How th connect XRL mic to the PC?

[CTPAX]

I got a XRL mic, but couldn't find an adapter, so I can plug it into my soundcard. Maybe I made something wrong, coz the mic gives low quality signal and lot of noise. Does anyone know how EXACTLY to make the cable?
This is what I made:


XRL Jack
^
0----------------------------I_I
0 -ground I I
0----------------------------I_I
I I
ground-I I

Any mistake?

[CTPAX]

****, the diagram sucks. It is not the way I posted it http://www.audioforums.com/forums/smile.gif

Well, I connect the left and right pin of the XRL to the left and right of the jack, and the middle pin to the ground pin. Is this right?

And why so much noise?

[Vernon Kuehn]

I'm at work and can't get my hands on an XLR plug so I can't remember right from left. Each pin should have a number if you look closely. My memory is that Pin 1 is ground. Pin 2 is your choice for the "hot" lead. Pin 3 is the other half of the audio circuit and in this case you will probably connect it to ground.

As Paul Harvey would say: "And Now, the rest of the story."

The mic jack on your sound card probably uses a mini phone-jack the same size as found on a lot of head sets. The mic jack on your sound card probably expects you to use one of the "computer mics" you find in the retail store and one of those three wires is a power source to drive the dinky amplifier in the "computer mic." Figure out which one it is (the "ring" of the mini-plug I think.) and do not use it. Connect the ground from your XLR to the "sleeve" on of mini-plug and your "hot" wire to the "tip" of the mini-jack. Now you are ready to 'rock n roll'.

Even though sound cards may have a mic jack, they are prepared to make friends easily with the typical mic that comes with an XLR connector. You are going to be short of gain to the tune of 15 or 20 db so start planning on acquiring a pre-amp sooner or later.

Happy Soldering.

[CTPAX]

Are you sure pin 1 is groud - I curently have 3 for ground and 1&2 for left&right at the jack, and works - the noise is probably from the creative mic preamp. Thanks anyway!

[Vernon Kuehn]

I'm leaving work and will look at a plug just for good measure when I get home.

There is no left and right to the mic input to the Sound Blaster. Every mic jack on a consumer sound card that I have looked at is MONO. That third wire is DC Voltage to power the preamp they expect to be built into the tradition computer microphone.

[CTPAX]

Well, I opened the mic and the 1 pin was ground indeed. The 2 was the "hot" but what for is the 3 pin? What other half of the circuit? Maybe you should explain me a little about this XRL. What for is the 3 pin? Hoever I connected pin 1 to ground, pin 2 to hot and there was nobody home. Then I connected pin 3 to ground just in case. Nothing...

I need help!

[CTPAX]

Aha - pin 2&3 are the two cables which are soldered to the mic. The black one is ground from the mic body. This means that I'll probably have to connect pin2 or pin3 to the ground, but it is still not working. Why? And when I had connected pin 3 to ground, pin 1 and pin 2 to the left and right, the mic was working!?!?!?!?!

Which way should I connect the mic so it may finally work?

[Vernon Kuehn]

Just hang on for the ride. Yor're gonna make it. http://www.audioforums.com/forums/wink.gif

Let's take quick side trip and introduce you to the concept of BALANCED and UNBALANCED circuits. You're mic will work either way. Indeed pins 2 and 3 in your XLR are the two sides of the audio circuit. Neither one is the "hot" side and the other the "ground" side. They are equal halves of this back and forth flow of audio voltages. To keeps multiple mics in phase we normally declare Pin 2 as the hot lead or the positive lead. If you went to the input of a balanced circuit you would find that both 2 and 3 are isolated from ground and the ground is connected to a center point of the transformer if one is used. In today's modern solid state inputs, equal amounts of resistors and capacitors isolate pin 2 and pin 2 from ground. The two sides of the circuit (pin 2 and pin 3) are BALANCED in their relationship to ground. It takes 3 wires to make a balanced circuit work. (O.K., TWO wires and the earth itself in the case of a balanced audio line provided by the phone company.)

Hook the ground (Pin 1 of your XLR) to either pin 2 or pin 3 and you how have a two wire ciruit. One side is truly the HOT side and the other side is the RETURN and GROUND combined. Since one side is the same as ground and the other side is isolated from ground, it is UNBALANCED. For short distances and in locations where there is not a lot of electrical stray interferance in the air, either one can provide excellent sound.

Now, back to your SoundBlaster or equivalent. Your mic plug will be a three wire device. Two wires are the UNBALANCED mic audio circuit. The third wire delivers a DC voltage from the computer power supply so you can use a mic with built in amplifier and not need a battery in the mic. This voltage circuit depends on the same GROUND wire that the audio circuit does. For your purposes, when you figure out which wire from the plug going into your computer has the DC voltage on it, tape it up, pretend it doesn't exist. Now you have two useful wires coming from your computer mic jack. One is ground and one is the HIGH side, the HOT side.

After you tried my suggestion and your mic quit working, I have to assume that on the computer end you tapped into the DC VOLATAGE wire instead of the two wires which are the audio circuit.

P.S. This will work, and once you get it working you will be proud and happy.... for a while. WRITE THIS DOWN: You will find it works in a very limited way. Good mics do not come with built in amplifiers designed to match up with the input cirucits of computers. Good mics do not put out the amount of power that SoundBlaster wants coming in. Plan on graduating to some kind of (quality) pre-amp to boost your mic before it goes to the SoundBlanster and then you will feed it into the LINE INPUT which is a three wire circuit that allows stereo or two channel input. I went through the struggle you are going through right now about 5 or 6 years ago and have stepped up a couple of times in how I feed the sound in. Saving my pennies right now to move on to the next level: I want a card that will do 24 bit sound and 96kz sampling rate.