Comparison Marshall Acton Multi-Room vs Teac SL-D910

— Built-in memory. Own memory allows you to store and play music and other content directly through the audio system, without the use of external media (which can be damaged or lost). Such memory can be based on hard drives or SSD modules; the first option provides good capacity at a low cost, the second one is faster and more reliable.

— USB port. A classic USB port, which in this case is usually used for flash drives, external hard drives, or other devices with a mass storage function, such as miniature audio players. USB functionality includes at least direct playback, but other options may be provided, such as file sharing with built-in memory (see above). In addition, if necessary, a connected device (for example, the same pocket player) can also be charged through this port.

— Card Reader. Device for reading information from memory cards; such carriers are very popular in modern electronics. Most often, card readers are designed for various versions of SD or microSD cards, but other options may occur; this point in each case should be clarified separately. The purpose of this function is very similar to the USB port described above: it is primarily used for direct playback, but other functions may occur.

— CD. The presence of a CD drive means at least the ability to work with...discs recorded in the CD Audio format (up to 74 minutes of high-quality sound, divided into tracks). In addition, modern audio systems often provide support for discs with MP3 files; in this format, you can fit a whole collection of albums on one disc, but the sound quality is lower.

— DVD. Ability to work with DVD optical discs. These discs are much more capacious than CDs, which allows you to record not only music in high quality, but also movies; in fact, most often DVDs are used precisely as media for storing video. This standard is also gradually being replaced by more modern media, but it is still very far from the final "death". Note that DVD drives are also compatible with CDs, but not vice versa.

— Blu-ray. A high-capacity optical disc format that emerged as a standard for storing high-definition video with multi-channel audio (DVD's capabilities were no longer sufficient for such volumes of data). Blu-ray discs are almost never used for audio content. Because of this, and also for a number of other technical reasons, support for such media is extremely rare in audio systems.

— Vinyl records. Built-in player for playing music from vinyl records. Technically, such media are completely obsolete, but they still have a lot of loyal fans. In addition, quite a few audio systems with this feature support recording to USB (see "Advanced"); this can be useful for owners of "vinyl" who want to transfer their record libraries to more modern media.

In addition to those described above, other types of media may be provided in modern audio systems. For example, some models are equipped with USB type B inputs, thanks to which they can connect to a computer via a USB connector and work as computer acoustics with advanced features (such as copying music from a PC to external media or vice versa).

The type of tuner installed in the audio system. In this case, the type refers solely to the way of setting; for digital broadcasting, see "Tuner bands".

— Analogue. Tuning to the desired frequency in such tuners is carried out mechanically, usually using a wheel and a scale with a slider. Analogue receivers are simpler and cheaper than digital ones, but they are less accurate — you can only approximately set the frequency with such control. This can make it difficult to tune in with numerous stations in a small frequency range (especially for FM broadcasts in large cities). In addition, these tuners "do not know how" to memorize stations. Therefore, analogue modules are used relatively rarely; they are mainly equipped with low-cost audio systems, as well as devices in the “retro” style, where a mechanical scale and a tuning knob are mandatory design elements.

— Digital. The direct tuning of the tuner in such models is performed by an electronic circuit; the user only sets the required frequency by giving commands to the electronics using buttons, a rotary wheel or other control element. Digital tuners are more advanced than analogue tuners, they are more accurate in tuning and can support various additional features — station memory (see below), automatic search, etc.

Radio bands accepted by the music centre tuner. To date, the most common support for such ranges:

— FM. Part of the ultra-short wave (VHF) band between 87.5 MHz and 108 MHz. It uses frequency modulation, which allows you to broadcast music in stereo with a fairly high sound quality, as well as transmit RDS signals (see RDS). At the moment, most music radio stations in the CIS broadcast in this range, as a result of which FM is supported in the vast majority of audio systems. The disadvantage of this option is the limited reception area — a maximum of several tens of kilometers from the transmitter — so FM broadcasts can usually be listened to within the same city and surrounding areas.

— AM (from the English amplitude modulation — amplitude modulation) — broadcasting using amplitude modulation. Usually this term means broadcasting on medium waves in the range of 520-1610 kHz; most consumer AM receivers are designed for these same frequencies. The reception range of AM stations can be hundreds of kilometers, but the sound quality is lower than on FM, so this format is broadcast mainly by “talk” and news radio stations.

— VHF. In this case, the sub-band 65.9-74 MHz is meant, using the so-called OIRT modulation. In this format, VHF broadcasting was originally conducted in the countries of the Soviet Union and Eastern Europe, but at the moment it is not very popular due to the development of FM. VHF is technically similar to FM (see above), the...main differences are the occupied frequency band and the inability to transmit RDS signals in VHF (see RDS).

— DAB+. DAB is an abbreviation for Digital Audio Broadcasting, i.e. "digital broadcasting"; and "+" means an improved version of this standard. Formally, DAB + is not only a range, but also a signal transmission format: unlike all the options described above, it, as the name implies, is digital. This gives a number of advantages over traditional transmitters — in particular, a greater range with less power and high quality of the broadcast sound. In addition, this sound is practically not subject to distortion: weak interference does not affect its quality, and when the transmitter power is critically reduced, the signal is not distorted, but disappears entirely. The latter, however, can be written down as disadvantages; but the really significant drawback of this option is perhaps its low prevalence (so far) in the CIS countries. Technically, such broadcasting can be carried out in any band above 30 MHz, but in fact several options are used (depending on the country) related to the VHF band. Note that DAB+ tuners are capable of receiving original DAB radio broadcasts, but not vice versa.

The number of radio stations that can be stored in the tuner's memory.

By itself, the memory greatly simplifies the work with the tuner. Instead of having to manually search for your favorite stations each time, it is enough to “remember” them and in the future simply select the desired wave from the list in the receiver’s memory. The number of memory cells in modern audio systems can reach several tens; this will be especially useful for residents of metropolitan areas, where there are many stations on the air, as well as for those who often have to travel and tune the receiver to local frequencies.

The total sound power provided by the audio system at maximum volume, in other words, the total power of all the speakers provided by the device (including the subwoofer).

The higher the power, the louder the system will sound and the larger the area it can cover. On the other hand, high power significantly affects the price, dimensions, weight and power consumption of the device. In addition, when evaluating and comparing according to this indicator, it is worth considering some nuances. Firstly, some manufacturers go to the trick and give in the characteristics not the average, but the peak sound power; such numbers can be quite impressive, but they have very little to do with real loudness. So if it seems to you that the claimed power is too high, it's ok to clarify what exactly is meant in this case. Secondly, when comparing, it is worth considering the presence of a subwoofer — it plays an auxiliary role, but it can account for more than half of the total system power. Because of this, for equal total power, a device with a subwoofer may be quieter than a model without a subwoofer: for example, a 2.0 40W system will have 20W per main channel, while a 2.1 40W model may have 20W per subwoofer, and only 10 watts for the main speakers.

Nominal sound power (see "System power") on each of the main channels of the audio system. This indicator is most often indicated in models with a subwoofer (see "Number of channels"); knowing it, you can estimate the power distribution between the main speakers and the subwoofer.

The subwoofer power rating is a bass driver used in 2.1 and 3.1 systems (see "Number of Channels"). For rated power in general, see "System Power"; and in the case of a subwoofer, this indicator allows you to evaluate the volume and richness of the bass produced by the audio system, as well as the ratio between the power of the main channels and the “subwoofer”).

The total frequency range reproduced by the acoustics of an audio system. Measured from the lower threshold of the lowest frequency speaker to the upper threshold of the highest frequency: for example, in a 2.1 system with main speakers at 100 – 22000 Hz and a subwoofer at 20 – 150 Hz, the total value will be 20 – 22000 Hz.

In general, the wider the frequency range, the fuller the reproduced sound will be, the less low and high frequencies will be lost due to insufficient acoustic capabilities. On the other hand, do not forget that the actual sound quality also depends on a number of other parameters — primarily the frequency response. In addition, human audible frequencies range from 16 Hz to 22 kHz; deviations from these values are very small, and the upper limit also decreases with age. Therefore, from a practical point of view, it does not make sense to provide too large a frequency range; and impressive performances like 10 – 50000 Hz, found in top-class models, are usually more of a kind of "side effect" of high-quality speakers (and at the same time — a marketing ploy) than a really significant moment.

The presence of an equalizer function in the audio system.

Equalizer allows you to change the timbre of the sound by adjusting the volume for individual frequency bands. The simplest version of this adjustment provides 2 bands (high and low frequencies), but most often there are more bands. Anyway, the equalizer can be useful both for fine-tuning the sound to your own preferences, and for compensating for the shortcomings of external or standard acoustics, connected headphones, etc. - for example, if the speakers "fail" certain frequency bands. In addition, many audio systems have a set of equalizer presets (presets), usually designed for different styles of music - "Classic", "Rock", "Pop", etc. You may also be able to create and edit your own presets.