Comparison FiiO BTR1K vs FiiO BTR3

The sampling rate of the digital-to-analogue converter (DAC) installed in the amplifier. Recall that such a converter is responsible for converting digital audio into an analogue audio signal, which is then processed by the main amplifier and fed to the headphones (or other analogue audio device).

The sound in digital form is most often recorded as follows: the original sinusoid of the analogue audio signal is divided into separate sections (samples) — “steps” of a certain length and height, and each of these steps is encoded with its own set of numbers. The sampling rate determines how many such steps there are in a certain section of the original audio signal. Accordingly, the higher this frequency, the more accurately the digital record corresponds to the original signal; on the other hand, an increase in the number of samples per unit of time increases the volume of files and increases the requirements for the hardware power of digital circuits.

Specifically, for a DAC, the native sampling rate of such a module is, in fact, the maximum sampling rate of the incoming digital signal that the converter can effectively handle. With higher input values, the sound quality will at best be limited by the capabilities of the DAC, at worst, the amplifier will not be able to work correctly at all. Anyway, higher numbers in this paragraph (ceteris paribus) mean a more advanced and high-quality converter; on the other hand, this moment significantly affects the...cost, and you can evaluate all the capabilities of a high-end DAC only on audio materials of the appropriate quality.

As for specific numbers, the lowest value that can be found in headphone amplifiers is 44 kHz. According to the laws of physics, it is this sampling frequency that is the minimum necessary for the full transmission of all human-audible sound frequencies (16 — 22,000 Hz), and it is this frequency that is used in the Audio CD format. Many models provide values in 96 kHz and 192 kHz (this is already enough to work with different types of DVD-Audio), and in the most advanced devices this figure can reach 384 kHz and even 768 kHz.

The capacity of the digital-to-analogue converter (DAC) installed in the amplifier. Recall that such a converter is responsible for converting digital audio into an analogue audio signal, which is then processed by the main amplifier and fed to the headphones (or other analogue audio device).

The sound in digital form is most often recorded as follows: the original sinusoid of the analogue audio signal is divided into separate sections (samples) — “steps” of a certain length and height, and each of these steps is encoded with its own set of numbers. In this case, the "height" (level) of each step cannot be an arbitrary value — a specific value is selected from a specific list. The bit depth determines how many options this list contains: for example, an indicator of 16 bits means a list of 2 to the power of 16, that is, 2 ^ 16 \u003d 65536 level options. Accordingly, the higher the bit depth — the closer the level of each sample will be to the level of the corresponding section of the sinusoid, the smaller the deviation from the original signal in cases where the original level falls between fixed values. Thus, a high bit depth has a positive effect on the quality and reliability of the sound; on the other hand, it significantly affects the volume of audio materials and the requirements for processing power of the equipment for their processing.

Specifically, for a DAC, the native bit depth of such a module is, in fact, the maximum bit width of the inc...oming digital signal that the converter is able to effectively handle. With higher input values, the sound quality will at best be limited by the capabilities of the DAC, at worst, the device will not be able to work correctly at all. Anyway, higher numbers in this paragraph (ceteris paribus) mean a more advanced and high-quality converter; on the other hand, this moment significantly affects the cost, and you can evaluate all the capabilities of a high-end DAC only on audio materials of the appropriate quality.

As for specific values, the standard options in modern headphone amplifiers are 16 bits, 24 bits and 32 bits. The first value is used, in particular, for the Audio CD format, the second is found in the lossless APE and ALAC formats, and 32 bits may be required to work with FLAC and certain high-end standards.

The nominal impedance (impedance) of the headphones for which the amplifier was originally designed.

Modern headphones can have different impedance. In particular, among the most popular options are 16 ohms and 32 ohms, and advanced models have values from 300 ohms and even from 600 ohms. High-resistance is considered to be "ears" with a resistance of 100 ohms. These characteristics improve the purity of the sound, but require increased signal strength — and built-in amplifiers in handheld devices, computer audio cards, etc. usually have difficulty with this. Therefore, external amplifiers are often used for this very purpose — to effectively "shake" high-end headphones with high impedance. For the same reason, some of these amplifiers are not compatible with low-impedance “ears”: there are many devices that require headphones with an impedance of at least 32 ohms, or even higher, and in some models the lower limit of the operating range can reach 100 ohms. As for the maximum resistance, the range of its values is very impressive — from 32 ohms in relatively simple portable "amps" to thousands and even tens of thousands of ohms in high-end stationary models.

Anyway, you should not violate the manufacturer's recommendations for headphone impedance. If the resistance of the “ears” is too low, at best, the sound will be s...ubject to noticeable distortion, at worst, equipment failure and even fire may occur. Too high resistance, in turn, not only reduces the volume, but also worsens the frequency response.

Rated power delivered by the amplifier when connected to headphones (or other load) with an impedance of 16 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. And 16 ohms is a rather low resistance indicator even for low-resistance "ears"; such characteristics are provided mainly in general-purpose headphones designed for pocket gadgets with low-power amplifiers.

As for the choice for specific power values, it depends on the sensitivity of the headphones used, as well as on the sound pressure level (in other words, loudness) that 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". At the same time, it is worth noting that at 16 ohms, even the most low-power modern “amps” are capable of delivering about 20 mW — this is enough to drive headphones with a sensitivity of 88 dB (far from the highest figure) to a vo...lume of 105 dB (the minimum value recommended for a complete listening experience). And in most amplifiers, when operated with a given impedance, they provide much more power. So paying attention to this point and going into the calculations makes sense mainly either with low sensitivity of the "ears" (less than the mentioned 88 dB), or if you want to end up with a level above 105 dB.

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.).

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.

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.

The presence of a Bluetooth module in the amplifier for direct wireless communication with other devices - primarily with audio sources that also support this technology (for example, a smartphone, tablet or laptop).

The main convenience of Bluetooth amplifiers is, first of all, the absence of additional wires, which can create various inconveniences. At the same time, the range of wireless communication is usually at least several meters. On the other hand, during normal transmission via Bluetooth, the digital audio signal is heavily compressed, which worsens the sound quality. To correct the situation, Bluetooth models may include aptX technology, which increases the purity of the signal almost to the level of wired Audio CD (or even Hi-Res Audio - in the aptX HD version); however, such functionality significantly affects the cost, and sophisticated music lovers often easily notice the difference between aptX and a wired connection.

In light of all the above, Bluetooth does not make sense to install in stationary equipment, so nowadays such modules are used only in portable amplifiers (see "Type"). At the same time, some of these models are positioned not so much as amplifiers, but as Bluetooth adapters for wired headphones. Nevertheless, such a solution can be a good alternative to classic wireless headphones: decent wired "ears" in combination with a Bluetooth amplifier can provide higher sound quality at a comparable,...or even lower cost, and often such a set turns out to be even more "long-playing" in terms of work without recharging.

Initially, sound transmission via Bluetooth provides a rather strong signal compression, which can greatly spoil the impression when listening to music. To eliminate this shortcoming, various technologies are used (the most popular of which is the aptX codec). Of course, in order to use any of the technologies, it must be supported not only by the amplifier, but also by the Bluetooth device with which it is used.

— aptX. A Bluetooth codec designed to greatly improve the quality of Bluetooth audio. According to the creators, it allows to achieve quality comparable to Audio CD (16-bit/44.1kHz). The benefits of aptX are most noticeable when listening to high-quality content, but even on regular MP3 it can provide a noticeable improvement in sound.

aptX Low Latency. A specific variation of the aptX described above, designed not so much to improve sound quality, but to reduce delays in signal transmission. Such delays inevitably occur when working via Bluetooth; they are not critical for listening to music, however, when watching videos or playing games, there may be a noticeable out of sync between the image and sound. The aptX LL codec eliminates this phenomenon by reducing latency to 32ms, a difference that is imperceptible to human perception (although it is still too high for serious tasks like studio work with sound).

— AAC. A codec used primarily in Apple portable technology to improve Bluetooth audio. In this sense, it is similar to aptX...(see relevant paragraphs), but noticeably inferior to it in terms of capabilities: if the sound of aptX is compared with Audio CD, then AAC is at the level of a medium-quality MP3 file. However, this is quite enough for listening to the same MP3s, the difference becomes noticeable only on more advanced formats.