Any noise or sound that we hear generates a form of mechanical energy released by an object’s vibrations as a sine wave of audible frequency propagates through the movements of the air, vibrating air particles as it moves around.
Some of that sound energy is used to create the very songs and music we so love to listen to, while under other circumstances, different frequencies of sound waves that resonate loudly at deafening levels require people such as helicopter pilots or heavy machine operators to wear special ear protection devices.
Sound waves, with the use of electromagnetic or electrostatic techniques, can be converted from mechanical into electrical energy.
Once transformed into an electrical force, it can then be directed to amplifiers, speakers, and any other such devices to be transformed again into sound waves that we can now listen to, control, and manipulate through various electronic equipment.
Getting the Sound to and from Your Electronic Equipment
Once the mechanical force of a sound wave hits the diaphragm of a basic microphone, it creates a vibration between a coil and a magnet within and near that coil, producing a small electrical current.
Once converted into an electrical signal at the microphone, it can then be routed through to various electronic equipment where it is manipulated into various effects, recorded and stored for reproduction, and amplified to be reproduced through your speakers.
While redirecting your signal from various sources to different input devices, you usually look to maintain the authenticity of your signal throughout the process without any loss in quality and without picking up any interference.
Since the signal is handled and transferred around through various wires, cables, and their connectors, this is where the type and quality of your cables becomes a critical issue, as it can have a significant impact on the quality of your output signal, as they offer the potential to pick up and add noise to your signal and corrupting it.
To forestall this, you have to choose the right type of cable from one of two classes they fall into—balanced or unbalanced.
An unbalanced cable consists of two wires within a cable, one being the signal wire and the other the ground wire, while a balanced cable has two signal wires and a ground wire.
On the balanced cable, each of the two wires transmits the same signal, although the two signals are reversed in polarity, thus canceling each other out.
Once the two signals get to the other end of the cable, the polarity of one signal is flipped, so they fall in phase in sync with each other.
The magic happens where the noise frequencies picked up by both signals cancel each other out when they get at the other end, leaving you with exactly the same sine wave as you started with.
What’s the Difference Between Analog and Digital Signals?
To put it in simple terms, the term analog is generally defined as “something that is similar to something else.”
As mentioned earlier, when a sound is generated, such as a 1000 Hertz sine wave tone, for example, the mechanical energy generated produces a continuous waveform going from a positive to a negative state and back again, 1000 times per second.
Once that physical state of a signal is then applied to a microphone, the microphone replicates the exact same waveform, but as an electrical or voltage signal, again going from negative to positive 1000 times per second—thus creating an electrical waveform “analogous” to its original mechanical sine wave.
If you’d amplify that analog electrical signal to drive a speaker, you would then hear the exact same tone coming out of the speaker. Video and audio cables were first designed to carry analog signals as a continuous electrical sine wave analogous to the information itself.
Digital signals, on the other hand, bears no resemblance at all to the original information signal, encoded instead or “sampled” and then turned into a series of numbers (“1” and “0” bits), according to industry standards.
On a CD, for instance, the sampling rate is at 44,000 samples per second, storing 44,000 numbers for every second of music that is recorded on it, which then needs to be converted into a voltage sine wave that will simulate the original sound wave.
The 5 Most Common Analog Cables and Their Connectors
Analog signals are much simpler to manipulate and transfer to different audio/video equipment than digital signals.
There are five common cable types, referred to as TRS, TS, XLR, RCA, and Banana plugs, that are usually used to transfer analog signals.
TRS and XLR are used for balanced connections, while TS, RCA, and Banana plugs provide unbalanced connections.
TRS is an abbreviation for “Tip Ring Sleeve,” describing the physical appearance of the connector’s stem with a pointed tip at the very end, a band or ring in the middle, and the sleeve right next to the protective cover.
The Tip of the connector provides a connection for the positive signal, the band for the negative signal, which is used to remove the noise, therefore making the cable balanced, and the sleeve which provides a connection for the ground.
But they can also be used for an alternate function, such as conveying a stereo signal, as for headphones for example, where the tip is connected to the left channel, the band to the right, and the sleeve is connected to the shield.
Used as a stereo connector, however, the TRS cable does not provide a balanced signal as it doesn’t carry the reversed (negative) signal to remove the noise from the line.
You can get them as 1/4-inch (6.5mm) for pro-audio applications or 1/8-inch (3.5mm) for consumer audio products (such as earbuds), and they also come as a 2.5mm mini-jack connector.
TS instrument cables resemble and come in the same sizes as the TRS but only have a tip and a sleeve for connections.
They cannot be used to balance your signal and are usually used for mono signals.
The 1/4-inch (6.5mm) is typically found on guitar cables, but they come in the same sizes as the TRS cables.
The tip of the connector is considered the “hot” or the carrier of the signal, while the sleeve is used as the ground or to connect the cable’s shield.
They are designed for signals at the instrument level but not at the line-level, usually found as 1/4-inch (6.5mm) jacks such as for guitars and other pro applications.
They are also used for consumer audio products as a 1/8-inch (3.5mm) alternative.
To avoid unwanted interference and noise being picked up, the TS unbalanced cables should not be any longer than 15 or 20 feet (4 to 6 meters).
Warning: TS speaker cables are commonly used to connect speakers to amplifiers and are therefore constructed to carry a much higher voltage with a larger “hot” wire and being less shielded, specifically designed to handle the higher voltage from the amplifier to the speaker.
Care must be taken not to mistakenly use TS instrument cables in place of TS speaker cables as you could damage your equipment with underrated cables—although your amp will seem to work initially, the high level of current going through the cable’s small gauge wire can eventually melt the cable’s insulation and cause a short that would damage your amplifier.
On the other hand, using unshielded TS speaker cables instead of instrument cables will cause all sorts of interference to be picked up from the surrounding electronics, such as hum and buzz from your amplifier’s transformer, PA speakers, lighting systems, and possibly cell phones to be reproduced within your signal through the speaker’s output sound.
XLR is a trademark name for the 3-pin connector in which there is a positive, a negative, and a ground connection.
The balanced XLR cables are commonly used for transmitting microphones or balanced line-level signals, connecting the microphones to the mixers, and connecting output signals to “powered” speakers.
XLR cables are locking connectors, preventing them from unplugging while in use.
They are also different from the other cables by having a male connector at one end and a female connector at the other end.
The XLR female connection is always at the sending end of the equipment (e.g., microphone) or the cable, while the receiving end of the cable is at the male connector.
Because they have a different connector at each end, several XLR cables can be hooked together to provide a longer cable when needed.
RCA cables have a standard plug consisting of a central pin surrounded by a compression ring segmented into four pressure tabs that, while squeezing down the tabs against the external metal sleeve of its mating receptacle, provide the connection with positive ground contact while the signal itself is transferred to the various components of the system through its center pin.
Often referred to as phono plugs, RCA connectors have been and are still used on most consumer audio-visual (A/V) equipment for many years.
The connectors on RCA cables are usually color-coded red for the right audio signal, white or black for the left signal, and yellow for the composite video signal, and they are very commonly found in the back (and sometimes made accessible from the front) of A/V systems.
You might also want to know that an orange color-coded RCA connector is sometimes used to carry S/PDIF formatted digital audio signals.
Banana Connectors are single wire electrical connectors used for joining wires to equipment.
The male banana plug is inserted into the female banana socket or banana jack securing a firm contact with good electrical conductivity through their concept of the male plug’s spring-loaded metal stem applying an outward pressure against the inside walls of the cylindrical female jack.
Banana connectors come in 4mm and 2mm stem diameter with the stem split lengthwise and slightly splayed, a stem made of 4 leaf springs arrayed at 90° from each other to provide a tight contact all around the female jack wall, and a stem with a single leaf spring on one side to push the pin against the side of its mating jack.
Besides their use to join audio wires on the back of many power amplifiers, these connector plugs are frequently used to terminate patch cords leading to electronic test equipment when used with shielded cables on multimeter probe leads.
Some connectors referred to as “stackable” banana connectors also have a 4mm hole into their back end to accept additional connectors.
Wire Gauge Sizes
The same as for any other electrical wires, audio cables are available in all wire gauge sizes.
It is recommended, for instance, to use a heavier gauge such as 14 or 12 gauge and even 10 gauge for speaker cables connected to high power applications, low-impedance speakers (4 or 6 ohms), or for longer cable runs exceeding 50 ft.
For shorter runs connected to 8 ohms speakers, 16 gauge wiring will usually be fine, as the wire’s internal resistance increases proportionally with its length adding to the speakers’ impedance—thicker wire presents less resistance to current flow.
So once you’ve determined the resistance of your wires for the length you’re using, the resistance of the wire should be less than 5% of the speaker’s rated impedance.
There are no set rules for this as there are too many variants to consider, but generally speaking, these few examples will give you a rough idea of how it works.
1. 18-gauge wire will usually be fine for speaker runs of less than 25-ft with power level systems of up to 50-Watts RMS.
2. 16 gauge wire:
- for normal speaker runs between 25 to 50-ft or...
- for shorter than 20-ft run for 75-100 Watts power level.
- for short lengths connecting to moderate power subwoofers of less than 225 Watts.
3. 14 gauge wire for 100-ft plus speaker runs or shorter lengths with higher power applications such as 2 or 4-ohms sub-woofers.
4. 12 gauge wires will handle a 20-ft run for 1950 Watts of power
5. 10 gauge wires connecting a run of up to 20-ft will handle 2000 Watts of power applications.
This is just to illustrate that with all the variants coming into play, this is not an exact science, so you shouldn’t hesitate to ask for assistance from a reputable source to figure out which cables would best serve your sound system.
Making Up Your Own Cables
In order to obtain and maintain a quality signal, you have to make certain that you have the right connectors, and cables in the proper lengths and sizes and with adequate shielding wherever required.
You’ll also have to ensure that every connection is properly soldered to each of its own respective connector terminals.
Note #1- You should also take into consideration that A/V wires are usually coded—the colored wires or the wires with a white stripe or dashed lines are your “positive” line, while the unmarked black is the “negative” lead.
Safety first. Starting on a project requiring tinning or soldering of wires requires the use of a soldering iron with a decent stand to hold the hot iron off any surfaces and objects risking damage.
You must keep the hot iron on the stand at all times except when using it to solder, at which time it’s held in your hand. Use a wire stripper to remove insulation from the cables and the wires—cutting and removing it with a sharp utility knife has the potential for the knife to slip and cut your hand or fingers.
Step 1- Tinning the wires
1.1- For sheathed cables with 2 or 3 wires inside a shield, remove the outer layer of the cable sheath about 3/4-in. back.
1.2- If there is a copper or aluminum shield present, pull it evenly all the way back over the remaining exterior sheath.
1.3- Pre-heat your soldering iron and wet the wiping sponge or a piece of rag and have it ready for wiping the tip of the iron, once heated to the right temperature.
1.4- Place the wire stripper so that the cutting edge is about 1/8-in from the base of the sheath for each of the inside wires and remove the insulation from each wire.
1.5- Twist the strands of wire together for each of the wires inside the cable so that none of the strands sticks out from the rest.
1.6- Dip the bare part of the skinned wires into a flux compound—this will promote the flow of the solder wherever there is flux plus remove and clean the wires from all corrosion.
1.7- Pick up your hot soldering iron and test its temperature by touching the solder on it—it should melt the solder when it’s hot enough. You can then apply flux to the tip and wipe it clean on the damp sponge.
1.8- With the tip cleaned, melt a small amount of the solder wire to coat the soldering tip. It will probably form a small drip at the end of the tip. If the drip is more than a tiny drop, shake some off, watching not to splash it onto yourself.
1.9- Touch one of the bare wires with the tip of the iron, and you’ll see the excess solder flowing on its own from the tip of the iron to be “absorbed” by the wire.
1.10- Repeat the process for every wire. All your wires are now tinned, and even if they’re not soldered to their connector, they will always remain neat and solid and never be frayed.
Step 2- Soldering wires to a connector terminal
2.1- Remove the connector’s cover to the terminal tabs and put your cable through it, so it is there to close up your connections when you’re finished—it’s easy to forget putting it on later and can be extremely annoying.
2.2- Secure the connector to a small vice or vice-grip, making sure it will remain still and not move while proceeding to solder the wires. Use a toothpick or a small screwdriver to grease all the connector’s terminals with flux.
2.3- Starting with the center terminal, insert the positive or central wire into the terminal’s small sleeve or slot (depending on the connector’s layout).
2.4- Melt a small bit of solder with your soldering iron to get a tiny drop on the tip.
2.5- Bring that droplet in contact with the wire and the terminal to heat the two of them up.
The melted solder must provide conductivity between the three surfaces to better heat up all the components to the same temperature—that is to say that if any part of the connection isn’t hot enough to melt the solder, you’ll end up with a “cold” joint and a blob of solder that will eventually deteriorate and beak down.
As long as the tiny bead of solder doesn’t blend into the other components but instead remains in a ball, you’ll know that the bond isn’t complete. The flux also plays a critical role in that process.
Important Note #2- A good and solid joint isn’t in the amount of solder applied but rather in how well it bonds with the metal parts—avoid and clean up “blobs” of solder.
2.6- Once your middle wire is properly soldered, follow the same process for all the other conductors, keeping the shield for last.
Step 3 - Soldering the Cable Shield to the Connector
3.1 - If you’re working with a cable that is shielded, you’ve already pulled it back over the cable in step 1.2.
With a woven shield, you now have to undo the strands down to where it is folded back, then bring all the wire strands together at the opposite side of the cable, where you can then bring them and twist them together tightly into a neat bare wire.
3.2 - Apply flux to the wire and proceed to tin it as described in steps 1.7 to 1.9.
3.3 - The sleeve’s terminal on the TRS, TS, and XLR connectors is also longer and thicker (required for strength) than the other terminals and has two tabs at its extremity made to be wrapped and clamped around the cable’s jacket to prevent any pulling on the cable from exerting any force against the terminals’ joints.
As the sleeve can be used for ground as well as shielding wire connection, be careful that the shield wire does not come into contact with any of the other connections, slip it into the terminal’s opening, and proceed to solder in place as described in steps 2.4 and 2.5.
3.4 - Once the sleeve connection is soldered, use your pliers to bend and wrap the tabs tightly onto the cable’s external jacket.
3.5 - You can now slide the cover down to the connector and screw it in place.—job completed!
If you’re working on setting up a home or a car sound system, you might enjoy some of our other audio articles, like Knowing the Difference Between Positive and Negative Speaker Wire and How to Test for Speaker Wire Polarity.