You will never look at the headphone jack and plug the same way again.
Headphone jack is dead!
Apple has killed the headphone jack.
Sounds familiar? Ever since Apple removed the headphone jack from the iPhone 7 in favor of a lightning port, other smartphone companies have quickly followed suit with the removal of the once omnipresent port.
“I am Jack’s complete lack of surprise.”
There are still a few major companies like LG and Samsung who choose to release their flagships with the headphone jack, but I suspect that could change with the upcoming trend of true wireless headphones.
The truth is that most mainstream consumers don’t care for the headphones jack. Good riddance, they say.
So, why should you care then?
- Do you want to enjoy audiophile headphones that only have a wired connection?
- Are you looking to buy an amplifier for your headphones?
- Are you looking to buy and upgrade your audio cable?
- Do you want to try balanced audio?
If you answered yes to any of the above questions, this guide is for you.
By the end of the guide, you will be comfortable with terms like:
- 3-pole mini
- Stereo mini
- 3.5mm single-ended (or unbalanced) cable
- 2.5mm balanced cable
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.
From Amazon. Male Connector (L) Female Connector (R)
Unfortunately, the audio industry has not unified in the way the electrical and mechanical trades have to describe the different gender of connectors. You will often find the word “plug” used to describe the male connectors while “jack” used to describe the female connectors.
The origin of the term “jack” can be traced 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.
In the early development days, there were many different jack 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 rounded tip from frying the circuit when inserted into incompatible equipment. A pointed tip jack will prevent a rounded tip plug from being inserted fully, hence solving the problem.
Regardless of the plug size, all headphone plugs have conductors. Conductors are the contact points of the plugs that close the circuit.
A headphone plug has a minimum of 2 conductors and commonly up to 5.
If it has 3 conductors, it may be called a 3 conductor plug. Some manufacturer uses pole to replace conductor. Hence, it can also be called a 3 pole plug.
Each conductor has a specific name:
- Tip (T)
- Ring (R)
- Sleeve (S)
All plugs have at least a Tip and Sleeve. It is the number of Rings that differentiate them. If the plug only has one ring, it is a 3 conductor plug or a TRS connector. If it has two rings, it is a 4 conductor plug or a TRRS connector.
- 2 conductor, 2 pole, TS
- 3 conductor, 3 pole, TRS
- 4 conductor, 4 pole, TRRS
- 5 conductor, 5 pole, TRRRS
Depending on available conductors, manufacturers can choose to configure jack and plug in various ways. Both must be complementary to each other.
Available Connectors: Only the tip and sleeve connectors are available.
The ground acts as a reference point for the signal but it also picks up interference noises like an antenna. The longer the cable, the higher chance the more noise will be picked up.
Common Usage: You can find TS connectors mainly with guitars, instruments, and applications that do not require a long cable connection.
Available Connectors: Aside from the tip and sleeve, there is an additional ring connector with two insulating bands around it.
|Pin||Unbalanced Mono||Balanced Mono||Unbalanced Stereo|
|2||Optional (Mic etc)||Signal - (Cold)||Right Audio Channel|
|3||Signal||Signal + (Hot)||Left Audio Channel|
As seen in the “Unbalanced Mono” column above, the engineer can choose to make use of the additional conductor to carry a microphone signal instead. In this case, where the audio is unbalanced, we may also sometimes refer to this as a single-ended plug.
Common Usage: Most common form of jack connectors. You see these on the end of most stock headphone cables.
Available Connectors: With a 4 conductor plug, we have two additional rings with three insulating bands.
|3||Right Audio Channel|
|4||Left Audio Channel|
Common Usage: It is the most commonly adopted standard for modern smartphones and gaming consoles where the cable supports a microphone and stereo audio connection at the same time.
Available Connectors: For a 5 conductor headphone plug, we have 3 ring connectors.
TRRRS connectors are used to support balanced stereo signal. You will find that XLR connectors (3 pin pairs, 4 pin, and 5 pin) are also a common choice for stereo balanced headphones. XLR connectors have been the standard balanced connector in the professional audio market for decades.
It is no surprise that when balanced headphone connections grew in popularity, the standard XLR became a go-to solution.
Sony did make a TRRRS headphone jack – 4.4mm Pentaconn connector.
Please be aware that the Pentaconn connectors are new and not adopted widely by the industry. You either have to get an adaptor to accommodate the 5 pole connector or purchase a compatible Sony amplifier.
If you are looking to make your own DIY cable with the 4.4mm Pentaconn connector, check out moon audio store.
If you are interested in the schematic of a headphones jack, you can hop on over here for a more detailed article.
When we describe the size of the headphone jack or plugs, we are referring to the diameter of the connector.
- 6.35mm Connector
This is the largest connector among the jacks. It is otherwise known as the ¼ inch connector.
|UGREEN Stereo Audio Adapter||6.35mm Male to 3.5mm Female||TRS|
|UGREEN Stereo Audio Cable||6.35mm to 3.5mm||TRS|
- 4.4mm Connector
|Yinyoo Upgrated 6 Cores Copper Stereo Earphone Cable||4.4mm to MMCX||TRRRS|
|FiiO 8-Stranded High-Purity Monocrystalline Silver-Plated Copper Cable||4.4mm to MMCX||TRRRS|
|Geekria Apollo Balanced Gold-Plated Adapter||4.4mm male to 3.5mm female||TRRRS|
- 3.5mm Connector
Known as the miniature size or mini for short. You can call it a ⅛ inch too.
|AmazonBasics 3.5mm Male to Male Stereo Audio Aux Cable||3.5mm to 3.5mm||TRS|
|Zeskit Aux Audio Cable||3.5mm to 3.5mm||TRRS|
|Nacodex Audio Cable||3.5mm to 2.5mm||TRS|
|Kingtop Combo Audio Adapter Cable||3.5mm male to 3.5mm female||TRRS|
- 2.5mm Connector
Known as the sub-miniature or sub-mini for short.
|NewFantasia Replacement Cable with Remote and Mic||2.5mm to 3.5mm||TRS|
|NewFantasia HiFi Cable Balanced Male||2.5mm to 2.5mm||TRRS|
A headphone plug:
- directly affects the audio signal it transmits.
- indirectly affects the overall quality of sound.
- tells us what the cable is capable or not capable of doing (mic, stereo support, etc).
Let us first understand two basic concepts with regards to the transmitted signal from the audio source to our headphones.
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).
Stereo signal simulates “natural” hearing by creating the impression of sound coming from different directions. This is accomplished by the separate audio channels producing sound in two different speakers (or stereo headphones). You can call this the “surround-sound” effect.
As for mono signal, the sound reproduced is intended to be heard from one position.
Balanced audio is all about 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 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 canceling of noise interference via a technique named Common Mode Rejection (CMR).
Any noise interference that hits the two balanced phases in the cable is imprinted equally on them. The receiving equipment (headphones in our case) only cares about the difference between the phases.
So, interference that adds equally to both phases creates no difference between them and is canceled out when they are recombined by the amplifier. This canceling process of noise while preserving the original sound is known as CMR.
This means that balanced cable can run longer than unbalanced cable and operate in noisier environments because it cancels any noise interference.
So when is audio unbalanced?
When the requirements to meet balanced audio are not met, the audio is considered unbalanced.
- The audio source is unable to produce a balanced output.
- The cable is not capable of carrying a balanced signal (TS, single-ended TRS connectors).
With the above two concepts, you should know that you can send 4 types of signal from the output (amplifier for example) via a cable to a pair of headphones.
- Unbalanced mono
- Balanced mono
- Unbalanced stereo
- Balanced stereo
Whether a signal can be fully supported or even supported at all depends on the number of conductors found on the plug.
|Output Signal||Jack Connector||Balanced Audio Connection|
It can be hard to digest if you are reading all this for the first time. The part where stereo uses two channels and balanced audio needing two copies of the same signal with reverse polarity tripped me up pretty good, too.
An easy way to understand is to first acknowledge that we need conductors to send and carry signals.
The more signals we need to send, the more conductors we need.
For example, if we want to send a balanced stereo signal, it needs to send
- one right channel (R+),
- one flipped right channel (R-),
- one left channel audio (L+),
- one flipped left channel audio (L-).
In total, it needs 4 signal wire and one ground wire which only a TRRRS connector can provide.
Thus, if a jack with an inadequate connector is used (like a TRS connector), the headphone doesn’t receive the complete set of signals to do the CMR. Hence, the whole audio connection becomes unbalanced.
Let’s see if we can put our new-found skill to good use.
Remember the “3 pole mini” term we mentioned right at the start of the article? What do you think it means?
Ans: 3.5mm TRS jack
Ans: 3.5mm TRS jack (Bonus Qns: why do we think is TRS and not TS?)
Ans: 3.5mm TRS jack (Bonus Qns: Is this a balanced cable?)
Ans: 2.5mm TRS jack 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?
Lastly, another practice question.
See if you can read the “Headphone Output” specifications of the Sony TA-ZH1ES and understand what they mean.
If you do, congratulations! You just leveled up your audiophile knowledge.