Acoustic systems are divided into two main types: active and passive. The main difference between them is the presence of a built-in amplifier in active speakers and the absence of one in passive ones. Each has its own advantages and disadvantages. Let's talk about passive acoustics.
What does it mean?
Passive speakers are not equipped with a built-in amplifier. This means that the speaker system will have to be assembled from several nodes, which is not always possible for a beginner to make a good sound or an average person. To make the speakers “play”, a minimal set of devices is required: a sound amplifier and switching (special speaker wires). Typical passive speakers can be seen in the kit with the music center: most often this kit is the player itself, a small amplifier and speakers connected separately to it through ordinary copper wires. Also, passive acoustics are used in concert stages. The very essence of such systems is its simplicity, as a result, in the reliability and the possibility of finer tuning.
An amplifier is selected for the speakers (the variety of which is amazing), in some cases a crossover is purchased (to separate the entire sound stream into separate frequencies), as well as speaker wires and cables, depending on the conditions. All this is an interesting and creative process. All speakers sound different: there is an opinion that passive acoustics (especially in a wooden case) sounds more pleasant and softer than active speakers in plastic, with a digital amplifier clearly selected for them,.
Advantages and disadvantages
The indisputable advantages of passive sound systems is simplicity. The column itself is:
- case - wooden or plastic;
- speaker - the main low-frequency;
- horn speaker;
- separation filter - distributes the sound signal over the speakers themselves.
The need to choose an amplifier can be treated differently, but there are a number of important advantages: you can choose an amplifier of the appropriate power with a margin, an appropriate load (which is an important factor in cases of using powerful speakers), choose the required number of channels and the method of fixing the cable in it (preferable screw terminals).
The price can be safely called an advantage: passive acoustics are cheaper than active speakers, you can afford an amplifier for the difference in price. For money, for which you can only buy active speakers, you can collect a whole sound system that can be further developed and improved over time (which can become an interesting hobby and play an important role in choosing for someone).
Now about the shortcomings. The main disadvantages of passive speakers are usually dimensions and weight: such speakers are rarely placed on a table or shelf, often attached to a wall or mounted on the floor, sometimes placed on racks. Accompanying switching also takes place: amplifier and cables, other equipment, if any. All this can become serious drawbacks if the installation is planned in small rooms.
There are several basic column types for their intended purpose. Depending on the operating conditions, the speakers are selected not only according to the power parameters, but also according to the design-purpose as such. Consider the main ones. Shelf speakers are designed to be mounted on a table, shelf or other horizontal surface. Such speakers can be placed on a table for a TV, a computer desk or on a shelf bolted to the wall. This option will be an excellent solution for a small room: you can use several speakers and sound space quite effectively.
Floor acoustics are installed on the floor: usually they have a vertical, multi-band configuration. Acoustics is also selected on the basis of power, room volume and installation conditions. Such speakers can be placed on the edges of the TV - you get a well-voiced home theater.
Outdoor acoustics can be placed in the corners of a small room, it will not take up much space and will perfectly sound it.
Concert acoustics is a whole complex of equipment and switching, which includes not only speakers (often multi-band) and an amplifier: usually a set includes separate low-frequency speakers (subwoofers), a crossover and other interesting devices. All this is called upon to sound concert halls and halls in a quality manner - it rarely falls into the hands of the layman, such speaker systems are not used at home.
Distinguish between "home" acoustics and "professional" (pop). These systems are designed for different tasks. Large halls, venues, discos and stadiums are voiced by professional systems: the systems produce high-quality sound and create high sound pressure. Professional speakers from concert ones differ in the following nuances :
- application in the design of high performance speakers;
- controlled angle of sound.
A home passive audio system can perform various functions: a shelf computer audio system or a home theater sound system. High-quality sound creates the most pleasant atmosphere in the house.
How to connect?
When connecting speakers to a sound amplifier, you should pay attention to the technical characteristics of the kit, such as power and resistance. Music will sound in full only in the case of correctly selected characteristics: the power of the amplifier should be equal to the power of acoustics or a little more powerful. In this case, the amplifier should not be “overclocked” at full power: the limit can be designated about 90% of its power - this will save the acoustics and will not distort the sound. Most of the operating time, the maximum load is usually not allowed.
When connecting, it is important to consider the resistance. Amplifiers are usually adapted for 2, 4, and 8 ohms. Resistances of 8 and 4 ohms are more common. For the operation of speakers with a resistance of 2 ohms, a 6 kW amplifier is required, which is high power and is not often found among ordinary people. The greater the load, the more likely it is to face power loss at best.
There are two main ways to connect speakers to an amplifier - parallel and serial connection. In each individual case, the resistance behaves differently: in a series - it develops, in a parallel - it falls. This is important to consider when you need to connect more than two speakers. It is also necessary to take into account the resistance of the cable, this is especially important for its large length: the smaller the cross-section of the core (thickness), the greater the resistance. When connecting speakers with thin wires over a long distance, you need to understand that the signal power will drop.
If the speakers are connected to screw terminals, it is important to observe the phasing: connecting the contacts to the corresponding “-” and “+”. For convenience, the wires and contacts are painted in black and red, respectively, “-” and “+”.
If phasing is not respected, sound reproduction problems occur: diffusers move in the opposite direction. This is especially noticeable when misphasing happened on only one of the two speakers.
In audio systems, the following connectors and types of connectors are usually used: Speakon, Jack (stereo / mono), XLR, and screw terminals. Screw terminals and other contact terminals are more common on older amplifiers or amateur-class equipment, and jack-type connections are also often used. Speakon (usually 4-pin) are used in two-way speakers to connect high-power speakers with large speaker cables. Suppose the task is to connect the assembled speaker system to a computer. The system consists of a sound amplifier and a set of speakers. Consider the simplest algorithm using an example: a computer, an amplifier, 2 or 4 speakers (satellite).
You can make contact between the computer and the sound system using the jack-rca * 2 cable, it is a mini Jack at one end and two “tulips” at the other. Mini Jack connects to a computer - into the headphone jack. Tulips are connected to the amplifier - in a linear connector, according to the colors. We connect the speakers with the amplifier by means of a copper two-core cable, fixing it to the screw terminals according to phasing. Then turn on the amplifier and set the sound level and other settings.
Sound waves are reflected from all hard surfaces: windows, cabinets, furniture and frames. When properly positioned in space, the system should sound good. To do this, the speakers are set according to purpose away from the listener and reflective surfaces. The sound will be especially good if in such a room the speakers are installed on a muffled surface, for example, with a carpet. In this case, the sound will not reflect so much from the walls and distort.
Subject to all these numerous conditions, a passive acoustic installation will bring a lot of pleasant emotions.
Having plunged into the world of sound, you can lose peace for a long time and really get carried away by the theme of acoustics, constantly experimenting with all the variety of techniques offered by the sound industry.
In the next video you will find an overview of passive bookshelf speakers Edifier P12.