Power (32 Ohm)
Rated power delivered by the amplifier when connected to headphones (or other load) with an impedance of 32 ohms.
By itself, the rated power is the highest average power that the device is capable of delivering for a long time without overloading; individual "jumps" of the signal may have a higher level, but in general, the capabilities of the amplifier are determined primarily by this indicator. At the same time, the physical features of the audio equipment are such that the actual power delivered to the load will depend on the resistance of this load. Therefore, in the characteristics of headphone amplifiers, data is often given for different impedance values. A resistance of 32 ohms allows you to achieve quite good sound quality by the standards of low-impedance headphones, while it is not so high as to create problems for the built-in amplifiers of smartphones and other compact equipment. Therefore, most wired general-purpose (non-professional) headphones are made precisely in this resistance, and if the amplifier characteristics generally indicate power for a certain impedance, then most often it is for 32 ohms.
In the most modest modern amplifiers, the output power at this impedance is
between 10 and 250 mW ; values of
250 – 500 mW can be called average,
500 – 100 mW are above average, and the most powerful models are capable of delivering
...f="/list/788/pr-19429 /">more than 1000 watts. The choice for specific power indicators depends on the sensitivity of the headphones used, as well as on the sound pressure level (in other words, loudness), which is planned to be achieved by the amplifier. There are special formulas and tables that allow you to calculate the minimum required power for a certain volume at a given sensitivity of the "ears". However, in the case of 32-ohm headphones, it does not always make sense to "get into the calculations." For example, the mentioned 10 mW is more than enough to drive headphones with a modest sensitivity of 96 dB to a volume of more than 105 dB — this is already enough to listen to music at quite a decent volume. And in order to achieve the same "ears" level of 120 dB, which provides a full perception of the loudest sounds (like explosions, thunder, etc.), you need to give out a power slightly higher than 251 mW. So in fact, you have to pay attention to this characteristic and resort to calculations / tables mainly in those cases when you have to use 32 Ohm headphones with a relatively low sensitivity — 95 dB or less.
Frequency range
Frequency range supported by the output amplifier; in other words, the range that this model is capable of delivering to headphones or another analogue audio device.
Theoretically, the wider the frequency range — the richer the sound of the amplifier, the lower the likelihood that the lower or upper edge of audible frequencies will be “cut off”. However, when evaluating this parameter, several nuances should be taken into account. Firstly, the average person is able to hear frequencies from 16 to 22,000 Hz, and with age, these boundaries gradually narrow. However, headphone amplifiers often have wider operating ranges, and they are very impressive — for example, for some models, a set of frequencies from 1 Hz to 60,000 Hz, or even up to 100,000 Hz, is claimed. Such characteristics are a kind of "side effect" from the use of high-end sound processing circuits; from a practical point of view, these numbers do not make much sense, but they are an indicator of the high class of the amplifier and are often used for advertising purposes.
The second nuance is that any headphones also inevitably have their own frequency limitations — and these limitations can be more significant than in an amplifier. Therefore, when choosing, it's ok to take into account the characteristics of the headphones: for example, you should not specifically look for an amplifier with an upper frequency limit of the full 22 kHz, if in the headphones that you plan to use with it, th...is limit is only 20 kHz.
In conclusion, also note that an extensive frequency range in itself does not guarantee high sound quality — it largely depends on other factors (frequency response, distortion level, etc.).
Signal to noise ratio
The ratio between the overall level of the desired signal produced by the amplifier and the level of background noise resulting from the operation of electronic components.
It is impossible to completely avoid background noise, but it is possible to reduce it to the lowest possible level. The higher the signal-to-noise ratio, the clearer the sound produced by the device, the less noticeable its own interference from the amplifier. In the most modest amplifiers from this point of view, this indicator ranges
from 70 to 95 dB — not an outstanding, but quite acceptable value even for Hi-Fi equipment. You can often find higher numbers —
95 – 100 dB,
100 – 110 dB and even
more than 110 dB. This characteristic is of particular importance when the amplifier operates as a component of a multi-component audio system (for example, "vinyl player — phono stage — preamplifier — headphone amplifier." The fact is that in such systems the final noise of all components at the output is summed up, and for sound purity it is extremely it is desirable that these noises be minimal
Separately, it is worth emphasizing that a high signal-to-noise ratio in itself does not guarantee high sound quality in general.
Coef. harmonic distortion
The coefficient of harmonic distortion that occurs during the operation of the amplifier.
Any electronic circuits are inevitably subject to such distortions, and the quality and reliability of the sound at the output depends on their level. Accordingly, ideally, the harmonic coefficient should be as low as possible. So, as a general rule, a level of 0.09% and below (hundredths of a percent) is considered good, and a level of less than 0.01% (thousandths of a percent) is excellent. The exception is lamp devices: higher values \u200b\u200bare allowed in them (in tenths of a percent), however, this point in many cases is not a drawback, but a feature (for more details, see "Lamp").
It is also worth noting that a low harmonic coefficient is especially important when using the amplifier as part of multicomponent audio systems — for example, when listening to music from a vinyl player with an external phono stage. The fact is that in such systems the sum of distortions from all components affects the final sound — and it, again, should be as low as possible.
Bass control
The presence of a separate
low-frequency control in the amplifier.
As the name suggests, this feature allows you to change the volume of the bass sound separately from the rest of the frequency range. In fact, such a regulator is the most simplified version of the equalizer (see below). A similar function is performed by the treble control, and in some models these functions are combined; however, it is much more common to find only bass adjustment, without treble adjustment. This is due to the fact that for many listeners, bass saturation is one of the key parameters of sound quality; but the adjustment of the treble in this sense is not so important.
Battery life
Operating time of the battery-powered amplifier (see "Type of power") on one battery charge.
Note that this indicator is rather conditional, since the characteristics most often indicate a certain average operating time: at relatively low power, with minimal use of additional functions, etc. So in fact, the battery life may differ from the claimed one by one , and the other side — depending on the features of the application. Nevertheless, in general, this parameter well illustrates the real capabilities of the device, according to the claimed operating time, it is quite possible to evaluate the overall battery life of the amplifier and compare it with other models: the differences in the claimed figures will most likely correspond to the differences in the real battery life (ceteris paribus ).
