Sometimes, the tech that goes inside our everyday gadgets is far more complicated than we assume it to be. This is the case with headphone plugs.
You might have noticed how some headphones have two bands, while others have three or more. But why is this the case? Let's find out.
Why Are There Different Types of Headphone Plugs?
Some headphones are more expensive than others, so let's first understand what a headphone plug does. Its primary function is to transfer the analog signals from the audio source to the driver unit(s). Simply put, it carries the audio from your phone to your headphones.
There are different types of headphone plugs depending on the number of insulating bands they have. These bands determine the number of connections (the non-insulated metal parts) that the plug has and the type(s) of sound it can support, plus the tasks it can perform.
Balanced vs. Unbalanced Sound
To help you better understand how headphone sound works, we've broken down how balanced sound compares to unbalanced sound below.
Balanced Sound
Headphones are prone to multiple interferences related to frequency, hardware, software, and so on. These add noise to the audio waves and make the listening experience poor. Basically, there's a lot of unwanted hisses, hums, and similar noises that hinder your music.
Through a process called common-mode rejection (CMR), we prevent this noise. Here, the audio output produced after this process is what we call a "balanced sound" as it's less noisy and therefore more pleasing.
To produce a balanced sound, a headphone plug needs three connections:
In any circuitry, a ground signal acts as a reference line to measure other signals. During the transmission, both the positive and negative signals pick up noise. To cut out this noise, the negative signal is inverted yet again via the CMR process.
Due to this inversion, the noise from both the signals negate each other—resulting in the now identical positive and negative audio signals remaining audible. This is what we call a balanced sound. Alongside noise cancellation, it also provides a slight audio amplification.
Unbalanced Sound
Unbalanced sound does not make use of the CMR process and hence doesn't provide any noise cancellation whatsoever—resulting in disturbances when hearing music. Unbalanced sound needs only two connections: ground and either a positive or hot signal.
Stereo vs. Mono Sound
You've probably noticed how your stereo headphones are able to produce sounds that feel distinct—i.e. near or far, to your left or right. This effect is produced when two different audio signals are sent to your headphones; one for your right headphone speaker and another for your left.
Stereo headphones are designed to make you feel like you're in the moment. This is only possible if the speakers can add a sense of depth, perspective, and direction to your music.
Conversely, mono sound is produced when both headphones speakers receive the same audio signal. There is no sense of depth, direction, or instrument separation in your song. Mono sound requires only one connection or channel, but stereo requires two.
Listen to the stereo test below to check whether your headphones are stereo or mono.
The Anatomy of Headphone Plugs
When you look at your headphone’s plug, you see lines or bands dividing the metallic part into sections. Each section of the plug is called a conductor or pole. A conductor acts as the contact point to establish a connection, either for your mic or audio.
The number of conductors a plug has represents the number of connections it can support. Headphone plugs have a minimum of two conductors and a maximum of five. These conductors are of three types:
All headphone plugs have a tip and a sleeve, but the number of rings varies depending on the number of bands. It's important to note that the black (or any color) band is not the same as a ring. The band is made of an insulating material that separates two conductors. The ring is a cylindrical metal piece between two insulating bands.
The 4 Types of Headphone Plugs
Before we get into the types of plugs, let’s understand how they are named. Headphone plugs are named as per the number of conductors or the type of conductors they have. For instance, if a plug has three conductors, it's called a 3-conductor plug or a TRS (Tip Ring Sleeve) plug.
Depending on the number of conductors, there are four types of headphone plugs: TS, TRS, TRRS, and TRRRS. Let's take a look at each and how they function.
1. TS plug
A TS plug has two conductors: a tip and a sleeve. Since the TS plug can carry only two signals, it supports an unbalanced mono audio connection. These plugs are mostly used with microphones and instruments like guitars.
| Conductors | Unbalanced mono |
| Tip | Positive Signal |
| Sleeve | Ground |
2. TRS plug
This plug has three conductors: a tip, a ring, and a sleeve. You can find these in headphones, speaker connectors, and so on. It can support unbalanced mono, balanced mono, and unbalanced stereo sounds.
| Conductors | Unbalanced mono | Balanced mono | Unbalanced stereo |
| Tip | Positive signal | Positive signal | Left positive signal |
| Ring | Microphone | Negative signal | Right positive signal |
| Sleeve | Ground | Ground | Ground |
3. TRRS plug
A TRRS plug has four conductors: a tip, two rings, and a sleeve. Most modern consumer-grade headphones use this plug as it has one additional connection for a microphone. It supports unbalanced mono, balanced mono, and unbalanced stereo sounds.
| Conductors | Balanced mono | Unbalanced stereo |
| Tip | Positive signal | Left positive signal |
| Ring | Negative signal | Right positive signal |
| Ring | Ground | Ground |
| Sleeve | Microphone | Microphone |
4. TRRRS plug
A TRRRS plug has five conductors: a tip, three rings, and a sleeve. It supports both mono and stereo in balanced and unbalanced versions. High-end balanced stereo headphones use these plugs.
| Conductors | Balanced stereo |
| Tip | Left positive signal |
| Ring | Left negative signal |
| Ring | Right positive signal |
| Ring | Right negative signal |
| Sleeve | Ground |
Headphone Plugs Affect Your Music
If you are an audiophile, you know that wired headphones offer a better sound quality than wireless. One of the reasons for that is the plug of your headphones. The number of bands of a headphone plug directly affects your audio.
Using a faulty or mismatched plug with your device can make your audio sound muted, noisy or silent. If you are planning to upgrade your headphones, don’t forget to check the plug before buying.
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