You’ll never look at the headphone jack and plug it in the same way again.
the headphone jack is dead!
Reading: The headphone jack
apple removed the headphone jack.
sound familiar? Ever since Apple removed the iPhone 7’s headphone jack in favor of a Lightning port, other smartphone companies have quickly followed suit with the removal of the once-ubiquitous port.
“I’m jack’s complete lack of surprise.”
There are still some major companies like lg and samsung choosing to launch their flagships with the headphone jack, but I suspect that could change with the next trend of authentic wireless headphones.
The truth is that most consumers don’t care about the headphone jack. have a good trip, they say.
then why should you care then?
who is this guide for?
- Want to enjoy wired-only audiophile headphones?
- Want to buy an amplifier for your headphones?
- Want to buy and upgrade your audio cable?
- want to try balanced audio?
If you answered yes to any of the questions above, this guide is for you.
by the end of the guide, you’ll feel comfortable with terms like:
- 3-pole mini
- stereo mini
- 3.5mm single-ended (or unbalanced) cable
- balanced cable 2.5mm
difference between a headphone jack and a headphone jack
Do you see these sockets that the above Sony TA-ZH1ES have? Those are headphones jacks. It is where you insert the headphone plugs to receive audio signals.
The headphone jack is a family of electrical connectors that are typically used for analog audio signals. It is also known by other names like phone jack, audio jack, aux input, etc.
female and male connectors
from amazon. male connector (l) female connector (r)
Unfortunately, the audio industry has not been unified in how the electrical and mechanical trades have to describe the different genres of connectors. you’ll often find the word “plug” used to describe male connectors, while “jack” is used to describe female connectors.
evolution of the headphone jack
who is jack?
The origin of the term “jack” dates back to 1874 when c.e. scribner patented what he calls a “jack-knife” connector.
The earliest known jack was a ¼ inch (6.35mm) version and still has mainstream usages which we describe below.
rounded to pointed tip profile
In the early days of development, there were many different connector designs. the rounded tip design was particularly popular because it was compatible with different manufacturers. the rounded tip quickly gained traction as the de facto tip profile for audio equipment.
but with the rise of stereo audio, a different tip profile was needed to prevent the old round tip from frying the circuitry when inserted into incompatible equipment. a pointed tip plug will prevent a round tip plug from being inserted all the way, thus solving the problem.
anatomy of a headphone jack
regardless of plug size, all headphone jacks have conductors. the conductors are the contact points of the plugs that complete the circuit.
a headphone jack has a minimum of 2 conductors and typically up to 5.
If it has 3 conductors, it may be called a 3-conductor plug. some manufacturer uses a pole to replace the conductor. therefore, it can also be called a 3-pole plug.
each director has a specific name:
- tip (t)
- ring (r)
all plugs have at least one tip and one sleeve. it is the number of rings that differentiates them. if the plug only has a ring, it is a 3-conductor plug or a trs connector. if it has two rings, it’s a 4-conductor plug or a trrs connector.
headphone plug nomenclature:
- 2 conductors, 2 poles, trs
- 3 conductors, 3 poles, trs
- 4 conductors, 4 poles, trs
- 5 conductors , 5 poles, trrrs
different plug-in connector configurations
Depending on the drivers available, manufacturers may choose to configure jack and plug in various ways. both must be complementary to each other.
2-conductor plug (ts)
Available Connectors: Only Barb and Sleeve Connectors are available.
The ground acts as a reference point for the signal, but also picks up interfering noise like an antenna. the longer the cable, the greater the chance that more noise will be picked up.
common use: You may find ts connectors mostly with guitars, instruments, and applications that don’t require a long cable connection.
3 conductor connector (trs)
Available connectors: In addition to the tip and sleeve, there is an additional ring connector with two insulating bands around it.
as seen in the “unbalanced mono” column above, the engineer may choose to use the additional conductor to carry a microphone signal. in this case, where the audio is unbalanced, we can also sometimes refer to this as a single-ended plug.
common use: most common form of jack connectors. you see them on the end of most standard headphone cables.
4 conductor connector (trrs)
Available connectors: With a 4-conductor plug, we have two additional rings with three insulating strips.
Common Usage: This is the most commonly adopted standard for modern smartphones and game consoles where the cable supports a microphone and stereo audio connection at the same time.
5 conductor connector (trrrs)
Available connectors: For a 5-conductor headphone connector, we have 3-ring connectors.
the trrrs connectors are used to support a balanced stereo signal. You’ll find that XLR connectors (3-pin, 4-pin, and 5-pin pairs) are also a common choice for balanced stereo headphones. XLR connectors have been the standard balanced connector in the pro audio market for decades.
It’s no surprise that when balanced headphone connections grew in popularity, the xlr standard became a go-to solution.
Sony did make a TRRRS headphone jack – 4.4mm Pentaconn connector.
Please note that pentaconn connectors are new and have not been widely adopted by the industry. you must obtain an adapter to accommodate the 5-pole connector or purchase a compatible sony amplifier.
If you’re looking to make your own DIY cable using the 4.4mm pentaconn plug, visit the luna audio store.
scheme of a headphone jack and socket
If you are interested in the schematic of a headphones jack, you can hop on over here for a more detailed article.
different sizes of headphone jacks/plugs
When we describe the size of the headphone jack or plug, we mean the diameter of the jack.
- 6.35mm jack
This is the largest connector among the jacks. also known as the ¼-inch connector.
- 4.4mm jack
- 3.5mm jack
known as thumbnail size or mini for short. you can also call it ⅛ of an inch.
- 2.5mm jack
known as sub-thumbnail or sub-mini for short.
why is the headphone jack important?
one headphone jack:
- directly affects the audio signal it transmits.
- indirectly affects the overall sound quality.
- tells us what the cable is or is not capable of do (microphone, stereo support, etc.).
Let’s first understand two basic concepts regarding the signal transmitted from the audio source to our headphones.
mono vs. stereo signal
two types of signal can be transmitted from the audio source to the headphones
- monaural (mono)
- stereophonic (stereo)
a mono signal uses only 1 audio channel while a stereo signal uses two audio channels (left and right).
The stereo signal simulates “natural” hearing by creating the impression that sound is coming from different directions. this is achieved by separate audio channels producing sound on two different speakers (or stereo headphones). you can call this the “surround sound” effect.
As for the mono signal, the reproduced sound is meant to be heard from one position.
balanced vs unbalanced audio
Balanced audio consists of interconnecting audio equipment and transmitting signals in a “balanced” manner.
To do that, we need a combination of an audio source (amplifier) that can produce a balanced output and a cable that is capable of carrying that balanced output.
A balanced output has two signal phases (or a hot and cold signal) per channel. Each phase has an equal impedance relative to ground, hence the name balanced.
A balanced mono cable typically has at least three conductors (trs) to carry the signal to the headphones. a balanced stereo cable has at least five conductors (trrrs).
advantage of balanced audio
The advantage of balanced connections over unbalanced connections is the cancellation of noise interference through a technique called common mode rejection (cmr).
Any noise interference hitting the two balanced phases in the cable is equally impressed on them. the receiving equipment (headphones in our case) only cares about the difference between the phases.
then, the interference that adds equally to both phases does not create differences between them and is canceled when the amplifier recombines them. This noise cancellation process while preserving the original sound is known as cmr.
This means balanced cable can last longer than unbalanced cable and operate in noisier environments because it cancels out any noise interference.
so when is the audio unbalanced?
When the requirements to meet balanced audio are not met, the audio is considered unbalanced.
- the audio source cannot produce a balanced output.
- the cable cannot carry a balanced signal (ts, single ended trs connectors).
the plug is the key
With the two previous concepts, you should know that you can send 4 types of signal from the output (amplifier for example) through a cable to a pair of headphones.
- unbalanced mono
- balanced mono
- unbalanced stereo
- balanced stereo
Whether a signal is fully compatible or even compatible depends on how many conductors are in the plug.
is it confusing?
It can be hard to digest if you’re reading all of this for the first time. The part where stereo uses two channels and balanced audio which needs two copies of the same signal with reverse polarity also tripped me up pretty well.
An easy way to understand is to first recognize that we need conductors to send and transport signals.
the more signals we need to send, the more drivers we need.
for example, if we want to send a balanced stereo signal, we need to send
- a right channel (r+),
- an inverted right channel (r-),
- a left audio channel (l+),
- an inverted left audio channel (l-).
in total you need 4 signal wires and a ground wire which only a trrrs connector can provide.
thus, if a jack with the wrong connector (such as a trs connector) is used, the headset does not receive the full set of signals to do the cmr. therefore, the entire audio connection becomes unbalanced.
let’s practice our new skill
Let’s see if we can put our new ability to good use.
remember the term “mini 3 pole” we mentioned at the beginning of the article? what do you think it means?
answer: 3.5mm trs jack
answer: 3.5mm trs jack (additional questions: why do we think it’s trs and not ts?)
answer: 3.5mm trs jack (additional questions: is this a balanced cable?)
answer: 2.5mm trs connector that can carry balanced signals
Do you see that the FiiO Q5 had two outputs? One with a headphone logo, another with “BAL” sign. Do you understand what that means?
Finally, another practice question.
See if you can read the sony ta-zh1es “headphone output” specs and understand what they mean.
if you do, congratulations! you just leveled up your audiophile knowledge.