DAC
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.
Playback
Types of media, data formats and signal sources supported by the CD player.
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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.
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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.Frequency range
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.
Signal to noise ratio
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.
Harmonic distortion
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.
Power consumption
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).