FI63313C - HOEGTALARE - Google Patents

Description

6331 3

The present invention relates to a loudspeaker according to the preamble of claim 1.

5 Such a speaker can be used for sound reproduction wherever particularly high demands are placed on sound quality.

The vast majority of current speakers are encapsulated-10 and speakers made using dynamic elements. The enclosure type can be closed, bass reflex or a transmission line solution. Piezoelectric elements are also sometimes used as treble elements. There are also fully or partially electrostatic 15 speakers.

Speaker designers have been working for years to improve the sound quality of the speakers. Much attention has been paid to the following details: 20 - transient response of the elements, reverberations, minimization of the effect of the diffraction phenomenon, reduction of box resonances, and - various forms of distortion, e.g. phase distortion.

These issues have been studied by measurements mainly in the anechoic-25 sa room, and attempts have been made to improve the mentioned properties by developing loudspeaker elements and box structures. It is generally claimed that the speaker is the weakest link in the audio chain. It is also known how differently the same speaker sounds in different rooms, and 30 in the same room placed in different places. Therefore, it is interesting to find out how good the absolute sound quality of today's "good * 1 speaker is when the listening room effect is eliminated. This can be studied with the arrangement shown in Figure 1. It has to study At a distance of 2 m there is a high-quality measuring microphone, e.g. by Dr. PA Fryer, KF Russel, and R. Lee (AES preprints 1U95 and 1567), etc. 10 listening tests under this arrangement have been conducted on several occasions during 1981. factor is an uneven frequency response.J if the frequency response (in this case, of course, the free-field response) is OK, there is little difference between the "direct" sound and that reproduced through the speaker. In fact, a good speaker sounds almost ideal when listened to in this way compared to how it sounds in a normal room.

The sound discoloration caused by the factors 20 mentioned in the previous paragraph will be heard in such a listening test. Thus, by improving these features, the sound quality of the speaker cannot be substantially improved. This is followed by a logical question: What speaker characteristics should be improved so that it 25 sounds good even in the echo mode? Or: What's wrong with the current speakers? The discoloration caused by the listening room is caused by at least the following reasons:

In the lowest decade of the frequency range the radiation pattern is a sphere (all encapsulated speakers), 30 - in the whole frequency range the radiation pattern is too wide, moreover too frequency dependent, not enough to take into account the significance of previous reflections.

For these reasons, the listening room's own acoustics 35 can far too degrade the speaker's own sound quality. The situation is particularly bad at the lower end of the frequency band 3 63313, where the power radiated by the loudspeaker and the reverberation time of the room are at the same time. In addition, it is in this frequency range that there are plenty of standing waves in the room, which further color the sound. This reveals two old notions that are incorrect: 1. The directivity of the speaker has generally been considered a negative thing. Sufficient directivity is a desirable feature, as it can increase the proportion of direct sound coming to the listening position relative to the reflected sounds. After all, the acoustics of the listening room are not directly affected by the sound. Of course, the directivity of the speaker must not depend on the frequency.

15 2. The excellent sound quality of electrostatic speakers is not only due to the principle of operation, but for the most part to the directivity. They are acoustic dipoles, and in this case they also have directivity at the "bass end. high price.

Based on the above-mentioned findings, the present invention makes it possible to considerably eliminate the drawbacks of previous speaker solutions and to provide a completely new type of speaker.

The invention is based on the following ideas: 1. An n-order (n> 1) gradient radiator is used. at low frequencies.

2. Bass elements are not encapsulated.

3. At the higher frequencies, the reproduction is provided by a group of radiators composed of 35 several elements, the directivity of which is almost constant and of a size suitable for the purpose of use.

The main beam of the radiator group is directed towards the listener, partly by utilizing all-pass filters, partly by dimensioning the 5 crossover filters and its own delays in a suitable manner.

5. An equalizer is operated with the speaker, which appropriately delimits the frequency range to be input to the speaker and performs the necessary 10 frequency response corrections.

More specifically, the loudspeaker according to the invention is characterized by what is set forth in the characterizing part of claim 1.

The loudspeaker according to the invention has considerable advantages over previous solutions:

Because the speaker is a gradient radiator at low frequencies, it is directional at these frequencies as well. The directivity is about 1 *, 8 dB when the speaker dimensions are small with respect to 20 wavelengths, and it is a 1st time gradient radiator. The directivity of a standard encapsulated speaker is 0 dB when the speaker is small in relation to the wavelength.

Because the radiation pattern at low frequencies is 25 octaves, the speaker excites the axial standing waves in the room in only one direction.

Since the directivity of the speaker is sufficiently large and somewhat constant over the entire frequency range, the proportion of reflected sounds is relatively smaller and thus also the coloration caused by the room.

Because in addition to greater directivity, the main beam is turned toward the listener, highly harmful reflections coming through the floor will be smaller.

35 - The stereo image formed by a pair of speakers is better due to the higher directivity.

5 6331 3 - The speaker as a sound source does not appear as dotted as a standard speaker.

Since there is no speaker box, there are no box resonances either.

The invention will now be examined in more detail by means of exemplary embodiments according to the accompanying drawings 2 to 6.

Figure 2 shows a perspective view of one loudspeaker according to the invention.

Fig. 3 shows a side view of the loudspeaker according to Fig. 2.

Figure 4 shows a block diagram of an equalizer used in a speaker system according to the invention.

Fig. 5 shows a circuit diagram of the equalizer 15 according to Fig. U.

Figure 6 shows a circuit diagram of a passive crossover filter used in a speaker system according to the invention.

The loudspeaker according to Figures 2 and 3 consists of a front panel, 20 loudspeaker elements 21, 22, 31, 32, 33 attached to it, a crossover filter 5, a stand 4 and an equalizer (Figure 1+).

The bass elements 21, 22 are otherwise conventional dynamic elements, but their voice coil, magnetic circuit 25 and cone suspension are dimensioned so that a large linear deviation of the cone is possible.

The elements are similar to each other. The construction is characterized in that it is open at the rear, i.e. the bass elements 21, 22 can radiate freely both to the front and 30 to the rear. Thus, it operates at low frequencies as a 1st order gradient radiator.

According to traditional thinking, the weakness of the structure is acoustic short-circuiting: at frequencies with a large wavelength compared to the distance around the front plate 1 35 or a wavelength or multiple of this distance, the front and rear waves partially cancel each other out.

6 63313

Similarly, the frequencies at which this distance is a half wavelength or an odd multiple of magnitude, front and rear stress wave to each other. In order to minimize the ripple thus generated in the frequency response, the elements 5 are arranged on the front plate 1 asymmetrically. Because the asymmetrical placement makes the radiation pattern even slightly asymmetrical, the speakers that make up the stereo pair are mirror images of each other. The equalizer (Fig. U) can be used to easily correct the attenuation of the bass 10 caused by an acoustic short circuit. Thus, the benefit of the construction in the form of greater directivity is significantly greater than the disadvantage of attenuating the bass. The loudspeaker elements 31, 32, 33 are also similar to each other, but of a closed type behind. The elements 15 are arranged on the same vertical axis. The functions between the active filter (equalizer) and the passive crossover are divided as follows:

In the passive filter, only the speaker element-specific filters are performed and the delays required by the different elements are generated.

The equalizer corrects the frequency response of the entire system directly.

The circuit diagram of the passive crossover filter shown in Fig. 6 shows that the bass elements 21, 22 are not connected in parallel in parallel, but the upper bass element 21 is fed through a delay circuit. The magnitude of the delay is approx.

160 ps, which corresponds to the situation that the upper bass element 21 would be about 5 cm behind than the lower one. This is done because the main beam of the elements would turn slightly upwards, towards the ball-30, and at the same time the strength of the signal reflected through the floor decreases. The effect of the delay circuit is clearly visible in the form of a radiation pattern in the vertical plane.

The bass elements have a common low-pass filter L, - C.

1 2

The loudspeaker elements are connected as follows: 35 - all have a common high-pass filter Cg - -L ^ the upper and middle elements have a sub-filter Lg-q and Lrj-C12 acting as a low-pass filter.

In order to turn the main beam upwards towards the listener and away from the floor, in the 5 frequency bands in which several elements are in the sound at the same time, the upper elements must be delayed relative to the lower ones. When the coils Lg and the "drops" of the treble elements one at a time from top to bottom, they simultaneously cause a suitable delay, and since the number of radiation sources decreases as the frequency increases, the directivity of the radiator group remains almost constant.

Due to the placement of the elements, the radiation pattern is considerably narrower in the vertical plane than in the horizontal-15 plane.

The purpose of the capacitor is to protect the bass elements from any DC voltages coming from the power amplifier.

The function of the equalizer (Fig. 5) is to correct the free-field response of the 20 speakers directly. It is implemented with active filters, the active elements of which are very good quality operational amplifiers ... Ag.

The equalizer is housed in a separate housing and is connected to the amplifier's TAPE MONITOR or PRE OUT / MAIN 25 IN jack.

It is essential for the end result that the following conditions are met:

The speaker must also be directional in the bass range. The only practical solution is a gradient-30 radiator.

In the middle and treble range, sufficient directivity is maintained by a suitable group of radiators. A gradient radiator can also be used with lower midrange sounds.

35 In the light of those factors, the following solutions can also be considered:

Claims (7)

A loudspeaker comprising at least two base elements (21, 22), 5 - at least two disk elements (31, 32, 33) arranged above the base elements (21, 22), a distribution filter (5) for generating an element-adapted filtering and a delay conditioned by the various elements (21, 22; 31, 32, 33), a frame (1), the base elements (21, 22) and the treble elements (31, 32, 33) being fixed and a frame (M, to which the frame) (1) is supported, characterized in that the body is constituted by an at least at least vertical disk (1), a frame or the like, the base elements (21, 22) are attached to the body (1) without enclosure, the treble elements (31, 32, 33) are assembled into a radiation group, the directional effect of the ratio to the frequency is at least nearly constant, and - the speaker is provided with an equalizer for rectifying the entire system frequency response. 2. A loudspeaker according to claim 1, characterized in that the radiation group composed of treble elements comprises at least three elements adapted to the same axis (31, 32, 33) on the same vertical axis. Loudspeaker according to claim 1, characterized in that all the treble elements (31, 32, 33) are mutually identical. . Speaker according to claim 1, characterized in that the base elements (21, 22) are mutually identical and matched on the same vertical axis. 5. A loudspeaker according to claim 1, characterized in that the disk (1) is formed as a rectangle and all elements (21, 22, 31, 32, 33) are