The guide categorizes TRS connectors based on two key criteria: the number of rings (TS, TRS, TRRS, TRRRS) and the connector size (2.5mm, 3.5mm, 4.4mm, 6.35mm). It provides detailed explanations of each connector type, including their pin assignments, common applications, and advantages. Whether you’re an audio enthusiast or a technician, this guide offers valuable insights into the world of TRS connectors.
Table of Contents
What is TRS Connectors?
TRS connector introduction
A TRS connector, short for Tip, Ring, and Sleeve, is a standardized electrical connector commonly used in audio equipment. It’s designed to transmit audio signals. While often referred to as a “phone jack,” the term TRS specifically denotes the three conductive contacts within the connector. Based on the number of rings, TRS connectors can be further classified as TS (Tip and Sleeve), TRS (Tip, Ring, and Sleeve), TRRS (Tip, Ring, Ring, and Sleeve), and TRRRS (Tip, Ring, Ring, Ring, and Sleeve). In the audio world, the most common sizes for TRS connectors are 2.5mm, 3.5mm, 4.4mm, and 6.35mm.
Applications of TRS plugs
- Headphones: Most headphones use a 3.5mm TRS plug.
- Microphones: Dynamic microphones usually use TS plugs, while condenser microphones may use TRS or TRRS plugs.
- Audio equipment: The input and output interfaces of audio equipment often use TRS plugs.
- Musical instruments: Some musical instruments, such as guitars and bass, also use TRS plugs to connect to speakers or effects.
Classification By Number Of Rings
Based on the number of rings, TRS connectors can be further classified as TS (Tip and Sleeve), TRS (Tip, Ring, and Sleeve), TRRS (Tip, Ring, Ring, and Sleeve), and TRRRS (Tip, Ring, Ring, Ring, and Sleeve).
TS Connector (3.5mm)
A TS connector consists of a tip and a sleeve, as shown in Figure 1-1. Typically, the tip is positive and the sleeve is negative. TS connectors are commonly used as microphone inputs and for replaceable cables on some headphones. Many popular headphone brands such as Sennheiser, Beyerdynamic, Audio-Technica, and HIFIMAN use TS connectors that are often interchangeable.
Figure 1-1: TS (3.5MM) Plug
TRS Connector (3.5mm, three-conductor)
A TRS (3.5mm) connector consists of a tip, a ring, and a sleeve, as shown in Figure 1-2. Common configurations include solder-joint and solder-pad types. In audio applications, the tip is usually the left channel (L), the ring is the right channel (R), and the sleeve is the ground (GND). This is the most widely used audio connector, found in computers, smartphones, MP3 players, and more.
Figure 1-2: Two commonly defined internal welding forms of TRS (3.5MM) plugs on headphone cables
The combination of two TRS plugs is also used to build balanced outputs and for use in some headphone transmission ends. Figures 1-3 show several commonly used application methods and wiring definitions. It should be noted that when used as a balanced interface, RS can be mistakenly short-circuited in Sony devices and used as a TS plug, but it must not be short-circuited in Musiland devices, otherwise it will cause the device to freeze and restart and cannot be used. If you want to achieve Beyerdynamic and Sony’s universal connection on the headphone end, just short-circuit R and S and use the TRS plug as a TS plug to achieve it.
Figure 1-3: Four common wiring definitions of TRS (3.5mn) plugs on headphones
Figure 1-4 shows a unique pin assignment used by the QUAD ERA-1 headphone.
Figure 1-4: QUAD ERA-1 headphone terminal wiring definition
TRRS Connector (3.5mm, four-conductor)
A TRRS (3.5mm) connector consists of a tip, two rings, and a sleeve, typically in a solder-joint configuration. Common applications include:
1. Headsets With Microphones
As shown in Figure 1-5, TRRS connectors are commonly used in headsets that combine both headphone and microphone functionality. There are two primary standards for pin assignments:
Earlier Apple devices had regional differences, with Chinese models using OMTP and international models using CTIA. However, later models incorporated chips that can automatically detect and adapt to either standard.
Figure 1-5: TRRS (3.5MM) connector two wiring definitions
2. Balanced Headphone Connections
As illustrated in Figure 1-6, TRRS connectors can also be used for balanced headphone connections, especially in Japanese-made headphones like Sony 1A, Audio-Technica, and Denon MM400. These configurations often require specific pin assignments and may have unique features like elliptical shrouds to prevent misalignment.
Figure 1-6: Denon MW400 headphone wiring definition and size considerations
3. Balanced Plug For Player
Figure 1-7 demonstrates various pin assignments for balanced player connections, including standard 3.5mm balanced and 3.5mm Pro balanced configurations. It also provides guidelines for common balanced headphone connections using TRRS connectors.
Figure 1-7: Wiring definitions for TRRS (3.5MM) plugs in three balanced modes
Application of TRS, TRRS plugs (three-level, four-level 3.5mm plugs) in coaxial transmission
Figure 1-8 shows several commonly used TRS plugs and TRRS plugs as wiring definitions for coaxial transmission, mainly for FiiO coaxial (TRRS), Mojo coaxial (TRS), Musiland coaxial (TRRS) and Hifiman coaxial (TRS).
Figure 1-8: TRS and TRRS (3.5MM) plugs are used in four wiring definitions for coaxial transmission
TRS,TRRS Right Angle plug (three-level, four-level L-shaped 3.5mm plug)
In addition to the straight 3.5mm TRS plug, there is also a curved plug, mainly in the form of an L-shaped plug.
1. NEUTRIK's 3.5MM Right Angle Plug
NEUTRIK’s curved plug, mainly in two versions: gold-plated and silver-plated, is a very mature plug product. Figure 1-9 shows the internal structure and assembly steps of the NEUTRIK TRS plug 3.5mm right angle jack.
Figure 1-9: NEUTRIK shell assembly diagram (original image from the NEUTRIK official website)
2. Japanese oyaide plug
Represented by the Japanese Oyaide plug, the internal structure of most curved plugs on the market is basically the same as that of the Oyaide plug. However, due to the extra overlap and transition inside, the fidelity is theoretically not as high as that of the direct solder joint type of the straight plug, but the difference is also extremely subtle. However, in terms of convenience of use, it is more user-friendly.
TRRRS Plug
TRRRS plug, full name Tip-Ring-Ring-Ring-Sleeve, has more contacts than the common TRS plug. This plug is designed to meet more complex audio and data transmission needs, especially in some high-end audio devices and mobile devices.
Figure 1-10: TRRRS Plug Wiring Definition
Classified By TRS Plug Size
Beyond the number of conductors, connectors can also be distinguished by their diameter. In fact, diameter is often the sole dimension mentioned in casual conversation. Common connector sizes include 3.5mm, 2.5mm, 4.4mm, and 6.35mm.
Figure 2-1: 2.5mm,3.5mm,6.35mm plug
2.5MM Plug
The 2.5mm audio connector, a miniature version of the 3.5mm jack, is primarily designed for compact portable devices such as smartwatches and specialized MP3 players. While its smaller form factor suits space-constrained applications, particularly in mono TS configurations, this connector type offers limited compatibility compared to the widely-adopted 3.5mm standard. The relatively delicate construction also makes it more susceptible to wear and damage over time.
Figure 2-2: 2.2mm gold plated audio jack
3.5MM Plug
The 3.5mm audio jack has established itself as the most prevalent connector in consumer audio devices, offering remarkable versatility across various applications. Its balanced design strikes a perfect compromise between size and durability, while supporting multiple configurations from basic TS to advanced TRRS formats. This universal compatibility has led to its adoption in virtually all portable audio devices. Though repeated use may eventually affect connection quality, the connector’s compact form factor and extensive compatibility continue to make it the go-to choice for personal audio equipment.
Figure 2-3: gold plated 3.5mm audio jack
4.4MM Plug
In the field of high-end audio, the 4.4mm balanced plug is highly favored for its excellent performance. The balanced output effectively suppresses noise interference and improves the purity of sound quality. At the same time, the thick pin design enhances the stability of the connection and reduces the risk of poor contact. However, due to the relatively complex technology, relatively weak compatibility and high price, its popularity in the consumer market is limited.
Figure 2-4: gold plated 4.4mm audio jack
6.35MM Plug
The 6.35mm (1/4″) connector stands as the industry standard for professional audio equipment, widely adopted in guitars, bass guitars, microphones, and mixing consoles. Its robust design, featuring substantial pins and large contact areas, ensures exceptional durability and reliable connectivity.
Figure 2-5: gold plated 6.35mm audio jack
The 1/4“ audio connector’s superior construction makes it ideal for long-distance signal transmission with excellent interference rejection. While its size may limit portability, the 6.35mm format’s exceptional reliability and signal integrity make it indispensable in professional audio applications, from studio recording to live sound reinforcement.
Conclusion
As a classic audio interface, TRS connectors play an important role in audio equipment. With the continuous advancement of audio technology, TRS plugs are also constantly developing, and more new plug specifications and functions have emerged. I believe that in the near future, TRS plugs will appear in our lives in more diverse forms.
