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Basically, a loudspeaker has the task of converting alternating current into sound waves. This is done by causing a diaphragm to vibrate through a coil and a magnet. When the alternating current flows through the coil, it is magnetised and attracted and repelled by the built-in permanent magnet. The frequency of the incoming alternating current determines how fast the voice coil and the membrane attached to it move. This is how the pitch is determined, as the diaphragm causes the air molecules to vibrate at the respective frequency, thus generating sound waves. Such devices, which transform alternating current into sound waves, are also called sound transducers. This basic principle is implemented in various forms.

Generally, a distinction is made between the woofer, midrange and tweeter, whereby the name says it all: the tweeter reproduces the high frequencies, the midrange the medium function is made between the woofer, midrange and tweeter, whereby the name says it all: the tweeter reproduces the high frequencies, the midrange the medium frequencies and the woofer the low frequencies. Depending on the loudspeaker, the tweeter and midrange may well be fused into a single component. You've probably heard the term "low-mid" in speakers with a 2-way system. This is because the woofer in 3-way speakers only emits low frequencies, while in 2-way speakers it also covers the midrange.

When you hear the word subwoofer, you will come across various designations. These usually refer to the types of construction and the different acoustic processes.

• Closed or bass reflex: These are cabinet designs. Bass reflex boxes have an additional opening and are designed to amplify the bass in certain frequency ranges. The acoustic principle behind this is called the Helmholtz resonator.
• Downfire or frontfire subs: This is about the direction of radiation of the diaphragm. You can already guess from the terms that with downfire the diaphragm radiates towards the floor and with frontfire towards the front. The downfire sub opens up new possibilities in terms of placement - for example, it can fit under the sofa.
• Active or passive subwoofer: Since subwoofers are larger anyway, they can accommodate various components. With active subwoofers, the amplifier for the sub is housed in the cabinet. One of the advantages of this is that it can be controlled wirelessly by the receiver.

In a 5.1 set-up, the front speakers are set up in stereo tradition (distance to listener = distance between the left and right speaker) next to the TV at equal distances to the left and right respectively or mounted on the wall. The use of stands automatically ensures an optimal height of the front speakers.

The following applies to wall-mounted or shelf-mounted speakers: The installation height should be between 40 centimetres and 1.20 metres. If the height is outside this range, you can also angle the front speakers slightly up or down in the direction of the listener's position. It is important that the centre and front speakers are approximately on a straight line, possibly also on an arc slightly curved towards the TV/screen.

The centre speaker must be positioned as centrally as possible below or above the screen. Only then do pictures and sounds form a unit. If the centre is placed outside a height of between 40 centimetres and 1.20 metres, it should be angled slightly upwards or downwards toward the listener.

You can find more practical installation tips in our big guide.

In terms of wattage and sound, you can use both passive and active floor-standing or bookshelf speakers. Active speakers have the advantage that the amplifier is already integrated and you, therefore, see less technology. If you decide to use passive speakers instead of active speaker systems, you should pay attention to the ohm number, because the impedance is important to match if you want to connect an external AV or stereo receiver with passive floor-standing speakers.

The sound of a home cinema set is acoustically different from a stereo set. Nevertheless, it is possible to listen to music via a 5.1 sound system, only that the sound can then be heard from every direction, so to speak. At a concert watched on DVD or Blu-ray, this can be quite advantageous because the musical instruments and other sounds come exactly from the direction where they are played and the subwoofer provides crisp low frequencies. However, in order for all speakers to play during music playback, you need to make the appropriate setting on the AV receiver. Most models use the "All Channel" stereo function for this purpose. But Dolby Pro Logic II or Upmix (stereo) can also be used for this.

If, for example, you want to buy new loudspeakers in addition to an existing amplifier, you must first compare the power of the two. The wattage or the RMS value (Root Mean Square) is decisive. Otherwise, you may experience sound problems or damage if you connect a much too powerful amplifier with high output to a weak speaker with a low wattage - or vice versa. You will find the corresponding information on the cabinet or in the operating instructions.