The different jack connector formats

The Jack connector format is one of the oldest and most widely used, particularly in the world of music. Introduced at the end of the 18th century for use in telephone exchanges, it has since evolved into several different formats. Historically a 6.35mm jack, today we also find 2.5mm jacks, 3.5mm jacks, 4.4mm jacks and even 5.23mm jacks. But that's not all: a jack connector can be mono, stereo, balanced or unbalanced. So how do you choose the right jack connector?

Mono, stereo, unbalanced, balanced: TS/TRS/TRRS/TRRRS standards

Today, all formats are available in mono, stereo, balanced and unbalanced versions. However, due to specific standards, balanced jacks are often in 4.4mm jack or 2.5mm jack format, while 6.35mm jack and 3.5mm jack formats are used for mono or unbalanced stereo.

To distinguish the different types of connection possible, we use the TS/TRS/TRRS/TRRRS standards. "T" for "Tip", "R" for "Ring" and "S" for "Sleeve". This designation simply determines the number of contacts on a jack connector, whether in 6.35mm, 4.4mm, 3.5mm or 2.5mm format.

TS standard: 2 contact points

The 2-contact jack is generally used to transmit a monophonic signal. There is one contact for the signal (Tip) and one for ground (Sleeve - GND).

TRS standard: 3 contact points

Jack connectors with 3 contact points can be used for a variety of purposes:

• Transmit stereo sound.  "Tip" for the left channel, "Ring" for the right channel and "Sleeve" for ground.
• Transmitting a balanced mono signal, such as an XLR modulation cable. Tip" for the hot point, "Ring" for the cold point and "Sleeve" for ground.

TRS jack connectors are the most widely used on the market today. They are also widely used in professional applications, such as the insert function on mixing consoles.

TRRS standard: 4 contact points

TRRS jack connectors are generally used to transmit stereo sound and add a function such as a microphone or video signal. However, there is no standard pin placement for this type of connector. So always check compatibility with your device before using this type of connection.

For headphones and earphones with microphones, there are two main standards: CTIA (The Wireless Association) and OMTP (Open Mobile Terminal Platform). The difference between these two standards lies in the location of the microphone contact (AUX) and ground (GND), as shown in the diagram below. The CTIA standard is still the most commonly used today.

TRRRS standard: 5 contact points

TRRRS connectors are mainly used to transmit balanced stereo signals. This is the Pentaconn standard for the 4.4mm jack. TRRRS is also often used on 2.5mm jacks for balanced connections. The connection is shown below:

• Tip: left channel (+)
• Ring: left channel (-)
• Ring: right channel (+)
• Ring : right channel (-)
• Sleeve : ground

The replacement of the 3.5mm jack connector with USB-C on smartphones

Recently, many devices, such as the latest generation of smartphones, have tended to do away with their jack output in order to reduce their thickness. This has led to the emergence of earphones with USB-C connectors for transmitting audio signals.
The main question on most users' minds is: how am I going to listen to music and charge my phone at the same time? In the end, the answer is quite simple. All you need is a Y adapter and you're ready to go!
So what are the advantages of USB-C? There's the fact that DAC chips, DSPs and amplifiers will now be positioned on the side of headphone and earphone manufacturers. This means we'll have to worry more about buying headphones that we can make last over time, while still being able to change smartphones without affecting listening quality.
USB-C audio is promoted by Intel, which is nonetheless aware of the obstacles encountered in the 3.5mm jack/USB-C transition. That's why the company is even considering enabling analog transmission via USB-C for a smoother transition phase before going "all digital". However, as far as Hi-Fi equipment is concerned, this type of connection is still far from being replaced.