This year has been rich with new brands and models of CD-players. Recently a lot of new names have appeared in the domestic market, and the giants of electronics have presented a lot of novelties to the audiophiles.
A music CD player is quite a conservative product, so we can’t speak about any evident tendencies, any appreciable general idea, which prevail in this sector of electronic components. However, perhaps there is still something that unites CD-players – each of them has its own face, as well as a unique character of sound.
AS WE TESTED
Testing of each player was conducted in two independent stages. The first is a subjective evaluation, which consisted in listening to the turntable. The second was a hardware test of the turntable.
Sound
The main attention we paid to the stage of subjective testing, which was decisive in assessing the CD-player. The listening was conducted in the laboratory of Video&Audio magazine, which is well soundproofed, and whose walls are specially designed to reduce unwanted reverberation and sound distortion. Each CD player was listened to under the same conditions, complete with the same electronic components and on the same musical material.
For the test we used a pair of Triangle Heliade speakers, a Parasound Model 2100 preamplifier, a Parasound Model 2125 stereo power amplifier, and Nordost interconnect and speaker cables. For listening we used CDs with musical compositions conventionally of four big directions – classical, jazz, rock and electronic/pop music, as the most common and frequent genres. It is known that each of these directions has its own unique character of sound, which, first of all, is determined by the distribution of sound energy, and hence musical information by frequencies.
For example, rock music tends to have a lot of bass components, so the ability of a CD player stereo unit to reproduce low-frequency sounds of high quality becomes very important. In pop music, the bass is mostly rhythmic, and most attention is paid to conveying the middle, and especially the vocal performance. Classical music, especially symphonic, has a wide sound spectrum and a very high information content in different frequency ranges. In short, each genre gives a new appreciation for the CD player.
The classics were represented by excerpts from Wilhelm Richard Wagner’s operas “Lohengrin,” “Tannhäuser,” and “Der Ring des Nibelungen”. The choice is due to the fact that symphonic music allows you to evaluate the player’s ability to convey the scene and build the image of a large musical ensemble. Furthermore, classical symphonies, particularly Wagner’s symphonies, are very rich in intensity changes and numerous forte and pianissimo moments, which means that like no other genres they allow us to evaluate the dynamic characteristics of the stereo path and its ability to convey the loud and soft moments of the music in both sequential and single-moment fashion.
Jazz was mostly represented by small ensembles of several voices-contrabass, piano, saxophone, and drums, plus sometimes more vocals. Jazz, just like classical music, allows you to appreciate the dynamic capabilities of the stereo track. In addition, these two genres allow us to evaluate the ability to realistically reproduce the timbres of a variety of “live” instruments, the main tones of which are localized in different areas of the frequency range of the sound.
Rock music was represented mainly by Metallica and Deep Purple compositions of different years. Sometimes we listened to some experimental compositions by Ben Vaughn and Sheryl Crow. Pop music was represented by a wide variety of songs and artists from ABBA to Britney Spears. There were also CDs with purely electronic compositions, mostly in the ambient style. Electronic music reveals the stereo circuit’s ability to convey complex synthesized timbres.
Electronic compositions are often very saturated with a variety of sounds that are designed to create a particular atmosphere. The transmission quality of such sounds allows you to appreciate the player’s ability to create complex musical images, for which sometimes there may be no exact verbal description, but which can be understood either intuitively or on the basis of existential experience. It is important, that mostly CDs, compilations of compositions of one author/band, but recorded in different studios and at different times, were used. This allows you to abstract as much as possible from the peculiarities of a particular recording studio.
Measurements
The character of the sound is determined by all elements of the sound reproduction path, from the CD player optical disc drive to the loudspeakers. The ability of CD-player to produce adequate sound is largely characterized by the parameters of its stereo path. Measurements were made using a sound card and the original author’s software, which allows capturing and analyzing audio signals in real time. The set of programs provides computation of instantaneous audio spectrum by means of fast Fourier transform using Chebyshev, Kaiser and Bessel windows, calculation of harmonics coefficients and amplitude-frequency response.
In the process of testing we also used original author’s disks with samples of pulses, meanders, harmonic tones of different frequency, linear and logarithmic sweeps and different colored noises from white to brown . The final aim of the measurements is to obtain the characteristics of the audio signal generated by the stereo path of the CD player. First, it is the amplitude-frequency response AFR , which characterizes the tonal characteristics of the sound signal, the ability to adequately reproduce its level at different frequencies. The more linear the AFC, the better.
The second point of interest is the harmonic distortion factor, not just at one frequency 1 kHz , as it is usually given by the manufacturers in the datasheet, but over the whole frequency range and differentiated by harmonics from the second to at least the 11th. Sweep of the harmonic coefficient by frequency allows to estimate its linearity, i.e. the uniformity of sound transmission in terms of nonlinear distortions.
And differentiation by harmonics allows you to see in which area the harmonic distortion would fall, for example, in the bass. If the sound is in the region of e.g. 90 Hz, the second harmonic will give interference in the region of 180 Hz, the fifth harmonic in the region of 450 Hz, and the eleventh harmonic in the region of 990 Hz. By determining the number of harmonics and the frequency range of the sound, you can see where the maximum harmonic distortion occurs. Naturally, it should be done taking into account the hearing sensitivity curve.
Results
The final score was deduced from the set of subjective characteristics identified while listening to one or another CD-player. Measurements were auxiliary in nature and did not influence subjective evaluation. It is known that naturalness of sound, degree of stereo images localization, realistic transfer of musical space, quality of scene building and, finally, informative transfer and comfort of music are determined by rather small set of sound characteristics, the most important of which are transparency, detail, corporality, mobility and homogeneity of sound.
Transparency characterizes the clarity of sound, that is, the absence of all kinds of noise and interference caused by the stereo path. Detail refers to a stereo unit’s resolution, that is, its ability to deliver as much musical information as possible per unit frequency range per unit time. The corporeality is characterized by the undistorted timbres of musical instruments, the lack of sound coloration.
Sound mobility is determined by the dynamic characteristics of the stereo path, its ability to correctly reproduce sounds of minimum and maximum intensity both sequentially and simultaneously, as well as the ability to correctly convey the introduction of musical instruments. And finally, uniformity determines the balance of sound in the frequency range.
Is it worth investing in a CD player when streaming platforms and digital music seem to be the norm nowadays?