Comparison NAD C568 vs Pioneer PD-50

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.

Types of media, data formats and signal sources supported by the CD player.

— CD-Audio. The standard used for recording traditional Audio CDs. The CD-Audio format provides a sampling frequency of 44.1 kHz, 16-bits bits depth and 2 stereo channels. The bitrate of such a recording is 1411.2 kbit/s, which allows for very high sound quality (for comparison: in the case of MP3 files, 320 kbit/s is considered very good, and for lossless recording in the FLAC format, 950 kbit/s is quite enough With). And the maximum total track length for a full-size disc is just under 80 minutes. Thanks to all this, Audio CDs do not lose popularity among audiophiles, and this format is supported by all modern CD players (which, in fact, explains the name of this class of equipment).

- MQA-CD. An audio format that uses MQA (Master Quality Authenticated) technology from the American company Meridian Audio for audio encoding. It allows you to preserve the original audio quality while compressing files and restoring them - in the case of standard CD media, MQA-CD provides sound that is as close as possible to high-quality audio formats.

- MP3/WMA. MP3 and WMA are the most popular audio file formats used in modern consumer electronics. They can be recorded on optical discs, USB drives, and built-in storage devices. At the same time, in audio equipment, including CD players, support for both of these sta...ndards is most often found, and in terms of key features and sound quality they are similar - which is why MP3 and WMA in this case are combined in one point. Of the mentioned features, it is worth noting, first of all, that when encoding sound, these standards use the so-called. lossy compression: individual parts of the audio stream are transmitted with reduced accuracy, or even drowned out altogether. Thanks to this, the files are small in size; and the trimmed parts are selected in such a way that the impact on the overall sound quality is minimal, and when listening on ordinary household audio equipment (such as computer speakers or a portable player), the loss of quality is practically unnoticeable. But on Hi-Fi and Hi-End audio systems (and CD players are precisely designed for such systems), the difference in sound can be clearly audible, although here a lot depends on the subjective characteristics of the listener.

- SACD. The Super Audio CD format is a further development and improvement of the “regular” CD-Audio described above. Thanks to the use of new technologies, the number of audio channels available for one track has increased to 6 (which makes it possible to record not only stereo, but also multi-channel 5.1 audio on SACD), and the sampling frequency has increased to 2822.4 kHz (64 times higher than on Audio CD). In addition, sound can be recorded with different parameters - for example, part of the disc in 5.1, part in stereo 2.0. On such a disc, with several recording zones, the maximum sound duration reaches 109 minutes, and if there is only one recording zone - 180 minutes. It is worth considering that the SACD format itself cannot be read by conventional CD drives. And although “hybrid” SACD media, compatible with conventional CD drives, have become quite widespread, all the capabilities of this format can only be realized on a compatible player.

- DVD. An optical disc format that replaced CDs. In the case of CD players, support for this format usually implies the ability to play sound recorded using the DVD-Audio standard. This standard provides a bits depth of up to 24 bits, a sampling frequency of up to 192 kHz and the ability to work with 6 audio channels (5.1, except for recording at the maximum sampling frequency). And models with DVD drives that support MP3/WMA can usually read these files from DVDs. The capacity of a standard single-sided DVD is 4.7 GB, there are double-sided and double-layer media; and the duration of DVD-Audio recording depends not only on the type of disc, but also on the sound quality.

- AM/FM radio. The ability to use a CD player to receive AM and FM radio broadcasts in analog format (support for digital broadcasting is indicated separately - see below). The FM band allows you to transmit stereo sound in fairly good quality; True, the transmission range is limited by line of sight, but this is quite enough to cover even a fairly large city. Because of this, this standard is used by the vast majority of urban music stations. AM, in turn, has a much greater range, but is inferior in sound quality and does not support stereo broadcasts. Therefore, most of these stations are “talk”, and the standard itself is much less popular than FM - to the point that some models of CD players can only be equipped with FM tuners, without AM support (but not vice versa).

- DAB radio. Possibility of using a CD player to receive DAB digital radio broadcasts. The practical advantages of digital radio broadcasting over analogue include good range and high sound quality, due, in particular, to the almost complete absence of interference: the sound is either heard clearly and cleanly, or disappears altogether. In addition to the original DAB, the improved DAB+ standard is on the market; “plus” tuners are capable of receiving “regular” DAB broadcasts, but not vice versa. In any case, it is worth considering that in the CIS countries this type of radio broadcasting is still only in its infancy and has not yet become widespread. Therefore, before buying a CD player with a digital tuner, it doesn’t hurt to make sure that such broadcasting is available in your region (or at least planned to be launched in the near future) - otherwise you may overpay for unnecessary equipment.

— Network streaming audio. The ability to play network streaming audio with a CD player - in other words, playing music directly from the Internet, from specialized services like Last.FM or Grooveshark. The name “streaming” is due to the fact that during playback there is a stream of data through the network connection, which is converted by the player into sound; Simply put, each file is played directly from the network, there is no need to download it to local storage like a flash drive. And the main difference between such sound and Internet radio (see below) is that in this case the customer controls the playback. Essentially, working with streaming audio is similar to working with a regular player, except that the content being played is not in the player itself, but on a network resource. This feature by definition requires a connection to computer networks; Most often, a Wi-Fi module (see “Interfaces”) or a LAN connector is used for this purpose.

— Internet radio. The ability to use a CD player to receive and play Internet radio broadcasts. This feature is similar in many ways to the network audio described above - in particular, it requires a network connection to work, and the data is transmitted in streaming format; however, here the broadcast is similar to regular radio broadcasts and is controlled not by the customer, but by the radio station staff. In fact, many large stations broadcast their programs not only on traditional airwaves, but also via the Internet; There are also specialized projects that broadcast only on the Internet. In general, the choice of Internet programs is much wider than for conventional radio broadcasting - after all, such radio has no range restrictions. And the players themselves may provide additional tools for managing such broadcasting - for example, catalogs, search by genre, language, etc.

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).

Sampling frequency of a digital-to-analogue converter (DAC) installed in a CD player.

A DAC is an indispensable element of any system designed to reproduce digital sound. Such a converter is an electronic module that translates sound information into analogue pulses fed to speakers through amplification stages. The technical features of such a conversion are such that the higher the sampling rate, the better the signal at the output of the DAC, the less it is distorted during conversion. And in the case of CD players, this indicator must also be no lower than the sampling rate of the reproduced digital sound — otherwise the device simply will not be able to "digest" digital data from the media. So, an indicator of 92 – 96 kHz allows you to listen to CD-Audio (sampling frequency 44.1 kHz), but for DVD you need at least 192 kHz. In the most advanced DACs, the sampling rate can be 384 kHz. The latter, however, is rare: in most cases, high frequency is not critical, and such electronics are expensive.

Another indicator that determines the overall quality of the digital-to-analogue audio signal converter. For details on the converter, see "DAC Sampling Rate"; here we note that the bit depth is standardly expressed in bits, and the higher it is, the more accurately the signal at the output of the DAC corresponds to the original signal and the less distortion is introduced into it. In the case of CD players, 24 bits is considered the minimum necessary and at the same time quite sufficient; higher values — 32 bits — are rare, only in premium-level equipment.

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 ratio between the level of the useful signal and the level of extraneous noise at the output of the player.

This indicator describes the total amount of extraneous noise (of any origin) that affects the sound quality: the higher the signal-to-noise ratio, the less such noise and the clearer the sound, which is especially important for Hi-Fi and Hi-End systems. The minimum indicator for CD players is 85 – 90 dB, indicators up to 100 dB can be considered good, up to 110 dB — good, more than 110 dB — excellent.

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.