Number of channels
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”).
Connection
Connection interfaces that the audio interface is equipped with.
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USB A. Connection via standard USB port. Until recently, this was the most popular interface for external peripherals, found in almost all PCs and laptops. Nowadays, it is often replaced by a USB type C port (see the corresponding paragraph). Most USB A audio interfaces draw power directly from the PC or other host device.
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USB type B. The connector has a characteristic square shape, noticeably different from the well-known rectangular USB A ports. In audio interfaces, it is used to transmit signals from external sources to a computer for recording and processing.
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USB type C. A peripheral connector with a symmetrical contact group, which often replaces full-size USB ports on board modern PCs and laptops. Many new models of audio interfaces are being made for this interface. An exception to the rule is individual instances for Thunderbolt. For them, it is Thunderbolt that is indicated, and not USB type C.
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Thunderbolt v2. Initially, Thunderbolt is a universal connector used primarily in Apple computer equipment. On board audio interfaces it is used as a general peripheral connector (similar to USB). This uses the miniDisplayPort hardware port. The data transfer speed in this version reaches 20 Gbit/s. Recently, the v2 edition has been rep
...laced by the Thunderbolt v3 version (see the corresponding paragraph).
- Thunderbolt v3. A universal interface that is found mainly in Apple technology. In audio interfaces it is used as a general peripheral connector (similar to USB). Specifically, Thunderbolt v3 provides data transfer speeds of up to 40 Gbps and uses a USB type C hardware connector (as opposed to earlier versions based on miniDisplayPort).
- Lightning. A connector used exclusively in Apple portable electronics (since 2012). Accordingly, audio interfaces with such a port are aimed at ease of connection to iPhones and iPads. Note that today there has been a transition from proprietary Lightning to the common USB type C - the latest generations of Apple gadgets are produced with just such a peripheral connection connector.
- mini-USB. A smaller version of the full-size USB interface, created for portable equipment. It is found very rarely in audio interfaces.
- FireWire. Universal connector, also known as IEEE 1394 or i-Link. In terms of functionality, it is analogous to USB, and in some characteristics it even surpasses it. However, FireWare is much less common. Used to connect to computers and some types of specialized audio equipment.
— Dante Dante connectors are used to connect audio interfaces to a network to transmit audio digitally. In this case, a standard Ethernet port (RJ-45) is used for physical access to the network.Frequency range
The audio frequency range supported by the device. Most often we are talking about the range of frequencies that a device can produce in an analog audio output signal.
In general, the wider the frequency range, the fuller the sound, the lower the likelihood that the audio interface will “cut off” the upper or lower frequencies. However, it must be taken into account that the human ear is capable of hearing sounds at frequencies from 16 to 22,000 Hz, and the upper limit decreases with age. So from a practical point of view, it makes no sense to provide a wider range in audio technology. And the impressive numbers found in high-end devices are rather a “side effect” of advanced electronic circuits and are given in the specifications mainly for advertising purposes. Also remember that the overall sound quality is affected by many other factors besides frequency range.
Total Jack / XLR audio inputs
— 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).
Instrument
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.
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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.
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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.
Line
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:
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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.
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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.
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XLR. A round three-pin connector for outputting a line-level analog audio signal, oft
...en 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.To monitors
Output connectors for connecting monitor speakers or headphones. Connecting monitors to the output of an audio interface allows musicians, sound designers, or sound engineers to monitor audio quality in real time. In audio interfaces,
monitor outputs can be made in various formats, but most often there are various combinations of RCA, XLR and Jack connectors (6.35 mm), less often - the classic mini-Jack (3.5 mm).
For podcasts / streams
Audio interfaces designed for
recording podcasts and conducting live broadcasts on the Internet (streams). They are supposed to connect streamer and podcasting equipment such as microphones and headphones, and the functions in such models include fine sound adjustments, adjusting the balance between different audio sources, etc.
high Pass Filter (HPF)
Separate
adjustment of high frequency cut (HPF). This function allows you to change the sound picture by adjusting the volume of the high-frequency sound relative to the rest of the frequency range.