What are HIFI headphones and monitor headphones?

HiFi headset
Let's first understand what a HI-FI headset is: Hi-Fi is the abbreviation of High-Fidelity in English, literally translated as "high fidelity", and its definition is: a reproduced sound that is highly similar to the original sound.

So what kind of audio equipment's playback sound is Hi-Fi? So far, it is still difficult to draw definite conclusions. Professionals in the audio industry rely on various instruments and various means to detect various indicators to determine the level of Hi-Fi equipment, while audio enthusiasts often use their ears to determine whether the equipment meets the Hi-Fi in mind. . To judge the high-fidelity of the reproduced sound, not only high-performance equipment and software, but also a good listening environment are required. Therefore, how to correctly measure the Hi-Fi level of audio equipment, there is still a difference between objective testing and subjective evaluation.


Sound characteristics
1. The sound bottom is pure, without any unpleasant "hiss", "weng", "cock" sound.
2. The sense of balance is good, the sound is never too bright or too dark, the high, middle and low frequency energy is evenly distributed, and the fusion between frequency bands is natural and smooth, without abruptness and burrs
3. Good high-frequency extension, delicate and supple.
4. Deep dive at low frequency, clean and full, full of flexibility and strength, without any feeling of fatness or slowness.
5. Intermediate frequency distortion is very small, transparent and warm, human voice is kind and natural, thick, magnetic, not exaggerated and nasal.
6. Good resolution, rich details, and tiny signals can be replayed clearly.
7. Good sound field description ability, wide sound field, accurate and stable instrument positioning, enough information in the sound field, no feeling of hollowness.
8. There is no obvious dynamic compression, with a good sense of speed, no distortion or very little distortion at high volume.


Headphone classification
By type

There are mainly two categories of dynamic and electrostatic headphones.

According to purpose

Mainly home (Home), portable (Portable), monitor (Monitor), mixing (Mix), human head record (Binaural　Recording)

According to the degree of openness

Mainly open, semi-open, closed (closed).

(1) Open style: Generally speaking, it has a natural sense of hearing and is comfortable to wear. The HIFI earphones that are commonly used for home appreciation can leak the sound, and vice versa, the outside sound can also be heard. The earphones have less pressure on the ears.

(2) Semi-open type: There are no strict regulations, and the sound can only enter but not exit, or only exit but not enter, and make corresponding adjustments according to needs.

(3) Closed type: The earmuffs put a lot of pressure on the ears to prevent the sound from entering and exiting, and the sound is correctly positioned and clear. This is more common in the professional monitoring field. However, this type of earphone has a disadvantage of serious bass staining. W100 is an obvious one. example.

Sound quality evaluation
Range: the range between the highest and lowest notes that an instrument or human voice can reach

Tone: also known as timbre, one of the basic properties of sound, such as erhu and pipa are different timbres

Sound dyeing: The opposite of the natural neutrality of music, that is, the sound has some characteristics that the program does not have. For example, the kind of sound obtained by speaking into a jar is a typical sound dyeing. Sound coloration indicates that some components are added (or reduced) in the reproduced signal, which is obviously a kind of distortion.

Distortion: The output of the device cannot fully reproduce its input, resulting in distortion of the waveform or increase or decrease of signal components.

Dynamic: Allow to record the ratio of the largest information to the smallest information.

Transient response: the ability of the equipment to follow the sudden signal in music. The equipment with good transient response should respond immediately as soon as the signal comes, and stop abruptly when the signal stops. (Typical musical instrument: piano)

Signal-to-noise ratio: also known as signal-to-noise ratio, the contrast between the useful components of the signal and the strength of the noise, often expressed in decibels. The higher the signal-to-noise ratio of the device, the less noise it produces.

Air: An acoustic term used to express the openness of the treble, or the space between the instruments in the sound field. At this time, the high frequency response can be extended to 15kHz-20kHz. Antonyms include "dull" and "thick".

Low frequency extension: Refers to the lowest frequency that audio equipment can reproduce. It is a scale used to determine how deep a sound system or speakers can dive when reproducing bass. For example, the low frequency of a small subwoofer can extend to 40Hz, while a large subwoofer can dive to 16Hz.

Bright: refers to highlight the high frequency range of 4kHz-8kHz, when the harmonics are relatively stronger than the fundamental wave. Brightness itself is not a problem. Live concerts have bright sounds. The problem is that they are bright enough to be well controlled. Too bright (or even howling) is annoying.


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Features
First, the frequency response should be wide enough and fast to ensure that the signal distortion in the frequency band that needs to be monitored is as small as possible, and it has the ability to clearly reflect the sound characteristics of the monitored object;

The second is sturdy and durable, easy to repair and maintain.

From the point of view of usage, monitoring headphones are divided into studio monitoring, broadcast monitoring, sound reinforcement monitoring, special (special) monitoring, etc., among which recording studio monitoring is divided into simultaneous (on-site return) monitoring and downmix monitoring.

The main purpose
Because the monitor headset has the function of restoring the original sound, it can better help the wearer to distinguish high and low sounds, accompaniment sounds, etc., suitable for singers and announcers to wear to correct their own voice to a more professional level.

On-site return
On-site return is generally to send the accompaniment music, beat or musical melody to the recording singer, performer, etc., just like singing karaoke and playing music without the original singer. The purpose is to let each singer and performer hear the rhythm and music clearly and coordinate the recording. Therefore, the requirements for this type of headphones are not high, but the prerequisite is that the headphones should be closed or semi-closed, because the sensitivity of the condenser microphones used for recording is very high, and some subtle details will be picked up, including headphones. The sound leaking from inside.

Of course, most of the live monitor headphones used in the recording studios of some size are still better, such as AKG K240M, K141, SENNHEISER HD250, HD270, BEYERDYNAMIC DT770PRO, DT100, SONY MDR-7506, etc., because good headphones are easier to make The singer is committed.

Downmix monitoring
Downmix monitoring is the most demanding earphone sound. It requires to be able to restore all sounds as realistically as possible, with as little sound coloration as possible and close to the live sound location. This is also the effect pursued by fever headphones, so this type of headset can be used as a fever Use headphones. Such as AKG K240DF, BEYERDYNAMIC DT880PRO (now model is DT880), SENNHEISER HD250, etc.

Broadcast monitoring
Broadcast monitoring is mainly required for real-time monitoring by the broadcaster and guests, as well as directors and production directors when the radio station is broadcasting programs. It is said to be real-time, but in fact there is a delay, because many radio stations use the form of live broadcast. In order to prevent accidents and some conversations that are not suitable for public broadcast (such as swearing, excessive remarks and sudden reactionary remarks, etc.), it is necessary The broadcast is delayed by a few seconds, which is operated by a special broadcast delayer. This kind of broadcast requires the monitor headphones to have extremely high speech intelligibility and intelligibility, and can filter the noise that affects the intelligibility and intelligibility in speech, such as low-frequency interference, telephone noise, etc. Of course, there will be specially prepared earphones. The equalizer is working, but the quality requirements of the headphones are still relatively high. Because the sound of these headphones is relatively dry, the speech intelligibility is relatively high.

Sound reinforcement monitoring
The requirements for earphones for sound reinforcement monitoring can be high or low. As long as the monitoring headphones of ordinary dance halls can listen to the music and language content, and adjust the ratio of reverberation and vocals to a satisfactory level, the pre-monitoring (PFL) is accurate. Yes, low-end earphones like SENNHEISER HD433 and AKG K70 can meet the requirements. DISCO dance halls generally use single or binaural closed monitor headphones, which require strong low frequency, high sound pressure, strong sound insulation, and durable, such as some models such as SENNHEISER HD25SP, PIONEER DJ-1000, and Panasonic. For concerts and high-end sound reinforcement occasions, the requirements for monitor headphones are higher, but generally the main monitors are professional monitor speakers, and headphones are generally used as auxiliary monitors. High-end closed or semi-closed headphones are used. Yes, such as AKG K240M, K240DF, SENNHEISER HD250, HD265, HD25 and so on.

Dedicated monitor
This kind of monitoring abounds around us, such as the paging lady on the paging station, the telecom operator, etc. They all wear closed monitor headphones with microphones and require high language intelligibility. There are also pilot monitoring on airplanes, dispatch monitoring of racers, command coordination monitoring of tank crews, and sonar monitoring in submarines. Different special earphones are selected according to different needs.

Custom in-ear
Customized in-ear monitor (IEM) has obvious advantages over general-purpose and speaker-style stage return monitors. First, it has good airtight performance and can effectively isolate external noise. Second, it has fast transient response and can instantly capture beats and needs. The third is that it is closely embedded in the triangle socket and concha cavity of the human ear, and it is not easy to fall off even if the movement is large.

For long-term stage performers, bands, singers and other professionals who take stage performances as their profession, customized monitor headphones have become increasingly popular professional equipment.

On the stage, singers or band musicians have to listen to the accompaniment to sing, but the speakers on the stage are facing the audience, so the accompaniment that the singer hears is actually the accompaniment sound from the speakers on the stage and spread to the audience. The last wall then bounces back to the accompaniment. According to the propagation speed of the sound, there is a certain delay between the sound returning to the singer’s ears and the accompaniment heard by the audience. This delay is related to the reflection angle, reflection length, reflection intensity, and room size. Temperature is closely related; therefore, if the singer listens to the returning accompaniment and sings, the audience will hear the effect that the singer can't keep up with the rhythm! Therefore, in the front of the stage, there will be several very large back-to-listening speakers, facing the singer, not the audience. The function of these speakers is to allow the accompaniment to be fed back to the singer’s ears in time, so that the singer’s singing and singing The accompaniment blends together.

Sometimes the stage is very large, and the sound from the speakers at various points on the stage will deviate when reaching a certain point. When this point is fixed, this small deviation will not have a great impact, but if it is moved, these deviations will have a great impact, and even affect the performance.

Speaker-style stage return monitoring is usually difficult to be accurate due to noisy background sounds and distances. Therefore, a custom-made headset with good sound insulation effect and comfortable to wear comes into being.

The birth process of custom headphones is also related to hearing health. In the 1980s, Alex Van Halen, the soul of a famous American rock band (Van Halen), complained to the band’s tuner Jerry Harvey that the strong music made his hearing worse and worse, and he wanted to hear it on stage. The beat of the other players seemed very difficult. So Jerry Harvey began to choose a variety of materials, researched and developed and helped Alex make the first custom-made dual-unit in-ear monitor headphones. One way to isolate the strong sound of the instrument on the stage and reduce the damage to Alex’s hearing, and secondly, it made him You can know the beat signal of the team members, and then because of more and more demand, Jerry Harvey established Ultimate Ears (UE) in 1995 and became the creator of customized headsets. In 2007, Logitech acquired UE at a cost of 34 million U.S. dollars, while Jerry Harvey set up another portal to establish JH Audio, continuing to engage in the development and production of customized headsets.

With the gradual maturity of custom earphone technology, return-to-listening speakers are increasingly being replaced by compact custom in-ear monitor headphones. In addition, the appearance of customized headphones is stylish and changeable. Colors and graphics can be customized freely, and they can even be studded with diamonds. The appearance is quite dazzling. It is these advantages that have led to more and more performers (including singers, musicians, and hosts). Etc.) Choose custom headphones as a necessary setting for the performance on stage.

With the increasing use of custom monitor headphones, custom music earphones (CME-Custom Music Earphones) for general consumer use (CME-Custom Music Earphones), also known as custom music earphones, are also gradually emerging, which are different from the characteristics of monitor headphones, which are combined with sand and mud, and custom music. Headphones add an element of music appreciation in terms of tuning, and lower the intensity and excitement of the monitor headphones in part of the sound range, so that professional-grade equipment can be applied to the leisure of ordinary consumers.


The difference between monitoring and HIFI

HiFi earphones are oriented to civilian consumption and are used to enjoy music, listen to radio, and watch movies. They have the following characteristics: First, the frequency response is as flat and wide as possible, so that all kinds of music can be appreciated; second, the efficiency is relatively high. In order to adapt to the earphone amplifier circuit with relatively small output capacity of civil sound equipment; third, it is light in weight and comfortable to wear. The characteristics of a monitor headset are: first, the frequency response must be wide enough and fast to ensure that the signal distortion in the frequency band that needs to be monitored is as small as possible, and it has the ability to clearly reflect the sound characteristics of the monitored object; second, it is durable, easy to maintain and maintain.

There is a saying that HiFi headphones have sound coloration, but monitor headphones have no sound coloration. This statement is not very accurate. The so-called sound staining refers to sound distortion, which is caused by the addition of a non-existent sound signal during the playback process of the headset. If the design of HiFi earphones follows the principle of addition, that is, on the basis of being as faithful as possible, the sound can be appropriately polished to form a unique and beautiful tone; then the design of professional earphones follows the principle of subtraction, that is, the "professional spirit" of Ningque. , With the earphone monitoring function as the goal, on the basis of the sound as faithful as possible, the frequency bands that have a positive impact on performance are highlighted and emphasized, and the frequency bands that can cause negative effects are reduced. In fact, the increase and decrease of sound are relative. The emphasis on any frequency band is the reduction of other frequency bands. Both HiFi headphones and professional headphones adjust the frequency response to achieve the design function, and the premise is to be as much as possible The truth.

HiFi headsets and professional headsets are not very clear in actual use. The choice of monitor headphones is not only related to the monitoring purpose and monitoring environment, but also related to factors such as the tradition of the recording studio, the habits of the recording engineer, and the price of the headphones. In some studios, you can see AKG's K240DF and Sennheiser's HD250, as well as low-end HiFi headphones that are common on the market. The monitor headphones used in performances and rehearsals may be surprisingly low-end. The pursuit of monitor headphones is economical and practical, and a pair of golden pliers may not cut the wire. In the civilian field, many earphone enthusiasts choose recording and mixing earphones to listen to music. These earphones sound faithful and can well show the beautiful sound of front-end equipment.

Some young friends plan to use monitor headphones to enjoy music.

There are many places to bring adjustments, and generally speaking, it is only suitable for listening to a certain type of music monitored by it. High-end monitor headphones are too capable of revealing the appearance of front-end equipment and records. They often expose the shortcomings of low-end HiFi equipment and portable audio too thoroughly, and the sound quality of the entire system is not ideal. In addition, in order to reduce distortion and consider the use of multiple headphones in parallel, most high-end monitor headphones have low efficiency, high impedance, and require greater power drive. Most low-end civilian audio equipment does not have this output capability. If you want to use monitor headphones on low-end audio equipment, you should choose those designed for home recording studios and small recording studios with computer audio workstations as the core. It is better to use the corresponding grade HiFi headphones on the low-end audio equipment. .

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