Introduction: How to Make an XLR (microphone) Cable.
Making your own cable for the first time is a right of passage for aspiring audio engineers. It is also a totally useful skill for electric/electronic musicians, anyone working with live sound, and even folks interested in custom home audio. The supplies are inexpensive and you can easily make cables of higher quality and more specific customization than what is for sale in the store or online. The basics are straightforward and broadly applicable.
Step 1: Supplies!
A few simple tools are needed to make cables:
- A soldering iron
- An iron holder
- A small sponge
- Some solder, preferably lead-free
- Helping Hands (pictured above)
- Large and small wire cutters
- Small wire stripper
- Small needle-nosed pliers
- Utility knife
- A multimeter. (not strictly necessary for assembly, but helpful for testing your new cable)
For each cable, you will need:
1. A length of balanced audio cable. Balanced audio cable has at least two leads and a metallic shield or ground. Some cable (like the cable used for this demo) is quad cable, which has marginally better durability and noise perforance. The steps are essentially the same for standard balanced and quad. Canare and Mogami are both good brands. Balanced cable is sold by the foot or in rolls, typically for about $1 per foot.
2. One each XLRM (male) and XLRF (female) connector. These are the normal form-factor connectors on standard microphone cables. Each connector has three contacts. XLRM connectors have pin contacts where XLRF connectors have holes. Neutrik is an industry standard brand.
Soldering should be done in a well-ventilated space. The smoke may be hazardous with long-term exposure and can be irritating without much exposure.
Step 2: Working With Balanced Cable (in Six Sub-steps)
Before you even turn your iron on, you need to cut the cable and organize its ends.
1) Cut to cable length. Your microphone cable can be any length. Realistically, anything over 50' might be unwieldy or invite noise. 20' is a good length if you're not sure.
2) Make shallow lengthwise cuts at each end. Reveal the cable's innards by putting a shallow cut in the rubber casing at each end about 1.5" long. Cut deep enough to cut through the casing, but no deeper. You want to leave the metallic grounding shield intact.
3) Pull back the casing and unbraid the shielding if necessary. Some cables (notably Canare quad) will have braided shielding that will take some work to unwind, but you have to do so and do so carefully. The shielding will be the ground (the 'X' in XLR) and needs to be preserved as you work.
4) Trim casing and any non-shielding or lead material. Cut the rubber away and trim any cotton or plastic material out of the way. Only the leads and shielding/ground should remain. Trim leads and shielding to no more than an inch (1") past the new end of the rubber casing.
5) Strip the ends of the leads. Use your wire stripper and carefully strip about 1/4" of each lead.
6) Twist the shield/ground and the ends of each lead so they stay together. As shown.
Step 3: XLR Connector Anatomy
Before proceeding, let's review the components of an XLR connector so we know what we are talking about. We will review what gets soldered to what before starting that step, but a few concepts and terminology now will be helpful. As pictured, these parts are present in both XLRM and XLRF connectors:
Your cable ground, positive and negative lead will be soldered to the contacts on INSERT at each end of the cable. This is the only part of the connector that will receive any soldering. It is a problem if your cable leads or ground make contact with any other component, especially the metal casing.
The CHUCK is a plastic shield that will surround your connections and help prevent breaking from regular use. Some XLR connector brands may not include this piece. Bummer!
The BUSHING slides on to the cable BEFORE you solder the connections to the insert, and screws in to the CASING to finish the assembly.
Just four parts per connector. nbd.
Step 4: Tinning Leads and Ground
Tinning a contact means applying some solder to your lead/ground/etc ahead of time. Working this way, the solder will be in place and ready to use when you are connecting wire to contact. Time to solder!
Turn on your iron (which is, of course, resting safely in the iron holder) and let it heat for a few minutes. IT IS GOING TO BE HOT ENOUGH TO MELT SOLDER. This means it is also hot enough to burn you. Be careful!
Wet your sponge and have it handy. You will use it to wipe off the end of your iron if it gets dirty or has too much solder on it. Your iron makes a really satisfying tsssssst sound when you do this. Fun.
Place the end of the cable you want to work on in your helping hands tool.
To tin a lead or ground, first apply a small amount of solder to the iron. This improves conductivity. Use the iron to heat the metal to receive the solder and apply solder to the hot metal. As possible, you want to be heating the conductive metal contact and not the solder itself. Pull the solder away and then the iron once solder is applied. Do this for each conductive wire.
Trim the ends of your leads just a bit to even the ends. Trim your twisted ground to match the length of the leads. The leads and grounds should be about .7" beyond the rubber cable casing.
Once you have tinned your cable, PUT THE BUSHING ON THE CABLE RIGHT NOW (as shown above). Otherwise, you might forget and solder your insert to the cable without it, which usually results in having to undo and redo your soldering. Pain in the neck.
Step 5: Tinning the Inserts
Having tinned your cable, you should also put some solder on each contact of your inserts as shown. Heating the contacts from underneath and applying solder from above is a good technique to make sure the solder has a good bond to the contact. Use your helping hands to hold the insert while you work.
Step 6: KNOW YOUR CONNECTOR CONTACTS!
As you might have guessed, balanced cable ground and leads need to be connected to specific contacts on your XLR connector. But how to tell which connects to which???
Fortunately, the contacts of your connector are labeled: #1, #2, and #3. From here it is standardized. The ground (braided shield, remember) connects to #1. The positive lead connects to #2 and the negative lead connects to #3. Which is positive and negative? Typically, the lighter cable is positive. As long as #2 connects to #2 on each end and #3 connects to #3, the cable will work. If you are going to be wrong, be consistently wrong. Note that both XLRM and XLRF connectors are marked this way, both on the sides inside and outside the connector construction. They are arranged slightly differently between male and female. Pay attention or your cable might not work correctly.
SO WHY ARE THERE TWO LEADS ON A CABLE THAT CARRIES A SINGLE MONO MICROPHONE CHANNEL???????
This has to do with how balanced cable mitigates noise over long cable runs. The specific answer involves phase cancellation and is well documented through the google.com. That is its own subject for another time. Know that both leads (and the ground!) are doing important work in normal microphone connections.
Step 7: Solder Cable Ground and Leads to Connector Contacts
Time to make the connections!
First, orient the ground, positive and negative of your cable to the correct contact as shown above. Using your helping hands to hold the cable and connector in position. Getting a good angle can take some adjusting. Be patient and try not to force anything. A frustrated cable maker usually ends up with burns on their fingers...
Going in order, heat the connector contact from underneath until the solder melts. Using your small pliers (or your fingers if you are a dummy like me) push the tinned ground or lead into the liquid solder. Remove the iron and let the solder cool to solid before letting go of the cable wire. Repeat for each lead and connector pair.
Finished solders are clean without extra solder spilling off the contact. Leads and ground are well separated from each other, unlikely to make internal contact.
Step 8: Assemble the Connector
With your soldering finished, you can assemble the rest of the connector around the insert.
Put the CHUCK in place around your solder work.
The CASING fits over the INSERT. There are grooves that help you align the case correctly. On Neutrik brand connectors, there is only one possible way to put the case on.
The BUSHING (handily having been placed on the cable in an earlier step) screws into the back of the CASING.
IF/WHEN you screw up and forget to put the bushing on your cable before soldering the connector to cable, just carefully undo your soldering, put the bushing on, and redo your solder. Everybody makes this mistake, usually once when you sit down to make a bunch of new cables.
Step 9: Testing!
If you have a multimeter, you can use it to test continuity of each pin of your XLR cable.
Continuity mode on your multimeter makes a tone when the positive (red) and negative (black) probes make contact or touch opposite ends of a circuit, closing it. To test your cable, touch a probe to the corresponding pin on each connector end--i.e. touch probes to #1 and #1, #2 and #2, etc. You should hear a tone when corresponding contacts are touched.
It is good practice to then touch the wrong contacts and the case to make sure you get no tone. For example, touch #1 on one end and #3 on the other. You should have silence.
If #1 connects to #1, #2 to #2 and #3 to #3--and nothing connects where it shouldn't--you have a working microphone cable!
Step 10: Enjoy Your Cable!
That's it! Well done! Now go start a band and let the world know how you feel!