Shavano Music Online

    Making XLR Cables

    3/99 - Jens Moller - http://www.colomar.com/Shavano/xlr_cable.html
    Cables that have XLR connectors on each end are used by Low Impedance Microphones. There are other uses of XLR connectors, however this article focuses entirely on making a Low Impedance Microphone cable using 1 male XLR connector and 1 female XLR connector.
    For additional information about the wire used in a completed cable, see Audio Cables. This article uses to common types of XLR connector types - the main difference is in how the connector and contacts are held in place. Radio Shack sells one of these types, Switchcraft sells the other. All XLR connectors use one of these 2 construction methods.

    This assembly requires 2 conductor shielded audio wire. It should be fairly flexible and be designed for this purpose. The wire I used happens to have insulation that is clear and blue. You can have other colors. 'White and Blue', 'White and Black' and 'White and Red' are common colors. Substitute the lighter color wire in place of where I show clear and the darker color where I show blue.

    The male XLR connector is comprised of 4 distinct parts. The wire slides thru a black rubber support on the back end of the metal case. There are 2 screws on the metal case that are used to press the rubber support against the wire and help hold it in place - reducing stress on the solder joints in the rest of the connector.

    There is a plastic sleeve that protects against shorts occurring with the metal case once the contacts are fully soldered and assembled. If you are missing the plastic sleeve, use 2 turns of lightweight electrical tape on the finished solder joints.


    Parts of a male XLR connector


    Parts of a female XLR connector
    		The female XLR connector is similar to the male XLR connector and also is comprised of 4 distinct parts. It is assembled in much the same way. The metal cases are not interchangeable between the male and female XLR connectors.

    The Switchcraft connectors use a small flat head screw driver to secure the contacts/connector. This has a reverse thread and its not obvious when you first look at it how to tighten/loosen things. The Radio Shack part uses a common Phillips head (cross-point) screw and operates just like any other screw would.

    Disassemble one male and one female connector and set the parts aside. to loosen the Switchcraft contacts/connector, use a small flat head screw driver and turn it the same way you would to loosen any screw (counter clock-wise). This will cause the set screw to go deeper into the body (the opposite of what you would expect). Don't over tighten. For other types of XLR connectors, simply remove the small Phillips head (cross point) screw.

    Step 1 - Prepare the Wire


    Strip off 1/2 inch (13 mm) of outside insulation, exposing the shield. If the shield is simply twisted onto the other 2 wires in the cable, straighten it out, then twist it into its own bundle. If the shield is braided, use a pair of needle nose pliers (or a toothpick) to undo the braid and give you straight wires to twist together. Then strip 1/8 inch (3 mm) of insulation from the ends of the remaining 2 wires. Use a low wattage (30 watts or less) soldering iron to lightly tin the wires - just enough to cover the exposed wire.

    If you want to color code your leads (I do this when I make a number of cables up that will all look the same) - slide a piece of colored heat shrink tubing over the wire, then the case, then the plastic sleeve as shown above. You may have to loosen the 2 screws on the back of the case to allow the wire to slide thru - be careful not to let the screws fall out - they press against small rectangular pieces of metal that are a pain to put back in if they fall out.

    Step 2 - Attach the shield

    I'm showing both types of connector contacts here. Pin 1 is depressed (indented) on the female connector contacts (but not on the male).

    NOTE: The pins are numbered on the connector/contacts

    The shield connects to pin 1. To keep things from shorting out, slide a small piece of heat shrink tubing (or other available tubing) over the shield (approximately 3/8 inch (9 mm) in length). Slide this into pin 1 and warm the backside of pin 1 with a soldering iron. Hold the wire in place and paint pin 1 with your solder putting a very small amount of solder on the joint - just enough to make join the shield to the solder cup on pin 1. The heat shrink tubing will probably shrink during this time - thats what we want it to do. If it doesn't shrink, thats OK too.

    Step 3 - Attach the center wires and assemble.

    Put the light colored wire on pin 2 (directly opposite of pin 1) and heat the solder cup, painting a small amount of solder to the wire. Put the dark colored wire into the solder cup for pin 3 and solder it in place.

    Slide the plastic sleeve over the joints you just soldered, or if you don't have a sleeve, apply 2 turns of lightweight electrical tape.

    Slide the metal case on to the connector contacts. Its keyed so it will only go on one way. If you have a Switchcraft connector, turn the setscrew (its down a hole) clockwise to tighten it up to the hole - this will seem wrong to you when you do it - but its the result of the reverse threaded screw. Make sure that this is tight. If you have another type of connector, put in the setscrew and tighten it.

    If you used it, slide the heat shrink tubing approximately 2 inches (5 cm) from the end of the connector and shrink it in place.

    Note: To make the heat shrink tubing shrink, you need a heat source. In an industrial environment, you would use a heat gun (like a large portable hair dryer, except much much hotter). However, I find that careful use of matches works quite well. Put the tubing in place and light a match, holding it underneath the tubing (around 1/2 inch (13 mm) away) and moving it back and forth to cause the tubing to shrink. Start in the middle and work it around all sides of the tubing and be careful not to burn the wire, the heat shrink tubing or yourself. It normally takes 2 matches to shrink a piece the size shown here.

    Step 4 - Wire the male connector shield

    Prepare the other end of the wire in the same way as shown in step 1. Use the same color heat shrink tubing on this end as you did on the other end. In this example, the other end of my wire has a white piece of heat shrink tubing in place.

    The contacts look different than the other end. They are also numbered, but there is no detent/indentation for pin 1. Add a short piece of heat shrink tubing (3/8 inch (9 mm)) to the shield and solder it to pin 1.

    Step 5 - Wire the rest of the connector

    Put the light colored wire on pin 2 (directly opposite of pin 1) and heat the solder cup, painting a small amount of solder to the wire. Put the dark colored wire into the solder cup for pin 3 and solder it in place.

    Step 6 - Assemble and Test it

    Slide the plastic sleeve over the joints you just soldered, or if you don't have a sleeve, apply 2 turns of lightweight electrical tape.

    Slide the metal case on to the connector contacts. Its keyed so it will only go on one way. If you have a Switchcraft connector, turn the setscrew (its down a hole) clockwise to tighten it up to the hole - this will seem wrong to you when you do it - but its the result of the reverse threaded screw. Make sure that this is tight. If you have another type of connector, put in the setscrew and tighten it.

    If you have loosened the screws at the rubber supports at the base of the connector cases, now is the time to re-tighten them. This will compress the rubber against the wire and hold it in place.

    If you have a VOM or Multi-meter, you can verify that pin 1 goes to pin 1, pin 2 goes to pin 2 and pin 3 goes to pin 3. The cable is a pass thru and if you need to connect 2 or more XLR cables together, you simply need to snap them together to make what-ever length you need. You can also test it by plugging in a microphone into the female end of the cable and putting the other end into a PA mixer and try it out.

    Questions? Comments? .

    Photos taken with a Kodak DC25 Digital camera and Tiffen Close-up lens. Text added using JASC Paint Shop Pro.

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