What is a Headphone Jack? All You Need to Know

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What is a Headphone Jack

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Smartphone manufactures have been trying to kill the headphone jack since Apple ditched them in 2016 with iPhone 7. Others followed suit and now most flagship phones come without the 3.5mm jack.

But does that mean that headphone jacks are irrelevant?

No, in fact since the advent of Bluetooth headphones, people are realizing the true value of wired headphones. Sure they aren’t as convenient as Bluetooth, but a true audiophile cannot deny the superior audio quality that comes with wires.

Headphone jacks have been around for more than a hundred years and they aren’t going anywhere soon. We’ll discuss everything you need to know, so keep reading to find out.

History of Headphone Jacks

History of Headphone Jacks

Audio jacks date back to the early 19th century. Quarter inch audio jacks were used by switchboard operators in the 1800s. They were used to connect phone lines.

The first patent of the plug was known as the “jack-knife” connector and was made by C.E. Scribner in 1895. The name “jack” has stuck around since and has evolved into multiple variations.

This was a large jack and was popular until Sony released their Walkman in the 1970s. They were the first ever portable music listening device and featured the 3.5mm jack that is widely used today.

Wired Vs Bluetooth: Which One is Better?

Bluetooth quality doesn’t compare to good wired headphones plugged into a phone with a good quality DAC. Sounds get compressed heavily through Bluetooth so companies have been working on different codecs such as LDAC to ensure high quality audio stills gets through. Some arguments in favor of 3.5mm jacks include.

  • Their sound is always better compared to their wireless counterparts at the same price.
  • You’ll never run out of battery because they don’t need to be charged.
  • Bluetooth has connection and audio issues.
  • Even expensive wireless earbuds such as airpods last only a few years because of their lithium-ion batteries, which break down over time.

All the Downfalls of Bluetooth

  • There’s a lot of problems when it comes to Bluetooth, it can’t travel as efficiently through our body as it is mostly made up of water.
  • It relies on reflection to get its signals which works indoors with walls but you’ll experience cutouts when you use them outside.
  • A lot of people have experienced hissing or interference with their audio if someone near them is also using bluetooth.
  • Bluetooth saturation is also an issue if you’re using a lot of Bluetooth devices such as keyboards, mouse and then your headphone on top of that.

Now that you’re convinced of the relevance of wired headphones, let’s get into talking about headphone jacks and plugs.

Difference Between a Headphone Jack and Plug

Headphone jacks and plugs are used interchangeably but are different when you look at them by definition. The “headphone jack” by definition is actually the port or socket in your phone which you then insert your headphones into.

On the other hand, the plug is actually the part of your headphones that is then inserted into this socket. Colloquially, they are referred to as the “headphone jack”.

Jacks and plugs have assigned genders to make them easier to understand. The plug is known as the “male connector” while the jack is called the “female connector”.

Both the headphone jack and plug are complementary parts of an electrical circuit. They help transfer audio signals between your headphones and the audio source you’ve connected them to.

How Headphone Jacks and Plug Work?

How Headphone Jacks and Plug Work

Headphone plugs are inserted into headphone jacks which establish an electrical signal. This allows audio signals to flow from your device to your headphones. The pin of the plug is made up of metal and has conductors which help this flow of audio signals. They come in various finishes such as gold, nickel or brass.

The jack is hollow but is lined with conductors.

It is important to know that not all jacks and plugs are compatible.

The conductors from the plug and jack are complimentary so it is important they match.

They need to be the same and have the same number of conductors.

Wires inside your headphone’s cable match the conductors on their plug. So if your headphone plug has two conductors, it has two wires and three wires for three conductors and so on.

This also determines the number of conductors inside the jack. Conductors from your plug then line up with the conductors inside the jack and this then allows the audio signal to pass through.

What are Headphone Plug Conductors?

Headphone plug conductors are the meeting point between the plug and the jack. They help establish a connection between them and close the circuit.

When a plug is inserted into the jack, these conductors serve as contact points between them and allow audio signals to flow.

All Headphone plugs have conductors regardless of size. The number of conductors vary and they are paired with a jack that has the same number of conductors.

If you pair a jack and a plug that has a mismatched number of conductors then the circuit won’t close and the audio signal won’t be able to go through. If they don’t line up correctly, they can also interfere with certain functions and also trigger an electrical short.

How to Identify Headphone Plug Conductors?

You might have seen rings on your headphone plugs. They will help us identify the number of conductors your plug has. They are made up of a non-conductive material.

These are the three main headphone plug conductor names.

  1. Tip (T)
  2. Ring (R)
  3. Sleeve (S)
How to identify headphone plug conductors

The two conductors present in every plug are the sleeve (S) and the tip (T). A plug with just the sleeve and tip is known as a TS connector and has 2 conductors.

The addition of rings to the plug add new conductors to it.

Here are all the possible plug combinations.

  • TS connectors (Tip-Sleeve), or 2-conductor plugs
  • TRS connectors (Tip-Ring-Sleeve), or 3-conductor plugs
  • TRRS connectors (Tip-Ring- Ring-Sleeve), or 4-conductor plugs
  • TRRRS connectors (Tip-Ring- Ring- Ring-Sleeve), or 5-conductor plugs

Let’s talk about each one and see what they do.

1. TS Connectors

TS Connectors

TS only have two conductors with their tip and sleeve. The tip carries the audio signal while the sleeve acts as the return path and ground. They can only send one audio signal so they can only carry mono audio signals.

Mono audio is any sound that is recorded or played through only one audio channel.

If you’re recording audio for a guitar using a single microphone then it would count as a mono recording since you’re only using one channel.

TS connectors are frequently used with 6.35mm connectors which are used in instruments such as guitars.

These instruments do not require a long cable connection. The longer the cable, the more interference they’ll pick up so these cables are typically shorter.

2. TRS Connectors

TRS connectors

TRS has three conductors and is the most common type of headphone plug. This is what is popularly known as the 3.5mm plug.

Adding an extra conductor with the ring allows for balanced mono signals and unbalanced stereo signals. An unbalanced stereo signal is where the audio signal passes through to the headphones or any other device without manipulation.

One conductor is used as the return path and ground and the other two serve as left and right audio channels like those used in headphones.

TRS are commonly used with 3.5mm plugs but can also be found with 2.5mm jack and 6.35mm plugs.

3. TRRS Connectors

TRRS connectors

TRRS connectors come with four conductors and are also commonly found in headphones.

They serve as an addition to TRS signals that can handle unbalanced stereo signals and have an extra conductor reserved for the microphone.

However, they have two different formats when it comes to which conductor carries which typical signal.


  • OMTP – OMTP stands for Open Mobile Terminal Platform that sends the left and right channel audio signals through the tip and the ring. The conductor for the ground is on the sleeve, while the second ring handles the mic This format was followed by older phone Models such as Nokia, Motorola and Sony.

It is also used in some tablets, laptops and gaming consoles.

  • CTIA – CTIA stands for Cellular Telecommunications and Internet Association and is the newer standard. It transmits the left and right audio signal through the tip and first ring. The ground here is flipped compared to OMTP and handled by the second ring. The sleeve is left to handle the mic. This model is used on all newer smartphones and other electronic devices.

4. TRRRS Connectors

TRRRS Connectors

TRRRS connectors are the only ones that support balanced stereo signals.

A balanced audio has a ground wire along with two copies of the same signal, that are called hot (positive) and cold (negative) signals. Each audio channel gets two dedicated conductors which allows clear signals to transmit.

With them, the sleeve serves as the ground. The two rings above the sleeve carry hot and cold right channel audio signals. The remaining ring and the carry the hot and cold left audio signals.

These plugs are used in high-grade devices where clarity and great sound output is a must.

Why should you know about headphone jacks?

Looking at plugs should let you know which one supports a particular kind of signal or audio. It also gives you an idea of what kind of jack it will be compatible with. With TRS and TRRS, both being common in headphone plugs, you can take a look at them and find which one supports a microphone and which doesn’t.


If you are a seasoned audiophile, you already know that wired headphones offer better sound quality when compared to their Bluetooth counterparts that compress the audio you’re listening to. The high-res audio you are able to enjoy through your wired headphones can be credited to the plugs that help transmit audio signals seamlessly. The number of conductors also affects the audio so having a good understanding of them is crucial to know what you’re getting.

Using faulty or mismatched plugs isn’t ideal. It will lead to bad sound quality and also potentially damage both devices. If you’re a normal user then you can use either TRS or TRRS connectors with your 3.5 mm headphone jacks.

Hopefully this article gave you a clear understanding of different types of headphone plugs and which one should be using.