short out the differential signal without shorting the common mode phantom power.

You are not the only one with over 40 years experience around here and the tone of your posts is quite insulting and not just to the OP. What you really need to do is actually understand the suggestion before hurling these insults as you are not doing yourself or this forum any favours.

Every time you short pin 2 & 3, it doesn't hurt the Phantom power. It doesn't hurt the microphone. Reestablishing power to a condenser microphone is a noisy prospect. So when pin 2 & 3 are shorted, the microphone is not powered up. It is seeing no voltage since the voltage cancels out. And so tell me how many people here have plugged in condenser microphones with the volume up? You know what kind of sound that makes. The same will hold true with the pushbutton. I wouldn't keep responding if I didn't know it wasn't correct. Unfortunately I also know you can't fix stupid. So have your fun telling this poor person that everything will be fine shorting 2 & 3 together. I just happen to know better and you don't.

I like accepting insults from clueless people
Mx. Remy Ann David

RemyRAD, post: 350833 wrote: So when pin 2 & 3 are shorted, the microphone is not powered up.

Quite wrong! While the differential signal is shorted, the phantom power is only shorted to itself and NOT to ground. The microphone circuits still have power.

RemyRAD, post: 350833 wrote: It is seeing no voltage since the voltage cancels out.

Again wrong. The differential signal cancels out by being shorted (which is what we want to mute the mic.) but the common mode is still there (see above).

RemyRAD, post: 350833 wrote: And so tell me how many people here have plugged in condenser microphones with the volume up? You know what kind of sound that makes.

Yes I do.

RemyRAD, post: 350833 wrote: The same will hold true with the pushbutton.

No it won't!

RemyRAD, post: 350833 wrote: I wouldn't keep responding if I didn't know it wasn't correct. Unfortunately I also know you can't fix stupid. So have your fun telling this poor person that everything will be fine shorting 2 & 3 together. I just happen to know better and you don't.

I like accepting insults from clueless people
Mx. Remy Ann David

I am not prepared to trade insults with someone who has not yet realised their error. Nor will I crow when you realise your error.

Dear Remy I'm very sorry. I've been in the audio business for only 30 years now. I'm not only a live and recording sound engineer, but also a designer for both analog and DSP. I'm not throlling this forum so I ask for some respect.

I suggest you to apply the scientific way. Just run the experience I've suggested, and revise your theories according to the experimental results. I'm sure you will understand your ridiculous situation as forum moderator.

I make tens of mistakes a day but I always try to learn from them. You shouldn't hesitate to follow that way.

Remy,

I'm attempting to attach a pdf schematic of a typical mic output circuit and phantom power source as you seem to understand schematics. Please explain exactly how the power to the Mic pre-amp (across C1) will be affected by throwing the switch.

I contest with you that there will be NO DC current through the switch (either on or off!) therefore there will not be a uV of difference across C1. This is clearly not the same as unplugging the mic when C1 will discharge through the pre amp circuit.

What is patently clear though is that any differential signal will be shorted and hence the mic muted when SW1 is closed.

Attached files RemyRAD.pdf (13.5 KB) 

That is a single circuit that may in fact work. But most microphone transformers do not have a center tap to ground. That is only a single instance. So I might be half right or half wrong and you may be half right or half wrong. That's what's fabulous about audio. There are many ways to accomplish many of the same things differently. So this works for the poster, terrific. Not all microphones nor their inputs are all created equally.

fine'
Mx. Remy Ann David

RemyRAD, post: 350848 wrote: That is a single circuit that may in fact work. But most microphone transformers do not have a center tap to ground. That is only a single instance. So I might be half right or half wrong and you may be half right or half wrong. That's what's fabulous about audio. There are many ways to accomplish many of the same things differently. So this works for the poster, terrific. Not all microphones nor their inputs are all created equally.

fine'
Mx. Remy Ann David

True, I have never designed two different mic pre-amps to be the same, otherwise I would have only ever designed one!

The simple fact is that this will work for ANY truly balanced output circuit and all I gave was one very typical circuit as used in several of the wonderful mic's that you mentioned, as a simple understandable example. Suggesting this might only apply for the instance I gave is simply a VERY weak argument as the topology is unimportant provided that the mic power is derived equally from both + and - signal lines, which is a requirement for the output to be truly balanced. As Laurend said only the defunct T system would not - and that was not an inherently balanced system.

As has already been said, the output from the mic in use by the OP may well be using a pseudo balanced output where the negative line on pin 3 is simply decoupled to ground and power is not drawn from this line. This common on cheaper electret mics but this has nothing to do with the erroneous arguments you have put forward regarding balanced mic's.

Do you still want to call me stupid or would you like to apologise yet? :<)

BTW, the circuit I gave did not have a "grounded" centre tap and most transformer mic output stages DO have a centre tap and are bifilar or trifilar wound.

MrEase's schematic illustrates the particular case using a centre-tap on the transformer secondary for supply of power to the microphone electronics. This circuit is fine under normal conditions, but the transformer is in danger of sustaining a permanently magetized core from any fault that suddenly causes the phantom power current to stop flowing down one leg of the transformer. For this reason, transformers are not often centre-tapped, and the power is normally extracted through a pair of resistors forming a virtual centre-tap across the secondary. The point is that the general principle of muting by shorting pins 2 and 3 works for any balanced microphone output circuit, transformerless or with transformers, and the shorting action does not interrupt the power to the microphone. Whether the microphone is happy driving a short circuit is another story. The XLR M-F adaptor with a muting switch that I mentioned earlier has worked over many years for all the microphones I have needed to use it on, causing pop-free muting without any apparent stress to the microphone.

I've let this discussion continue, but I'll comment now as a moderator of this forum. Those who have seen my postings over the last several years know that it's not my style to brag about my length of experience in the audio field, both as a recording engineer and as a professional designer, nor do I get personal when I happen to hold a different opinion from that of another contributer.

Remy, I would like you to apply your much-vaunted experience and engineering knowledge to the concept of differential and common-mode signals co-existing at a single point in a circuit. Suitable circuit configurations can separate out these two components and deal with them separately. For example, a balanced input circuit has a differential amplifier that amplifies the differential component (signal) while rejecting common-mode components (e.g. noise). Phantom power works in a similar way, but in this case the common-mode component is the d.c. power flowing into the microphone and the differential component is the a.c. signal flowing out of the microphone. The shorting switch we have been discussing performs the opposite function to that of a differential amplifier, in that it causes the differential component (signal) to be rejected while leaving the common-mode component (d.c. power) unaffected. Correct pop-free functioning of the switch is subject to the microphone having a true balanced output, which may well not be the case in the OP's gooseneck talkback mic.

Remy, I think it would be good if you could look back over what you have posted so far in this thread, and also allow that the switch circuit we have been discussing will indeed mute the signal from the microphone without having any affect on the supply of phantom power to the microphone's electronics.

Well in all likelihood you damned guys from the UK are generally right! So I defer to 'yalls expertise. I'm just glad I have no need to mute a condenser microphone before it hits the preamp. I'm a post-preamp kind of guy. I don't like to muck around with anything in front of the microphone preamp. Even my phase inversion switches are on the output transformers. Why not the input transformers you might ask? Hell I don't know? I'm just an end abuser.

So yes I'm sorry, sorry sorry sorry for drumming up such an ill-fated discussion. My actions might be best spent quietly behind the console. I just know I've never wanted to interrupt a microphone while it's doing its job. I think that would be rude to do to Mr. microphone?

Ms. microphone a.k.a.
Mx. Remy Ann David

Boswell, post: 350853 wrote:
I've let this discussion continue, but I'll comment now as a moderator of this forum. Those who have seen my postings over the last several years know that it's not my style to brag about my length of experience in the audio field, both as a recording engineer and as a professional designer, nor do I get personal when I happen to hold a different opinion from that of another contributer.

Remy, I would like you to apply your much-vaunted experience and engineering knowledge to the concept of differential and common-mode signals co-existing at a single point in a circuit. Suitable circuit configurations can separate out these two components and deal with them separately. For example, a balanced input circuit has a differential amplifier that amplifies the differential component (signal) while rejecting common-mode components (e.g. noise). Phantom power works in a similar way, but in this case the common-mode component is the d.c. power flowing into the microphone and the differential component is the a.c. signal flowing out of the microphone. The shorting switch we have been discussing performs the opposite function to that of a differential amplifier, in that it causes the differential component (signal) to be rejected while leaving the common-mode component (d.c. power) unaffected. Correct pop-free functioning of the switch is subject to the microphone having a true balanced output, which may well not be the case in the OP's gooseneck talkback mic.

Remy, I think it would be good if you could look back over what you have posted so far in this thread, and also allow that the switch circuit we have been discussing will indeed mute the signal from the microphone without having any affect on the supply of phantom power to the microphone's electronics.

Boswell, again you've hit the nail on the head, and made it very understandable for me. You may have solved my problem (provided I can find the balance of the potentials at pins 2 and 3,) and I've learned something in the process. And without the belittling commentary. Not all of us have EE degrees which is why we have forums like this to begin with!

Thank you all for your replies, esp. Remy. It was your insistence that kept the discussion alive and let to Boswell's final enlightening explanation.

Just as a final help to Blawso, I've put together a quick schematic to explain Boswell's suggestion (with my trimmer refinement).

Note that the assumptions on the actual mic circuit are approximate and there is no guarantee of success!

Attached files Blawso.pdf (17.6 KB) 

Actually this may be a better solution if my assumption are anywhere near the mark!

Edit: There are some huge assumptions here as the unmodified suggested circuit would result in a huge differential signal to the pre-amp in normal operation! I'm just trying to illustrate the suggestion. Details (ie schematics) of the actual mic would be extremely helpful.

Attached files Blawso2.pdf (15.4 KB) 

Hello everyone,

Resurrecting this old thread to ask if the same principal of shorting pins 2 and 3 can be applied to a balanced line level signal.

I'm building a switcher box for communication between control room and 3 separate rooms, and I need to mute the talkback signal (coming from a mic preamp) individually for each room with a toggle switch.

Thank you very much.

Joao Brandao, post: 392889 wrote: Hello everyone,

Resurrecting this old thread to ask if the same principal of shorting pins 2 and 3 can be applied to a balanced line level signal.

I'm building a switcher box for communication between control room and 3 separate rooms, and I need to mute the talkback signal (coming from a mic preamp) individually for each room with a toggle switch.

Thank you very much.

Yes, the principle can be applied, but it has to be used with care, as some balanced drivers may overheat if their outputs are shorted together for any length of time. It would be better to add a pair of resistors in the signal lines coming from the pre-amp output with the switch wired across the ends of the resistors remote from the pre-amp. The value of the resistors is not critical, but they should both be the same. Try 220 Ohm. Depending on the input impedance of the following circuit, adding the resistors may reduce the signal level by 1dB or so, but this can usually be made up by adjustment of the gain control in the driven device.

Trying to put a push to talk switch onto a phantom powered microphone is asking for big trouble. Or perhaps just big pops. Mother nature doesn't like when you switch Phantom on and off of a microphone. This really won't work well. Push to talk of a microphone should happen after the pre-amplification stage and not at the input with phantom power.

And then it would be good to have a relay and a vactrol (LED/light dependent resistor) with a little resistor capacitor to time the ramp up/down for perfectly silent push to talk operation. That's the way to do it. It's really not as simple a process as just turning on or off a switch. It is if you like pops and explosions coming out of your speakers and people's headphones, (assuming anyone is wearing any?)

Where do people get these ideas?
Mx. Remy Ann David

Boswell, post: 393050 wrote: Yes, the principle can be applied, but it has to be used with care, as some balanced drivers may overheat if their outputs are shorted together for any length of time. It would be better to add a pair of resistors in the signal lines coming from the pre-amp output with the switch wired across the ends of the resistors remote from the pre-amp. The value of the resistors is not critical, but they should both be the same. Try 220 Ohm. Depending on the input impedance of the following circuit, adding the resistors may reduce the signal level by 1dB or so, but this can usually be made up by adjustment of the gain control in the driven device.

Thanks for your reply.

I think I understand what you're saying.

What if instead of shorting the pins 2 and 3 I use a simple 2 pole switch? In the "on" position the signal would flow across the switch and in the "off" position I wouldn't connect anything.

Does this have any disadvantage?

Then you are still switching the phantom power supply on and off to the microphone and with that you get explosive sounds coming out of your speakers that make people jump out of their shoes, come out of their skin, on the windshield like a bug at 100 km/h. Do it after the pre-amplification stage where there is no phantom power involved. Even if you were to get an external phantom power supply to keep phantom power on the microphone, switching it away from the microphone input (in order to mute) would then suddenly also be supplying +48 V to the microphone preamp... which is a little different from the .005 V AC that the microphone would be delivering to the preamp input. And the result is always a WOOFER excursion test impulse pop followed by all of the ladies tinkling in their panties.

I have more Poise. Because I know people can Depend on me.
Mx. Remy Ann David

RemyRAD, post: 393060 wrote: Then you are still switching the phantom power supply on and off to the microphone and with that you get explosive sounds coming out of your speakers that make people jump out of their shoes, come out of their skin, on the windshield like a bug at 100 km/h. Do it after the pre-amplification stage where there is no phantom power involved. Even if you were to get an external phantom power supply to keep phantom power on the microphone, switching it away from the microphone input (in order to mute) would then suddenly also be supplying +48 V to the microphone preamp... which is a little different from the .005 V AC that the microphone would be delivering to the preamp input. And the result is always a WOOFER excursion test impulse pop followed by all of the ladies tinkling in their panties.

I have more Poise. Because I know people can Depend on me.
Mx. Remy Ann David

Thanks for your input but I don't think you read my first post correctly.

I'm in fact talking about muting a LINE level signal, after the pre-amp, so no phantom power involved.

Joao Brandao, post: 393056 wrote: Thanks for your reply.

I think I understand what you're saying.

What if instead of shorting the pins 2 and 3 I use a simple 2 pole switch? In the "on" position the signal would flow across the switch and in the "off" position I wouldn't connect anything.

Does this have any disadvantage?

That scheme would work for the function of disconnecting the signal flow, but it would be likely to create pops and clicks during the operation, and would also be noisy in the off state. This is because the input circuit of the driven device would see a low-impedance signal when the switch is on and an open circuit when it is off. This is a large change in resistance, so any bias current flow is going to generate a change in voltage. In addition, an open-circuit state is susceptible to noise.

It's better to short-circuit the inputs as this is not only a much smaller change in resistance but it also keeps the driven inputs quiet in the muted state. The thing you have to contend with in this configuration is the load that the driving circuit sees. As I mentioned previously, the easy way to deal with that problem is a resistor in each signal line so the driver does not see a dead short.

Got it!

Thank you very much.

New guy searching for answers to a similar question. I've just been asked to announce our varsity football games and as a spectator in years passed was a bit annoyed by hearing "sidebar" dialog in from the announcers booth. I have purchased a small job box, XLR male and female sockets and a NC switch. I've read this entire thread but most of the discussions and all of the diagrams attached refer to phantom power. I don't believe I have that in my application. We're using a 6 channel mixer and my mike is an Sure PG48 which has a switch on the mike but it's difficult to operate. I also have available an audio technica unbalance mike and I also purchased 1/4" female jacks to install if I wanted to run a second mike. Lastly, I have available a 15 year old Beyerdynamic mike that my brother has had for 10 years but I could reclaim it. It is also balanced without phantom power. Would someone here be kind enough to share with me a schematic of how I might wire my PTT box for both the balanced and the unbalanced setups?

Wire your box with the two XLRs (M and F) pin-to-pin. Then connect your NC switch across pins 2 and 3. This will give you an in-line push-to-talk unit. It will be unaffected by phantom power if you need to use it on a rig with phantom power enabled. I don't advise that you fit jack sockets to the box as that compromises its use in PP-enabled environments.

When using unbalanced mics, it's important that you make sure phantom power is NOT enabled on the mixer. If your unbalanced AT mic has an XLR plug and works correctly when plugged directly into the mixer, then it will also work through the switch box. If your unbalanced mics have TS (unbalanced) jack plugs on their leads, make or buy jack-XLR adaptors that you bring out only when you have to use those particular mics.

I think I get what you're saying. This is in fact then like the diagrams posted only without the resistors for the balanced mic correct? And, for the unbalanced I would use the same jacks on the box, not the 1/4" that I was going to install for the unbalanced application? Sorry, but I'm technically challenged. I really don't know what phantom power consists of. I just remember back in the day we had mics with batteries in them but they weren't wireless. I assumed that was phantom power. Perhaps I should study up on that concept.

Yes, that's correct. It's usually OK to short-circuit the signal pins of a microphone because the output impedance is normally a few hundred ohms and the signal levels are measured in millivolts.

Phantom power is supplied by the mixer or interface to power microphones that have active circuity inside and/or need a polarizing voltage for their capsules. It is nominally +48V measured between a signal line (pin 2 or 3 on the XLR) and ground (pin 1). The important point is that both signal lines are at the same elevated phantom power voltage, and it's still the difference between the two lines that carries the audio signal.

You should not use jack connectors in circuits that can have phantom power applied, as jacks short-circuit signal-gound momentarily during insertion and withdrawal. XLR connectors, on the other hand, generally do not short-circuit during mating operations, so are considered safe if inadvertently plugged or unplugged with phantom power present.

The convention for phantom powering is that each signal lead on the powering device has a 6K8 (6800 Ohm) resistor to the +48V supply. This limits the short-circuit current to around 7mA per pin, which is unlikely to cause fires but can damage sensitive microphones, particularly ribbons.

Thank you. I will wire up the XLR's today and give it a shot at tomorrow's game...If it provides desirable results, I'm in. If not, I'll have to resort to keeping a hand on that channel's volume control throughout the game....Like I've been doing. (I did this throughout baseball last spring/summer and also for the first 2 JV football games this year) Now that I'm the varsity dude....I would like to be a little more efficient.

You need to input elco to the switch. This will smooth the power on input voltage and reduce that popping high voltage spike. The pop comes from that high voltage peak when you push the button, bu adding electrolythic cap there smooths out the spike.

There are good push to talk circuits, and then there are the loud popping style of push to talk circuits. An effective push to talk pop free circuit would be to utilize a couple of LED/light dependent resistor devices. You need to have two. One for turning on the microphone and one for turning off the microphone without a pop. And all one needs is a couple of capacitors and resistors to establish the turn on/turn off timing of the Opto devices. This little bit of circuitry can be installed in a small mini project box. Available at Radio Shaft. It can be put on the output of the microphone preamp, and you'll have precisely what you want from just $20 worth of parts. These optical devices can allow for more pristine audio to pass through the light dependent resistor, than through FET transistors. Which is another way to do it well. The FET then becomes a variable voltage resistor, with a semi conducting silicon transistor base, already to give you some distortion you wouldn't have normally had.

In a sense, what I've described is what goes into Universal Audio LA-2 compressors and 1176, limiters, on a more basic level. No detector circuitry nor output drive is necessary. So what this comes down to is a switch controlled dynamic range, noise gate without pops, clicks, hits nor errors.

Hey what about a VOX (Voice Operated Switch), circuit with a simple mute button? The microphone would automatically turn on and off when you speak. And only defeatable by a mute switch. And that's another thing to consider. NASA utilized these a lot in the space race, and now since they are virtually out of business, you might be able to pick up some good used radio gear? And wouldn't it be cool if all of your announcements were accompanied by a NASA bleep sound? So cool!

That's all for me (bleep). Copy that? (Bleep). He's running for the 50 yard line (bleep), 40 yard line (bleep), oh and he's sacked by Smith! (Bleep) might make for an interesting trend for live sport announcing? (Bleep).

I guess I say a lot of (bleep), that children shouldn't hear (bleep) that!
Mx. Remy Ann David