Many people who have been playing for an extended period of time may be guilty of this. Many may have learned quickly, or still do it after 30 years of playing. But what happens when you use an instrument cable instead of a speaker cable to run your amp? And, furthermore, what are the differences between them? This month we’ll explore the intricacies of cables, both of their composition, and of their purpose and function. We will also learn about the effects of making such a mistake, and why we should avoid this problem at all costs (well, the cost of going to the nearest store to get a REAL speaker cable, anyway).
Most cables are made of a copper core with some sort of metal connector (often nickel) and a polyester or rubber coating. Many high-end cables often use oxygen-free copper cores (very pure, for exceptional signal transfer) with gold connectors (gold transfers electrical currents well, and also resist corrosion). One can also get a variety of “gauges”, or cable thicknesses.
Generally speaking, a heavier gauge is preferred, as it allows the most signal to transfer (think of a water hose; a bigger hose allows more water to flow through). Also remember that shorter distances are easier on your signal. Just like the water hose that can lose water pressure, if it’s a really long hose, if your cable is too long, you can lose some of your signal and tone.
The main difference between the construction of an instrument cable or a speaker cable is that an instrument cable is shielded, whereas a speaker cable is not. This is due to each cable’s purpose and function.
Cable Purposes and Functions
Instruments put out a very weak signal path as compared to an amp. For this reason, instrument cables are shielded in order to keep unwanted RF interference (extraneous noise caused by other electronics nearby) to a minimum.
Amps put out a lot of power. Therefore, there is less of a need to keep out RF interference, as the signal is already powerful enough to resist the phenomena on its own. This is why speaker cables are generally unshielded.
The Dangers of Mixing and Matching
So what happens when you make the mistake of using the wrong cable for the wrong function? If you use a speaker cable in place of an instrument cable, you will get a lot of noise from your amp, monitors, even (theoretically) your cell phone. You will probably hear a constant, high-pitched squealing sound and a lot of static. This is because there is no shielding to preserve your instrument’s signal, and all that RF interference will “join” your instrument signal in its path to your amp.
Using an instrument cable in place of a speaker cable, however, is much more serious. Since the amp is attempting to put out far more power than what the cable is made to handle, the amp (and speakers, for that matter) get a little confused.
If you remember from my article “Speaker Impedance: How to Properly Match Your Amp Head with Cabinets“, amps are pretty “smart” in that they know at what impedance to run. Unfortunately, this instrument cable problem just throws a huge curve-ball to the amp, and it strains itself to push through the cable. The result can be damage to your speakers, your amp, or both.
So you have to ask yourself: Is it REALLY worth saving ten bucks on the cable at the risk of ruining my $500+ rig? I doubt it. Just go to the nearest music store and buy a speaker cable. Again, there are options like oxygen-free copper, gold connectors, and heavy gauge speaker cables that can be expensive, but any cheap speaker cable will be better than using an instrument cable.