Final Soldering Lesson--XLRs

Picking up where we left off, we'll get back to soldering XLR cables today. This is an incredibly useful skill, as we probably use more mic cables (and break more mic cables) than any other. Today, I needed to make up a few 6-foot XLRs for our Worship Director, Jon. Jon needed to hook up his little mixer to the speakers in his office. It's a simple job, here's what to do.

First, assemble the tools you'll need for the job. If you missed out on my first and second posts about soldering, you may want to go back and review. Here's what you need. Left to right, you'll need a soldering iron. You can find them at Radio Shack (one of the few things I buy there), or other electronics stores and of course online. You don't need a super-fancy one with electronic temperature regulation. Just a simple 15-30 watt pencil tipped iron will do. My iron is switchable between 15 and 30 watts, though I leave it at 30 almost all the time. Next, a pair of diagonal cutters. These are the smaller ones, and spring loaded. Very handy. You'll need solder of course, electrical grade--no plumber's solder. The rosin inside the core is different between the two, so get the right kind. It comes in different thicknesses, and as I write this I don't recall which I have, other than it's the thicker kind they stock at Rac-Shack. The super-fine stuff is nice for mini-jacks, but XLRs take so much solder, the thicker variety is faster.

Also in the picture are some wire strippers. I like the kind I can adjust to strip all the way to 24 gauge wire, then count on the fact that I've stripped so much (wire that is) that I can tell when I'm through the insulation of thicker wire without nicking the copper. You may wish to get a wire stripper that is calibrated for different gauges of wire while you're learning. A knife is very useful for cutting through the outer jacket of the mic cable. I use a box cutter I got when I worked at a grocery store in high school. But any sharp blade will do. Finally, there's my vice, which is some 30 years old. It looks terrible, but is just the ticket for holding on to the connectors without burning my fingers.

Let's get stripping! Not so fast! Before you do anything, you want to slip the housing of the XLR connector down the end of the cable. There's nothing worse than making a perfect solder joint on your connector, then realizing you forgot to do this step and having to de-solder the end off to put the housing on. Not that I've ever done that...

The first step is to carefully cut through the outer jacket of the cable. Make your slice about 1/2-5/8" from the end. I normally try to not cut all the way through, then bend the cable at the cut and just touch the blade to the jacket at the cut line. This will split the jacket without nicking a bunch of the copper shield. Separate the copper shield from the 2 conductors, taking care to round up all the bare copper strands. Wrap them tightly together. Now if you're using Mogami 2792 (and why wouldn't you?) you'll notice that both the 2 conductors are wrapped in black plastic. This black stuff is actually conductive, and it's one of the reasons this cable is so immune to interference. Any junk that makes it past the copper shield is then shunted to ground via this conductive plastic. As great as it is, it has to go at the ends of the conductors. If you don't take it off, you may find the cable buzzes slightly as the plastic forms a high-impedance ground to the positive and negative solder cups. So make sure you talk it off. Here, I've removed the coating from the red lead.

Next thing to do (after you get the black stuff off both leads) is to strip the ends of the white and red conductors. You don't need much, just about 3/16" should do it. Twist the copper strands together tightly, like you did for the shield. Next, we'll tin the leads. Just like last time, put some heat on the wire, and touch the solder to the other side. Just a little bit here, you don't need much.

You'll notice that when you heat the wire, the insulation will melt back a little bit. That's why you don't need to strip too much off. Next, take your connector end, in this case a Switchcraft AAA series--my favorite, and chuck it into the vice. You need to make sure it's not going to be moving around on you. You'll want to fill the solder cups with solder. It should look something like this:

That's kind of a lousy picture, but hopefully you can see the solder is coming just up to the top of the cup. Almost done now. Array the wires in the correct order for the pins. You want to make sure you follow the proper standards when building cables. With 2792, red would be hot or +, so it goes to pin 2. White is cold or -, so it goes to pin 3. The shield always goes to in 1. Switchcraft and Neutrik mold little numbers onto the ends so you know which is which. I like to start with the shield, since it's the biggest. Heat up the solder in the cup, then drop the wire in, making sure to heat up the wire too. You want to get it all nice and hot so the solder flows together. Then remove the heat and wait. The solder will go from shiny and molten to a bit dull and solid. Then you can let go (and cool off your fingers). Do the same for the other two.

It should look like the above. Notice the solder is just up to the top of the cup, and everything is nice and neat. You don't want solder dripping all over the place, and you especially don't want any stray copper or solder connecting any two pins.

Finally slide the housing up (you may have a few other parts if you're using Neutrik NC3 series). But this is why I love the Switchcraft AAA series. There are two parts to the connector, and when you're done soldering, slide it up, screw it together and you're done.

That's it! You've just successfully soldered an XLR connector on the end of some mic cable. Just make sure if you put a male on one end, you put the female on the other. Not that I've ever made that mistake...

If you missed the earlier posts on where to get supplies, or how to do unbalanced speaker connections, you can find them here and here.

I made this cable for $6.80. It's all top quality material, and it took less than 5 minutes (including picture taking). Buying one of comparable quality would set me (actually, the church) back at least $15-20. And it's just plain fun. So go make some cables, huh?

Soldering On

Well now that you know the reasons for building your own cables, and have the resources to do so, let's build some cables, shall we? What's that, you don't know why you should build your own cables? Well go back and catch up. We'll wait. All set? Here we go... BTW, you can click on any of the pictures to enlarge them.

Today, we're going to tackle some easy ones; an unbalanced 1/4" jack (which is a speaker cable in this case) and a 2 channel Speakon. The project in question here is a two channel, single cable interface that will take 2 amp channels from a guitar head amp (using two 1/4" plugs), send it via a two channel cable into a Neutrik Speakon NL4, through 2 individual speaker cables we have run under the stage to the backstage area, then come out in another Speakon to dual channel 1/4" cord to plug into the speaker cab. But that's really immaterial. Here's how we connect the ends.

First, the Speakon, because Speakon cable ends are super-easy. Start by stripping about 5/16" (or 8 mm) of insulation from the ends of the wires. Make sure you use a good wire stripper, that is set to not nick the inner conductors of the wire. It will look like this:

Notice that none of the small copper strands are cut off. If you have your strippers set to cut too deep, you'll start cutting out the copper, and that will decrease the efficiency of the wire. So don't do that. Now, at this point, simply shove the ends into the appropriate ports on the back of the Speakon, I found it's often helpful to back the screws out a little bit before putting the wire in. Just don't back them off too much; they will come out. 

In the case of an NL4, you will have 4 terminals labeled 1+, 1-, 2+, 2-. In the case of this wire, there is a red/white pair, and a frosty red/frosty white pair. Normal convention would be that the red is a hot (or positive) lead, so that would go into the 1+ terminal. White goes to 1-. Frosty red and white get tied to 2+ and 2- respectively. 

While it's good practice to follow standard industry conventions, what really matters is consistency. Make sure you always connect the same wire to the same terminal all the way through the cable. You don't want to swap the positive for negative. That's bad.

When you're done, the job looks like this:

All that's left to do is slide up the chuck, the threaded end, and slip the whole plug end into the housing. What's that? You forgot to send the chuck and threaded end down the cable before you put the end on? Don't feel bad, I do it more often than I care to admit, even after making thousands of terminations. Don't sweat it, just un-do the screws, take off the end and slip the threaded end and chuck on. You're back in business. It's a little more work when you forget with an XLR or 1/4", but it's not the end of the world. Try to develop a system that helps you not forget. I should note that NL4 connectors come with 2 chucks for different sizes of cable. Make sure you use the one that fits snugly for proper strain relief.

Connecting a chassis Speakon is not hard either. In this example, I have 2 chassis connectors; one on stage, the other backstage. The procedure is essentially the same--strip the wire, tin the wire, and only deviates when we get to the connector. I put a little dollop of solder on the pad of the connector first, like this:

If you look closely, you'll see the top pad has a layer of solder on top. Next, you'll apply heat with the tip of the iron to both the wire end and the pad. The goal is to completely melt the solder on the end of the wire and on the pad. When everything is nice and warm and melted, remove the heat and hold the wire in place. It will be pretty toasty, so be careful you don't burn your fingers. When you're done, the wire will be firmly attached to the pad, thusly:

Notice there is a nice solid flow of solder that completely encompasses the wire. You can give this a pretty good tug once it cools and it should not come off. If you can pull it off, or the solder looks dull and chunky, you have a "cold solder joint" and it will fail (and it won't conduct well before it fails). Heat it back up and do it again if that happens. Click on that picture to enlarge it so you can really see what I'm talking about.

At this point in the job, because I'm really anal, I wrap the entire thing with electricians tape before setting it in the wall plate. The job is done.

The process for terminating a 1/4" unbalanced plug (Switchcraft 280) is much the same as the chassis mount Speakon. Again, it begins with a proper strip and tinning of the wires. I make a slight adjustment here, and trim the white wire (or whatever is used as the ground, or negative wire) a little shorter than the red (or positive wire). This makes it easier to keep them apart inside the connector.

Like the Speakon, we put some solder on the pads like so:

You don't need to get crazy here, just flow a small amount onto the tip pad (the one on top, which will be positive) and the sleeve pad (the bottom/strain relief). The amount of solder is probably 2-3 times the thickness of the pad itself. Before joining the wire and the connector end, make sure the housing is on the wire, facing the right way. The 280 (and 297 for that matter) come with a insulation tube that fits tightly inside the housing. Make sure this is present, or you risk shorting the positive pad/wire to the housing. Next, heat the pad and wire at the same time to get the solder flowing all around the wire and pad. When done right, it looks like this:

Again, you can see the solder completely flows around the wire and is nice and shiny. This indicates a good joint. Use a set of needle nose pliers to carefully bend the strain relief tabs onto the wire. You want it to grip snugly, but not cut through the insulation. It's a good idea to let everything cool down a little bit before you do this step (if not only because you'll burn your fingers if you don't).

And that's about it. You can see I only stripped back enough wire to fit onto the pads. You don't want to strip off more than you need, as you risk a short. You may find you need to push the tip pad (the positive one) down a bit to fit inside the housing. That's OK, so long as you maintain a good gap between the sleeve pad. Don't push them too close, or they'll short.

Now, you may be wondering exactly how do you hold onto the soldering iron, the connector end, the wire and the solder all at the same time? Well, you could check into having 2 more hands attached; you could find a friend to hold some parts for you; or you could do what I do and use a cheap, old, heavy bench vice that I bought at Ames when I was 12.

It's ugly and beat up, but I've used it for literally thousands of connectors. I snug the connector in the jaws just enough to hold it, but not enough to distort the shape. It does a great job of holding 1/4" ends, XLRs, RCAs and even mini 1/8" connectors. I also slip the stripped wire ends vertically between the jaws and clamp them in place when tinning. With practice, I've gotten so I can tin 3-5 wires at once. It's all about the right tools.

So there you go. Unbalanced 1/4" connectors and Speakons. Next time around, we'll tackle balanced lines. Happy soldering!

Note: I edited this post on 8/16/14 to remove a section about tinning the ends of the cable when making up Speakon connectors. I don't do that anymore as I've learned the manufacturer doesn't recommend that. We learn as we go...

Onward Christian Solder-ers

If you didn't guess today's topic based on that fantastic pun for a title, we're talking about one of my favorite pastimes: Soldering. More specifically, making your own cables. I think I bought my last pre-made audio cable about 15 years ago. Since then, I've made all my own. Mic cables, speaker cables, instrument cables, even patch cables and patch bays. If it carries audio, I've made it. I don't think I've ever attended a church for any length of time and not ended up making audio cables. 

For today's post, I'll talk about why I make my own cables and what my favorite raw materials are. Upcoming posts will illustrate proper connection methods for various cable ends (1/4", XLR, Speakon, even BNC). But first...

Why make your own cables?

I give several answers to that question. First, I like to control the materials I use. Building my own allows me to specify the cable, the connector and how they're mated to one another. I have my favorite cable types for different applications (see below), and I really don't like the cable they use in cheap music and instrument (MI) store cables. It doesn't coil well, doesn't feel good and doesn't last.

Second, I like being able to control length. For example, in our current Upper Room setup, we have need for a bunch of 1' mic cables to run between DIs and our sub-snake. Those are easy to make up. We also needed some 8' cables for vocal mics. When I'm doing an installation, I like to make my cable exact length. It neatens the install, and makes it far easier to work on later on (and by exact length, I mean point A to point B, plus a service loop if needed). I've seen a stack of IEM transmitters sitting next to a mixer, literally 2' away, all connected by 25' cables. I wish I was making this up.

Third, there is significant cost savings. Whereas a high-quality 20' mic cable might cost $30 or more, I can make that same cable for half that, and it only takes me 5 minutes (when I'm making more than one). If you only need 2 cables, making them yourself might not save you any money (though the first to arguments apply), but when you're doing 10 or more, the cost savings really add up. And when you start looking at multi-channel cables, the savings really take off.

My Favorite Things

I've been buying nearly all of my connectors and wire from the same place for over 10 years. Markertek has a great selection of both (and a whole lot of other stuff), they ship fast and offer great customer service when needed. They're prices are also hard to beat. I compare others every so often, and they remain competitive. You may be able to find a local source for these parts as well, but I find it easier to hit the 'net, place my order and wait 3 days for the box to show up. Takes a little more planning, but I also stock standard components and cable in my office for emergencies.

So here's what I like to use. For mic cable, it's Mogami 2792 all the way. It is, hands down, the best mic cable made. It's great to handle, coils wonderfully and is exceptionally low on noise. Because of the unique shielding method (which we'll talk about when we make mic cables), it's nearly impervious to noise. I've run these mic cables right next to AC lines (I know, you're not supposed to) and never had a hum sneak in. It's also a great bargain at $0.49/foot as of this writing. Some people might like the Canare Star-Quad, but I hate it. It's incredibly hard to work with, isn't nearly as flexible as the Mogami and is more expensive. I've used literally thousands of feet of 2792 and never had a cable go bad (except for the one that got run over by the piano...)

For instrument cables, it's Mogami again, this time 2524. Though I've been known to use 2792 for it because that's what I normally stock, 2792 is low impedance, while 2524 is high impedance. For a low cost, permanent install cable, I will often turn to West Penn 291. It's a little harder to work with than some of the Mogami console cables (2944 for example), but it's often quite a bit cheaper. When I'm doing a ton of install lines, I'm not as worried about flexibility of the cable, so I don't mind using 291. And the $0.10/foot (or more) savings adds up over several hundred feet.

When it comes to connectors, there are several to choose from. One thing I don't do, and neither should you, is use any connector you bought at Radio Shack. They're junk. And expensive. Don't do it. 

Now that we have that out of the way, for 1/4" connections, I'm a Switchcraft man, all the way. Neutrik makes a good connector, but I don't like assembling them. Their pads are too small, and they take too much time. And they're big and expensive. Nope, give me a 280 for unbalanced lines and a 297 for balanced. I normally keep 10-20 of each on hand at all times.

For RCA, I won't use anything but a Switchcraft 3502. Others make them, but I like Switchcraft's. When it comes to XLR connectors, I'm divided. I was a long-time Neutrik addict, having soldered up literally hundreds of NC3MXs and NC3FXs. They also make a pretty trick IDC (insulation displacement contact) connector that doesn't require soldering. You can throw on of these on the end of some 2792 and have a mic cable made up in about 2 minutes, and you don't burn your fingers. But, I'm a cheapskate and they're about a buck more than the solder ones. Not bad if you want 5, but I use a hundred or more a year. 

As much as I love 280s and 297s for 1/4", I've never liked (not even a little) Switchcraft's XLR connectors. Sure, they're strong, but they are harder to put together than a kid's Christmas present. All those parts and little screws for the strain relief...yuck! However, a few years ago, Switchcraft won me over with their new AAA series. While there are 4 parts to an NC3, the AAA has 2. The pins are integral to the shell, and the strain relief is built-in to the back housing. Slide the housing on the cable, strip the ends, solder it up, screw it together and bam! you're done. Two minutes an end, tops. Best of all, they're comparably priced with the NC3 series. 

I'll still order NC3s if the AAAs are out of stock, but when I can get them I use AAAs. Always get the metal housings, too. Don't cheap out and try the plastic to save a few cents. You will be disappointed. 

For speaker cables, you can't beat the Neutrik Speakon series. Get rid of those 1/4" cables on your wedges and go Speakon. You'll have a lot fewer monitors coming unplugged accidentally...

Later, we'll talk about making video cables, too; so I'll throw in a plug for those parts. Again, I'm sold on one type of connector that I've used thousands of times. Kings 2065 series is the way I roll. You have to get the right connector to match your cable, but that's not hard. I keep things simple and stock one cable, Canare LV-61S RG-59, and one connector 2065-7-9. LV-61 is the 2792 of video cable. 

So there you go. Order up a mess of those connectors and a few hundred feet of cable and we'll get going. Onward, Christian Solder-ers!