Comparison Yamaha A-S1100 vs Yamaha A-S2100

Most modern amplifiers have toroidal transformers - with a toroid-shaped core, in other words, a donut. This type is considered optimal for amplifiers of any level up to Hi-End: it creates a minimum of "extra" electromagnetic radiation and, accordingly, interference. Some time ago, E-core transformers were also widely used, but they are considered obsolete and are becoming less common today.

The range of audio frequencies that the amplifier is capable of handling. The wider this range, the more complete the overall picture of the sound, the less likely it is that too high or low frequencies will be “cut off” by the output amplifier. However, note that the range of sound audible to a person is on average from 16 Hz to 20 kHz; There are some deviations from this norm, but they are small. At the same time, modern Hi-Fi and Hi-End technology can have a much wider range — most often it is a kind of "side effect" of high-end circuits. Some manufacturers may use this property for promotional purposes, but it does not carry practical value in itself.

Note that even within the audible range it does not always make sense to chase the maximum coverage. It is worth, for example, to take into account that the actually audible sound cannot be better than the speakers are capable of giving out; therefore, for a speaker system with a lower threshold of, say, 70 Hz, there is no need to look for an amplifier with this figure of 16 Hz. Also, do not forget that a wide frequency range in itself does not absolutely guarantee high sound quality — it is associated with a huge number of other factors.

In itself, the signal-to-noise ratio is the ratio of the level of pure sound produced by the amplifier to the level of extraneous noise that occurs during its operation. This parameter is the main indicator of the overall sound quality — and very clear, because. its measurement takes into account almost all the noise that affects the sound in normal operating conditions. A level of 70 – 80 dB in modern amplifiers can be considered acceptable, 80 – 90 dB is not bad, and for advanced audiophile-class devices, a signal-to-noise ratio of at least 100 dB is considered mandatory.

If the specifications do not specify for which output the signal-to-noise ratio is indicated, it usually means its value for the linear input (see "RCA (par)"). This is quite enough to evaluate the quality of the device for this parameter. However, some manufacturers indicate it for other inputs — Main, Phono; see below for more on this.

signal-to-noise ratio when the amplifier is driven through the Phono input. This interface is for connecting turntables; its features are described in the “Inputs” section below, and for the meaning of any signal-to-noise ratio, see the corresponding section above.

The sensitivity and dynamic impedance of the amplifier when a signal is applied to the balanced XLR input.

Under the sensitivity of any input (except optical) is meant the lowest signal voltage at this input, at which the amplifier is able to provide normal nominal power values (see "Power per channel (8Ω)"). This parameter determines, first of all, the requirements for the signal source. On the one hand, the voltage provided by this source must not be lower than the input sensitivity of the amplifier, otherwise the latter simply will not give the claimed characteristics. However, a significant excess in voltage should not be allowed, otherwise the sound will begin to be distorted. More detailed recommendations on choosing an amplifier by sensitivity are described in special sources.

For any input other than optical, it is believed that the higher this indicator, the less distortion the amplifier introduces into the signal. The minimum level of input impedance in modern models is considered to be 10 kOhm, and in high-end devices it can reach several hundred kOhm.

The signal level and dynamic resistance (impedance) at the REC output provided in the amplifier.

This output is intended for connection to a recording device. For details, see "REC (to a recording device)"; here we note that the output signal level must be no less than the input sensitivity of the connected device, otherwise the recorded sound will turn out to be too quiet.

The design of modern amplifiers is such that this parameter primarily determines how efficiently the entire circuit works with a low-resistance load: the lower the output impedance, the easier it is to provide the necessary power at such a load. The standard value today is actually 1 kΩ (at 1 kHz); this, usually, is sufficient for most tasks solved by Hi-Fi and Hi-End class amplifiers. The need for other values arises only in special cases; for their description it is worth referring to specialized sources.

The features of the REC output are described in detail in "REC (to a recording device)" below.

Signal level and dynamic impedance provided by the device at the preamplifier output (see "Outputs" for details).

The signal level must not be lower than the sensitivity of the power amplifier (see "Type") to which the signal is received — otherwise the power amplifier will not be able to provide a normal signal level already at its outputs.

Dynamic resistance (impedance) of the preamplifier output. This value is exactly the same as the input impedance of the REC output — see the relevant paragraph above. For more information about the exit itself, see "Exits".

The number of line inputs in the amplifier design using the RCA interface. Unlike the Main input (see above), which can work with the same connectors, when connected to a linear RCA, the signal goes through all the stages of processing provided for in the amplifier — for example, adjusting the balance or frequencies (see "Adjustments"), etc. .P.

See “Amplifier Input (Main)” for details on the connector itself. Here we note that when using RCA as a linear interface, a pair of such connectors is considered one input. This is due to the fact that only one channel can be transmitted over one coaxial cable, so a pair is needed to work with stereo sound.

The number of signal inputs (of any type) determines how many signal sources can be simultaneously connected to the amplifier. Accordingly, it is worth choosing a model according to the number of inputs, taking into account the expected number of such sources: after all, it is easier to connect them all and select them through the amplifier’s remote control or control panel than to fiddle with reconnecting every time.

The number of stereo inputs in the design of the amplifier with XLR connectors having three pins and capable of providing the so-called balanced connection. Note that we are talking about an analogue line input, the signal from which passes through all additional processing circuits (for example, bass / treble settings, see "Adjustments"); do not confuse it with Main and balanced digital AES / EBU — these are different interfaces, despite the identity of the connectors.

The main advantage of this connection is that the functions of noise reduction and shielding from interference are performed by the cable itself. This moment is especially useful when it is necessary to connect system components located at a large distance from each other (from 2 m): a balanced cable maintains signal purity even at a rather large length. The quality of such a connection is at least indicated by the fact that balanced XLR is a standard interface for professional recording studios. And its presence in the amplifier, usually, indicates a high level of the device.

There are usually two XLR inputs in amplifiers — this is the minimum number needed to work with stereo sound, and more is most often not required in fact.