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Burnedfingers 2nd September 2012 11:52 AM

Adapter to test Shure Countryman headset mic
2 Attachment(s)
I need some help in making an adapter so I can test headset mics like the Shure Countryman or an Avlex headset mic in my standard test bed. I want to make an adapter so I can plug in the countryman, supply the needed phantom power so the microphone is usable, install DC blocking caps on the output ,and last plug into the standard XLR connector in my test bed.

If you thinking why would I want to do this I will answer the question before it is even asked. Where I work I seem to have a hard time sometimes trying to find a matching wireless Shure transmitter and wireless receiver of the same frequency so with an adapter I could simply plug into a standard XLR connector and test the mic and figure out if the cord needs replaced or the mic element has been damaged.

I have on hand the socket in which to plug the mic into and a used project box. What I need to know is which terminals I need as signal and ground in order to input a phantom (battery supply) and how much phantom voltage is needed. Typically a 9 volt battery or 2) AA's power up Shure wireless microphones. So, do I need a 3volt phantom supply?

imix500 3rd September 2012 01:37 AM

We used the Masque mic comparator where I used to work. You can also use the Shure cylindrical preamps used for small condensers i.e. 98,91 etc.

I don't think most elements are terribly picky about bias voltage but the manufactures do publish a window to operate in.
I am using an inline AMT preamp slightly modified to test dpa and senn capsules.

Burnedfingers 3rd September 2012 09:43 AM

I'm sure the people I work for won't pop for something high dollar for testing mics. I'm thinking something like a AKG B29L might work also. I don't need to match outputs of mics I just need something I can make/put together so I can save myself time and eliminate a butt chewing when it comes to trying to find something that I can plug the headset mic into so it can be tested. In the state of disarray that things are generally in our back room it is hard to find what you need. Naturally what I want to make will be financed out of my pocket is is simply to make my life a little more uncomplicated. I do appreciate your input and help. I still think I need to try to come up with something I can build and use that will be cost efficient to me and easy to use. I think a 3 volt battery supply will work find for the countryman mic and the Avlex mics that I generally run into. I think I just need the mic pin out and I don't have one in my service van to check the pin out on and I cannot seem to have any luck finding information on the net.

imix500 3rd September 2012 04:37 PM

Which Countryman are you using? I should have the pinout for Shure here somewhere.

Burnedfingers 3rd September 2012 09:54 PM

Its just an E6 earset with a TA4 female connector.

imix500 3rd September 2012 10:10 PM

In case you had not found it-

Pin1 = S
Pin3 = W
4.7k pin 2 to Pin 3
5V Zener Diode
stripe end to Pin 3
other end to Pin 1

Here's a diagram:

Pretty sure the Zener just keeps voltage across the element under 5v and the resistor loads a ccs in the pack. So, neither should be needed.

Burnedfingers 3rd September 2012 11:32 PM

This is probably a stupid question but I assume the picture is that of a TA4 female connector on the mic and the back view. That is what I get when I turn a female connector around.

So if I am powering it off say a 3volt supply then eliminate the zenier and add a cap to ground? Add a blocking cap from pins 2 and 3 of the TA4 connector to pins 2 and 3 of the XLR?

What I am going to send it to has no phantom capabilities and I need to block the DC from going into the input of the mixer amp.

imix500 4th September 2012 12:04 AM

Yes, if you take the female connector apart you should see the Smd resistor and Zener.

Actually, shield would go to pin 1 and 3 of the xlr, and the blocking cap from white to pin 2. That would be the simplest way to do it, and most modern balanced preamps are fine with the inverting input tied to ground.
You could try it, but the element wants to see a really high input impedance so you might need a suitable preamp right at the output of the elements cable before the console.

Burnedfingers 5th September 2012 11:08 AM

1 Attachment(s)
Will this work?

Right side of hand drawn diagram should show the TA4 female jack (mic wiring) that will remain the same.

The TA4 male connector I will mount in a metal box. This is everything to the left of the dotted line.

Note the small mixer I will use on the bench has no phantom and I need to block the DC coming back from the battery.

imix500 5th September 2012 11:51 AM

Feeding a non inverting signal into both inverting and non-inverting input (pin 2&3) won't work unfortunately. The mic is unbalanced but you can connect it to the balanced preamp by tying pin 3 (inverting input) to ground and feeding audio to pin 2. This kinda tricks the preamp to accept an unbalanced signal.
As I said most modern consoles are absolutely fine with this.
Alternatively, you could use a balancing transformer but it's not nessesary to get the rig working.

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