Even the most experienced musicians can forget essentials parts of their equipment from time to time. It is often that a fellow band mate or soundman may lend you a cable, but it is essential to ensure that the one you are using is indeed the proper cable for the job.

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?

Instrument cables and speaker cables aren’t interchangeable as they are both designed for two different purposes.

Although they may look similar if you use one in place of the other it can creative an unpleasant interference sound or damage your equipment causing it to fail.

Both cables do share the same kind of connector —1/4″ phone plugs hence why confusion can arise when it comes to using one in place of the other. However an instrument cable is shielded to protect it from interference whereas a speaker cable is not.

Instrument cables are low power and high impedance they convey a weak unamplified signal from for example, your guitar to your amp, where it’s boosted up to a useable level. It has as small voltage and consists of a single small-diameter “positive” inner wire which runs through a shield conductor, which works as the ground connection. Alongside this is has various insulators, outer coating and it is small and lightweight making it good for cable flexibility.

Speaker cables are the opposite. They have high power and low impedance. They carry a strong signal from you amplifier to your speakers and they have a high voltage. They also have two wire conductors; these have a large diameter in order to allow greater signal flow from amp to speakers.

Using an instrument cable as a speaker cable may be ok at a low signal level however at a high signal level, the amp power attempts to flow through the instrument cable’s small conductor, resulting in distortion or cable connector failure and overheating.

If you use a speaker cable as an instrument cable the large conductors aren’t shielded as they normally carry strong, already-amplified signals, and any noise they pick up is inconsequential, making shielding unnecessary. If used as an instrument cable though, the unshielded conductors can pick up interference from fluorescent lighting, amp power supplies and various other external AC sources. This will leave your with low-frequency humming or buzzing.

So even if they look the same on the outside, the two types of cable are quite different and not interchangeable. Use a speaker cable to connect your guitar to your amp, and you will hear electrical interference noise. Use an instrument cable to plug your amp into your speaker cabinet and the small conductor may not be able to handle the power output and could cause major problems.

Although most manufacturers make it clear which one is which by labelling it clearly on the cable, there may be instances where you won’t be sure. If this is the case, simply unscrew an end of it. A speaker cable has two independent wires, one connected to the tip and one to the sleeve. These wires will likely be red and black or white and black. There should be no braided wires or a foil rap present let alone connected to any pin. If it’s an instrument cable, you will see one or two wires covered in some form of shielding. The shielding can be a braided wire mesh or foil wrap around the one or two wires. If the ¼-inch connector is a TRS end (this is a stereo end with a Tip, Ring, and Sleeve, like on head phones) then you know it is not a speaker cable.

It is always best to use the correct cables for the job. Shop our range of cables online.