moltenmetalburn
Active member
Here is some great reading on guitar cables by Premier Guitar.
When we started playing a few decades ago, guitar cables had sproingy coils and crackled when we moved. They cut out after a dozen or so gigs and were basically something to be fought with. Unavoidably, they had an adverse impact on our sound.
Today, cables comprise a multi-tiered industry of their own, ranging in price and design from just a few bucks for a no frills wire to thousands of dollars for the kind of cutting edge technology that you’ll only find in the best studios on the planet. Somewhere in between is a world of choices that can be overwhelming once you start exploring what a “good cable” is all about.
For some, “good” means absolute neutrality. Then again, neutrality might be the last thing you want – consider Hendrix’ penchant for high capacitance coily cords due their ability to tame the highs of early Strats that had no tone control for the bridge pickup. Depending on your gear and the sound you’re looking for, there is a cord out there that will do exactly what you need it to do – open up your mids, make you a little spankier, make you a little boomier, etc.
There really are sonic differences between guitar cables and those differences have everything to do with a cable’s design. Some are more traditional, with a stranded conductor inside a shield. Some use two conductors plus a full shield. Some seek out premium copper and shielding materials. Some go even farther yet in their eternal quest for tone. And – beyond the wire – we found a lot of difference in the feel of these cables.
We all know that a guitar cable is just a wire that carries a signal from the instrument to the amplifier. However, that wire must be shielded from noise sources that are ubiquitous in our modern environment, whether from nearby magnetic fields (such as your amplifier’s transformers), from nearby power lines and house wiring, and even from radio frequencies that fill the air around us. (Just plug in your guitar with an unshielded speaker cable and you’ll struggle to hear your tone over all the humming and buzzing.)
A cable is typically shielded via a braided conductor attached to ground that surrounds the insulator of the inner conductor. The inner conductor itself must be fully capable of carrying the voltage produced by the pickup, which isn’t too tough an assignment in the case of a guitar cable – we’re talking about voltages in the 0.1V to 1.0V range.
The shield may also carry signal by design, since the signal is composed of a positive and negative phase. The inner conductor carries the + signal and is termed “hot.” The negative signal is called the “return” and is usually carried by the shield which in this case must be connected at both ends.
Some designers use a separate second wire to carry the return signal. The shield encircles both wires, which is then connected to ground on only one end. In that case, the shield only serves to protect from external sources of noise – it doesn’t actually carry a signal like with a single conductor cable.
The theory with this two-conductor-plus-shield design is that it reduces the tendency of the + signal to bleed to ground through the shield. There are some high end manufacturers that insert another type of shield between the signal wires and the ground shield, too. This is often a thin conductive carbon polymer. One cable designer we talked with explained that the extra shield helps prevent the + signal from seeking a route to ground and thus reinforces the strength of the signal.
Where the Rubber Meets the Shield
Just under a cable’s jacket made of rubber, plastic, cloth or other material, you’ll find a metallic shield formed from thin copper strands and wrapped in either a flat spiral or a braid. Some cables also use a shielding made of aluminum foil reinforced with polymer film. This second kind of shield is usually not the sole source of shielding in a cable, but is instead usually combined with the spiral or braided copper shield.
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The effectiveness of the shield is directly proportional to the surface area of insulator that it covers and is expressed as a percent (usually over 90%). Spiral wrap is favored in many high end cables because of a proposed advantage in signal carrying ability and completeness of wrap, while braided shield is quite a bit stronger and resistant to physical distortion. A very tight braided shield makes for a stiff cable.
Following the Conductor
The conductor of choice in most cases is copper, though there are high end cables using silver for its increased conductance. Whatever wire gets used has inherent resistance (that weakens your signal) and the interaction between shield and core also induces a capacitance in the cable (which hides those sparkling highs). Conductors used in guitar cables may be solid or made up of fine strands often wrapped together in a spiral – and sometimes the strands are braided together in a complex configuration, as well.
If copper strands are used they may be bare or tinned with a metal coating. The idea here is that the all-important high frequencies tend to be carried at the very exterior layer of the copper strands. If left untinned, there may be some oxidation over time which will interfere with these surface-seeking high freqs and reduce their presence. However, tinning them with solder also reduces their conductance. To compensate, some manufacturers tin with silver, which theoretically might enhance and protect the highs.
...the capacitance of a cable is considered one of its most important design parameters. The lower the capacitance the better the high frequency response. That does not necessarily mean that the lowest capacitance cable is the best sounding – but it’s a step in the right design direction.
But designing a cable’s conductor is even more complex. Some cables use extremely fine strands of copper, while some have a lesser strand count – expense is a factor in this decision. Some solid copper conductors use techniques to align the copper molecules to theoretically enhance signal. They may also use a special subinsulator to protect the copper from flexion fatigue. Stranded copper is stronger in this regard and doesn’t need special protection. Solid silver conductors are more susceptible to fatigue and breakage. Some cable designers, citing transmission line theory, use a twisted pair of center conductors for the hot signal. There even are designs that use two complete cables twisted together and then joined at each connector to achieve their sonic goal.
Insulated From Reality
The material used to insulate the internal signal wire is also of major importance. Basically, this material is what separates the two signal paths. Insulation is a dielectric (non conductive) material that is rated according to its insulating abilities by what is called a “dielectric constant.” The importance of insulation in cable design is that with two current-carrying surfaces separated by a dielectric material, a capacitor is created. The larger the value of the capacitor, the greater tendency it has to conduct high frequencies to ground – just like in your guitar’s tone control.
As you probably guessed, the capacitance of a cable is considered one of its most important design parameters. The lower the capacitance the better the high frequency response. That does not necessarily mean that the lowest capacitance cable is the best sounding – but it’s a step in the right design direction.
Luckily, in recent years even inexpensive cables have been able to achieve fairly low capacitance due to development of better dielectric materials based on polyethylene and other polymers. Older cable designs depended on rubber or neoprene insulators, both of which yield much higher capacitance. High-end cables may use enhanced polymers to lower capacitance even more. The thickness of the insulator and as well as its geometric accuracy may also affect the ultimate cable sound.
Frequency Transmission
What started off as a discussion about an innocent piece of wire with a couple of shiny plugs has gotten quite complex. One last thing needs to be considered – how guitar frequencies are transmitted by a cable.
Most basically, the signal carried by a cable’s conductors has bandwidth – a sound’s lowest to highest frequencies. In the case of an electric guitar or bass, this bandwidth is not really all that wide. The signal sent from the guitar also has phase relationships among its frequencies, which are defined by the string vibrating in the magnetic field of the pickup, and then affected by the character of the wire in your cable.
In all, creating a great-sounding cable is certainly not a matter of chance. How a designer puts all of these cable parameters together creates and defines a cable’s sound and character. And those are key factors making a guitar cable more or less attractive to you, the potential buyer.
