Headphone amplifiers: what are they and why are they needed?

It is not hard to guess that a headphone amplifier is needed to increase the signal strength, so that the headphones give the desired sound volume. Accordingly, many users have a natural question - why do we need such separate amplifiers for PCs, laptops, as well as players and smartphones, if they already have volume? We will answer these and other questions in our review.

Most often, audio amplifiers for headphones are compact in size, they can be divided into 2 main types. Some are used for the so-called "earplugs", these are the most compact models in which the output voltage is 0.5-2V. Others are suitable for full-size accessories, these products are large in size and have an output voltage of 1 volt or more.

If headphones in smartphones usually strive for some golden mean between the battery life of the gadget and its dimensions, then in external amplifiers the focus is on maintaining high quality sound reproduction.

When creating a smartphone, manufacturers focus on the minimum power consumption of working parts, since this will allow a longer use of a miniature battery, as a result, instead of high-quality full-fledged microcircuits and discrete elements in built-in headphone amplifiers, an extremely economical microcircuit is usually selected. It should be noted that such savings often go sideways, and instead of high-quality sound, the user hears some unnatural and even annoying audio recordings.

The only way out in this case is to install an external mobile amplifier... It is connected to the headphone jack or line-out. Accordingly, the headphones themselves are already connected to the portable device. Amplifiers for "plugs" are usually miniature in size, and for full-sized ones, slightly larger ones are used. In addition to the improved signal quality, audio amplifiers can also extend the battery life of smartphones, since they draw quite little current from an external device., and in order to amplify the signal, they consume the energy of their own battery.

Stationary amplifiers are widely used. They are powered from an outlet, so it is impossible to use them on the road or in the absence of power. Portable amplifiers are more practical, they have a separate battery power supply or rechargeable battery.

In practice, the device that we know as a sound amplifier for headphones solves two main tasks:

• provides a sufficient sound volume level;
• transmits audio signal without noise and distortion.

At the same time, the second function is just as important as the first, because the sound quality is still the weakest link despite the good volume of many modern mobile phones. Let's just imagine a couple of cars that accelerate to 120 km / h. But at the same time, one moves extremely confidently, while the other shakes, it is constantly drifting from one side to the other due to poor suspension or damaged wheels.

The same applies to the amplifier: volume is only one parameter of an acoustic device. She is undoubtedly important. But only as the very first condition, the second factor of comfortable sound reproduction is the quality of the audio signal, in the overwhelming majority of cases the price of the entire device as a whole largely depends on it.

Headphones are a working tool for many people. This device allows you to enjoy music tracks, to reveal their sound in a new way, and at the same time not to worry that excessive volume will interfere with households or neighbors. However, to reveal the full range of the melody will not work without a headphone amplifier. Besides, the headphone amplifier is needed to transmit bass and midrange, in its absence they are practically not detected.

Thus, the use of amplifiers allows you to get high-quality surround sound from a flat and quiet sound... Even the most primitive device will allow you to reveal the full breadth of the sound range with full bass. The high frequencies also become more intelligible: the sharpness of the sound disappears in them, while the listener can clearly distinguish the separation of the instrument.

First you need to distinguish between a hi-fi device and a typical portable amplifier. In most cases headphone amplifiers are quite modest in size, thanks to which they can be used with a mobile phone outside the home environment.

Such a device is powered by a removable battery. Stationary Hi-Fi devices are characterized by the fact that all power consumption in them depends only on the amount of electrical current consumed from the outlet, while the power consumption of portable products largely depends on the amount of load and voltage.

According to the laws of physicists, the amount of current consumed is directly proportional to its voltage and inversely proportional to the voltage supplied to the source... Accordingly, the higher the headphone impedance parameter, the less current consumption will be at the output. Depending on what elements are involved in the structure of the mechanism, all amplifiers can be conditionally divided into three categories: tube, as well as transistor and hybrid.

These mechanisms contribute to enhancing softness. They provide Much softer amplification of sound reproduction in comparison with other types of equipment, the sound at the output is warm and comfortable, and the lamps glowing in the dark help create a kind of atmosphere of comfort. However, this unit makes increased demands on the conditions of its operation.

It can only be used in a well-ventilated, ventilated area, always inaccessible to pets and small children, as the lamps get quite hot during operation and can cause burns if handled carelessly.

Models powered by germanium transistors convert the waves into crisp, accurate sound. They do not have any particular style, therefore they can be used to connect with a wide variety of types of audio materials. The devices are compact in size, in addition, they consume much less power than all other types of amplifiers. The transistor device works best with low impedance headphones.

Such devices use both elements in their circuit: both a lamp and a transistor. Similar model ideal for low-impedance headphones, where the lamp provides a soft sound, and the transistor is responsible for the detail and signal strength... Hybrid versions are usually chosen strictly for each specific type of headphone, since the quality and volume of the resulting sound largely depends on this.

Based on the characteristics of the operating mode and the dependence of the output current of the device on the parameters of the electromotive force of the input signal, all devices are divided into several classes.

In this case, sound amplification is performed on the linear section of the current-voltage characteristic, where there are no distortions. Devices of this group are distinguished by the best linearity of amplification, they are distinguished by the complete absence of any distortion of the received signal., but their efficiency is extremely low - it is in the range from 15 to 20%.

Such devices are considered uneconomical, since they consume a lot of energy and are almost always wasted. Another disadvantage of devices of this class is that they get very hot during operation.

This is where the sound wave amplifier takes place exclusively during the half-cycle of the sound. That is, it can be noted that the amplifier operates with a small cutoff, thus, its own amplifier of group A operates for all half-waves. As a result, at the output, the current value decreases, and the efficiency increases many times, reaching 60-70%.

This is an intermediate link between A and B, such amplifiers can reduce the distortion of the audio signal. The efficiency parameter of these devices is also intermediate and corresponds to 40-50%.

Tops the TOP of popular amplifiers. According to some users, it was voted the best in 2019. The model is by no means new, but it still has not lost its relevance. This is a stationary amplifier that can handle full loads with ease. With a resistance of 600 ohms, it provides 100 mW per channel, which is comfortable for human hearing. There is a pair of RCA connectors for input, as well as 2 audio jacks with a 6.3 mm connector and a line-out.

The sound of this amplifier is voluminous, precise, biting, has good dynamics, clarity and naturalness. And the manufacturer even received an award for the stylish design of the equipment.

A transistor amplifier for modern headphones that considered optimal in terms of price / quality... Power is supplied via USB, the equipment is compact and lightweight, which makes the model convenient for use in the field. Take this portable amplifier with you to work, travel, or travel with ease. However, if desired, it can also be used stationary, for this you just need to connect the equipment to a computer and enjoy the sound of your favorite tracks.

A reliable DAC is installed inside, PCM audio files up to 96 kHz / 24 bit are supported. There is no native DSD. The sound is quite pleasant, detailed, linear, creates a not quite wide, but at the same time clearly traced audio scene. Of course, in comparison with the first model, the design is quite simple and somewhat outdated, but it does not cause any negative associations.

A relatively budgetary and very compact sound amplifier, one might even say that This is a completely pocket-sized option that takes up almost no space... However, with such dimensions, this device is able to output sound not only to the headphones themselves, but also through the coaxial connector, as well as through the rear output, bypassing the amplifier. Connection and power supply exclusively via USB.

The manufacturer created such an amplifier as an alternative to the standard audio card of laptops and personal computers, for this purpose it copes 100%. The sound is quite high-quality and detailed, without pronounced bass, as is often the case with cheap models... The general handwriting can be called rather neutral.

Many music lovers are now interested in the question of how to choose the right device to amplify the sound of headphones. The modern industry offers a wide variety of amplifiers - These are Hi-Fi and Hi-End, wireless models on bluetooth and connecting via cable for low and high impedance devices, balanced mini-amplifiers and studio products, there are also options for the hearing impaired and devices with an optical op-amp input.

It is for them that we will give a number of main factors that you need to pay attention to when choosing the optimal model.

• Personal perception. Be sure to test the device in the store, it should create a sense of complete and comfortable immersion in the acoustics for the listener. It can be an even, accurate sound or, conversely, soft - in any case, it should suit you, so that from listening to your favorite song you only experience a feeling of complete satisfaction.

• Choosing the right amplifier type... Depending on your individual preferences, you can choose one of three types of amplifier, each of them was discussed just above. For the highest quality sound reproduction, you should select devices taking into account the characteristics of the headphones and their technical parameters.

• Number of connectors... If you intend to listen to audio materials with friends, then it is better to pay special attention to this criterion. Some devices have the ability to work with two or even three pairs of headphones at once.

• DAC... A USB digital-to-analog converter, such an element in the amplifier circuit allows even the oldest melodies to be felt in a new format. This criterion is especially relevant if the bulk of audio files are played from a personal computer.

• Connection methods... Some amplifier models allow you to select the connection options for your device. If you own a CD player or a traditional stereo system, then it is best to choose an amplifier of the type that supports each of the possible connection options. If the stereo equipment has an RCA type connection, you should buy an amplifier with the same switching option.

For information on which headphone amplifiers are popular with buyers, see the following video.