CROSSOVER CIRCUIT

Abstract: Crossover circuit intended to be mounted in loudspeaker boxes with at least two loudspeaker elements (1, 2) and arranged to divide an incoming electric signal in respect of its frequency. High frequencies are thus directed to the loudspeaker element (1) intended for high frequency reproduction, and low frequencies are directed to the loudspeaker elements (2), intended for low and/or intermediate frequency reproduction. In order to improve the transient reproduction and also to improve the reproduction of the spacial, sound information a new type of parallel resonance circuit has been brought into the crossover circuit. The parallel resonance circuit mainly consists of an inductor (9) arranged in series, a capacitor (10) connected in parallel to said inductor, and a further capacitor (11), in series with a resistor (12), is connected in parallel to said inductor and capacitor.

Description: CROSSOVER CIRCUIT Background of the invention The present invention relates to a crossover circuit, for two or more loudspeaker elements, of the kind that, de¬ pending on the frequency, divides an incoming electric signal into two or more frequency bands, each of which are directed to that loudspeaker element which are arranged to reproduce the frequency band. The technical development makes steady progress. In par¬ ticular this applies to equipments for different kinds of sound reproduction, e.g. music. At construction and manufacture of amplifiers, record players, tape recorders, radio and TV sets etc. , considerable work is done in order to develop the technique to make the equipments reproduce the original sound as close as possible, i.e. there is an aim to minimize the distortion. This con¬ cerns every part included in the sound equipment and of course also the loudspeaker unit, .which often consists of a box, preferably made of wood, comprising one or more loudspeaker element. When stereo sound is to be reproduced, at least two loudspeaker units are required. If the aim is to reproduce high quality music, sophisticated loudspeaker elements and electronic equipments are re¬ quired today. As the reproduced sound cannot be better than what is achieved by. the weakest link in the "chain", it is of course important, that every part of the sound equipment set-up achieve the capacity or standards stated. In many sound equipment set-ups, the loudspeakers in par¬ ticular are the weakest link, which is- due to the fact that the loudspeakers work mechanically. The sound equipments have electrically and electronically -βURHAi _ OMPI_ ' - lP0 been developed rapidly during the last few years, and today record players, tape recorders and amplifiers can be manufactured relatively unexpensive with the quality preserved. The loudspeaker elements, however, which are mechanical components and work according to well-known principals since long, have not been subject to the same technical development. Every loudspeaker element is im¬ paired by defects and has its own, often unique, repro¬ duction characteristic. When connecting a loudspeaker element to sound equipments of different kinds, some kind of adapter circuit is usually required, and when several loudspeaker elements are connected to one and the same output or channel, there is also required a crossover circuit included into this adapter circuit. It is the task of the crossover circuit to direct electric signals with low frequencies to loudspeaker elements for low frequency reproduction, and electric signals with high frequencies to high frequency loudspeakers. In case also loudspeaker elements for intermediate frequency reproduction are used, the dividing filter directs the intermediate frequency register to the intermediate fre¬ quency loudspeaker. There is today a number of different solutions of cross¬ over circuits for two or more loudspeaker elements. The main task of such a crossover circuit is i.a. to achieve as constant an impedance as possible for the amplifier and to filter and direct different frequencies and fre¬ quency bands to the loudspeaker element(s), which are arranged to reproduce the frequency bands respectively. Today's crossover circuits are of varying success. The purpose of the invention and its most important charac¬ The purpose of the present invention is to achieve a cross- _OΓPI over circuit with which two or more loudspeaker elements can be managed, so that the original sound, i.e. the sound, which is originally produced by for example an orchestra and which has be-en recorded and stored on a tape, a record or the like, at playback is lead from an amplifier to two or more loudspeaker elements and is reproduced with as little distortion as possible. A pur¬ pose of the invention is thus to damp and to adjust the acoustic characteristic of the loudspeaker in the fre¬ quency band 300-1200 Hz. It is hereby important that the spacial information is reproduced as little distor¬ ted as possible. The number of components included in the dividing filter should also be as few as possible in order to facilitate and cheapen the production and also to make the dividing filter small and thereby easily located. This is solved by arranging in series with that or those loudspeaker element(s), which are arranged for intermediate and/or low frequency reproduction, and the circuit components connected to said loudspeaker elements, there is arranged at least one parallel resonance circuit including an inductor, a capacitor connected in parallel to said inductor, and a component circuit connected in parallel to the inductor and the capacitor, said compo¬ nent circuit consisting of a capacitor and a resistor, connected in series, and that there is arranged, parallel with said parallel resonance circuit and the loudspeaker element for intermediate and/or low frequency reproduction and thereto connected circuit components, at least one loudspeaker element for high frequency reproduction and thereto connected circuit components in order to achieve an efficient transient reproduction and also a good re¬ production of the spacial information of the electric signal. Description of the drawxngs The invention will in the following be described in a preferred embodiment with reference to attached drawings, Figure 1 shows a crossover circuit according to the in¬ vention, comprising two loudspeaker elements, Figure 2 shows a crossover circuit, including three loudspeaker elements, and Figure 3 shows a four-way crossover circuit according to the invention. Description of embodiment Figure 1 shows a passive crossover circuit, a two-way type, i.e. the crossover circuit includes two loud¬ speaker elements 1 , ~~~ 2r. A first loudspeaker element 1, a high frequency element, is intended for reproduction of high frequencies, and a second loud speaker element 2, a low frequency element, is intended for reproduc¬ tion of low and/or intermediate frequencies. In one end of the crossover circuit there are arranged a first and a second contact point 3 » ^ » to which exter¬ nal electric signals, which carry sound information, are led from e.g. an amplifier (not shown). A first com¬ ponent grid is arranged to control electrical signals with low frequencies to the low frequency speaker 2. In this component grid the one connection of the low fre¬ quency speaker 2 is joined to the second contact point of the crossover circuit. A capacitor 5 is connected in parallel to the low frequency speaker 2, and an in¬ ductor 6 is arranged in series with the low frequency speaker 2 and the capacitor 5- These components form a low-pass filter and cut high frequency signals. A further capacitor 7 s connected in parallel to the -inductor 6, the first capacitor and the low frequency speaker 2, respectively. A re¬ sistor 8 is connected in parallel with the capacitor 7. This circuit, consisting of the capacitor 5 > 7 » the inductor 6, the low frequency speaker 2 and the resis¬ tor 8, is connected in series to a filter circuit, a parallel resonance circuit, comprising an inductor 9 > whose opposite end is connected to the first contact point of the crossover circuit, a circuit connected in parallel to the inductor 9 and the capacitor 10, said circuit consisting of a capacitor 11 connected in series with a resistor 12. The second component grid of the crossover circuit consists of four components besides the high frequency speaker 1. The component network is mainly arranged to provide the high frequency speaker 1 with electric high frequency signals and is constructed to function as a high pass filter. Hereby the one connection of the high frequency speaker 1 is joined to the second contact point 4 of the crossover circuit. A capacitor 13 is connected to the high frequency speaker in series and an inductor l is arranged parallel with the capacitor 13 and the high frequency speaker 1. A further capacitor 15 is con¬ nected in series to the inductor 14, the capacitor 13 and the high frequency speaker 1. A resistor 16 is arranged in series with this capacitor 15• This component grid cuts signals with low frequencies. The resistor 16 is arranged to limit the power supply to the high fre¬ quency speaker 1. With the construction of the crossover circuit in accordance with the invention, a crossover circuit is obtained, which in the low and intermediate frequency register appears as a filter of the fourth de¬ gree and in the high frequency register appears as a fil- ter of the third degree. This means that signals with frequencies below and above the crossover frequency of the filter which, with a suitable component choice, is 2.600 Hz, are strictly defined from each other. By the set-up of the parallel resonance circuit, i.e. the inductor 9, the capacitor 10, 11 and the resistor 12, resonance phenomena are obtained, which i.a. cause a better transient reproduction from the high frequency speaker element 1 and a clearer reproduction of low and intermediate frequencies via a low or intermediate fre¬ quency speaker 2, 17. This is mainly due to the fact that the parallel 1 resonance circuit electrically damps the acoustic characteristic of the loudspeakers, particularly in the frequency band 300-1200 Hz. Also the spacial sound information is hereby better reprodu¬ ced. The signal, which- passes through the crossover cir¬ cuit, is changed in so far as the transient characteris¬ tic of the high frequency speaker 1 shows a steeper rise of the positive flank of the signal, i.e. the rise time is shortened. The connection, according to the invention, of a cross¬ over circuit can, except in a two-way system, also be applied in a three- and fourway system, respectively, i.e. the crossover circuit can be placed in loudspeaker units where three, four or more loudspeaker elements are included. See figures 2 and 3« In both cases the parallel resonance circuit, with the inductor 9 » the capacitor 10, 11 and the resistor 12, has been arranged in series with the loudspeaker element for intermediate frequency re¬ production and the component grid connected thereto. Figure 2 shows a crossover circuit comprising three loudspeaker elements; one loudspeaker 18 for low fre¬ quency reproduction, one loudspeaker 17 for intermediate r. " frequency reproduction and a third loudspeaker 1 for high frequency reproduction. The crossover circuit according to figure 2 can diagram- matically be divided into four component grids where the components, connected to the low frequency speaker 18, form a first component network, the components connected to the intermediate frequency speaker 17 form a second component network, the components connected to the high frequency speaker 19 form a third component network, and the components arranged between the first and the second component network form a fourth component network. The first component network, then, consists of a low fre¬ quency speaker 18, an inductor 20 connected in series to said loudspeaker, a capacitor 21 connected in parallel with the inductor 20 and the low frequency speaker 18, and an inductor 22 connected in series with the capacitor 21, the inductor 20 and the low frequency speaker 18. Con¬ sequently the fourth component network consists of an in¬ ductor 23 connected in series to a capacitor and to a capacitor 2^ , whose one leader-in is connected between the capacitor 24 and the inductor 23» This fourth compo¬ nent network is a high-pass filter and lets through signals with intermediate or high frequencies. The second component network includes, besides the parallel resonance circuit according to the invention, also a component circuit connected in parallel with the intermediate frequency speaker 17 » said component circuit consisting of a capacitor 26 connected in series to a resistor 27. An inductor 28 is arranged in series with the intermediate frequency speaker 17» the capacitor 26 and the resistor 27. A further capacitor 29 is connected in parallel to the inductor 28 and the intermediate frequency speaker 17- The third component network comprises a high fre¬ quency speaker 19» a capacitor 30 connected in series to said speaker 19, and an inductor 31 connected in parallel to the capacitor 30 and the low frequency speaker 19. Another capacitor 3 is connected in series with the in¬ ductor 31 » the capacitor 30 and the high frequency con¬ denser 32. As mentioned above the crossover circuit, according to the invention, can also be modified so that four or more loudspeaker elements can be connected. Figure 3 shows an example of a crossover circuit for four loud¬ speaker elements. A further component grid has then been connected, which includes another high frequency element 34, an inductor 38 connected in parallel to said high frequency element, and a capacitor 35 connected in series to the inductor 38 and the high frequency element 34. This second high frequency element 34 and the filter components connected thereto, are" preferably dimensioned so that the component grid reproduce the highest audible frequencies, thus being a complement to the high frequency speaker 19 » arranged in the three-way system. The four-way filter co¬ incides principally with the three-way filter, yet with the difference that some of the components included in the crossover circuit must be given other values so that an adjusting of the signal transmission is achieved. The invention is of course not limited to the described embodiments but can be varied in a number of ways within he scope of the invention. -£22

Claims: C L A I M A crossover circuit, for two or more loudspeaker elements which, dependant on the frequency, divides an incoming electric signal into two or more frequency bands, each of which is provided with that/those loudspeaker element(s) which are arranged to reproduce the frequency bands, c h a r a c t e r i z e d t h e r e b y, that in series with that or those loudspeaker element(s) (2), which are arranged for intermediate and/or low frequency reproduc¬ tion, and the circuit components (5 » 6, 7* 8) connected to said loudspeaker elements, there is arranged at least one parallel resonance circuit including an inductor (9) > a capacitor ( 10) connected in parallel to said inductor, and a component circuit connected in parallel to the in¬ ductor (9) and the capacitor (lθ), said component circuit consisting of a capacitor (ll) and a resistor (12), con¬ nected in series, and that there is arranged, parallel with said parallel resonance circuit and the loudspeaker element (2) for intermediate and/or low frequency repro¬ duction and thereto connected circuit components (5, 6, ~ 7 , 8), at least one loudspeaker element (1) for high frequency reproduction and thereto connected circuit components ( 13 » l4, 15) in order to achieve an efficient transient repro¬ duction and also a good reproduction of the spacial in¬ formation of the electric signal.

Inventors: LILJEROTH N, QVICKLUND L
Applicants: LILJEROTH N, QLN AUDIO HANDELSBOLAG, QVICKLUND L
Application year: 1980
Main classification: H04R3
IPC codes: H04R3