Loudspeaker box

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Two identical loudspeaker boxes are required for stereo playback (two-way bass reflex boxes , left without front cover).
Modern speaker set for a 5.1 home theater system . There are two slim column speakers at the front left and rear right, and the subwoofer in the middle . There are three more loudspeakers directly under the TV set.
The loudspeaker boxes have a decisive influence on the sound quality of a system. HiFi enthusiasts therefore spend up to several thousand euros on high- quality loudspeaker boxes like the one in the picture (so-called " high-end range ").

A loudspeaker box is the unit of loudspeaker (s) and a housing . In addition to cabling , there is usually a crossover network and insulation material in the loudspeaker box . Amplifiers are also included in so-called active boxes . In parlance, loudspeaker boxes are often simply called loudspeakers or boxes .

In contrast to the integrated loudspeakers in a compact music system, loudspeaker boxes are individual elements of a stereo or home theater system and are set up spatially separated from the audio amplifier . Up until the 2000s, they were used almost exclusively in pairs in stereo mode . With the widespread use of digital home theater systems with surround sound , which require at least six or more loudspeaker boxes - such as the Dolby Digital 5.1 used for DVDs and the 7.1 multi-channel formats for Blu-ray Disc - corresponding loudspeaker systems increasingly came onto the market. Among other things, because of the associated use of a separate, individual subwoofer box for the bass range (the number “1” in 5.1 / 7.1), this led to a significant reduction in the typical dimensions of the two main and front speakers.

Classifications

Loudspeaker boxes can be differentiated according to many criteria, which often overlap. Depending on the area of ​​interest (user, trade press , manufacturer), there is a difficult manageable number of terms that are not always technically informative.

Classification according to HiFi and PA

PA speakers are designed for live use on concert stages. Accordingly, in contrast to hi-fi speakers for home use, mechanical robustness and level stability are more important than high sound quality and external design.

An initial rough separation can be made between “home use” ( HiFi ) and “public” purpose.

Loudspeakers for sound reinforcement at concerts and the like have to meet special requirements: In addition to the highest possible sound output ( maximum volume ), the focus is on robustness and functionality. PA boxes ("Public Address") have to withstand harsh operating conditions (weather, transport, frequent assembly and dismantling), and handling (weight, possible stackability) also plays an important role; Size and appearance as aesthetic issues are secondary.

The dividing line between private and professional use is harder to draw. In event halls , churches or exhibition rooms , boxes are used that do not have to meet PA requirements, but have special acoustic features; mostly it is about avoiding reverberation and other centering of the reproduction (for example with "sound showers"). While such boxes only cover part of the listening spectrum, studio monitors again require hi-fi quality.

This entire article, like the following classifications, mainly refers to hi-fi applications or home applications of loudspeaker boxes.

Classification according to size

The sheer dimensions of a loudspeaker box say little about its reproduction quality. The general rule is that significantly more air volume has to be shifted, especially for low frequencies ( bass ) at the same volume ; Larger speakers in larger enclosures tend to find this task easier.

Desktop speakers

They are used to reproduce computer sound information, for example the soundtrack of websites or games . As at the desk (English desk is) little space and proximity does not require high volumes, they are usually no bigger than a beverage carton . More complex versions are supplied with an additional small subwoofer .

The cheap design of many commercially available devices (colloquially howling cube ; plastic housing, small dimensions) practically does not allow HiFi playback. The same applies to many sound bars and docking stations ( iPod , smartphone ).

Compact speaker

In terms of external dimensions, such boxes can have a volume of four or forty liters; The types and designations offered are correspondingly diverse. What they have in common is that - as so-called full-range loudspeakers - they (should) cover almost the entire human hearing spectrum and that they need a raised floor space for appropriate positioning.

The simplest versions are the boxes supplied with small systems . They often do not offer HiFi playback.

Bookshelf loudspeakers make more claims. This term is often used for boxes that "fit on the shelf" because of their small size. Real bookshelf speakers are optimized for installation close to the wall: they only offer a balanced frequency response when adjacent surfaces support the radiation in the low and mid-range. Such coordination has nothing to do with the rest of the quality; Boxes designed for free installation deliver unwanted sound components on the shelf ("puffing bass "), and bass reflex tubes that may be arranged on the back lose their function.

HiFi compact loudspeakers in the narrower sense hardly differ from floorstanding speakers in terms of price and quality. All you need is a stand for correct vertical positioning (rule of thumb: tweeter at ear level, i.e. about one meter above the floor).

Studio monitors are high-quality compact hi-fi speakers that have also been optimized for a linear frequency response in the near-field range, i.e. deliver a balanced frequency response even at closer listening distances than in the usual stereo triangle . In advertising brochures, the term is sometimes misleadingly used for simple small boxes.

Floorstanding speakers

Floor-standing speakers are usually at least 90 cm high, so they do not need an additional substructure for correct positioning: They “stand” flat on the floor. The spectrum ranges from small, graceful columns to taller structures with hundreds of liters of volume.

In terms of the best possible sound reproduction even at higher levels , floorstanding speakers are the first choice; This category also includes the most expensive hi-fi boxes. However, since the size of the room to be covered plays a decisive role, large speakers can deliver worse results in small rooms than high-quality compact speakers.

Division according to the number of boxes

If one radio sets and the like is not regarded as a special case of "active speaker with additional electronics", individual boxes are limited in home use on small devices such as sound bars.

stereo

The two-channel variant is the classic version for spatial reproduction ( stereophony ). Two identical boxes - sometimes with a mirror-inverted chassis arrangement, if this is not symmetrical - are used.

The stereo pair can be supplemented by one or more subwoofers . If the stereo boxes are intended for such a combination from the outset, they are called satellites : their lower transmission range then ends with the fundamental spectrum, around 80  Hz . The combination is also referred to as a "Sub / Sat system".

In principle, any full-range speakers also benefit from subwoofer support if the sound adjustment is correct (level adjustment, phase position ).

Multichannel

It is evident that the spatial image can be significantly improved if several loudspeaker boxes are distributed around the listening position - provided, however, that the recording already contains correspondingly different soundtracks . The Quadro system introduced in the 1970s ultimately failed because of this requirement ; after the detour via cinema formats, however, its successors also found their way into home use as multi-channel systems . Today such groups of boxes are mostly used to reproduce film sound around television sets .

With all the confusion of terms (“Surround”, “Pro Logic”, “ DTS ”, “ THX ”, “ 7.1 ” etc.), there are essentially four types of loudspeaker boxes:

  • the front speakers ("main speakers", "main speakers") correspond to the usual stereo boxes (see above)
  • the center box ("center speaker") is positioned in the middle in front of the listening position and is mainly used to reproduce the voice spectrum
  • Effect loudspeakers (“rear speakers”) left and right behind the listening position usually only cover a limited, medium frequency range
  • Subwoofers only reproduce the lowest frequencies; Since these cannot be directly localized acoustically , the positioning of such loudspeakers is relatively uncritical

The most common are so-called 5.1 systems , consisting of two front and two effect boxes as well as a subwoofer and a center box. However, there are also much more complex groupings with five full-range speakers, four effect boxes (see “ 7.1 ”) and a large number of subwoofers.

3-way floorstanding speaker with four chassis: two mid-range speakers, a tweeter in between, a woofer on the side

Division according to the number of paths

The entire listening spectrum can only be reproduced to a limited extent with a single loudspeaker. Large membrane surfaces , which can shift the volume of air required for bass, strongly bundle the sound at higher frequencies; Conical diaphragms also have to struggle with partial vibrations . Small membrane surfaces can follow rapid deflections more easily and have a better omnidirectional behavior, but they weaken the bass reproduction.

For this reason, individual loudspeakers (“chassis”) are optimized by their manufacturers preferably for the reproduction of specific frequency ranges . In loudspeaker boxes there are usually several chassis of different shapes and sizes, each specializing in different frequency ranges. For their part, the speaker manufacturers decide which areas are actually assigned to the individual chassis there - using the crossover, which divides the amplifier signal into separate paths (called "branches").

A crossover branch can also control several loudspeakers in parallel; on the other hand, loudspeakers such as coaxial chassis require more than one branch. Therefore, the number of chassis does not have to match the number of paths.

Broadband box

Actually it should be called the “one-way box”; The term broadband loudspeaker is common in parlance . In these boxes, a single converter is responsible for reproducing the entire frequency band, so a crossover is not necessary. This principle is mostly found in simple speakers and small satellite speakers, but also in some higher-priced hi-fi speakers that were deliberately developed to avoid negative effects from multi-way speakers. The housing is usually designed as a horn or transmission line in order to use the rearward emitted bass component as efficiently as possible. In principle, broadband loudspeakers are less suitable for higher sound pressures, as the disadvantages described increase disproportionately with increasing deflection of the diaphragm, on the other hand, when limited to room volume , they can sound clearer than multi-way speakers because the inevitable falsifications due to crossover and overlapping areas do not occur.

Two-way box

A bass / mid-range speaker and a tweeter are generally used here. Most compact boxes are built according to this system. A 19 to 28 mm dome tweeter is generally combined with a 10 to 22 cm cone woofer. This principle is used both with bookshelf speakers and with small floorstanding speakers.

example
  • 1 "dome tweeter: 2 kHz ... 20 kHz
  • 8 "cone woofer: 40 Hz ... 2 kHz

Two and a half way box

“Half way” means that two of the frequency paths overlap (partially work in parallel). In practice, it is usually a box with three speakers: a tweeter and two (mostly identical) bass / mid-range converters, one of which only covers the low-frequency range, while the second covers the low-frequency range and mid-range.

example
  • 1 "dome tweeter: 2 kHz ... 20 kHz
  • 6 "cone woofer: 40 Hz ... 2 kHz
  • 6 "cone woofer: 40 Hz ... 400 Hz

Another possibility is to operate both woofers surrounding the tweeter in parallel. This is called the D'Appolito arrangement . Depending on the number of woofers, two-way or two-and-a-half-way speaker boxes are available.

example
  • 6 "cone woofer: 40 Hz ... 2 kHz
  • 1 "dome tweeter: 2 kHz ... 20 kHz
  • 6 "cone woofer: 40 Hz ... 2 kHz
  • 6 "cone woofer: 40 Hz ... 400 Hz

Three-way box

The three-way loudspeaker has a tweeter, midrange and woofer for better transmission of all frequencies. They are usually equipped with a 1-inch dome tweeter, a mid-range speaker in a 4 to 6.5 inch format and a woofer in a 6.5 to 12 inch format. The allocation of the frequency bands to the different loudspeakers is carried out by a crossover with cut-off or transfer frequencies specified by the developer. Mid-range speakers and tweeters are built in as coaxial chassis in some designs. As the picture on the right shows, more than three loudspeakers can be used: The two mid-range speakers of the box work in parallel on the same branch. (Their grouping around the tweeter is called the D'Appolito arrangement .)

example
  • 1 "dome tweeter: 2 kHz ... 20 kHz
  • 5 "cone midrange: 200 Hz ... 2 kHz
  • 10 "cone woofer: 40 Hz ... 200 Hz

In addition to conical mid-range speakers, there are also dome mid-range speakers. Systems with it generally look like this:

example
  • 1 "dome tweeter: 2 kHz ... 20 kHz
  • 3 "dome midrange speaker: 500 Hz ... 2 kHz
  • 12 "cone woofer: 30 Hz ... 500 Hz

Others

The number of ways can be increased further

  • to increase the maximum radiated sound power,
  • To reduce intermodulations and
  • to enable a more even radiation pattern.

Loudspeaker boxes with more than three ways are more likely to be found in the upper price segment. However, coordinating the interaction of several converters requires a lot of effort: crossovers cannot divide the sections like pieces of cake, there are always more or less wide overlapping areas. The problems regarding the harmonization of volume, phase position and many other things add up with every further branch. A frequency response that is as linear as possible, not only in front of the speaker, but also to the side, approximately at a 30 ° angle, is essential for high-fidelity reproduction. In contrast to multi-way constructions - as they were popular in the 1980s - today only as many converters and branches are used in high-quality boxes as are actually necessary. In principle, you can get very far with three-way constructions. In the area of ​​PA and stage sound systems, three-way constructions that are optimized for efficiency are usually used.

Classification according to housing type

In addition to its simple support function for the chassis, the housing is used to influence the reproduction characteristics of the speakers; especially to reinforce the low frequency range:

In the latter case, however, a “rearloaded horn” is usually meant. The other types can also vary greatly in structure and appearance.

In turn, influencing the sound emitted from the front is not only used - for amplification - by various horn constructions, but also, for example, omnidirectional radiators : This is about uniform radiation behavior, which is usually achieved using dispersion cones.

Classification according to special application

  • Subwoofers are special speakers designed to support more compact full-range speakers at the lower end of the frequency.
  • PA speakers (PA stands for Public Address) are used for sound reinforcement at concerts and events.
  • Studio speakers are used in music production to listen to unfinished mixes and individual signals.
  • Splash- proof or underwater loudspeakers are loudspeakers that are moisture-resistant or are optimized for the requirements of sound radiation underwater.

Feed

Passive boxes

Typical passive speakers receive the signal from an external amplifier to the input sockets and distribute it to their loudspeakers via the crossover. Two- and multi-way passive loudspeakers separate the signal provided by an external power amplifier with the help of capacitors, coils and resistors, rarely with transformers. It is rare to find an equalization network that is looped in before the power amplifier.

Partially active boxes

Partially active loudspeakers are loudspeakers with a built-in additional power amplifier, usually for the bass or deep bass range, while the mid-range and tweeter are controlled externally. In this way you can relieve the power amplifier and also have the option of equalizing the bass range.

Passive loudspeakers with an additional active subwoofer work according to the same principle, only that the deep bass range is not in the same housing.

Active boxes

As powered speakers are called speakers, all necessary power amplifiers have built-in (so they need an additional power supply).

The control takes place with small signals (cinch) or digitally via cable / fiber / computer interface / wireless. The latter is only possible with active speakers.

Active loudspeakers can do without passive crossover (s) if each frequency range has its own power amplifier. However, it is also possible to separate the chassis using a passive crossover. In general, active loudspeakers are also actively equalized. Equalization such as chassis separation can be carried out electronically using an active filter or using a DSP.

The best-known example of an active speaker is the (active) subwoofer, as it is used in conventional surround systems. Radio boxes - which do not receive the signal via cables - also have built-in power amplifiers.

The technically correct differentiation between “active” and “passive” is more complicated. A loudspeaker is called “actively controlled” if there are no crossover components between the output of the power amplifier - regardless of whether it is built into the speaker or not - and the connections of the chassis. The advantage of such an operation lies in the better control of the loudspeaker by the amplifier (higher damping factor ). Any processing of the frequency range takes place in the signal path before the output stage .

This is the case with the classic subwoofer: A low-frequency signal from the output of a preamplifier or similar is sufficient (optional “Hi Level” connections transform output stage signals to low-frequency level). An active circuit then processes the frequency response and the loudspeaker is driven directly from the output of the subwoofer amplifier. Multi-way speakers with only one built-in amplifier for all chassis, on the other hand, fall under passive mode because there is still a crossover in front of the speakers.

Other possible functions

  • remote control
  • Volume control (required for digital playback)
  • Switching between different frequency responses and radiation patterns
  • Temperature monitoring of the loudspeakers in order to avoid destruction, adjust crossover frequencies if necessary and compensate for temperature-dependent parameters
  • Monitoring of the diaphragm deflection in order to avoid destruction and, if necessary, to adjust the crossover frequencies

Crossover

The crossover is a filter that divides the frequency response of the input signal into different frequency ranges for the individual loudspeaker chassis.

Passive crossover

Circuit diagram of a passive two-way crossover
(12 dB / oct, with level reduction of the treble branch)

The simplest form of a downstream passive crossover in a two-way system consists of a coil in the signal the woofer and a capacitor before the tweeter: the two - each in series to the speaker connected  - components ensure that higher frequency components from the woofer and lower held from tweeter become.

In practice, both the mode of operation and the structure of the switch are usually much more complex. In addition to coils and capacitors, passive crossovers almost always also contain resistors - for example to compensate for the higher efficiency of the tweeter, i.e. to adjust its level to the other loudspeakers. Since the frequency separation does not work like an abrupt “cut” either, the individual branches always overlap each other more or less; this is where the slope of the filter comes into play. The more “sharper” the separation should be, the more components are required. However, the steeper the filter flank, the more pronounced effects such as phase rotation and overshoots occur.

In addition, crossovers can not only set the limits of the signal ranges, but also compensate for irregularities in the frequency response, for example via suction or trap circuits . Even broadband loudspeakers usually have a crossover network - although the name seems absurd in this case, individual transducers in such boxes cover approximately the entire spectrum.

When setting up a good crossover network, the frequency response at different beam angles and the impedance of the loudspeakers must be taken into account.

Passive crossovers are the most common form of loudspeaker boxes. Despite its fundamental influence on the sound, manufacturers of prefabricated boxes often save on this component group: low costs and easy assembly of the crossover are often in the foreground, which leads to less good circuits.

Active crossover

If each converter in the box has its own amplifier, a crossover can also be positioned in front of the transducers. There are two different types of active crossovers: analog active crossovers and digital active crossovers. With active crossovers in addition to the functions described above also are control loops possible, such as monitoring the diaphragm deflection to avoid destruction or adjust filter. A correctly designed active crossover is at least equivalent, but usually significantly better than a corresponding passive crossover.

Analog active crossover

Analog active crossovers use electronic amplifiers in the filter stages. The advantage is that complex switch circuits can be implemented more easily and with less distortion.

Digital active crossover

With digital crossovers, flexible filters can be used, which are not possible with analog active crossovers or only possible with a great deal of effort, for example the setting of delay times for individual paths, very steep-sided filters or the compensation of room influences.

Membrane stabilization

Loudspeaker boxes sometimes have membrane stabilization in order to compensate for undesired distortions caused by the swinging out of the membranes, especially the woofers. A negative load impedance or input impedance is simulated on the voice coil . An electronic feedback control with measurement of the diaphragm deflection is the motional feedback . However, these circuits themselves tend to oscillate, which is why the feedback factor cannot be selected too high and the compensation effect is limited. In addition, such feedback circuits are ineffective in the case of pulse signals because there is no control time. A compensation circuit that is also effective for transients is the patented TPS equalization circuit (Transducer Preset System) according to Pfleiderer, which represents a complete electrodynamic inversion of the transducer behavior connected in series. Finally, there is also the acoustic version of the dipole woofer .

Insulation and damping

These two measures are often confused; not least because the material sold as "boxes insulation" most of the sound damping is used.

When it comes to insulation , the aim is to prevent sound from spreading through the housing walls, i.e. to keep them from vibrating. The most effective here are housings that are as massive as possible made of heavy ( dense ) material. In addition, insulation materials such as bitumen sheets , tiles or lead shot mats can be attached inside . Further options are housing stiffening (inner struts) and a multilayer structure of the walls, if possible made of different materials. In practice, wood fiber boards made of MDF or pressboard are mostly used; But there are also housings made of aluminum , slate , concrete and other things.

The attenuation, on the other hand, is intended to prevent certain frequencies of the internally reflected sound emitted from the rear of the membrane from finding their way out - through bass-enhancing openings such as reflex tubes, but also through the membrane (s) itself. Damping materials (polyester wadding, sheep's wool, open-pored foam ) absorb the sound energy by converting it into heat. The type and quantity of materials selected depend on the interaction between the loudspeakers and the housing: Too much damping hinders bass reproduction (pure subwoofer boxes, for example, do not need any damping materials); At the same time, such substances cause a virtual increase in the internal volume of the housing, which in turn affects the bass tuning of the speaker.

With some materials, both effects come into play: sand-filled housing walls and chambers, for example, not only insulate the box through their weight, but also because part of the energy is converted into heat through the movement of the grains.

To avoid resonances that are caused by the geometry of the housing ( standing waves inside), other measures are often better than the attachment of damping material. In addition to avoiding large parallel surfaces over sloping or curved walls, "internal Helmholtz absorbers " can be used here . They are particularly suitable for absorbing the main vertical resonance in typical cuboid floorstanding speakers, but also very effectively attenuating individual standing waves in the course of horn and transmission line enclosures.

Types of speaker fronts

The design of the loudspeaker front, d. This means that the shape of the front panel and the position of the boundary surfaces (edges) of the housing, if they are not significantly larger than the wavelength, have a decisive effect on the direct frequency response and the directional characteristic.

The effects of the loudspeaker front on the frequency response of an otherwise ideal loudspeaker can be considerable in the case of unfavorable shapes (which one sometimes even finds in practice). Variations in the range between −1  dB and +10 dB are possible. Mounted on an infinitely large baffle, the loudspeaker would have an exactly linear frequency response at +6 dB. Small, angular housings that are symmetrical to the loudspeaker are unfavorable. Large, rounded or chamfered enclosures with slight asymmetries show a much more good-natured frequency response that can be equalized comparatively easily. This equalization is called baffle equalization or baffle step equalization.

A skilful baffle design leads to a similarly good-natured course as that of a sphere, which leads to a direct sound frequency response of ± 0.5 dB. However, a negative effect remains. Overall, less sound is emitted into the room for high frequencies than for low frequencies, because at high frequencies only the front half-space is excited, while at lower frequencies the entire room is excited.

Flat baffle / half-space radiator / full-space radiator

Loudspeaker box with pyramid-like housing (old four-way construction)

Loudspeakers can be mounted on a flat baffle. They should be let in because edges lead to additional reflections and thus ripples in the frequency response. If the baffle is significantly smaller than the wavelength (which is usually the case in the bass range, for example), the sound energy is radiated into a solid angle of 4 , i.e. H. in the full space. If the baffle is significantly larger than the wavelength (which is mainly the case in the high frequency range, for example), the sound energy is emitted in a solid angle of 2 , i.e. H. in the half space. The sound level increases by 6 dB (coherent superimposition of the sound source and the reflected phantom sound source), but the sound power only by 3 dB.

The transition between these two behaviors is known as the baffle step ; for a linear direct sound frequency response it must be equalized by adding 6 dB more energy to the loudspeaker for lower frequencies. The radiation energy emitted into the diffuse field increases by 3 dB.

  • Mounting on a small baffle:
When a loudspeaker is mounted on a small baffle that is not significantly larger than the wavelength, a so-called 4- radiator is obtained. Usual loudspeakers work in this operating mode in the bass and fundamental range.
  • Mounting on baffle:
When mounting a loudspeaker on a large baffle, you get a 2 radiator. The sound pressure increases by 6 dB, the radiated sound power by 3 dB.

Recessed wall

The fluctuations in directivity in the bass (2 ), fundamental (4 ) and midrange (2 ) can be eliminated by installing it close to the wall, mounting it on the wall or installing it in a wall. In this case, the loudspeaker is (maximum) a 2 radiator in each frequency range , i.e. that is, it has a directivity of 3 dB. However, the box must then be matched to this setup. Active monitors often have a bass equalizer for this purpose (not to be confused with bass roll-off).

Wave guide / flat horn

  • Wave guide : Also called a short horn. In contrast to a 2- radiator, the sound radiation is placed in a flat hollow. This increases the characteristic sound pressure in dB / W / m. Appropriate shaping ensures constant bundling in the work area and avoids the problems of edge diffraction at the housing edges.

Classic (long) horn

  • Classic horn loudspeakers : The loudspeaker is coupled to the environment via a long horn, which in addition to the bundling of sound - in contrast to the waveguide - is associated with an improvement in the adaptation of the radiation resistance. With a horn loudspeaker, very high sound pressure levels of> 100 dB / W / m can be achieved, but - except for very large systems - the risk of resonances and non-linearities increases. If correctly dimensioned, horn loudspeakers are also able to generate a directional effect that is constant over the frequency, as they provide all diaphragm diameters along the course of the horn, from the horn neck to the horn mouth, of the wave front.

Cinemas used to have horn loudspeakers behind the screen, the opening of which was the same as this. With their high efficiency, these systems accommodated the low amplifier power, but offered a comparatively high sound quality. They are not suitable for stereophony.

Reproduction errors due to room acoustics

Discoloration of the direct sound

The most noticeable reproduction defect of a loudspeaker is a discoloration of the direct sound. In order to be able to better estimate the effects on the sound, averaging over 1/6 octave is usually used. The deviations in the range from 100 Hz to 10 kHz are of particular interest, where values ​​of around ± 1 dB are audible. Below 100 Hz and above 10 kHz the sensitivity to level errors decreases, the frequency response above 15 to 17 kHz is only of minor relevance.

For the assessment of the direct sound, the floor reflections associated with the construction in the fundamental and bass range should also be taken into account. Although it is diffuse sound, on the one hand this portion is only very slightly delayed (e.g. 0.3 ms at a distance of 3 meters and 80 cm height of the woofer), and on the other hand it is an integral part of the construction at the latest for floorstanding speakers.

Runtime error

Group delay of a passive 3-way system with 2 woofers, bass-midrange and tweeter

The perceptibility of delay and phase errors depends on the frequency, but the amount from which they are perceptible is disputed.

Narrow band resonances

Narrow-band resonances (e.g. of the housing) cause only minor errors in the direct sound frequency response and in the group delay, but audible changes when musical instruments oscillate.

Double space

Recordings generally "see" two spaces before reaching the ear:

  • Recording room in the studio / concert hall,
  • Play room at home.

Even if both rooms have the same sound, the duality of space has a negative impact on the sound (for example, a self-recording that is recorded in the living room and then played back there).

Step response of a passive 3-way system with 2 woofers, bass-midrange and tweeter
Waterfall diagram of a passive 3-way system with 2 woofers, bass-midrange and tweeter
Horizontal bundling as isobar display for a passive 3-way system with 2 woofers, woofer and tweeter

Bi-wiring and bi-amping

Speakers who have more than one "way" feature (see above) have the Terminal sometimes more than two fundamentally necessary connections - for signal and ground - on. This allows the individual loudspeakers to be controlled separately. In the standard configuration, the homopolar sockets are each bridged (short-circuited); If you remove the connector, you have two options, namely bi-wiring and bi-amping . Basically, the operating modes should be called “Multi-Wiring” or “Multi-Amping”, since a box can contain more than two loudspeakers; In practice, such terminals also have more than two pairs of connections.

  • Comparison of loudspeaker connection using single wiring or bi-wiring

  • Bi-wiring terminal (with additional option to adjust the treble level)

Bi-wiring

Bi-wiring (“double cabling”) means connecting each loudspeaker to the amplifier using its own cable . A possible improvement in the sound is cited as an advantage of such an interconnection, but this cannot be proven.

Bi-amping

With bi-amping, each loudspeaker is driven by its own amplifier output stage. There are basically different operating modes of bi-amping with passive crossover and bi-amping with active crossover.

Passive bi-amping

With passive bi-amping, the passive crossover, which assigns the signal components to the respective loudspeaker chassis, is separated. Each branch can now be controlled with a separate output stage. The advantage of passive bi-amping is that the volume ratio between the separate paths can be regulated with the appropriate amplifiers. The often propagated audible advantages of passive bi-amping with unchanged volume ratios are usually only available in areas that are generally classified as imperceptible. In listening tests , no difference was detected so far.

Active bi-amping

With active bi-amping, an active crossover is inserted into the system in front of the power amplifiers and the power amplifiers are usually connected directly to the loudspeaker chassis. The effort required for such a configuration is significantly higher than the effort required for passive bi-amping. As a rule, such a conversion leads to a complete re-tuning of the loudspeaker. Furthermore, all the advantages and disadvantages are equivalent to using an active switch versus using a passive switch.

See also

literature

  • Dickason, Vance: Loudspeaker Construction . Extended and revised new edition. ISBN 3-89576-116-8
  • Dickreiter, Michael: manual of the recording studio technology . Very extensive, almost 1,000 pages, 2 volumes. ISBN 3-598-11320-X
  • Stark, Berndt: Loudspeaker Manual . 8th revised edition. ISBN 3-7905-0904-3
  • Walz, Georg: Successfully building loudspeaker boxes yourself . 2nd Edition. ISBN 3-7723-5894-2
  • Olson, HF: Direct Radiator Loudspeaker Enclosures , Journal of the Audio Engineering Society Vol. 17, No. October 1, 1969, pp. 22-29.

Individual evidence

  1. ↑ Peter Strassacker: The woofer, basics. In: lautsprechershop.de. Retrieved on January 18, 2019 (The correct technical term is tweeter . The shape often used tweeter is a short form in the jargon).
  2. ↑ Peter M. Pfleiderer: HiFi in a nutshell: playback technology for unadulterated hearing . Books on Demand , 2014, ISBN 978-3-7357-9736-0 . ( limited preview in Google Book search)
  3. ↑ Bi-Wiring guide ( Memento from March 18, 2007 in the Internet Archive ) stereoplay.de, March 17, 2003. Accessed on October 30, 2014.
  4. ↑ http://www.audio.de/vergleichstest/familientest-lautsprecherkabel-atlas-cables-328441.html
  5. ^ RA Greiner: Amplifier-Loudspeaker Interfacing , Journal of the Audio Engineering Society, Volume 28, Issue 5, pp. 310-315, May 1980.
  6. ↑ Fred E. Davis: Effects of Cable, Loudspeaker, and Amplifier Interactions , Journal of the Audio Engineering Society, Issue 39, No. 6, June 1991
  7. ↑ Jim Lesurf, "Bi-Wiring from amplifier to loudspeaker," University of St. Andrews, Scotland, 2002, accessed November 10, 2014
  8. ↑ http://www.audioholics.com/frequent-questions/the-difference-between-biamping-vs-biwiring Audioholics

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