Comparison Universal Audio Apollo Twin X Quad vs Universal Audio Apollo X4

The number of input and output channels that the audio interface is equipped with. See below for more details on each type.

— Input channels. Input (in) channels on audio interfaces designate the number of different audio signals a device can accept for recording overnight. Their number plays a decisive role in multi-channel sound recording, connecting several instruments or vocals at the same time. When choosing an audio interface, consider not only the number of input channels, but also the types of connectors (see “Inputs”).

— Output channels. Output channels output (out) is the number of audio signals that can be sent to other devices or equipment for playback. The outputs of the audio interface can be used to connect to amplifiers, monitors, speaker systems, headphones, etc. A large number of output channels will come in handy when creating sound mixes, multi-channel recording or multitasking in a studio environment. For simpler tasks, it is enough to have from 2 to 4 output channels. When choosing an audio interface, consider not only the number of output channels, but also the types of connectors (see “Outputs”).

The number of preamplifiers in the design of an audio interface, designed to work with a weak signal - which directly comes from a microphone, pickup, etc. Each preamp corresponds to one low-level input channel. For example, if an audio interface has four preamps, it can simultaneously process signals from four microphones or other devices connected to those preamps. Professional studio audio interfaces are often equipped with a large number of preamps to provide flexibility and the ability to record from a large number of sources simultaneously.

— Total audio inputs Jack / XLR. The total number of analog audio inputs such as Jack (6.35 mm) and/or XLR (this interface can be combined with a “jack”). Note that such connectors can play the role of both a line input and a microphone or instrument input. For more details, see the relevant paragraphs.

— mini-Jack. The standard 3.5 mm mini-Jack is usually used in audio interfaces as an analog (line) input for two stereo channels, as well as as a microphone audio input (see the corresponding paragraphs).

An input jack used to record audio from a microphone, which may transmit low signal levels and requires amplification. It often includes a microphone preamplifier - it amplifies a weak signal to a level that is suitable for recording or processing in an audio interface. The most common types of microphone inputs are:

— mini-Jack (3.5 mm). The standard mini-Jack audio connector (3.5 mm) provides average signal quality, which is why it is poorly suited for professional tasks such as studio recording. As a result, the “purely microphone” variety of the 3.5 mm jack is relatively rare, but still has a right to exist. It is also worth considering that microphones can use mini-Jack plugs for different numbers of contacts (from 2 to 4).

— Jack (6.35 mm). The shape and arrangement of contacts of Jack sockets (6.35 mm) are similar to the corresponding varieties of the 3.5 mm standard, but they are larger in size. Due to the larger contact area and less tendency to interference, plugs of this format are found in microphones of all price categories. In addition, a balanced connection is often made through the 6.35 mm jack - a special type of connection used in professional audio equipment that allows signal transmission even over fairly long wires without interference.

- XLR. In audio equipment, three-pin XLR connectors are most often used to connect a...microphone. XLR provides a reliable and tight connection, and the interface sockets often have locks to secure the plugs. Connection through this connector is also carried out in a balanced way - using three wires instead of two. The peculiarity of this signal transmission is that external interference is filtered, in fact, by the wire itself, which allows you to transmit a high-quality audio signal even with long cable lengths. Often the XLR connector can be combined with Jack (6.35 mm).

Connectors used to connect musical instruments (acoustic or bass guitars, keyboards, etc.). Most often they are made in the form of 6.35 mm Jack format sockets, but there are other options (see below). The audio signal from pickups has its own specific characteristics, so the instrument input typically features a higher input level and special impedance matching to ensure optimal sound quality.

— Jack (6.35 mm). Jack sockets (6.35 mm) are most widely used as instrument audio input. They are very large in size, thereby ensuring tighter contact, and support a balanced connection (for transmitting a high-quality signal without interference over fairly long wires). The number of Jack connectors (6.5 mm) usually corresponds to the number of tools that can be simultaneously connected to the device.

- XLR. A characteristic round connector, often combined with a Jack interface (6.5 mm). XLR is equipped with a locking lock and three contacts (there are other options in terms of quantity, but they are practically not found). The connector is used to transmit an analog signal through a balanced connection, which provides high immunity to interference - sufficient for professional use.

The type of line input provided in the device. Uses the line input to feed audio from an external source to the audio interface.

The following types of connectors can be used for line input:

— mini-Jack (3.5 mm). A socket for a standard mini-Jack plug (3.5 mm). The connector serves as an audio input for two stereo channels. It is designed primarily for portable electronics such as smartphones, pocket players, etc. In stationary devices, Jack (6.35 mm), XLR and RCA are more popular.

— Jack (6.35 mm). A common audio connector for transmitting an analog signal. In design, this type of socket is as similar as possible to a mini-Jack (3.5 mm), but differs in size. Jack connector (6.5 mm) provides tight contact and is less susceptible to interference. It also supports a balanced connection - high-quality transmission of audio signals over fairly long wires with effective protection against interference.

- XLR. The XLR standard is considered professional - not only because of the high quality of signal transmission, but also because of its fairly large size and the presence of locks for securely securing the plugs. However, only one channel of audio can be transmitted over one cable, so XLR outputs are usually installed in pairs - based on stereo sound. Also note that these connectors can be combined with Jack sockets (6.35 mm). They als...o allow you to implement a connection in a balanced format with a high degree of noise immunity and the use of fairly long wires without affecting the frequency of the analog signal.

- RCA. Connector for coaxial cable with tulip type plug. The standard RCA input consists of two jacks - for stereo sound, left and right channel. One analog RCA connector can only transmit one channel of audio, so the number of such connectors corresponds to the number of channels supported by the device.

— Total audio outputs Jack / XLR. The total number of analog audio outputs such as Jack (6.35 mm) and/or XLR (this interface can be combined with a “jack”). Note that such connectors can play the role of both the Main output and the linear output. For more details, see the relevant paragraphs.

— mini-Jack. The standard 3.5 mm mini-Jack is usually used in audio interfaces as an analog (line) output for two stereo channels, as well as as an output for connecting headphones (see the corresponding paragraphs).

The type of line output provided in the audio interface design. It outputs a line-level analog audio signal. This interface is mainly used for connecting recording devices, outputting a signal to playback equipment or to an external amplifier. And the types of connectors used for linear output can be as follows:

— mini-Jack (3.5 mm). A standard socket for the popular mini-Jack plug (3.5 mm), used as a line output. This connector is mainly used to connect some models of active speakers, while two stereo channels are usually output through one mini-Jack (3.5 mm). Note that headphone outputs, which also use a mini-Jack, are considered separately - see the corresponding paragraph.

— Jack (6.35 mm). A larger analogue of the mini-Jack connector (3.5 mm) for outputting an analog stereo signal. The Jack output provides a more reliable and noise-free connection, making it ideal for professional applications. Effective protection against interference is possible with a balanced connection method. To save space, the 6.35 mm output can be combined with an XLR connector (see the corresponding paragraph). The disadvantage of this design is the impossibility of using both interfaces simultaneously. Jack line outputs (6.35 mm) adhere to the “one channel per connector” principle.

- XLR. A round three-pin connector for outputting a line-level analog audio si...gnal, often with a balanced connection type. Transmission is carried out over three wires instead of two, and during it the noise induced on the wire is eliminated. This allows the use of fairly long cables without compromising the “purity” of the signal, making this type of connection excellent for professional audio equipment. XLR is also considered a professional interface, both due to the ability to work with a balanced signal and due to increased reliability: such connectors are often equipped with locks to secure the plugs.

- RCA. Analog linear audio output using RCA connectors - so-called “tulips” (due to the characteristic shape of the plugs). The standard output of this type consists of two connectors - for the left and right stereo channels. Also note that RCA connectors can be used in other output interfaces, but they have their own names.

An output used to transmit digital audio over a fiber optic cable. The optical interface allows the transmission of multi-channel audio and is characterized by complete insensitivity to electronic interference. At the same time, optical fiber is very fragile - care must be taken when handling the corresponding cables. Such cables become unusable from sharp bending or strong pressure.