Frequency range
The audio frequency range supported by the device. Most often, we are talking about the frequency range that the device can output in an analogue audio signal at the output.
In general, the wider the frequency range — the fuller the sound, the lower the likelihood that the transducer will “cut off” the upper or lower frequencies. However, note that the human ear is able to hear sounds at frequencies from 16 to 22,000 Hz, and the upper limit decreases with age. So from a practical point of view, it does not make sense to provide a wider range in audio technology. And the impressive numbers found in high-end devices (for example, 1 – 50,000 Hz) are more of a "side effect" of advanced electronic circuits and are given in the characteristics mainly for the purpose of advertising. Also recall that the overall sound quality is affected by many other factors, in addition to the frequency range.
Signal to noise ratio
The signal-to-noise ratio provided by the converter.
This parameter describes the ratio of the volume of the pure sound produced by the device to the volume of its own noise (which is inevitably created by any electronic device). Thus, the higher the signal-to-noise ratio, the clearer the sound, the less the DAC's own noise affects the audio signal. Indicators up to 80 dB can be considered acceptable, up to 100 dB — not bad, 100 – 120 dB — good, more than 120 dB — excellent. However, it is worth remembering that the overall sound quality is affected not only by this parameter, but also by many others.
Note that the signal-to-noise ratio is often associated with such a characteristic as the dynamic range (see above). They are similar in general meaning, both describe the difference between an extraneous background and a useful signal. However, the noise level in the calculations is taken differently: for the signal-to-noise ratio, the background of the converter “at idle” is taken into account, and for the dynamic range, the noise that occurs when a low-level signal is output. This is the reason for the difference in numbers.
Coef. harmonic distortion
The coefficient of harmonic distortion produced by the converter during operation.
The lower this indicator, the clearer the sound produced by the device is, the less distortion is introduced into the audio signal. It is impossible to completely avoid such distortions, but it is possible to reduce them to a level that is not perceived by a person. It is believed that the human ear does not hear harmonics, the level of which is 0.5% and below. However, in high-end audio applications, distortion rates can be much lower — 0.005%, 0.001% or even less. This makes quite a practical sense: the distortions from the individual components of the system are summed up, and the lower the harmonic coefficient of each component, the less distortion there will be in the audible sound as a result.
Inputs
Inputs provided in the design of the device.
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Mini-Jack (3.5 mm). A standard 3.5mm mini-jack is typically used as an analogue (line) audio input to two stereo channels. It is designed mainly for portable devices like smartphones, pocket players, etc.
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Jack (6.35 mm). Connector used as an analogue audio input. It is similar in design to the mini-Jack 3.5 mm (see the relevant paragraph), but it is larger and provides more reliable contact. As a result, this connector is not used for portable, but mainly for stationary audio equipment, including professional. The second feature is that the 6.35 mm Jack can play the role of both a line input and an instrument/mic input. The latter is found in audio interfaces (see "Type"), while such devices may be provided with combined connectors that combine Jack and XLR (see the relevant paragraph). In addition, it is worth noting that a balanced connection is often made through a 6.35 mm jack — a special kind of connection used in professional audio equipment and allowing you to transmit a signal without interference even over fairly long wires.
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RCA. Characteristic round connectors for a tulip-type plug; can be used in different interfaces, but "RCA input" usually means an analogue audio line input. Note that only one channel of audio can be transmitted through one analogue RCA connector; t
...herefore, the number of such connectors corresponds to the number of channels supported by the device (for example, a stereo input consists of a pair of RCA jacks).
— Phono. A specialized input for connecting a vinyl player, or rather, a turntable pickup. The peculiarity of the audio signal from the pickup is that it is “skewed” in frequencies, and in order to bring the frequency response back to normal, it is necessary to pass the sound through a phono stage. Accordingly, the presence of the Phono input means the presence of a phono stage in the device and the ability to work as a preamplifier for vinyl players. Keep in mind that there are two types of pickups — MM and MC, and before buying a device with a Phono input, it is advisable to check which of these varieties it is compatible with. However, it is not uncommon to find support for both options at once.
— XLR. In audio technology, three-pin XLR connectors are most often used. Theoretically, they can have different purposes, but in fact, when they say "XLR input", they usually mean an analogue audio input — either linear or microphone / instrumental (in the latter case, this connector can be combined with a 6.35 mm Jack — see the relevant paragraph). This connector is popular in professional audio equipment, and there are two main reasons for that. Firstly, XLR provides a reliable and tight connection; locks are often provided in the sockets to secure the plugs. Secondly, the connection through this connector is carried out by the so-called. in a balanced way, on three wires instead of two. The peculiarity of such 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.
— Coaxial S / P-DIF. Input for a digital audio signal, one of the varieties of S / P-DIF (the second variety is optical). Allows you to transmit both stereo and multi-channel audio. RCA is used as a connector, but this input should not be confused with RCA inputs (see the relevant paragraph). The coaxial interface uses a fundamentally different signal format, all sound channels are transmitted through one connector, and even a special cable must be used for such a transmission — shielded. Compared to the fibre used in the optical interface, this cable is more susceptible to electromagnetic interference, but less delicate.
— Optical. Input for digital audio signal transmitted via TOSLINK fibre optic cable. This interface is a kind of S/P-DIF and is similar in capabilities to the coaxial input (see the relevant paragraph) — in particular, it allows you to transmit multi-channel audio. The key difference and the main advantage of such a connection is complete insensitivity to electromagnetic interference. On the other hand, fibre optic cable is quite fragile and susceptible to damage, it must be protected from strong pressure and bending.
— Balanced digital (AES / EBU). Professional interface for working with digital audio signal. Most often based on an XLR plug, but do not confuse the AES / EBU input with the XLR input: the first version works with a digital signal, where all audio channels are transmitted through a single connector, the second with an analogue one, according to the “one connector per channel” principle. But a common feature of both interfaces, in addition to the type of plug, is that they provide a balanced connection — a connection in a special format in which interference induced on the wire is extinguished directly in the wire. This allows long cable lengths to be used without compromising signal quality.
— MIDI. Input for connecting MIDI devices: keyboards, turntables and other controllers. These inputs are found exclusively in audio interfaces (see "Type"). Recall that a MIDI stream is not a sound, but service information for virtual musical instruments. Therefore, data received through this input is not processed by the device, but simply transferred to a computer, tablet or specialized equipment via USB type B (see below), MIDI output (see "Outputs") or another similar connector.
— BNC. Coaxial connector with bayonet or threaded fixation. Most often used similarly to coaxial S / P-DIF — to receive a digital audio signal. It is mainly used in professional equipment, one of the advantages is the presence of a latch, which increases the reliability of the connection.
— USB (type B). Connector for connecting to a computer as a peripheral device. It has a characteristic square shape, which is noticeably different from the well-known rectangular USB ports. And the methods of using such a connection can be different. So, traditional DACs (see "Type") when connected via USB Type B usually play the role of an external sound card and are used to output sound from a computer to headphones, speakers or other audio device. Audio interfaces, on the contrary, transmit the signal received from external sources to a computer for recording and processing.
— USB-C. The presence of a modern USB-C port for connecting to a PC or laptop. Like the USB port (type B), it can transmit a signal in two directions, depending on the type of device.
— IR control input. Connector for connecting a remote infrared receiver for the remote control. The role of such a receiver can be played either by a separate specialized device or by another component of the audio system that has an IR control output and is compatible with this remote control. The meaning of this function is that the DAC, after mounting all the components of the audio system, may end up in a place where the remote control “does not reach”. In this case, you can connect an external receiver to the device and send signals from the remote control to it, and the receiver will already transmit a signal to the controlled device.
— Trigger. Service input used to control the power of the device. This input is connected to the trigger output of another audio system component (such as an amplifier), and when this component is turned on / off, the DAC will turn on and off at the same time. This makes life easier for the user, eliminating the need for "excessive movements" to turn the DAC on and off.
