David Lamkins picked up his first guitar a long time ago. As best he can recall the year was 1967: the year of the Summer of Love. Four decades later David has conjured up an amalgam of folk, rock and jazz solo guitar music for the occasional intimate Portland audience.
LCW on Bandcamp
location: Portland, OR USA

Facets: cables, construction, preparation, @musings info

Making your own cables

If you're handy with a soldering iron, wire cutter and knife you can make your own instrument cables. Now there's nothing at all wrong with ready-made cables; they're available in a wide range of materials and price ranges. Making your own cables, however, is a good way to experiment with combinations of materials that may not be available off-the-shelf. Additionally, you can save a bit of money even if your cables use the same materials as ready-made cables. You don't have to pay for profit, advertising, support, returns and other overhead expenses which can multiply a cable's cost by three to five times over the cost of materials.

First a quick review of soldering technique. The most important thing to remember is to heat the joint, not the solder. In other words, the solder must melt when it comes into contact with the materials being soldered. That means that you must apply heat to the the materials, not the solder. If you melt the solder on iron and then attempt to apply that to the joint, the solder will cool upon contact with the unheated joint. This gives you a "cold" solder joint which will be mechanically and electrically inferior and will probably fail within a short time.

A forty-watt iron is a good choice for working on cables. A lower-powered iron may be slow to heat the joint. This may lead to cold solder joints or to melting insulation because you can't heat the joint fast enough, allowing the heat to spread beyond the joint. A higher-powered iron will require more care to prevent the application of too much heat.

A clad tip is preferred for longevity. A bare copper tip tends to quickly erode; you'll have to file it frequently to maintain a usable shape.

I shouldn't have to tell you this if you're handy with a soldering iron, but for the sake of completeness: always use rosin-core solder. Use a fairly small gauge since it melts faster.

Other tools you'll need: small wire cutters, a decent wire stripper that can handle small gauges, and a knife. All of these should be sharp.

Finally, you'll need some kind of jig to hold the work while your're soldering. This will depend upon your ingenuity and dexterity. You'll want to be sure that the work doesn't move for about five seconds after you've removed the soldering iron. This gives the joint time to properly cool. If the work moves while the solder cools you'll end up with - you've probably already guessed it - a cold solder joint. I use a pair of vice grips (using very gentle pressure to keep from crushing the connector barrel) or a pair of pliers with a rubber band around the handle.

Let's talk next about types of cables. The vast majority of instrument cables are made using shielded coaxial cable. However there are two additional possibilities. The first is a shielded twisted-pair cable. The signal is carried by the twisted pair, while the shield is connected at only one end (normally the amplifier end). The rationale for this is that the twisted pair and the shield both contribute to cancelling and isolating noise.

The other alternative is a star-quad cable. This is effectively two twisted pairs within a common shield, offering further noise cancellation. The pairs are arranged like this:

star-quad detail

When wiring an instrument cable using star-quad wire, the opposing wires are connected together and wired the same way as a twisted-pair.

Here's a summary of how the three types of cable are wired:

TypeEnd 1End 2Conductor Function
CoaxialShield to sleeveShield to sleeveGround/sheild
Center conductor to tipCenter conductor to tipSignal
Twisted PairShield to sleeveShield unconnectedSheild
Center conductor A to sleeveCenter conductor A to sleeveGround
Center conductor B to tipCenter conductor B to tipSignal
Star-QuadShield to sleeveShield unconnectedSheild
Two center conductors A to sleeveTwo center conductors A to sleeveGround
Two center conductors B to tipTwo center conductors B to tipSignal

To prepare cable for soldering, first cut it to the desired length. Next cut away about 3/4" to 1" of the outer insulation from each end. Use a sharp knife and score the insulation without cutting through to the delicate shield wires. Your goal is to strip the outer insulation without damaging the shield. Pay attention when you remove the outer insulation. If more than a half-dozen or so shield wires come along with the insulation, chop off the end of the cable and try again.

If there's any additional plastic or fiber wrap under the outer insulation, carefully cut that away. Next you'll prepare the shield for soldering. There are two kinds of shields suitable for use in an instrument cable: braided and spiral. (Foil shields are intended for use in permanent installations where the cable doesn't move.) A spiral shield is simply unwrapped and then twisted together. A braided shield must be pushed back and unravelled using a pointed tool; once you've separated the strands then twist them together.

If you're preparing a twisted-pair or star-quad cable, cut the shield off at one end of the cable. Use a bit of shrink-wrap tubing or electrical tape to prevent the cut-off shield from making contact with the connector.

Next you'll prepare the center conductor(s) for soldering. Some coaxial cables have a thin black conductive plastic layer around the inner insulator. Remove this. For any wire that will connect to the tip of the plug, strip about 1/4" of the insulation from each inner conductor, twist the thin strands of each conductor together and tin the wires. Likewise for the inner conductors that will connect to the sleeve of the plug on the end of the cable from which you've removed the shield. As with preparation of the shield, strive to avoid clipping off any of the fine conductors when stripping the insulation. Cut the wire back by an inch and start over if you clip off more than about three strands from an inner conductor.

To tin a conductor apply the soldering iron to one side of the wire and the solder to the side opposite the iron. Allow the solder to flow into the stranded conductors then remove the heat.

For inner conductors that will share the shield connection to the sleeve, strip back most of the insulation and twist the wires together with the shield wires.

As the final step in preparation, tin the shield wires. If you're preparing the shield end of a twisted-pair or star-quad cable, make sure that the solder also flows into all of the wires that you've twisted with the shield.

Now it's time to solder the wires to the connectors. Work out ahead of time how the connectors will be physically assembled. In most cases you'll need to slip the connector shell (and perhaps an insulating sleeve) over the cable before your solder. You'll be using two-conductor plugs having sleeve and tip connections. The tip connection is always located centrally within the connector body. The sleeve connection is towards the outside; it may take the form of a solder lug or may be combined with a pair of tabs used to clamp the cable. Measure ahead of time and use your wire clippers to trim the tinned ends of your center conductor(s) and shield/ground wires for the best fit. If your connector has the style of clamp that requires you to bend a pair or metal tabs around the cable, be sure that the tabs will bite into the cable's outer insulation after you're finished soldering.

There are two common styles of soldered connectors. The Switchcraft style (also used by G&H) has a long metal piece with clamping ears as noted above. The Neutrik style (also used by Amphenol) has a plastic clamp that closes around the outer insulation when you assemble the connector body. My personal preference is for the Neutrik style connector as it allows more room for soldering and seems to clamp the cable more securely. Some people supplement the Switchcraft style clamping scheme with layers of shrink-wrap tubing around the inner connection (and sometimes over the outer shell after final assembly. I'd rather not have to strip away the heat-shrink tubing when repair becomes necessary. Still, there are some applications where the Neutrik style connector shells won't work. If you do use Switchcraft style connectors, I'd advise foregoing the heat-shrink treatment until you have some experience with how well the connectors hold up without it.

Solder the wires to the connector, assemble the connector shell, and repeat for the other connector. If you've been careful with matching up the wires on each end and haven't used too much solder or heat (both of which may cause shorts), you should now have a functioning cable.

If your cable hums, crackles or doesn't pass the guitar's signal, unscrew the connector shells on both ends and double-check your work. If the problem isn't obvious you can unsolder the connectors (make sure to clean off any excess solder), clip a bit (an inch is plenty) off each end of the wire and start over.

That's all there is to making your own cables. You should be able to find quality raw cable for somewhere between fifty cents and a dollar a foot. Connectors should cost roughly a dollar and a half to five dollars each. That places the cost of a homemade ten-foot cable at about eight to twenty dollars and a twenty-foot cable at about thirteen to thirty dollars. Assuming reasonable care in construction, these cables will last you a long time. The cool thing is that you get to experiment with combinations of materials and wiring techniques not readily available in off-the-shelf cables.

October 05 2008 02:35:49 GMT