Perhaps you’re an audiophile wanting to get more out of your sound system. Or, you’re a beginner who wants to learn the fundamentals of headphone jack sizes.
Regardless of what stage you’re in, this guide was made to help you. By the end, you’ll get a clear understanding of how headphone jacks work and how you can use them to your advantage. Let’s begin!
What Are Headphone Jacks?
Headphone jacks are ports that are in a “fixed” position. They are used to plug in headphones, headsets, and earsets. The headphone jacks allow different devices to connect and play audio at a higher quality when in use.
History of Headphone Jacks
The origin of the word “Jack” started in 1874. The first known jacks were measured at 6.35mm (¼ inches) and still have mainstream uses today.
Originally, the jack was used for plugging and unplugging connections during manual calls. In the 20th century, the average jack size became smaller. At this time, the 3.5 mm (also called the mini size jack) was used. The 3.5 mm became more popular through the use of headsets on transistor radios.
During the 21st century, the 2.5mm jack (also called the sub-mini) was introduced. As the technology evolved, headphone jacks have been able to reach different functions. We’ll explain them in detail below.
Rounded Tip Profile
In its early days, there was a myriad of different jack designs. The rounded tip increased in popularity because it was compatible with different manufacturers. As a result, the rounded tip profile became the de-facto profile for sound equipment.
As stereo audio started to develop, a newer profile tip was needed; the previous design from burning the circuit. Pointed tip jacks were made to solve this problem, preventing the round tip plug from being fully inserted.
What Makes a Headphone Plug?
Multiple components make up a headphone plug. Here are some of them:
Every headphone plug has conductors. If it has 3 conductors, it’s considered a conductor plug. Some manufacturers call it a pole instead of a conductor.
How to Identify Conductors
There are three different components of a headphone conductor:
Each conductor has a sleeve and tip. The number of rings is what makes them different. If it has one ring, it is a TRS connector or a three-conductor plug. If the conductor has two rings, it is a TRRS connector or four-conductor plug.
Types of Conductors
2 Pole Connector
The TS connector has a straightforward connection. One part of the connector carries the audio signal, and the other works as a ground and return path. The ground is the reference point but picks up interference noises like antennas. The longer the wire cable, the higher the possibility noise will be picked up.
Common Usage: You can use TS connectors with instruments, guitars, and applications that don’t require a long connection.
TRS (3 conductors) Plug
With an added connector, you have additional possibilities to aid unbalanced audio signals and balanced mono signals. With the unbalanced mono signals, a sound engineer can use an additional conductor to carry microphone signals.
Common Usage: This is the most common jack connector. You’ll see this on entry-level headphone cables.
TRRS (4 conductors) Plug
The TRRS conductor follows the CTIA (Cellular Telecommunications and Internet Association) standards.
Common Usage: The TRRS conductor plug is used in most modern gaming consoles and smartphones. It works where the cable supports the stereo connection and microphone at the same time.
TRRRS (5 conductors) Plug
TRRRS conductors support balanced stereo signals. XLR connectors have been the standard connector in the professional sound industry for decades.
Common Usage: TRRRS conductors are used for sound recording studios. They have the highest amount of conductors, making it easier to use for professional audio equipment.
How Do Headphone Jacks Connect?
For a plug and a headphone jack to connect correctly, they must have the following attributes:
- Have a similar wiring schematic
- Same headphone jack size
It’s important to know that headphones are analog devices. Analog signals are AC voltages. The signals are carried through electricity through conductive wires. The wires in the cable are matched to the cable plug. The source jack has a conductor that delivers specific signals.
The goal is to make contact between the plug conductors and jack to let the audio signal flow. It flows from the cable source to the head jack based on the wiring schemes. In most scenarios, we cannot see the physical connection between a jack and a headphone plugin without removing the jack.
Types of Headphone Jacks
USB Connected Jacks
USB port jacks are usually found in gaming headsets. The line output and port are found in virtually every sound source. They are also used for laptops and PCs because the port is where the flash media information passes.
USB connected jacks are used for competitive eSports players, have additional buttons, and are well adjusted.
- Unlike traditional headphones, USB headphone jacks have a built-in amplifier, resulting in a clear and resonant sound.
- Some USB headphones that are connected with USB jacks don’t need a digital-to-analog converter. That’s because the headphones have their in-built chip with similar functionality.
There is one disadvantage with USB headphones: they consume a lot of power. The port flows at a current of 5 volts. Of course, this issue doesn’t occur if you connect the headset to your computer.
USB-C is used by the latest smartphone brands such as Samsung, Huawei, and Google. Although USB-C is different from jacks, it is essential to know the basics of USB-C audio. Without further ado, let’s provide a deeper explanation.
USB-C is a double-sided (24 pin) connector that’s larger than a micro USB-b connector. Micro-b connectors or Micro USB connectors are used for tablets and smartphones. USB-C became the more popular option, as it is seen in modern phones such as Google Pixel 3, Samsung Galaxy Note 10, and a Huawei P20 Pro.
If you’re looking for the 3.5 mm jack, the USB-C acts as a replacement. You can use the USB-C jack to connect your devices to headphones. The USB-C connector can be quite confusing because some devices don’t follow a universal standard. The mini-jack is an exception because it works once installed.
To play digital audio through your headphones, you’ll need an amp and a DAC (digital-to-audio converter). The amp is used to increase sound while the DAC changes the audio signal so your headphones can hear the original sound.
The mini-jack uses an amp and DAC to send signals to your headphones. On the other hand, USB-C has two different types: which further complicates things. You’ll have a Passive Adapter (without a DAC) and an Active Adapter (with DACs). Additionally, you’ll have two modes of audio output: phones with in-built DACs (delivers analog audio) and phones without in-built DACs (delivers digital audio).
If your phone doesn’t have an onboard DAC, the audio signal is sent via your device’s USB-C port. This means the conversion is done through the adapters or headphones instead of your phone.
Unfortunately, not all entry-level headphones have this feature. The issue with this is that the adapter/headphone must have its own DAC if not included. Another problem is when you use an Active headphone, the device needs to support the Audio Device Class and Audio Accessory Mode.
Audio Accessory mode allows a USB-C port to deliver analog sound through the connector and into something plugged in. However, the USB Audio Class 3.0 helps the USB support digital audio. It has additional features such as hot word detection, noise cancellation, and more.
If the USB 3.0 Audio doesn’t have support, its features won’t work correctly (i.e., noise-canceling).
Passive adapters rely on the DAC for conversion and an amp that’s in the device. This means the adapter or headphone’s job is to pass DAC and amp signals.
In addition, passive adapters without an in-built DAC can be used for devices that have analog audio outputs. Analog means it uses the DAC’s of a device to bring the signal to a headphone (i.e., the Huawei P20 Pro and Sony Xperia X32) that uses analog output.
If the adapter or headphone has a DAC and the phone has a DAC, the adapter will bypass the internal DAC and use the one located in the headphones. If you use a passive adapter with no DAC and a phone, it will work.
You’ll notice this is a real issue due to the compatibility problems you’ll face. This issue is due to a mixture of active/passive headphones and the manufacturer’s rush-in standards.
Headphone Jack Sizes
There is a multitude of headphone jack sizes that are suited for different audio applications. Here are the most common sizes:
The 2.5mm is known as the micro jack. It’s mainly used for video cameras and two-way radios. Previously, they were used for mobile devices, but they were unable to meet the manufacturer’s standards. That’s when the 3.5 mm jack was used for their devices.
If you’re looking for a small plug for your headphone, the 2.5mm is the best option. It’s called a 2.5mm jack because it has a 2.5mm diameter. You’ll find the 2.5mm for audio transmissions, but it’s rarely seen because manufacturers began using the mini-jack.
What’s the main difference between a 2.5mm and a 3.5 mm jack? Size. The 3.5 mm jack is 50% larger and is more commonly used.
What are 2.5mm Jacks Used For?
- 5mm jacks connect headsets to devices (video camera, landline phones, two-way radios, and cordless phones). Also, the 2.5mm jack has the same plug configuration as the 3.5 mm and 6.35mm jacks.
The 3.5mm jack is a common connector and is used for virtually all devices. This is the same plug that USB Type-C and Apple manufacturers replace. Repairing plugs is easy, but Type-C or lighting plugs are an exception.
Here are the main characteristics of a 3.5mm jack:
- The TS connector has two signal conductors (negative and positive).
- The TRS cable is used for accessories. It uses three pins: ground, left, right.
- The TRRS cable is designed for Nokias. It uses four pins: ground, microphone, left, and right.
- An alternative TRRS form in which the pins are designed for Sony, Samsung, iPhone, and HTC.
Again, check the rings to determine if a headphone jack is a stereo or mono—most of the time, it’s 3 or 4 rings. Remember, the stereo jack uses 2+ rings, so don’t get confused. Three rings are used to support stereo sound but don’t support microphones. This means you’ll only be able to listen to music but not take a call.
Four rings support both microphone and stereo usage. However, they aren’t compatible with a few audio devices. Mono mini-jacks do exist, but they are rarely used. Always check the rings first to ensure you’re buying the right one.
What Are the 3.5mm Jacks Used For?
While audio purists will believe that the ¼ inch is durable, you won’t notice any audio differences between them. The size is the most noticeable difference between the two, which makes 3.5mm jacks a standard choice for smartphones and tablets.
How they’re used:
- Cheaper and works immediately if you want to make calls
- The 3.5mm jack is a universal jack used for laptops, PCs, portable audio players, and smartphones
Audio Lightning Jack
Lightning jacks are used to create output sound without lowering quality. The Lightning Jack or connector transmits and produces a clearer sound than the 3.5mm jack, which can only communicate in 16-bit quality and has a compressed output sound.
Here are some advantages lightning jacks have over previous models:
- With lightning jacks, you can provide electric power to your device from a direct source.
- You can add additional features, such as fitness sensors and digital inputs.
- Increases chance of digital value exchange between the signal source and headphone device.
- Lightning jacks give you perfect sound reproduction without any compression or distortion within the in-built DAC.
6.3 mm Jack
The 6.3 mm jack is the first headphone jack, which was used for vintage audio equipment. In the past, this jack has been used with DVD players. Today, the 6.3 mm jack is used for electric guitars, musical instruments, etc.
Now, the 6.3 mm jack is rarely used. You’ll only see the 6.3 mm jack in metal detectors, older microphone models, and professional music equipment.
At its basic level, the 6.3 mm jack might either support stereo or mono sound. Mono (monophonic) sound is where you have only one audio. There is no left or right like stereos; you’ll hear your audio come from one source.
On the other hand, stereo sound reproduces sound in two audio channels. This results in a natural two-dimensional sound distribution. For instance, if there is a special sound effect on the left channel, you’ll hear this if the headphone jack supports a stereo output.
Look up the number of rings to determine if a 6.3 mm jack is mono or stereo. Mono jacks have two rings, which are also called tips and streams. The tips and sleeves have one black line that separates one conductor from another.
When are 6.3mm Jacks Used?
Here are some uses:
- The mono version is used for synth, keyboards, and guitars.
- The stereo version acts as a stereo cord (where the audio signal is split to the left and right channels).
- 3mm jacks are used to connect amplifiers for basses, guitars, and other audio equipment.
How Do Headphone Jacks Work?
The plug is the reason why audio sources can connect to the headphone jack. It is the audio plug that’s on the end of headphone wires that takes effect. After the plug is in the mobile phone socket, if the plug works, it will allow you to hear anything you want from your phone. Now let’s further explain how headphone jacks function.
Because of these different approaches, you can hear stereo and mono sounds with ease. Headphone jacks have three formations (TRRS, TRS, and TS). Mono means that you’ll hear one channel left and right. Stereo transmits audio on both channels, which gives you a more natural and vivid sound in two dimensions.
The Importance of Headphone Jacks
Knowing the anatomy of headphone jacks will help with installing audio equipment in your home. Since the TRS and TRS plugs comply with CTIA standards, you can distinguish between jack diameters and remain safe.
However, headphone plugs can indirectly or directly affect your sound quality. They let you know which headphones support a microphone connection and which ones don’t. That way, you can decide what devices you can connect by looking at the rings.
What is Audio?
Audio is defined as the representation of sound. Sound is represented through binary numbers (digital signals) or through electrical voltage (analog systems). A digital-to-audio converter converts the signals to create sound energy to receive audio in our headphones jacks.
Balanced vs. Unbalanced Audio
Balanced audio is a process of transmitting signals and audio equipment in a “balanced” manner. There needs to be an amplifier that produces the balanced output, and a cable is needed to carry the balanced output.
Balanced output uses two signals per channel. Both hot-and-cold signals have an impedance that’s relative to the ground. Hence why the name “balanced.” Balanced stereo cables use a TRRRS (five conductors) system. A balanced mono cable uses a TRS (3 conductors) system to deliver an audio signal to the headphones.
Why Use Balanced Audio?
Balanced audio has an advantage over unbalanced audio because of its ability to cancel noise. This occurs through a method called Common Mode Rejection (CMR). Any noise that reaches the balanced cables is imprinted on them.
CMR is the process of keeping the original sound while canceling noise. Interference that adds equally to both phases is canceled out when sent to the amplifier. This means that balanced audio can last longer than unbalanced audio and cancels sound interference so it can operate in a noisy environment.
What is Unbalanced Audio?
When certain requirements are not met, the audio is unbalanced
- The cable cannot make a balanced signal
- The audio source cannot create a balanced output
What Are Size Adapters?
Size adapters are used to take your current headphone plug and place them in a specific jack. The most common size adapters are:
- 35mm TRS
- 5mm TRS
- 5mm TRS
While these are the most common size adapters, there are hundreds more in the market. Get a size adapter to ensure that your headphones are connected to the right device.
What is Wiring Adapters?
Wiring adapters are used to improve the connection between jacks and headphones. For instance, if the headphone jack doesn’t have a TRS plug, you can use wiring adapters to hear the sound clearly.
What Other Devices Do Headphone Jacks Plug Into?
It is possible to connect your headphone jacks to other devices. Here are some of them:
The majority of modern speakers are designed for speaker-level signals and have a low impedance. This means they won’t work correctly when connected to headphone outputs.
However, there are mobile/handheld speakers that can connect to laptops, smartphones, etc.
Microphones are connected through headphone jacks that accept their audio signals. For instance, the TRRS headphone jacks could accept microphone jacks that connect through 3.5mm connectors.
This occurs when you connect a smartphone to your car’s auxiliary input. Most home amps have an aux input that accepts headphone signals.
To conclude, knowing the headphone jack sizes is important if you’re creating a home or outdoor studio. The jacks allow you to connect devices and enjoy clear-sounding audio.
Next time you plan on shopping, consider the headphone jack sizes to ensure you’re getting the best audio experience possible.