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...