Volume control

from Wikipedia, the free encyclopedia

Volume controls (also: volume control ) are used to adjust the volume on electronic entertainment electronics such as audio amplifiers , mixers , hi-fi systems and televisions as well as on electrically amplifiable musical instruments such as electric guitars and basses .

use

In addition to manual setting in an open control loop, there are also closed control loops, e.g. B. with the automatic volume adjustment to the driving noises of a car, also with an automatic recording level control (also here it is about the size of the audio level) or with the feedback damping to avoid the unpleasant self-oscillation (whistling tone) in electroacoustic systems (ELA). With the latter, the volume is often regulated in special frequency ranges.

The volume can be set manually or electronically ( software , remote control ) as well as analog or digital and has an effect on the height (level or amplitude) of the audio signal in front of the power amplifier.

The actuator is usually a voltage divider in the form of a potentiometer (electronic or mechanical).

realization

Depending on the type and operation, there are different devices for setting the volume:

  • mechanical rotary or slide potentiometer
    • for remote control even with a flanged motor (motor potentiometer)
  • Resistor array, implemented with fixed resistors that can be switched via relays
  • Audio frequency transmitter with multiple secondary taps of different signal levels
  • electronic potentiometer (analog or digital integrated circuit ) with
  • Digital-to-analog converter with
    • variable resolution
    • variable supply voltage

Mechanical and electronic potentiometers usually have a logarithmic control characteristic for volume setting in order to cover a large dynamic range with linear adjustment. Volume potentiometers are marked with log or a number 2 after the resistance value .

In order to be able to influence both channels of a stereo signal at the same time, there are stereo potentiometers, these have two potentiometers of the same type on a common shaft. A quality feature of these mechanical potentiometers and also of electronic potentiometers is the synchronization deviation, that is, the symmetry of the resistance ratios. It is given in decibels .

The electronic volume setting offers the advantage that the control can take place independently of the signal circuit and thus unreliable contact does not have the effect of a disturbance; Reliability and service life are higher, the signal path does not have to be routed via remote control elements. The resolution and the channel equality is also better with electronic volume controls than with rotary potentiometers.

An inexpensive linear potentiometer can be used to adjust the balance (opposite control of both stereo channels). In integrated or even digital circuits for setting the volume, additional functions for influencing the sound are often integrated.

Loudness curves of the human ear. At low volume levels, the sensitivity decreases significantly at low frequencies. At high frequencies there is only an insignificant change.

In order to take into account the frequency-dependent volume impressions of the human ear (see graphic), there is what is known as aurally accurate volume adjustment , referred to in English as loudness . In this case, the frequencies with lower sensitivity of the ear (i.e. bass and treble) are raised at low levels. This ensures that the entire frequency range of a piece of music can be heard even at low volumes.

Digital signal processors ( DSP ) process the audio signal completely digitally by first digitizing it (if necessary) with an analog-digital converter and then converting it back again with a digital-analog converter . In addition to the volume setting, they can be equipped with a variety of other functions, e.g. B. Noise blanking, reverb, raising / lowering of certain frequency bands.

Agreement to regulate the volume of TV commercials in Germany

In German TV commercials, the so-called "peak level rate" was used by the TV broadcasters for the volume before 2012. The viewer then had to - if he did not want to be exposed to such a volume - the advertising z. B. turn the level down by remote control and turn it up again at the end of the advertising. ARD and ZDF are now broadcasting (ARD since January 1, 2012) advertising blocks in volume with “average values”. In doing so, they follow the rules of the Association of Public Broadcasters in Europe (EBU).

In May 2012, all broadcasters in Germany joined this regulation.

literature

  • Michael Dickreiter, Volker Dittel, Wolfgang Hoeg, Martin Wöhr (eds.), "Handbuch der Tonstudiotechnik"; 8th, revised and expanded edition; 2 volumes; Publisher: Walter de Gruyter; Berlin / Boston, 2014; ISBN 978-3-11-028978-7 or e- ISBN 978-3-11-031650-6 .
  • Thomas Görne: sound engineering ; Fachbuchverlag Leipzig by Carl Hanser Verlag; Munich et al. 2006; ISBN 3-446-40198-9 .
  • Siegfried Wirsum: Practical sound reinforcement technology. Device concepts, installation, optimization ; Franzis-Verlag GmbH; Munich 1991; ISBN 3-7723-5862-4 .
  • Gustav Büscher, Alfred Wiegelmann: Little ABC of electroacoustics (= Radio-Praktiker-Bücherei ; Vol. 29 / 30a); 6th, completely revised and expanded edition; Franzis Publishing House; Munich 1972; ISBN 3-7723-0296-3 .

Web links

Individual evidence

  1. ↑ ARD and ZDF turn down the volume for advertising. Spectators should no longer be frightened during commercial breaks. ARD and ZDF will reduce the volume to an average level. The private broadcasters are still hesitating. welt online, November 15, 2011, accessed on May 11, 2012 .
  2. ↑ Television 2012: Uniform volume on all TV channels and commercial breaks. Preisgenau.de, November 15, 2011, accessed on May 11, 2012 : “A recommendation from the European Broadcasting Union (EBU) should please many TV junkies. The recommendation provides that television broadcasters should design their volume uniformly. This should be made possible by switching to so-called loudness measurement and control. This should eliminate the differences in volume that arise, for example, when switching between different TV channels. In this country, all TV broadcasters have now decided to follow this recommendation. "