This is part one of a two-part post. For part two, click here
Grab a cup of coffee or tea, and get comfortable. We're going to take a deeper look into the basics about cables.
Now that we’ve covered the topic of 1/4” connectors, the only thing left in a guitar's signal path is the cables. Although it’s most common for people to purchase off-the- shelf pre-made cables, it helps to know a bit about cables because chances are that pre-made cables use similar materials.
Types Of Cables
Generally speaking, there are 3 types of cables guitarists use: Instrument, Patch, and Speaker. Each of them have their own properties that allow them to excel at whatever it is they have to do. Instrument and Patch cables are very similar in that they are both based on concentric designs. Speaker cables feature a different design as it has to carry large signal currents.
Types of Cables - Instrument Cables
No guitarist can be without an instrument cable. They are what connects an electric or acoustic (with pickup installed) guitar to whatever signal processing is next in the signal chain. Even if you use a wireless system, you will need an instrument cable of some form to connect to the wireless belt pack. Pre-made instrument cables can vary widely in price, from sub-100HKD to over 1000HKD. So why the huge difference? Partly because of the actual quality of materials used, and partly because of branding. Let’s open the ‘branding’ can of worms a little later and focus on materials. Since we mostly deal with mono signals, this means that we’ll be needing a two conductor cable. All professional level instrument cables use a concentric design. This means that one conductor is wrapped by another. The core of the cable almost always carries the hot signal, where the shield carries the ground signal. They are separated by an insulating material to ensure that the wires don’t short out and that your signal stays intact.
The quality of the core is where pricing can play a difference. The core is usually made of copper as it’s a great conductor. Copper, however, does come in many different grades. The most common way to measure the purity of copper is by its OFC rating. OFC stands for Oxygen Free Copper and is usually used only by professional cable makers. If the cable you purchase does not have an OFC rating, chances are that the copper used in its core contains copper oxides, which does your signal no good.
Now almost all audio cables don’t use one solid piece of copper for their core. Instead they are usually made up of many thinner strands of copper. This is what gives audio cables it’s flexibility. (Solid core cables are generally used for TV or broadcast signal cables.) The number and the thickness of the strands all build up to give the cable an AWG rating. AWG stands for American Wire Gauge. Interestingly, the lower the number, the thicker the cable. This is important because you don’t want the cable too thick or too thin. Too thick, the cable will be inflexible and portability becomes an issue. Too thin, the electrical properties may work against the quality of the signal. Instrument cables for guitar usually have an AWG rating of 18 to 22.
Resistance + Capacitance
Another factor that affects the quality of cables is its electrical properties. Despite copper being a great conductor, it is not perfect. Any material will have a certain amount of resistance over a given length. The same applies to capacitance as you have two conductive materials separated by an insulator (which, by the way, is the definition of a capacitor). In order to keep your guitar signal’s integrity, you want these two to be in your favor, which means low resistance and low capacitance. A cable with high capacitance would give a similar effect as rolling down the tone knob on your guitar slightly. Though, this may be desirable to some musicians, as a guitar tech, I would usually want to keep as much signal integrity as possible. If I do want to roll off the treble end, I can always do so later on in the signal chain. If you lose the treble end early in the signal chain, it is very difficult to get it back without the signal sounding shrill and piercing.
As far as the construction of an instrument cable, the outermost layer would be the jacket. This is what determines the actual thickness of the cable (not just the core). This thickness has nothing to do with AWG. However, this thickness has a lot to do with the plugs we subsequently use on both ends, as some plugs have restrictions as to maximum thickness of cable it allows. The thickness and material also has a lot to do with real life situations. As a guitar tech that has to fly to a lot of gigs, a thick cable will not be an advantage when it comes to packing a hard case full of tools and supplies. Another reason why I’m not a huge fan of thick inflexible cables is because of the hazard it causes on a live stage. When thick cables are uncoiled, they tend to hold the shape of its coiled form. What you end up with is a cable that is not fully sitting on the ground. Chances are that parts of the cable will sit slightly off the ground in a loop, which is a huge safety risk in the side/back stages where it’s usually dark and a lot of crew are rushing around. Another consideration is whether the jacket material is resistant to the different elements it will be exposed to on stage. By elements, I don’t just mean the humidity or temperature, but also oil residue from smoke generators, intense heat from fireworks or other pyrotechnics, and so on.
That's it for part 1. Now that the basics of cables are covered, we will talk about Patch Cables and Speakers in part 2.