Have you ever wondered why one cable makes your amp hum all the time while others don’t? How about when to get about unbalanced and balanced cables — and what that means exactly? Or, if those $80 boutique cable your gearhead friend always talks about really worth it?
If so, we’re here to help. Our Cable 101 guide gives you all the basics about instrument and speaker cables. Knowing this helps you choose the ones that give you best sound and avoid ruining your gear.
At the least, you’ll never stare at a wall of cables in confusion again.
What’s in a cable?
Let’s start with what exactly is in a cable. Knowing what goes into them will help you understand how some work differently than others.
The real guts of a cable are the conductors. This is the copper wiring at the very center of the cable. The exact wiring depends on a few things: Whether it’s balanced or unbalanced, or made for an instrument or speaker. We’ll get into those differences a little later.
In any case, the conductors transmit the signal. This includes the electrical current, voltage and sound. It travels from the source, such as a guitar, microphone or turntable, to the receiving device. That device could be an amplifier, PA system, speakers or mixer.
Next to the conductor wires is a ground wire. This blocks interference, or outside noise, from entering the conductor. Interference give you hums, buzzes, feedback or other unwanted sounds.
After that, insulation and filler material keeps everything in place. They also help make the cable flexible enough to be wrapped or bent without the wires getting damaged.
Speaker cable versus instrument cables
On the outside, speaker cables and instrument cables look the same. Often, the only way you can tell is the difference is if they’re marked by the manufacturer. Therefore, it’s tempting to mix and match them. But, what’s going on inside each is quite different. Using the wrong cable can cause unwanted noise or damage to your equipment.
The difference has to do with impedance. For audio cables, that means how much resistance there is to signal in a cable. An instrument cable has a thinner copper conductor wire than speaker cable wire. This means it can carry less signal, and therefore has a higher impedance, than a speaker cable.
Instrument cables are made like this because the signal is weaker than the signal coming from an amp, PA or mixing board. It doesn’t need a heavy-duty wire with less impedance to handle it.
However, outside interference can affect that weak signal. Currents from nearby electronics can be picked up by the cable. This causes hum, buzzing, feedback or even cross-talk, which is sounds picked up from another nearby cable.
To prevent this, instrument cables, or shielded cables, have a braided copper shield inside them. The shield is wrapped around the wiring to further protect the wire from those outside interferences.
A speaker cable has a conductor wire that’s much thicker than an instrument cable wire. This way, it can carry the much more powerful signal from to the speakers. It has less impedance than an instrument cable.
Speaker cables are unshielded because the signal is much stronger. Outside sources can’t interfere with it.
Since they’re designed differently, swapping instrument and speaker cables causes problems. Their impedances are different, and the receiving devices are expecting the correct levels of impedance.
Using a speaker cable for an instrument will result in a lot of extra noise coming through the amp. This is because the cable is designed to carry a more powerful current than an instrument provides. All that outside interference seeps in along with the weaker current.
The problem is much worse if you use an instrument cable for a speaker. Instrument cables aren’t designed to handle the heavy signal load going to a speaker. The wire carries as much as it can, but the excess current causes problems.
In some cases, the actual cable will rupture as the powerful speaker current is transferred to the rest of the instrument cable in the form of heat. Or, if the pressure is too much for the cable to handle, your amp gets damaged when the current gets backed up. Either way, however, you’ll get a weaker sound from your speakers because your cable is not carrying all the current it’s supposed to.
Balanced versus unbalanced cables
Another difference when it comes to cables is balanced versus unbalanced cables. In a nutshell, balanced cables produce less unwanted noise than unbalanced ones. This is thanks to an extra wire inside them. As a result, they’re more expensive than unbalanced cables and require the right equipment to work properly.
An unbalanced cable has two wires. One sends the signal while the other is the ground, which gets rid of excess current that can produce unwanted noises. However, it also acts as an antenna, attracting other noises.
For this reason, unbalanced wires shouldn’t run more than 20 feet. Shorter cables just aren’t long enough to pick up enough interference to create noise. When the cable is longer than that, enough hum can build up to become audible.
That’s where balanced cables come in. They also have a ground that eliminates excess current, but also attracts outside noise. The difference is a third wire that sends the same audio signal but with the signal’s polarity reversed.
When you flip a signal’s polarity, you get its positive or negative counterpart. The original signal and the single with the reversed polarity cancel each other out.
Think of it as adding +20 and -20, or +45 and -45 in simple math. When you add the same positive and negative integer, you get zero.
When these two signals get to where they’re going, the device that receives it flips the signal on the negative cable to positive. Now, the signals are back in phase, both with positive polarity. The sound they’ve been carrying will register.
Of course, the cable picked up noise along the way. However, that noise registers with a positive polarity on both wires. When the signal on the negative wire gets flipped, it becomes positive. But, the noise that got picked up started as positive. Reversing the polarity makes it negative, and so it cancels out its positive counterpart on the other wire.
So, why bother with unbalanced cables at all? Well, for starters there’s the cost. That extra wire in the balanced cables hikes up its price.
Next, you need equipment that can pick up a balanced signal. Otherwise, the reversed-polarity signal gets thrown away and you just end up with the noise anyway. A guitar amp won’t reverse the polarity, for instance, so there’s no point in using a balanced cable.
Fortunately, not every situation requires a balanced cable. Most instruments, like electric guitars and keyboards, produce enough signal to drown out any noise. That’s why it’s more important for microphone cables: they don’t send as strong a signal as an instrument.
And, you can take steps to reduce any noise that does make it through. Try plugging your amp into its own outlet, for instance, rather than a power strip with other items in it. Keep the cable away from other electronics — neon bar signs at a bar or club are common culprits. And, find a better place than the top of an amp for your cell phone.
Different terminal ends
Looking at the ends of a cable tells you what kind of cable it is and whether it’s balanced or unbalanced. Some are obviously very different, like a three-pronged terminal end or a tip. Others are more subtle. Here’s a quick rundown on the different terminal ends and what they mean.
External Line Return, or XLR, cables are always balanced. They’re often used for microphones or speakers. One end has three prongs, one for each wire inside the cable. The other end has three corresponding holes. They’re made like that to snap in and not come loose.
Tip-Ring-Sleeve, or TRS, cables have ¼ -inch or ⅛-inch tips that look like the ones on your earbuds. The tip has two rings wrapped around it, one for each conductor wire inside it. These work as either as stereo or mono, or balanced or unbalanced, depending on the system you’re using.
Tip-Ring-Ring-Sleeve, or TRRS, cables, look and act similar to TRS. The difference is they’re in stereo and have three rings: One for the left and right channel each, and then a third for a microphone input.
Tip-Sleeve, or TS, cables also look like the TRS cables but only have one ring. TS cables also come in both ¼-inch and ⅛ -inch tips. They’re mono and unbalanced, so they should be kept shorter to avoid picking up noise.
Finally, RCA cables are named after the company that created them, Radio Company of America. They usually come in pairs often color-coded red and white or yellow and white. Each tip has one prong with a metal ring around out. When they are in pairs to transmit stereo sound, each wire carries a different channel of the stereo signal.
These are best for wiring stereo systems or turntables to DJ mixers. Both wires have has a conductor and a ground, but are unbalanced.
In the digital realm, there are MIDI and USB cables. These don’t transmit sound like analog cables. Instead, they send digital information to and from digital devices.
MIDI, short for Musical Instrument Digital Interface, cables resemble XLR’s. Instead of three prongs or holes, however, they have five prongs or holes on either end, arranged in a ring. A MIDI cable sends performance data from a digital instrument.
For example, when using a MIDI keyboard, the MIDI cable send what note you played, how hard or soft you played it, what sound you’re using, etc.
USB cables have flat terminal ends and often plug into computers. They’re used in many applications besides music and just send plain computer data.
How to choose cables
Of course, all these different options means more choices to make when it’s time to buy a cable.
First, consider of course whether you need an instrument or speaker cable. Next, consider length. If you need to be more than 20 feet from your guitar, for instance, you’ll want to avoid sending an unbalanced signal to the amp.
In this case, consider a Direct In, or DI box and second, shorter cable. This way, you can send a balanced signal to the box. The DI box reverses the polarity and sends the unbalanced signal along the shorter cable to the amp.
After that, make sure you know which connections you need. Does your PA or mixer take XLR or TS and TRS cables? Some take both, or mostly XLR with a few extra ports for TRS cables. Depending on your setup, you may need cables with mixed terminal ends: XLR on one end and TRS on the other, for instance.
From there, you have a huge variety of cables to choose from. Prices literally range from $10 to $100 or more. The more expensive ones have features such as gold terminal ends, solid versus wound wiring or better copper mixtures.
There’s a fair amount of controversy in the audio world about whether or not the most expensive cables are worth it. Most audio tests show that the best cables do produce better-quality signals with less noise than cheaper cables. But, whether or not the average person can actually hear that difference is debated.
To help you decide what kind of cables you need, think about the situation where you’ll use them. For pro audio and recording, you may want to go for the high-end cables. You’re relying on them to create a document that will (hopefully) be heard over and over again on a variety of different speakers.
In a purely live situation, once you play the music it’s over. While you want to sound your best, people won’t be hearing that moment over and over. And, in live situations such as a clubs or bars, your gear is more likely to become worn or damaged. Therefore, you may consider a mid-range cable that gets the job done but doesn’t break the bank.
Or, consider if you just need cables for a practice room. In this case, an inexpensive cable that just doesn’t produce any extra noise is fine. The money you save can be put toward other gear.
How to care for cables
Now that you’ve done your research and shelled out your money, you’ll want to go as long as you can without having to do that again. That means knowing how to care for your cables.
For starters, keep them clean. A little gunk on the cable itself may not make a big difference. But, dirt and grime on the tip can give you a crackling sound or possibly cause a short. In particular, dirt can build up around the rings on TS and TRS cables, in the holes on the female end of an XLR or around the prong on the male end.
You can use rubbing alcohol on cloth to clean them. Just wait until they’re completely dry before using them. Also, clean the connectors on your amps, PA, mixers, pedals and any other gadget your cables use.
While you're using the cables, try not to step on them. Remember there are a few different wires at work inside a cable. Adding pressure can damage the wires and cause a short. For the same reason, don’t tie cables in knots or stretch them out. Any of these can damage the internal wires.
Finally, wrap your cables properly. The quickest, most common method is to wrap a cable from your hand down around your elbow and back up. However, it’s not the best way.
Instead, use the “Over Under” method. Hold the cable in front of you at its end. Your palm should be facing up and the tip of the cable is facing away from you. Make a loop with the wire by picking it up with your free hand and placing it over the end you’re holding. That’s the “over” part.
For the next loop, hold the cable with your palm facing up. As you make the next loop, turn your hand so your thumbs meet as you place the cable loop in your hand. The’s the “under.” Keep wrapping switching over and under methods until you’re done.