The sampling rate is the frequency at which a signal is sampled. For example, at a frequency of 2 Hz, 2 data points are acquired per second. The physical rule for the sampling rate is that it must be twice as high as the frequency to be sampled. Since human hearing stops at about 20k Hz, a sampling rate above 40k Hz is sufficient to eliminate the losses caused by sampling. Today, 48k Hz is usually used. You can also find 96k Hz or higher sampling rates. Whether this is audible is debatable. The Hypersonic Effect describes the phenomenon and it is claimed that the auditory bones perceive up to 50k Hz. We use ADC and DAC with 48k Hz.

Active noise cancellation uses microphones and speakers to filter out background and ambient noise. The technology is primarily used in over-ear and in-ear headphones. As a result, you can no longer hear the background noise on an airplane, for example, and the flight becomes more pleasant. 

In addition to low-noise music enjoyment, you can also simply ensure more silence. Likewise, the transparency mode can be used to specifically mix in outside noise when jogging, so that you can hear cars approaching from behind, for example.

Active speakers are characterized by the fact that the amplifier is already built in. This has the advantage that music sources, e.g. a CD player or record player, can be connected directly and you don't need any other devices. Likewise, a cell phone can normally be streamed directly via Bluetooth.

Another advantage is that each chassis (i.e. tweeter, midrange or woofer) has its own power amplifier, which leads to more precise sound dynamics with rich bass. Especially the bass needs a lot of power.

For the same reason, the crossovers in the active speakers are better, because the power amplifiers are behind them and better filters can be built with active components.

Audiophile, or fidelity, is the high quality reproduction of music. An audiophile is therefore concerned with the most faithful reproduction of music possible and optimizes his music system in this way. Many spend a lot of money for the optimal or also faithful reproduction of music. However, we all have subjective hearing, which is why not everything that pleases one person also pleases another. Like the frequency response of loudspeakers, the frequency response of the ear also differs from person to person, which is why the perception of music or sounds is different.

Many audiophiles largely reject digital technology and prefer to listen to analog records, which are transmitted via tube amplifiers to the speaker with an analog crossover. Likewise, special (and often very expensive) cables are used for faithful transmission, which are supposed to suppress various effects, such as the Hall effect. For this reason, much of what is called audiophile is also relegated to the realm of the esoteric. Note: Digital equipment can also have outstanding sound quality.

If a reproduction is audiophile, it is described as natural, in the here and now, realistic, detailed, analytical or realistic. Bass, midrange and treble should be neutral and none of the three pitches should stand out.

Of course, no one knows how the recording really sounded in the studio, and music recordings are also post-processed in the studio, so that the piece of music can already be very different from the recording situation. Likewise, the room, e.g. a concert hall with its sound characteristics, can play a big role in how an instrument sounded at the moment of recording. From this aspect, too, "audiophile" is a subjective term.

In the documentary "Amy" about the life of Amy Winehouse is shown how she sings "Back to Black" and then is cut to the later song. A good example of the good studio work of Marc Ronson and there the dispute can begin, which was now actually "original". Here is the trailer, for those who don't know the documentary. Very worth seeing.

In principle, the super small Balanced Armature drivers work like a dynamic loudspeaker with permanent magnets and a coil. However, the construction is different than in classic drivers. Here, a magnet floats freely and produces the necessary vibrations via a diaphragm. The structure is flat.

Several drivers can be installed in an in-ear headphone. Each is then responsible for a specific frequency range. Balanced armature drivers used to be relatively expensive, but are now already used in inexpensive headphones. 

When it comes to transmitting data between devices over short distances, Bluetooth is the main method used today. Data is transmitted in the 2.4 GHz frequency band. However, before data can be transmitted, the devices (up to and including Bluetooth 4.x) must be paired with each other.

With Bluetooth 5.0, both the audio data transfer rate and subsequently also in 5.2 the energy consumption for audio transfers were changed in such a way that high sound quality with very low energy consumption was made possible. This led to the mass distribution of ear plugs.

The A2DP (Advanced Audio Distribution Profile) is used to exchange stereo audio formats between devices. Different audio codecs (pair of algorithms used to encode and decode data) are applied. The Bluetooth standard is the Low Complexity Subband Codec (SBC), where the original format is encoded, transmitted and decoded. This encoding is theoretically done at 346 kb/s. However, this depends strongly on the strength of the Bluetooth connection. Generation losses that occur are thus possible in the inaudible range with a good connection. Nevertheless, especially with mp3, AAC, FLAC and aptx, (also LC2, LDAC, LHDC and UAT) further codecs have developed. AAC (265-kbit) and aptx (345 kbit/s) offer this bandwidth regardless of the connection strength. For both transmission types, both the sender and the receiver must support these formats. 

Here we are in an area where we believe that sustainability and compatibility with ever new protocols is not possible and so far we have opted for the Bluetooth out of the box codecs, as good Bluetooth connections should be possible indoors. 

A Digital Analog Converter (DAC, digital signal converter) turns a digital signal into an analog signal. This analog signal is ultimately processed by the speakers and converted into sound. There are various methods for this conversion. Today, a DAC is of outstanding importance when it comes to sound quality. 

DACs are used in almost all audio devices that deal with digital audio sources.

In the opposite direction, DACs are called ADCs or analog-to-digital converters. They are used to digitize the analog signal recorded by a microphone, for example.

Devices to which headphones or power amplifiers can be connected are often also called DACs. The upwardly open price scale for these devices also shows esoteric tendencies here.

Unit of measurement for loudness. The decibel scale ranges from 0 dB to 120 dB and is logarithmic. Hearing is damaged from about 85 db of continuous exposure. The volume of a normal conversation is approx. 60 db, the rustling of leaves approx. 30 db and a hair dryer approx. 90 db.

A digital sound processor or digital signal processor. It processes digital signals and modulates them. In loudspeakers, it is responsible for shaping the frequency response in such a way that the audiophile experience is optimized and errors in sound reproduction are minimized. 

Modulation can completely change the character of a speaker. So it works as a digital equalizer.

The power amplifier is the last electronically active (i.e. amplifying) stage of a power amplifier. After that, the signal goes to the passive loudspeaker or, in the case of active loudspeakers, to the chassis.

There are different classes of power amplifiers.

Class A: Class A amplifiers are used in the absolute high-end range, as long as no large power is required, because it is energetically very inefficient and converts a lot of current into heat even without an input signal. In Class A amplifiers there is always a voltage present and they get very hot.

Class B: Two transistors amplify the positive and negative signal. Where the signal crosses the zero line, distortion occurs because the transistors only turn on at a certain voltage.

Class AB: The most commonly built power amplifiers are Class AB amplifiers. These work like a Class B amplifier except the power is very low, then it runs as a Class A amplifier.

Class C: Not used in audio because of its distortion.

Class D: Class D amplifiers work on the basis of pulse width modulation. The amplification is controlled by high-frequency pulse widths, which switch the power transistors on and off and which have to be filtered again afterwards. The high-frequency (well above the audible range) signals must match each other exactly, making the construction of these amplifiers very challenging. The process allows extremely powerful amplifiers with very small package sizes.

Class G: Works like a Class AB but is built to be more energy efficient due to different voltages needed at different loads.

Who is interested in the details is invited to watch the following video. (In German)

Unit of measurement for the frequency. The number of oscillations per second is the number before the unit of measurement. 50Hz is the frequency of our power grid. Thereby the electric voltage oscillates 50 times between 0 Volt (V) - 220V - 0V - minus 220V - 0V 

Hi-Fi is the abbreviation for High Fidelity. Hi-Fi is based on standards (e.g. EN61305) that define the conditions under which a sound device has fidelity. These standards are met today by almost all devices (except perhaps radio alarm clocks or cheapest playback devices). 

Although one should not look at the price but at the performance or price-performance ratio, high-end is often understood to mean the most expensive, most luxurious or best product.

In terms of sound quality, high-end should actually be a synonym for "audiophile". A high-end loudspeaker should provide the most faithful reproduction possible. Regardless of the price. 

The hypersonic effect is described in a controversial study by Tsutomu Oohashi, in which people could perceive frequencies above 25k Hz in single cases. In many other (also "double-blind") studies, participants could not hear ultrasound isolated from or together with lower frequencies. There were also different test results for the general perception by the body. However, it is assumed that the body can feel ultrasound emission in the long term. 

Coaxial speakers have at least two drivers arranged on one axis. This arrangement is more in line with natural sound production than side-by-side drivers because the sound comes from one point. Loudspeakers with coaxial drivers therefore build up a natural sound stage more easily.

A monitor speaker (also studio speaker) is often active because of the advantages of active speakers and is used to listen to music without distortion and as accurately as possible. In the studio, of course, it is important that the finished song has no errors at the end, which is why the display must not suppress or distort the slightest crackle.

Studio monitors are interesting products for audiophiles, because they do exactly what counts in audiophile music enjoyment. They provide a faithful transmission of the music without changing it by bass or treble boost. For many listeners, however, these speakers are also fun to use.

Headphones that are inserted in front of the ear canal. The housing is smaller than the auricle. This means that external noise is not strongly attenuated. The advantage is that the headphones are not stuck in the ear canal.

Over-ear headphones are larger than the earcup and are worn above the ear. Thus, they press less than on-ear headphones. 

Due to the large design, the headphones can also accommodate large diaphragms for sound generation. Most reference headphones can be found in this category and due to the good shielding of the ear from external noise, Active Noise Cancelling technologies can be used.

Passive speakers receive the signal from an amplifier or power amplifier. In them is usually an analog crossover that distributes the sound to the various tweeters, midrange and woofers (bass).

So you need the passive speaker and a corresponding amplifier. Audiophiles enjoy choosing the best combination of devices and have a soft spot for analog technologies, which is why passive speakers are more common in this area. However, there are also active speakers with DSP and outstanding audiophile sound, e.g. our soundbar.

Each room has its own audio characteristics. These have an extreme influence on the quality of the audio reproduction.

The audio characteristics depend on the proportion of direct sound, reflections and reverberation in the total sound level and the time delay and direction of reflections and reverberation.

A room with good audio properties reduces reflections and reverberation in such a way that a spatial impression of the sound is maintained and yet the room does not have an unwanted influence on the sound.

Damping of reflections and reverberation is achieved, for example, by carpeting, curtains and special damping panels on the walls, which prevent reflections and reverberation by breaking the sound. (diffusers)

S/PDIF (Sony & Philips Digital Interface) is a specification for a one-way (unidirectional), self-synchronizing and serial interface for electrical and/or optical transmission of digital stereo or multi-channel audio signals. 

The same specification is used by the TOSLINK interface for optical transmission.

A subwoofer delivers very deep bass usually with a frequency below 80 Hz. Since humans cannot locate sounds below 80 Hz, a single subwoofer is sufficient. In home theater systems, the subwoofer often delivers only very deep sound effects.

There are downfire subwoofers and frontfire subwoofers. With the first, the sound is emitted downwards, and with the second - to the front.

Stereo comes from the Greek and means rigid, fixed or also spatial.  

From around 1930, attempts were made to improve recording quality by positioning several microphones in the room, which ultimately led to stereo sound, i.e. the spatial reproduction of what was recorded. The recording technique was initially called binaural. The term was then also patented, which hindered its further use, and as a result "stereo" came to the fore as a derivative of stereography, i.e. the three-dimensional representation of images. In the early days, there was often no attempt at all to create a spatial representation of what was being recorded; instead, different sounds, noises or instruments were distributed among the channels. However, the recording techniques and microphone types still used today were basically developed as early as the 1930s. Stereo, as a spatial recording of music did not become a real issue until the early 1960s. In the 1960s, broadcasting also switched to stereo.

In the studio, the individual audio tracks are usually recorded separately and can then be positioned in the room by the sound engineer to give the impression that the music was recorded by a band. This process is called stick stereophony.

The stereo effect is created by the two loudspeakers playing sounds with differences in time of flight or / and intensity, taking advantage of the psychoacoustic phenomenon of humans, allowing them to locate the origin of a sound source.

The stereo effect naturally only occurs in the so-called "sweet spot", the point where the sound waves of the two speakers mix. For optimal playback, the speakers are positioned in an isosceles triangle to the listening position and ideally at ear level (or are tilted accordingly, as with our soundbar). The installation location and the room architecture also significantly influence the listening experience.

TOSLINK is the optical variant of the S/PDIF interface (Sony & Philips Digital Interface). It is unidirectional, self-synchronizing and serial and transmits electrical and/or optical digital stereo or multi-channel audio signals. 

As a rule, fiber optic cables are used, which are not disturbed by magnetic waves.

Wireless Local Area Network or WLAN for short is a radio standard that transmits in the 2.4 GHz and 5GHz range and follows the IEEE 802.11 standard according to the WIFI Alliance.

WLANs play a central role (in addition to the Internet connection in the home) in the area of multi-room applications. A wide variety of devices can communicate with each other via WLAN applications. However, in our opinion, Bluetooth has some advantages in terms of ease of use when connecting from device to device. Setting up WLAN connections is still much more complicated than with Bluetooth.