DE102008021500A1 - speaker - Google Patents

Abstract

The method involves arranging an opposite phase switched rear sound center (2) away from a forward sound center (1). The center (1) is attached over a rear phase shifter circuit. The circuit is switched to rear phase response assigned to the rear sound center along a main jet direction of a loudspeaker (11) i.e. dipole loudspeaker. Phase difference between rearward and forward phase responses is reduced in basses, and the circuit strongly damps exciting voltages with increasing frequencies. Critical frequency of the circuit is selected smaller than magnitude.

Description

The The invention relates to a method for sound reproduction by a loudspeaker, and a loudspeaker with a connected to an excitation voltage forward sound center and an antiphase switched over at least one phase shifter circuit connected to the excitation voltage rearward sound center for implementation of the procedure.

Dipole speakers are well known in the art. Dipole speakers have the advantage over simple speakers of a lower volume level perpendicular to the main beam direction. This allows the sound to act more targeted on the listener. A disadvantage of the Dipollautsprechern, however, is the largely symmetrical radiation of the sound in the main radiation direction to the audience and in exactly the opposite direction. In the opposite direction, the speaker, especially in the home, often placed against a wall. From there, the sound waves radiated backwards reflect back and produce disturbing interference. A Dipollautsprecher is for example from the US 5,073,945 known.

adversely the well-known Dipollautsprechern is in particular the fact that the two-phase switched loudspeaker chassis in the area low frequencies due to the large wavelength compared to the acoustic distance of the two chassis from each other to a negative interference of the sound waves in the main radiation direction to lead. As a result, the bass frequencies are in the main beam direction with a lower volume level compared to the original sound perceive. On the other hand, it comes in the area of the middle to positive interference, so that there is an exaggeration of the Sound pressure level is found.

It Object of the invention, a method for sound reproduction by to provide a speaker opposite in the prior art, a strong sound pressure level in the basses and a reduced sound pressure level in the middle generated as well as to provide a speaker, with which such a procedure can be carried out.

Regarding of the method is the object by an initially mentioned method met with the features of claim 1.

First are conventionally a forward sound center and a rearward sound center out of phase switched and directed away from each other. Both sound centers are connected to the same exciter voltage. At least the backward one Sound center is on via a phase shifter circuit the excitation voltage connected. Due to the antiphase circuit exhibit the forward at the forward sound center adjacent Excitation voltage and the at the rear sound center applied backward excitation voltage without consideration the phase shifter circuit has a phase difference of δ = 180 ° against each other. Therefore, especially the Basses in the main beam direction destructive, because their wavelengths in relation to the acoustic distance of the two sound centers are big. Under acoustic distance we cover the distance understood that the sound from the forward to the backward Has to cover the sound center. The phase responses φ (f) along the main beam direction of the speaker are thus in the basses by up to δ = 180 ° to each other postponed.

According to the invention, at least the rearward phase shift is shifted. Advantageously, this produces phase equality of the two phase responses at lower frequencies than the dipole frequency f _dipole . The dipole frequency f _{dipole is} the frequency at the phase coincidence of the two phase paths of the freed around the phase shifter circuit, pure dipole speaker occurs.

A particularly favorable emission behavior arises in the basses in the main beam direction with a phase shift of the rearward phase response of approximately φ = -45 ° at an excitation voltage corresponding to the resonance frequency f _{b of} the built-in rear sound center.

The Phase shift of the rear phase path is decreased with decreasing excitation frequency. This will be the Effect of the increasing retardation of the rear and Forward sound waves in the main beam direction at the same permanent acoustic path between the two sound centers at least reduced and the sound pressure level remains in the main beam direction wide frequency ranges largely the same.

By the shift of the frequency of the phase equality to lower Frequencies down, forms in the middle, so by f = 300 Hz, a phase difference in the main beam direction, which leads to a Reduction of the sound pressure level leads and thus the There in the conventional Dipollautsprecher occurring overshoot counteracts the sound pressure level.

Due to the preferred phase shift of about -45 ° in the region of the cut-off frequency f _g = 75 Hz, the elevation in the centers is significantly attenuated.

The sound center can at least one Include speaker chassis. A loudspeaker chassis is understood here to mean a frame which is suitable for vibrating air by means of an electromagnetically driven membrane.

The Sound center works in a volume that is audible from one Short circuit avoiding housing is limited. A backward volume has the rear sound center and a forward Volume has the forward sound center. The two Volumes are separated. Under an acoustic short circuit avoiding volume or housing becomes a volume here or housing understood, in which the sound center Forward and backward emitting sound waves do not interfere with each other destructively, so do not short circuit. Short circuit avoiding enclosures can essentially be closed trained housing.

In addition to the shift of the rearward phase response, the phase shifter circuit increasingly attenuates higher frequencies. According to the invention, the phase shifter circuit has a cutoff frequency f _g which is smaller than the larger value of the quantity {1 / 3f _dipole , 1.55 f _b }. Here f _b is the resonance frequency of the rear sound center built into the loudspeaker box.

By the attenuation of higher frequencies of the rear Sound center are the frequency responses in the main beam direction in the centers opposite the dipole speaker horizontal educated. Also, this is the usual elevation diminished in the middle, and the listening experience is with it improved in the centers.

Due to the attenuation of higher frequencies, the sound pressure level in the main beam direction is smoothed at frequencies above the mids. Because at higher frequencies arise at certain wavelengths above the resonant frequency f _b by destructive interference minima and thus fluctuations in the sound pressure level. These fluctuations are countered by the fact that the rear sound waves with higher frequencies are increasingly attenuated. It forms less destructive interference in these frequency ranges and the fluctuations of the sound pressure level are significantly reduced in the main beam direction.

impedance peaks the rear sound center are at least smoothed a suction circle. Depending on the execution the speaker as a closed box, bass reflex box, bandpass speaker or transmission line speakers or similar form, two, three or a plurality of impedance peaks at the rear Sound center, which lead to tonal distortions. To smooth the impedance peaks, each of the peaks associated with a suction circuit adapted. The resonant frequency of the absorption circuit corresponds to the respective frequency of the impedance peak and the quality of the absorption circuit is adapted to the width of the impedance peak.

It has been shown that the inventive method in a simple way by an aforementioned speaker with the characterizing features of claim 3 are performed can.

The back phase shifter circuit attenuates, on the one hand, exciting voltages of higher frequencies, and has a cutoff frequency f _g smaller than the larger value of the {1 / 3f _dipole , 1.55 f _b ) amount, and the phase shifter shifts the one rearward acoustic center associated phase along a main beam direction of the speaker and thus reduces a phase difference of the rear and the forward phase response in the bass.

Preferably The two sound centers each work in an acoustic one Short circuit avoiding volume. The volume can bulges have in it. It can be at both ends open tubes with outer openings act, which are referred to as bass reflex ports. rear and forward housing with two at each end open tubes in the forward and backward Volumes are also called biventiliertes Bandpassgehäuse designated. Housing or volumes themselves from a convoluted tube, one end of which is open and in the other end of a speaker is used as Transmission line housing or volumes known. All these Volumes or housings may be used as embodiments realized the invention. The number of openings or the formation of the volume change the impedance curve at the rearward sound center, putting one generate different numbers of impedance peaks.

The Phase shifter circuit can be designed differently. A backward between excitation voltage and backward Sound center switched phase shifter circuit can be used for a rearward sound center connected in series Inductance and / or a parallel capacitance exhibit.

Advantageously, the rear phase shifter circuit is a low pass 1 , Order realized as a series-connected coupling coil, with an inductance substantially the quotient of the back loudspeaker wi Resistance and the limit frequency f _g corresponds. The values of the coupling coil according to the invention are in the range of L = 5-30 mH.

The Coupling coil is conveniently between a positive pole one speaker chassis and the negative pole of the other speaker chassis in Series switched.

In a development of the invention is the rear Phase shifter circuit formed as a low pass higher order. In particular, a series connection with a capacitor and an ohmic resistance parallel to the rear Be switched sound center. The ohmic resistance can also be designed adjustable as a potentiometer. The controllable phase shifter circuit allows the phase shift to the respective conditions to adapt more precisely.

Preferably, at least one absorption circuit is connected in parallel with the rear loudspeaker chassis. It can be seen that an increase in the impedance of the rear loudspeaker chassis occurs in the region of the resonant frequency f _{b of} the rear loudspeaker chassis. To smooth the increase in the impedance of the rear loudspeaker chassis, a suction circuit in the form of a series resonant circuit is connected in parallel. The resonant frequency of the rear series resonant circuit corresponds to the resonant frequency of the built-in rear loudspeaker chassis, wherein the quality of the rear resonant circuit is preferably adapted to the width of the impedance maximum. The rear series resonant circuit has a contact between the coupling coil and a pole of the rear loudspeaker chassis.

In preferred embodiments of the invention is the number the absorption circuits the number of impedance peaks of the rear Sound center adjusted. Preferably, the speaker has two separate volumes with one sound center each, with a bass reflex recess in the rear Volume and a bass reflex recess in the forward Protrude into volume and the rear sound center two impedance spikes are assigned and each of the impedance spikes an associated each their own absorption circle is assigned.

In another preferred embodiment of the invention two bandpass recesses protrude into the rear Volume and two band-pass recesses in the forward Volume into it and the rear sound center are assigned to three impedance spikes and each of the impedance spikes is assigned to her each adapted absorption circle.

Of the loudspeaker according to the invention can be based on be formed on known transmission line housing. Here is a rear transmission line volume as one enclosed by a preferably tortuous tube Formed volumes whose one end is open and the sounds radiates and in the other end the rear sound center is used. Accordingly, the forward volume also shaped in accordance with a Transmissionline housing.

In a particularly preferred embodiment of the invention is additional to the rear, a forward phase shifter circuit intended. These may be high passes of various Act okay.

Preferably the forward phase shifter circuit intervenes two different poles of the two speaker chassis switched Coupling capacitor on. The coupling capacitor can be in series be arranged with the coupling coil. While the coupling coil a Phase shift on the rear loudspeaker chassis achieved by about -45 °, is through the coupling capacitor a phase shift on the forward loudspeaker chassis about + 45 ° brought about. By combination the forward and backward phase shifter circuit is a longer horizontal training of the sound pressure level possible in the frequency response deeper into the bass range.

Preferably is at least one parallel to the forward sound center Forward Saugkreis provided according to the rear suction circuits is constructed.

Parallel to the front chassis can also one, two, three or more suction circuits may be provided, each having an impedance peak associated with the front chassis.

Of the Structure of the suction circuits parallel to the connections of the front Chassis can be designed according to the absorption circuits of the rear chassis be.

Of the Forward highpass can be in 2nd order parallel to the forward Sound center one to a preferably adjustable ohmic resistance comprise capacitor connected in parallel.

The Invention is based on six embodiments in 21 figures described.

there demonstrate:

1a : a dipole speaker according to the prior art,

1b : A schematic representation of a 360 ° -Schalldruckpegels the Dipollautsprecher according to 1a at f = 100 Hz,

2a : a loudspeaker according to the invention with phase switching according to the invention,

2 B a schematic representation of a 360 ° sound pressure level of the loudspeaker according to 2a at f = 100 Hz,

3a : a frequency response of the dipole speaker in the main direction,

3b a phase response of the forward and rearward speaker chassis of the dipole speaker,

4a : a frequency response of the loudspeaker in the main beam direction,

4b a phase response of the front and rear loudspeaker chassis of the loudspeaker in the main beam direction,

5a : the impedance of the built-in rear loudspeaker chassis as a function of frequency,

5b : the impedance of a built-in rear-mounted loudspeaker chassis with series resonant circuit as a function of frequency,

5c : the impedance of the phase circuit as a function of the frequency,

5d : the voltage applied to the rear loudspeaker chassis with a phase circuit,

5e : the phase shift of the backward AC voltage as a function of the frequency,

6a : a loudspeaker according to 2 with a second phase shifter circuit,

6b a loudspeaker with a third phase shifter circuit,

6c a loudspeaker with a fourth phase shifter circuit,

7 : a speaker according to the invention with forward phase switching,

8a a forward phase circuit with a forward phase shifter circuit,

8b in: forward phase switching with a second forward phase shifter circuit,

8c in: forward phase switching with a third forward phase shift circuit,

9 Phase response of the rear loudspeaker chassis with and without phase shift circuit and forward phase response.

10a a circuit according to the invention in a bass reflex loudspeaker,

10b an impedance curve of the bass reflex speaker in 10a without suction circuits,

10c an impedance curve of the bass reflex speaker in 10a .

11a a circuit according to the invention in a bandpass loudspeaker,

11b an impedance curve of the bandpass speaker in 11a without suction circuits,

11c an impedance curve of the bandpass speaker in 11a ,

The 1a shows the basic circuit of a Dipollautsprechers 8th according to the prior art. The dipole speaker 8th has two oppositely directed speaker chassis 1 . 2 on, which are connected in phase opposition. On both speaker chassis 1 . 2 is the same excitation voltage U ₀ on. Each of the two speaker chassis 1 . 2 is in a separate case 4 . 5 accommodated. The two housings 4 . 5 are at their two back walls 6 . 7 placed against each other and acoustically separated. They are firmly connected.

1b shows the height of the sound pressure level SPL in a schematic two-dimensional plan view of the arranged in the coordinate origin Dipollautsprecher 8th , In this case, the height of the sound pressure level SPL is represented by the distance to the coordinate origin in the associated listening direction lying between α = 0 ° and α = 360 °. The 1b represents the sound pressure level SPL at a frequency of f = 100 Hz. 1b shows that the sound pressure level SPL in the main beam direction α = 0 ° and in exactly opposite, rearward direction α = 360 ° is highest. The sound pressure level SPL is perpendicular to the main direction, ie at α = 90 ° and α = 270 °, vanishingly small. This means, perpendicular to the main direction of the Dipollautsprechers 8th the listener can theoretically hear nothing. In fact, he hears due to sound reflections, z. B. on the room walls, vibrations of the housing 4 . 5 u. A. Really still quiet tones.

Disadvantageously, the dipole speaker radiates 8th also with maximum sound pressure level in the rearward direction. Because the speaker 11 Usually standing near the wall, is via the rear speaker chassis 1 . 2 a considerable power blasted directly against the wall. From there, the sound waves reflect and create disturbing sound reflections in the room. The sound pressure level SPL increases with a horizontal 36 ° circulation around the dipole loudspeaker 8th a substantially double lobe shape with longitudinal axis along the α = 0 ° -180 ° line.

The speaker according to the invention 11 indicates in a first embodiment according to 2a one opposite the in 1 schematically shown Dipollautsprecher 8th a significantly different sound pressure level profile (SPL curve) along its 360 ° circulation. The dependence of the sound pressure level SPL on the beam direction is in 2 B shown. The sound pressure level SPL is maximum in the main beam direction α = 0 ° and minimal in the rear beam direction α = 180 °. Intermediate values of the sound pressure level SPL are achieved at α = 90 ° and α = 270 °. This means that the highest volume in main beam direction α = 0 ° is achieved while the speaker 11 At its back is the quietest. In addition, the listener can still hear sounds perpendicular to the main beam direction, at α = 90 °, 270 °.

The speaker according to the invention 11 also includes two oppositely directed and antiphase switched loudspeaker chassis 1 . 2 , Parallel to the two connections 1a . 1b . 2a . 2 B the two speaker chassis 1 . 2 are two connections for the excitation voltage U _O connected.

For one thing is between the positive pole 1a of the forward loudspeaker chassis 1 and the negative pole 2a the rear speaker chassis 2 a rear phase shifter circuit 15 connected in the form of a coupling coil L _C. In addition, it is parallel to the rear loudspeaker chassis 2 a sucking circle 20 in the form of a series resonant circuit L _R C _R R _R connected in parallel. The one terminal of the series resonant circuit L _R C _R R _R is between the coupling coil L _C and the positive pole 2a the rear speaker chassis 2 intended.

Hier ist die Induktivität der Kopplungsspule L_C so gewählt, dass sie dem Quotienten aus rückwärtigem Lautsprecherchassiswiderstand Z_R und der Grenzfrequenz ω_G der Phasenschieberschaltung entspricht. Bei der Wahl

ergibt sich eine Phasenverschiebung φ zwischen den beiden Lautsprecherspannungen folglich zu φ = –45°.The inductance of the coupling coil L _C causes a phase shift φ of the rear loudspeaker chassis 2 applied voltage U _R opposite to the forward loudspeaker chassis 1 applied voltage U _V , which corresponds to the excitation voltage U _O in this embodiment. The magnitude of the phase shift φ is determined by taking into account the effects of the rear series resonant circuit L _R C _R R _R approximately to φ = -arctan

Here, the inductance of the coupling coil L _C is chosen such that it corresponds to the quotient of the rear speaker chassis resistance Z _R and the cut-off frequency ω _{G of} the phase shifter circuit. In the election

Consequently, a phase shift φ between the two loudspeaker voltages results in φ = -45 °.

Usually, the impedance Z _{R of} the built-in rear loudspeaker chassis behaves 2 as a function of the frequency f = ω / 2π of an AC voltage applied to it in accordance with qualitatively 5a ,

5a shows that the impedance Z _{R of} the rear speaker chassis 2 with falling frequency f at a resonant frequency f _b = ω / 2π increases sharply to fall at even lower frequencies f again. This leads to an increase in impedance in the range of the resonant frequency f _{b of} the built-in rear loudspeaker chassis 2 and disturbs the function of the coupling coil L _C in the frequency domain by f = f _b .

In a conventional manner, the impedance increase in the region of the resonant frequency f _b by the rear loudspeaker chassis 2 parallel connected series resonant circuit L _R C _R R _R compensated. The series resonant circuit L _R C _R R _R has a resonant frequency which corresponds approximately to f _b . The quality of the series resonant circuit L _R C _{R R} R _R is chosen so that in the region of the resonant frequency f _b lower resistance of the series resonant circuit L _R C _R R _R , the total impedance Z _ges of the series resonant circuit LRCRRR and rear loudspeaker chassis 2 according to 5b smoothes.

so gewählt, dass die Phasenverschiebung φ zwischen der auch am vorwärtigen Lautsprecherchassis 1 anliegenden Erregerspannung U₀, und der Spannung U_R am rückwärtigen Chassis 2 bei φ = 45° liegt. Die Gesamtimpedanz Z_Cges mit Kopplungsspule steigt im Wesentlichen linear mit zunehmender Frequenz f an. Durch den rückwärtigen Lautsprecherchassis 2 werden deshalb tiefe Frequenzen (Bässe) weniger gedämpft als die mittleren (Mitten) und höheren Töne (Höhen). Das rückwärtige Lautsprecherchassis 2 ist damit stark basslastig. Siehe dazu auch 4a und dort den Frequenzgang des rückwärtigen Lautsprecherchassis 2. 5c shows the total impedance Z _Cges with additionally switched coupling _coil L _C according to 2a , The size of the inductance of the coupling coil is through

chosen so that the phase shift φ between the on the forward loudspeaker chassis 1 applied exciter voltage U ₀ , and the voltage U _R at the rear chassis 2 at φ = 45 °. The total impedance Z _Cges with coupling _coil increases essentially linear with increasing frequency f. Through the rear speaker chassis 2 Therefore, low frequencies (bass) are less attenuated than the middle (middle) and higher tones (highs). The rear loudspeaker chassis 2 is thus heavy Basslastig. See also 4a and there the frequency response of the rear speaker chassis 2 ,

5d shows the principal voltage behavior U _R at the rear loudspeaker chassis 2 as a function of the frequency f of the applied excitation voltage U ₀ . Due to the inductance of the coil L _C decreases with increasing frequencies f of the voltage drop U _R at the rear speaker chassis 2 ,

5e schematically shows the phase difference between the rear U _r and forward U _V voltage on the rear and on the forward loudspeaker chassis 1 . 2 , At very low frequencies f, the coupling coil L _C has little effect on the phase shift. The coupling coil L _C is, as I said, chosen such that at the resonant frequency f _{b of} the built-in rear loudspeaker chassis 2 a phase shift 45 ° sets, while the phase shift increases with increasing frequencies f to 90 °. These are theoretical values that neglect the ohmic resistance of the coil. Taking into account the ohmic resistance, the stated values are lower.

A comparison of the phase of the in the 3a . 3b represented Dipollautsprechers 8th on one side and in one 4a . 4b illustrated loudspeaker according to the invention 11 on the other hand, shows advantages of the speaker according to the invention 11 opposite the dipole speaker 8th on.

The 3a . 3b show the frequency and phase responses of the Dipollautsprechers 8th and the forward 1 and the rear speaker chassis 2 in the main beam direction. Thus, the sound pressure level SPL of the Dipollautsprecher 8th with the front and rear loudspeaker chassis switched on 1 . 2 low in the main beam direction α = 0 ° in the range of the bass at f <100 Hz. In the middle, at f = 100 Hz to f = 500 Hz, an exaggeration of the sound pressure level SPL occurs.

Front and rear loudspeaker chassis 1 . 2 the conventional dipole speaker 8th work in opposite phases. At low frequencies f and the associated large wavelengths λ has the antiphase circuit of the two chassis 1 . 2 As a consequence, the sound waves in the main beam direction α = 0 ° approximately cancel each other out by interference. As the frequency f increases, so does the size of the housing 4 . 5 certain acoustic distance between front and rear loudspeaker chassis 1 . 2 an increasingly important role, so that with increasing frequencies f a steadily decreasing destructive interference occurs. From f> 1 / 3f _{dipole sets in the opposite effect and the radiated waves of the front and} rear speaker chassis 1 . 2 interfere constructively in main beam direction α = 0 °. Then the acoustic distance of the two chassis 1 . 2 in antiphase circuit half the wavelength of the radiated sound. The constructive interference arises in 3a at f = 300 Hz (= f _dipole ), which corresponds to an acoustic distance of about 0.57 m between the two loudspeakers. At even higher frequencies f minima arise in the sound pressure level SPL of the speaker 11 if the (2n + 1) / 2 times the wavelength associated with the sound matches the acoustic separation of the two chassis 1 . 2 equivalent. Such a (first) minimum is in the frequency response of the dipole 8th in the 3a to recognize at about 650 Hz. The dipole frequency f _{dipole is} the frequency at the phase coincidence of the two phase paths of the freed around the phase shifter circuit, pure dipole speaker occurs.

3b shows the phase response φ (f) in the main beam direction α = 0 ° that of the rear and the forward loudspeaker chassis 2 . 1 radiated sound waves with respect to the excitation voltage U ₀ . From the difference δ of the two phase shifts results in the phase difference in the main beam direction α = 0 °. At about f = 300 Hz (= f _dipole ), the phase difference δ = 0 °. The front and rear loudspeaker chassis 1 . 2 radiated sound waves are then shifted in the main beam direction by exactly one wavelength against each other. They thus interfere constructively.

In the bass, however, the phase difference δ increases due to the ever increasing wavelength λ and at low frequencies f almost δ = 180 °, so that in the main beam direction α = 0 ° almost complete extinction of the sound waves 3a occurs.

The opposite show the 4a and 4b a comparatively different behavior of the sound pressure level SPL with the front and rear loudspeaker chassis connected 1 . 2 , in accordance with the invention by the circuit of 2a are coupled. The frequency response of the speaker 11 is in 4a located. In addition are in 4a the frequency response of the front and rear loudspeaker chassis 1 . 2 shown.

According to 4a If the drop in the sound pressure level SPL in the direction of lower frequencies f occurs only at frequencies around f = 90 Hz. The shift Exercise of the drop in the bass to lower frequencies f is due to the cause of the phase shift through the coupling coil L _C. Along higher frequencies than f = 90 Hz, ie still bass frequencies, there is a substantially horizontal sound pressure level SPL of the loudspeaker 11 in front. The basses are rendered more realistic.

As an additional positive effect occurs a lowering of the sound pressure level SPL against the Dipollautsprecher 8th in the middle frequencies, ie between 200 and 300 Hz. This drop is due to the second effect of the coupling coil L _C , which has a stronger impedance Z with increasing frequencies f ( 5c ). Higher frequencies f are thus from the rear speaker chassis 2 emitted with significantly lower sound pressure level SPL. This behavior shows the graphical representation of the sound pressure level SPL of the rear loudspeaker chassis 2 in 4a , The sound pressure level SPL of the front loudspeaker chassis 1 essentially corresponds unchanged to the sound pressure level SPL of the Dipollautsprechers 8th according to 3a ,

4b shows the phase responses φ (f) of the loudspeaker according to the invention 11 in the main beam direction α = 0 °. In the range of the resonance frequency f _{b of} the built-in rear loudspeaker chassis 2 , here at f _b = 75 Hz, a phase difference of about δ (f) = 90 ° occurs. The phase difference δ (f) of the two front and rear loudspeaker chassis 1 . 2 radiating sound waves is less than the dipole, according to 3b , In the case of the dipole, it is δ (f) = 135 °, and it is thus 45 ° better in the loudspeaker according to the invention. This is also due to the fact that the phase responses φ of the rear speaker chassis 2 are frequency-dependent and partially compensate for the phase shifts caused by the relative displacement of the forward and rearward soundwaves due to the increasing wavelengths λ at constant acoustic loudspeaker chassis pitches.

In 9 are the phase responses φ (f) of the rear loudspeaker chassis 2 with and without coupling coil L _C and the forward loudspeaker chassis 1 applied together. Significantly, the phase shift caused by the coupling coil L _C is approximately -45 ° at the resonance frequency f _b . The phase shift increases along the phase response towards higher frequencies. The shift of the phase response leads to a shift of that frequency at which both phase currents in the main beam direction have the same phase, towards smaller frequencies, here from f = 300 Hz to f = 180 Hz.

In the 6a . 6b and 6c a second, third and fourth embodiment of the invention are shown, all embodiments are developments of in 2 illustrated base circuit with different phase shift circuits 15 ,

The phase shift circuits 15 have in addition to the coupling coil L _{C on} other components. In the second embodiment according to 6a is to the absorption circuit 20 a capacitor connected in parallel.

In the third embodiment, the absorption circuit 20 an RC element connected in parallel. The ohmic resistance is designed as a potentiometer controllable, and thus the rearward phase φ is adjustable.

In the fourth embodiment, the phase shifter circuit is 15 over the third embodiment by a further coil, which is connected in series to the coupling coil L _C extended

wobei Z_V der vorwärtige Lautsprecherchassiswiderstand ist und f_G hier die Grenzfrequenz des vorwärtigen eingebauten Kondensators C ist, die ebenfalls kleiner als der größte Wert aus der Menge {1/3f_Dipol, 1,55 f_b} gewählt wird. Im Gegensatz zur Kopplungsspule L_C wird hier eine Phasenverschiebung zwischen den an den beiden Chassis 1, 2 anliegenden Spannungen U_V, U_R von +45° erreicht. 7 shows a fifth embodiment of the invention with a forward phase shifter circuit 16 from coupling capacitor C _C and a forward suction circuit 21 with a series resonant circuit L _V C _V R _V parallel to the forward loudspeaker chassis 1 , While the coupling coil L _C causes a negative phase shift of the rearward phase φ, the coupling capacitor C _C causes a positive phase shift of the forward phase φ. The capacity of the capacitor is calculated according to

where Z _{V is} the forward loudspeaker chassis resistance and f _G here is the cut-off frequency of the forward mounted capacitor C, which is also chosen smaller than the largest value of the set {1 / 3f _dipole , 1.55 f _b }. In contrast to the coupling coil L _C here is a phase shift between the two chassis 1 . 2 applied voltages U _V , U _R of + 45 °.

8a . 8b and 8c show on the basis of the embodiments of the rear phase shifter circuit 16 of the 6a . 6b and 6c a sixth, a seventh and an eighth embodiment of the invention. Here are to change the phase shift of the forward loudspeaker chassis 1 applied voltage U _V to the excitation voltage U ₀ three different forward phase shifter circuits 21 shown.

In the sixth embodiment, a coil is parallel to the forward series resonant circuit L _V C _V R _V switched while in the in 8b shown seventh embodiment in series with the coil, a potentiometer is provided, with which the phase shift is additionally regulated. 8c shows an eighth embodiment of a phase shifter circuit 21 with additional capacitor.

10a shows an embodiment of a circuit according to the invention in a bass reflex speaker 30 , The bass reflex speaker 30 has the rear speaker chassis 2 and the forward loudspeaker chassis 1 on. The rear chassis 2 works in a backward volume 32 and the forward chassis 1 works in a forward volume 31 , In each of the two volumes 31 . 32 is a bass reflex opening 33 . 34 brought in. One in the rear volume 32 at the bottom end introduced rear bass reflex opening 33 is as opposed to the backward volume 32 at the inner end open tube formed with an outer opening. For the forward bass reflex opening 34 the corresponding applies to the forward volume 31 ,

The at the rear chassis 2 Measured impedance curve Z _R has two impedance peaks according to 10b on. The two impedance peaks are in the circuit according to the invention by two parallel to the rear chassis 2 switched suction circuits 20 smoothed. The smoothed impedance curve is in 10c shown. The resonances of the two rear absorption circuits C _R , I _R , R _R and C ' _R , L' _R , R ' _R are equalized to the frequency values of the two impedance peaks. The quality of the two absorption circuits C _R , L _R , R _R and C ' _R , L' _R , R ' _R is dimensioned such that they substantially according to the widths of the two impedance peaks 10c compensate.

The 11 show a circuit according to the invention for a bandpass loudspeaker 40 , The bandpass speaker 40 also includes a forward 31 and a backward volume 32 , Here is each of the two volumes 31 . 32 again through a partition 41 . 42 divided into two volumes. A forward partition 41 carries the forward loudspeaker chassis 1 and a rear bulkhead 42 carries the rear speaker chassis 2 , In both volumes 31 . 32 are each two openings, so-called Bandpassöffnungen 43 . 44 . 46 . 47 brought in. All of which each have an outer opening and an inner opening. Two rear bandpass openings 43 . 44 are separated from each other in the rear volume 32 intended. The lower rear bandpass opening 44 goes through the partition 42 by. The same applies mutatis mutandis to the lower forward Bandpassöffnung 47 , The two upper bandpass openings 43 . 46 protrude into the volumes 31 . 32 into it.

11b shows that on the rear chassis 2 measured impedance behavior without absorption circuits 20 , It has three impedance peaks in the region of the resonance frequency f _b . To smooth the three impedance peaks, three absorption circuits C _R , L _R , R _R adapted to the impedance peaks as described above are provided; _C'R , L' _R , _R'R ; C '' _R , L '' _R , R '' _R provided. The absorption circuits C _R , L _R , R _R ; _C'R , L' _R , _R'R ; C '' _R , L '' _R , R '' _R are parallel to the rear chassis 2 connected.

1

vorwärtiges Speakers / Sound Center

1a, 1b

connections

2

rear Speakers / Sound Center

2a, 2 B

connections

4

vorwärtiges casing

5

rear casing

6

rear wall

7

rear wall

8th

dipole speakers

11

speaker

15

rear Phase shifter circuit

16

direction forward Phase shifter circuit

20

rear acceptor circuit

21

vorwärtiger acceptor circuit

30

Bass reflex speaker

31

vorwärtig closed volume

32

rear closed volume

33

rear Bass reflex port

34

direction forward Bass reflex port

40

Bandpass speaker

41

direction forward partition wall

42

rear partition wall

43 44

rear Bandpass openings

46 47

direction forward Bandpass openings

C _C

coupling capacitor

C _R L _R R _R

custom acceptor circuit

C ' _R L' _R R ' _R

custom acceptor circuit

C '' _R L '' _R R '' _R

custom acceptor circuit

f, ω

frequency

f _b , ω _b

resonant frequency

f _G , ω _G

cut-off frequency

f _dipole

Dipolfrequenz

L _R C _R R _R

rear Series resonant circuit

L _V C _V R _V

vorwärtiger Series resonant circuit

L _C

coupling coil

SPL

SPL

U _R

rear tension

U ₀

excitation voltage

U _V

direction forward tension

Z _v

direction forward Speakers Impedance

Z _R

rear Speakers Impedance

Z _ges

impedance rear loudspeaker chassis and series resonant circuit

Z _Cges

impedance rear loudspeaker chassis, series resonant circuit and coupling coil

α

beam direction

δ (.)

difference the phase responses

λ

wavelength

φ (.)

Phase response, phase shift

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 5073945 [0002]

Claims (12)

Method for reproducing sound through a loudspeaker ( 11 ), by a forward sound center ( 1 ) and an antiphase switched away from him rearward sound center ( 2 ) via at least one rear phase shifter circuit ( 15 ) are connected to an excitation voltage (U _O ), which at the rear sound center ( 2 ) associated rearward phase along a main beam direction of the speaker ( 11 ) and thus a phase difference (δ) of the rear and the forward phase response in bass is reduced and the rear phase shifter circuit ( 15 ) Attenuates excitation voltages with increasing frequencies more strongly and a cutoff frequency (f _g ) of the rear phase shifter circuit ( 15 ) smaller than the larger value is selected from the set {1 / 3f _dipole , 1.55 f _b } and the rear sound center ( 2 ) is associated with at least one impedance peak, which is characterized by at least one rear suction circuit ( 20 ) is smoothed. Method according to claim 1 or 2, characterized in that the number of rear suction circuits ( 20 ) the number of the rear sound center ( 2 ) matched impedance peaks. Method according to claim 1 or 2, characterized in that the forward sound center ( 1 ) at least one forward phase shifter circuit ( 16 ) and a cutoff frequency (f _g ) of the forward phase shift circuit ( 16 ) smaller than the larger value is selected from the set {1 / 3f _dipole , 1.55 f _b } and the forward sound center ( 1 ) is associated with at least one impedance peak, which by at least one adapted thereto forward Saugkreis ( 21 ) is smoothed. Method according to claim 1, 2 or 3, characterized in that the number of forward and backward suction circuits is equal to the number of forward and rearward sound centers ( 1 ) 2 ) matched impedance peaks. Loudspeaker for carrying out a method according to Claims 1 to 4 with a forward sound center connected to an excitation voltage U _O 1 and an antiphase connected via at least one phase shifter circuit ( 15 ) connected to the excitation voltage U _O rear sound center ( 2 ), the rear phase shifter circuit ( 15 ) Attenuates exciter voltages with increasing frequencies and has a cut-off frequency f _g which is smaller than the larger value from the set {1 / 3f _dipole , 1.55 f _b } and which corresponds to the rear sound center ( 2 ) associated phase along a main beam direction of the speaker ( 11 ) and thus reduces a phase difference (δ) of the rearward and forward phase response in basses and with at least one parallel to the rearward sound center ( 2 ) switched rear suction circuit ( 20 ). Loudspeaker according to claim 5, characterized in that the forward and the rearward sound center ( 1 . 2 ) in each case in an acoustic short circuit avoiding forward or rearward volume ( 31 . 32 ) are arranged. Loudspeaker according to claim 5 or 6, characterized in that the number of rear suction circuits ( 20 ) the number of the rear sound center ( 2 ) is matched to associated impedance peaks. A loudspeaker according to claim 5, 6 or 7, characterized in that the number of forward suction circuits is equal to the number of the forward sound center ( 1 ) is matched to associated impedance peaks. Loudspeaker according to claim 5 to 8, characterized in that the forward sound center ( 1 ) at least one forward phase shifter circuit ( 16 ) and a cutoff frequency (f _g ) of the forward phase shift circuit ( 16 ) smaller than the larger value selected from the 1 set {1 / 3f _dipole , 1.55 f _b } and the forward sound center ( 1 ) is assigned at least one impedance peak, and at least one adapted forward Saugkreis ( 21 ) is provided, which smoothes the impedance peak. Loudspeaker according to one of Claims 5 to 9, characterized in that a bass reflex recess projects into the rear volume and a bass reflex recess into the forward volume and two impedance peaks are assigned to the rear sound center and each of the impedance peaks has a respective absorption circuit (C _R , L _R , R _R , C ' _R , L' _R , R ' _R ). Loudspeaker according to one of claims 5 to 9, characterized in that two Bandpassaussparungen protrude into the rear volume and two Bandpassaussparungen in the forward volume and the rear Schallzentrums three impedance peaks are assigned and each of the impedance peaks their respective adapted absorption circuit (C _R , L _R , R _R , C ' _R , L' _R , R ' _R , C'' _R , L'' _R , R'' _R ). Loudspeaker according to one of claims 5 to 9, characterized in that the forward Volume ( 31 ) and the rear volume ( 32 ) are each designed as transmission line volumes and that the rear sound center ( 3 ) a plurality of impedance peaks is assigned and each of the impedance peaks has a respective respective absorption circuit (C _R , L _R , R _R , C ' _R , L' _R , R ' _R , C'' _R , L'' _R , R'' _R ) is assigned.