Comparison NAD C568 vs NAD C 516BEE

The model of the digital-to-analogue converter (DAC) installed in the CD player.

The DAC is one of the most important components of any modern CD player. It is this module that is responsible for converting digital data recorded on an optical disc into an analogue audio signal that is fed to an external device (amplifier, speakers, etc.). Accordingly, the characteristics and overall quality of the DAC largely determine the sound quality in general. Knowing the DAC model, you can find detailed data on it — characteristics, reviews, test results, etc. — and evaluate how the capabilities of the converter meet your requirements.

Wired and wireless interfaces for connecting external devices provided in the design of the CD player.

— Airplay. A technology for transmitting multimedia data over a Wi-Fi wireless connection (see below). Developed by Apple and widely used in its portable devices, in particular the iPod touch, iPhone and iPad, but is also available for equipment from other manufacturers. Allows you to broadcast audio files to compatible devices (in streaming audio mode, see "Playback" for details), as well as images, text data, and even video. The presence of AirPlay in a CD player will make it possible to connect devices supporting this technology to it for direct playback, as well as display information about files — song title, artist name, etc.

— Wi-Fi. A wireless interface that can be used for two purposes: connection to computer networks (including the Internet) and direct connection with smartphones, tablets and other external equipment. The first option is convenient for implementing network functions — streaming audio, Internet radio(see "Playback"), AirPlay (see above), DLNA(see below). Connection to computer networks can also be carried out through a wired LAN interface (see below), however, Wi-Fi is more convenient due to the lack of wires and the ability to wor...k through obstacles (including walls) at a distance of several tens of metres. And connection with external devices can be provided primarily for remote control of the player.

— Bluetooth. A wireless technology developed for the direct communication of various devices with each other. Provides a distance of up to 10 m (in specific cases — and more, but this option is not relevant for CD players). Specific Bluetooth capabilities may vary depending on the protocols supported by the device. In the case of players, this function is usually used to broadcast audio to wireless headphones or Bluetooth speakers; this connection is convenient due to the absence of a wire, but the sound quality can be noticeably lower than with a wired connection. The reverse option may also be provided — broadcasting sound from a smartphone, tablet, etc. for playback through the player and acoustics connected to it; but this application, like others, is extremely rare.

— LAN. A standard interface used for wired connection to computer networks — both to "local computers" (with or without Internet access), and directly to Internet providers. Accordingly, the presence of such a connector in a CD player implies support for network functions — for example, DLNA or Internet radio (see "Communications"); specific networking capabilities vary by model.

— RS-232. It's a COM port. A specialized connector used to connect the player to a computer and control its settings from a PC. Such control can be more diverse and at the same time simpler and clearer than working with a standard panel or remote control.

— DLNA. A technology used to connect various electronic devices into a single digital network with the ability to directly exchange content. Devices for which support of this standard is claimed are able to interact effectively regardless of the manufacturer. A DLNA CD player can, for example, play music from a computer hard drive in the next room. Connection to the Network can be carried out both wired (LAN) and wireless (Wi-Fi) way; both options are described above.

— USB (type A). This connector is used to connect various USB peripherals to the device. In the case of CD players, we are most often talking about "flash drives" and other external drives: when they are connected to USB Type A, direct playback of the content recorded on such a drive is possible. Usually, this connector is installed on the front panel of the player, and some models of connectors may have more than one.

— USB (type B). This interface allows you to connect a CD player to your computer as a peripheral device. Such a connection can provide a wide variety of possibilities: playback of sound from a PC through the player and acoustics connected to it, control of the player's settings through the service programme, firmware updates, etc. (the specific set of capabilities depends on the model).

— Card reader. A slot for reading memory cards — most often the most popular modern SD format, although theoretically other options can be provided. This feature allows you to play music directly from memory cards. Such media are convenient because card readers are installed in almost all modern laptops, many tablets, smartphones (albeit for smaller cards), etc. However it must be borne in mind that even among SD cards there are several generations that are incompatible with each other; therefore, before using a card reader, you should definitely clarify which cards it is designed for.

— Connecting an iPod/iPhone. The presence in the CD player of special functions for working with portable Apple devices — iPod players, iPhone smartphones, and in most cases — iPad tablets. Such functions may include, for example, switching tracks on the player and managing playlists from the player's remote control; anyway, they make life much easier for those who would like to listen to music from the "apple" technology. Note that in the case of CD players, to connect such equipment, it is usually not a special dock that is used, but a regular general-purpose USB type A port (see above), with which the device is connected via a special cable. Occasionally there are models equipped with external docking stations (which, however, are most often also connected via USB).

The range of audio frequencies that a CD player can reproduce. In general, this parameter determines how full the output bandwidth is, whether too high or too low sound is cut off. However, it is worth noting here that the human ear is able to perceive sound only within the range of 16 – 20,000 Hz (deviations from the upper threshold in different directions are possible, but small, and it decreases with age). All modern CD players cover this range, therefore, in the case of such devices, the sound frequency indicators are reference and practically do not affect the sound. And impressive numbers like 2 – 40,000 Hz, 5 – 60,000 Hz, etc. — this is a kind of "side effect" of the design of a high-quality device; manufacturers use these numbers for marketing purposes, but again, they do not affect sound quality. Also, do not forget that actually audible frequencies are also limited by the characteristics of the speaker system, external amplifier and other equipment connected to the CD player. For example, speakers with a lower frequency range of 150 Hz will “cut off” all lower frequencies, and it doesn’t matter what the lowest bass the player can produce is 16 Hz, 20 Hz or 50 Hz.

The dynamic range of a CD player.

Technically, dynamic range is the logarithm of the ratio between the maximum input signal at which the level of distortion is low enough (tolerable) and the sensitivity of the amplifier. In a simplified way, this parameter can be described as the difference between the minimum and maximum sound levels that the device is capable of reproducing with high quality. The higher the dynamic range value, the better the device handles with sound that has significant volume differences, such as orchestral parts.

Note that when playing different sound standards (see "Playback"), the dynamic range of the player will also be different — for example, for SACD its value is usually much higher than for Audio CD. CD players typically list the highest value that gives the best impression of the device's performance. However, manufacturers often specify for which type of digital audio the dynamic range data is given.

The coefficient of harmonic distortion (harmonics) output by the CD player.

This parameter, along with the signal-to-noise ratio described above, characterizes the overall sound quality of the player. It is calculated by dividing the total sum of harmonics by the value of the main signal at a reproduced sound frequency of 1 kHz, and is expressed as a percentage. Significant levels of harmonics lead to deterioration in sound — from a general feeling of "roughness" and "excessive density" of the sound to the appearance of clearly audible noise; accordingly, the lower the harmonic distortion, the better. In relatively inexpensive CD players, this figure is measured in tenths of a percent, in top models it may not exceed several thousandths of a percent.

Inputs provided in the design of the CD player.

Note that the specific use of the inputs used for audio transmission varies by model. So, in some cases, it is possible to process sound with the built-in means of a CD player (adjusting the balance, frequencies, etc.); in others — signal conversion from analogue to digital format or vice versa (for example, broadcasting sound from the optical output of a Blu-ray player to acoustics), in others — real-time recording of the input signal, etc. But for service connectors, the purpose is quite clear.

Specific types of inputs can be as follows:

— Mini-Jack (3.5 mm). A standard connector widely used in modern audio equipment and other electronics, mostly portable. Technically, the mini-Jack input can be used for different types of signal, but in fact in CD players it most often plays the role of a line interface and is mainly used to connect the mentioned portable equipment — for example, audio players.

— Trigger. Service input used to automatically turn on the CD player. If you connect this input to the trigger output of another audio system component (for example, an audio receiver), this component, when turned on, will supply a control signal to the player and wake it up. In other words, the control device and the player will turn on at the same time, at the touch of a button — this is more convenient than turning on th...e equipment separately.

— Coaxial S/P-DIF. Interface for transmitting sound in digital format. Allows you to work with multi-channel audio up to 7.1 format inclusive. Technically an electrical variation of S/P-DIF; differs from the optical one described below, on the one hand, by greater sensitivity to electromagnetic interference, on the other hand, by a less delicate connecting cable. Note that this interface uses RCA connectors and a coaxial cable. However, unlike the "regular" analogue RCA (see above), in this case, all audio channels are transmitted over a single cable, and the wire itself must be shielded — when connected through a regular wire, there is a high probability of distortion due to interference.

— Optical. A modification of the S/P-DIF standard (see above), which involves signal transmission via a TOSLINK fibre optic cable. Being identical to the coaxial interface in terms of audio transmission capabilities, the optical connection is at the same time completely immune to electromagnetic interference, which makes it possible to achieve extremely high signal fidelity. The disadvantage of this connection is the fragility of the cable — it does not allow sharp bends and strong pressure, which can damage the fibre.

— Balanced digital (AES/EBU). Digital audio output in balanced format. This format provides noise immunity even with a long cable length, which is especially important in professional applications; in fact, the presence of an AES / EBU input indicates a rather high class device. Technically, this interface can use different connectors, but CD players usually use XLR jacks and plugs. From the "normal" (analogue) XLR, such a connection differs, in fact, in a digital format.

— RCA. Similar to the RCA outputs (see above), in this case we mean an interface for transmitting an analogue audio signal in the “one wire per channel” format, and one input is a pair of connectors for the left and right stereo sound channels.

— Control input (IR). Connector for connecting an external infrared remote control receiver. When properly placed, such a receiver will allow you to use the remote control even in places where the signal from the remote control cannot reach the main (built-in) sensor — for example, in another room. Note that not only individual sensors can be used as external receivers, but also other components of the audio system that are compatible with the remote control — for example, receivers or tuners.

— BNC. A type of coaxial connector used for various purposes. However, in this particular case, the BNC input is most often provided for working with an external clock generator responsible for timing the digital audio signal pulses. The need to use such equipment is due to the fact that when transmitting a signal between the components of an audio system, for various reasons, deviations of pulses in time may occur. This phenomenon is called "jitter". Deviations, it would seem, are very small (measured in picoseconds), but even such a small thing can significantly degrade the sound quality and increase the noise level. To avoid this, premium audio systems can use an external clock generator: by transmitting service pulses to other components, it sets the “general rhythm” under which the data packets move, and prevents desynchronization. To connect such a generator, a BNC input is usually provided. However, in some models this connector can also be used as a digital audio input, similar to the S / P-DIF described above.

— XLR. Formally, XLR is the name of a connector that has a round shape, several pins and a retainer to hold the plug in the socket. However, in this case we are talking about a very specific interface: an audio input with a three-pin plug used for balanced connection of an analogue audio signal. The peculiarity of this connection is that the cable itself plays the role of an interference filter, which allows you to transmit an audio signal with high reliability even over a rather long wire. At the same time, such reliability is rarely required for ordinary consumer audio equipment, so XLR is considered to be a professional connector. Note that, like RCA, in this case, one channel of sound is transmitted through one connector, and the standard XLR input consists of two jacks (for a stereo signal).

The power consumed by the CD player. Usually, unless otherwise noted in the notes, this refers to the power during normal operation. Note that the actual power consumption at a particular point in time may differ from this indicator — for example, when a model with its own power amplifier (see "Built-in amplifier") is operating at low volume or vice versa, when playing a song with sudden volume jumps. However, when organizing the power supply of the audio system, it is necessary to focus on this indicator.

Note that the power consumption cannot be lower than the power of the built-in amplifier (if present, see above). However, some manufacturers may go for tricks — for example, indicate power consumption only in preamplifier mode. As a result, the power consumption stated in the specifications is significantly lower than the actual value when the amplifier is turned on (and sometimes even lower than the rated power of the amplifier alone). In such cases, the actual power consumption can be estimated by adding the claimed power consumption to the power of the amplifier and taking a margin of 20 – 30% for energy losses due to non-perfect efficiency of electronic circuits. For example, for a 50 W model with a 2x60 W amplifier, this value will be about 200 ... 220 W (50 + 2x60 \u003d 170, plus a loss correction).