Preamplifiers: why are you needed and how to choose?

High quality sound reproduction requires special technical equipment. The selection of a preamplifier takes special attention in this matter. From the material in this article, you will learn what it is, what it is used for and how to choose the best option correctly.

A preamplifier is nothing more than a preamplifier or an electronic amplifier, converting a weak electrical signal into a stronger one. It is a device used as an input and router selector between the source and the power amplifier. It is necessary to decrease or increase the sound volume level.... Its control and adjustment are located on the front panel. At the back are the connectors required to connect an amplifier (microphone), a turntable, and other devices.

The preamplifier is responsible for preparing the signal coming from a microphone or other source for the required amplification. It is able to boost a low signal as well as clear it. This improves the quality of the incoming sound.... In addition, the preamplifier can be used to adjust the signal or mix several sounds into 1. This device is used to adjust the sound to the initially set power level. It is located as close as possible to the signal source (for example, a microphone, radio receiving tuner, turntable). This feature ensures that the received sound is converted and transmitted unchanged to the power amplifier.

Regardless of the level of complexity of the design and output impedance, the task of any preamplifier is to transmit a high-quality signal... There are many preamp circuits.

A phono stage is required to correct the frequency response. This is a corrector amplifier with a special frequency response. The signal from the magnetic cartridge is lower compared to linear sources. The built-in phono stage allows direct connection of a turntable. With its help, it is possible to return the signal to its original value.

Initially, correctors were built into amplifiers, marking the input with the inscription PHONO. Most devices of this type are now outdated, so it is almost impossible to find them. The boards can be purchased separately, built-in to devices with an amplifier. The difference between an equalizer and a preamp is that it returns the sound to its original level, and the amplifier changes it. This is the main difference between the devices.

However, a phono stage is not always necessary when working with sound. For example, if the preamplifier has special phono MM or MC inputs (or one of them), there is no need to use an external phono stage. However, if the device is equipped with only line inputs, you will not be able to do without a phono stage.... It will provide the required sound voltage.

The preamplifier is good because makes it possible to switch different sources... He is also responsible for the smoothness of volume control, adjusting the stereo balance, treble and bass, and in some models is also responsible for "loudness". Some units have built-in phono preamplifiers with MM or MC inputs (or both). Built-in phono preamps are attributes of preamplifiers.

Today, you can find preamplifiers of three types on sale: instrumental, microphone and universal. Each type of product has its own characteristics. Any preamplifier has at least 1 input and line output. The stereo preamplifier is capable of changing the sound timbre. Thanks to the use of reproducing equipment, it is possible to achieve linearity with practically no sound distortion. Other modifications make it possible to achieve a new sound of famous musical instruments. Moreover, each individual model of the device has its own character of sound. In view of this, the device has to be chosen taking into account the sound suitable for a particular person... However, the characteristics of the models are different.

For example, some products are bought for microphones, others are needed for guitars. In the assortment of leading manufacturers, you can find modifications on lamps, with a timbre block, on field-effect transistors, stereo amplifiers, differential devices with high performance characteristics.

The instrumentation amplifier is distinguished by the presence of a lot of useful characteristics. It has the ability to adjust the gain by means of 1 resistor. This allows the gain to be varied as required. These systems can be crossed with digital devices, which opens up more possibilities.

The symbiosis of analog-digital technology is devices with an adjustable control coefficient. On sale you can find systems of an integrated type, combined with a microcontroller. Instrument preamplifiers can automatically change gain and ranges for improved measurement resolution... These devices have high input impedance and high common mode rejection.

These devices amplify the signal from the microphone to line level. Individual microphone options improve sound quality to a great extent. Most of these devices are equipped with an INA 217 microcircuit. Thanks to it, the minimum level of sound distortion and a low noise path at the input is ensured. Such devices are good for low impedance microphones with a characteristic weak signal level.

These devices are relevant for studio and dynamic microphones. These devices can have 1, 2 or 3 transistors. In addition, they are hybrid and tube. Products of the first type are designed to improve sound quality, including removing extraneous noise. Lamp analogs are good because make the sound velvety and warm... However, the price of these modifications is high.

The versatile preamp models have their own characteristics. If instrument analogs allow you to directly connect instruments, and microphones are needed when working with microphones, then universal devices combine both options. When working with them, you can change the operating mode from instrumental to microphone and vice versa.

Various leading companies in the world are engaged in the production of preamplifiers. Among them are several brands, whose products are in special consumer demand and are highly appreciated by professionals. These manufacturers offer buyers a range of high-quality products, including Hi-Fi or High-End transistor models.

• Audient Ltd Is a UK brand for high quality discrete microphone devices.

• Manley Laboratories, Inc Is an American manufacturer of quality tube preamplifiers with soft sound.

• Universal Audio, Inc - 1 of the leading manufacturers of professional recording models.

• Forusrite Audio Engineering Ltd - British manufacturer of professional 8-channel type preamplifiers for old and modern technology.

• Prism Media Products Ltd - manufacturer of various types of devices, including semiconductor-type models, engaged in the production of high-end products.

When buying a high-quality preamplifier for a phonograph record pickup or other device, you need to pay attention to a number of factors. Primary among them are such criteria as input and output voltage. The output voltage should not be less than the input amplifier. The input power depends on the device itself for which the preamplifier is selected. (for example, a microphone, player or phone).

It is important to pay attention to harmonic distortion as well as linearity in the audio range... When choosing between tube and semiconductor options, you need to take into account your own nuances. For example, tube versions give good sound, but in terms of the signal-to-noise ratio and the coefficient of nonlinear distortion, they are inferior to their transistor counterparts. They are capricious in everyday life, more dangerous to operate and more expensive than other models.

When buying, you need to check the operation of the device. It is important to evaluate the sound at low, standard and high volumes. In addition, you need to understand the difference between one-, two- and three-channel options. Multichannel modifications are needed for expanding studios. In addition, it is necessary to take into account the type of connected device, fit into the workspace, the number of channels and the need for additional options. In addition to adjusting the sound gain, some models are equipped with other functions useful for recording. One of them is a low-pass filter that cuts frequencies up to 150 Hertz. Thanks to him, it is possible to get rid of low frequency noise.

Other useful options include incorporating a transformer into the sound path. Other two-channel amplifiers are equipped with a stereo support option. It is responsible for uniformly adjusting the gain level between channels. This makes it easier to work with sound when using two microphones. Other preamps have a built-in MS matrix for Mid-Side recording.

The connection of the pre-amplifier to the power amplifier is carried out directly to the device itself. Wherein it is inadmissible to install a short-circuited contact connector in the PRE OUT terminals. This is the cause of damage. In order not to damage the preamplifier and get the highest quality sound from the system, it is better to follow the instructions of a particular model when connecting. It is important to correctly connect your signal sources to the rear panel inputs and outputs of your specific preamplifier. As a rule, for the convenience of the user, they are indicated in different colors. The plug should fit as tightly as possible into the sockets of the devices.

If the XLR cables are balanced, the connection is made via the CD inputs. In this case, you need to select the symmetrical connection type for the CD using the settings menu.... After that, you must connect the cables of the power amplifier to the output connectors of the preamplifier.

For information on the function of the preamplifier, see the following video.