JPH03217199A - Horn type loudspeaker - Google Patents

Abstract

PURPOSE:To attenuate the peak of a high harmonic resonance frequency without attenuating the sound pressure of a fundamental frequency by fitting a canceler loudspeaker at a position, where the phase of the higher harmonic resonance frequency to be attenuated is inverted in respect to the closed end sound pressure fitting a main body loudspeaker to a closed end, and driving the canceler loudspeaker with the same phase as the main loudspeaker. CONSTITUTION:A canceler loudspeaker 5 is fitted at a 2/3l position from a main loudspeaker 4 of a horn 1 and driven with the same phase as the main loudspeaker 4. The synthesized sound pressure in the horn 1 is not attenuated at a fundamental resonance frequency f1 although the resonance is canceled at a third harmonic resonance frequency 3f1.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a horn that has a speaker attached to one end of an acoustic tube called a finite-length horn, and that dissipates sound waves from the speaker from the other end of the acoustic tube. Concerning improvements to type speakers.

[Conventional technology]

FIG. 8 shows an example of a conventional horn-type speaker for efficiently reproducing bass sounds by utilizing the resonance of this type of acoustic tube.

In the figure, 1 is a horn, 2 is a speaker unit attached to the closed end of the horn 1, and sound waves emitted from the speaker unit 2 are radiated from an opening 1a of the horn 1.

When the horn 1 has a shape that is close to straight and has a small spread rate, the sound waves are reflected at the opening 1a, causing a resonance phenomenon.

The fundamental resonance frequency f1 in this case is f. =C/4I! ．． 0: Speed of sound l: Chief becomes.

Inside the horn 1, sound waves are repeatedly reflected and interfere with each other, creating standing waves.The resonance caused by this standing wave causes the length of the horn 1 to be 174 wavelengths, 374 wavelengths, 574 wavelengths, etc.
...occurs at a specific frequency.

A high output sound pressure can be obtained at this frequency.

However, when trying to widen the bass reproduction band by using only the aforementioned fundamental resonance frequency f1, f=3f,...
It is necessary to reduce the peaks of the output sound pressure due to unnecessary high-order resonances such as 5f, 7f, . . . in FIG. 9.

Therefore, as shown in FIG. 10, a sound absorbing material 3 or a resonator is installed on the inner surface of the bone 1 at a position corresponding to the peak to attenuate higher-order resonance.

[Problem to be solved by the invention]

This method of damping high-order resonance is based on the fundamental resonant frequency r
, is also attenuated as shown by the dotted line in Figure 11.

(Object of the Invention) The present invention provides a flat sound pressure frequency characteristic at the high-order resonance frequency by attenuating a specific high-order resonance without attenuating the fundamental resonance frequency f1 as in the conventional method. The purpose is to obtain.

[Summary of the Invention] The present invention relates to means for a bone-type speaker to achieve the above-mentioned object, and relates to a bone-type speaker having one end as an open end, the other end as a closed end, and a finite-length bone speaker attached to the closed end. This objective is achieved by attaching a canceling speaker driven in the same phase as the main body speaker to the side surface of the acoustic tube at a position where the high-order resonance sound pressure is maximum and in phase opposite to the closed end.

[Embodiments of the invention]

Next, an example of implementation of the present invention will be described with reference to FIG.

In this example, the length of the horn 1! This is to satisfactorily reproduce the frequency f1 having a wavelength λ four times that of the wavelength λ, and attenuate the peak of the frequency 3f+.

In this horn type speaker as well, the sound wave 3f emitted from the main speaker 4 has an opposite phase at a point 2/3l from the main speaker 4, as shown in FIG.

That is, the sound pressure in the horn 1 due to the zero-body speaker 4 in this embodiment is as shown in FIG. 3(a) at the tertiary resonance frequency 3f, and as shown in FIG. 3(b) at the fundamental resonance frequency f. .

2/3 from the main speaker 4 of the horn 1 like this! Attach the cancellation speaker 5 to the position &j and drive it in the same phase as the main speaker 4.

The sound pressure in the horn 1 due to this cancellation speaker 5 is as shown in FIG. 3(C) at the tertiary resonance frequency 3f+, and as shown in FIG. 3(d) at the fundamental resonance frequency f1.

Therefore, the synthesized sound pressure inside the horn 1 is at the third resonance frequency 3
f. In Fig. 3(e), the fundamental resonant frequency r becomes as shown in Fig. 3(f), and although the resonance at the tertiary resonant frequency 3f is canceled, the fundamental resonant frequency f1 is attenuated. It will not be done.

Another embodiment of the invention is shown in FIG.

In this embodiment, for the fundamental resonance frequency f1, the 3rd and 5th order
This is for attenuating the next resonance frequency.

In this embodiment, the length of the bone 1 is E-4 m, the effective diameter of the opening 1a is 380 mm, and the diameter of the diaphragm of the zero-body speaker 4 and cancellation speaker 5 is nominally 180 mm. The cancellation speaker 5 is installed at the midpoint of the length of the horn 2.

The effect of this canceling speaker 5 is to attenuate the 3rd and 5th order resonance frequencies in contrast to the attenuation of the 3rd order resonance frequency 3f in the previous embodiment.

Comparing this example with the horn-type speaker without the cancellation speaker 5 shown in FIG. 4 shown in FIG. 5, in the frequency sound pressure characteristics shown in FIG. In this embodiment, as shown in FIG. 7B,
The peak between 70 11z and 1 30 11z can be attenuated.

The characteristics around the fundamental resonance frequency 11 of 30 to 50 Hz remain unchanged.

FIG. 6 shows a cabinet type embodiment in which the horn 1 is a folding horn.

The height of this cabinet is 1295mm, Ii] 4 3
6mm, depth 650mm, plate thickness 18mm.

The sound pressure frequency characteristic of this embodiment is shown in C of FIG.

It can be seen from this characteristic that the peaks of the third and fifth resonance frequencies are attenuated by the cancellation speaker 5, and the level of the fundamental resonance frequency f1 remains unchanged.

[Effects of the Invention] As described above, the present invention provides a canceling speaker at a position where the high-order resonance frequency that is to be attenuated is in opposite phase to the closed end sound pressure in the horn with the main body speaker attached to the closed end. By installing and driving in the same phase as the zero body speaker,
This attenuates the peak at the higher-order resonance frequency without attenuating the sound pressure at the fundamental frequency.

Therefore, in a bass horn type speaker that expands the bass range, the peaks generated by the harmonics are attenuated,
This horn-type speaker has a flat bass range and can be reproduced well.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of an embodiment of the present invention, Fig. 2 is a sound pressure diagram in the horn at the tertiary resonance frequency with respect to its fundamental resonance frequency, and Fig. 3 is a diagram of the sound pressure in the horn between its fundamental resonance frequency and the tertiary resonance frequency. A sound pressure diagram showing the relationship; FIG. 4 is a sectional view of another embodiment; FIG. 5 is a sectional view of a conventional horn-type speaker corresponding to the embodiment of FIG. 4; FIG. 6 is a sectional view of another embodiment. 7 is a sound pressure frequency characteristic diagram shown in FIGS. 4 to 6, FIG. 8 is a sectional view of a conventional horn type speaker, FIG. 9 is a sound pressure frequency characteristic diagram thereof, and FIG. 10 is a high frequency characteristic diagram. A cross-sectional view of a conventional horn-type speaker with attenuated next-order resonance, and FIG. 11 is a sound pressure frequency characteristic diagram thereof. 1...Horn, 4...Wooden speaker, and...Negative speaker. (a) (c) Figure 3 (b) (d)

Claims (1)

[Claims] One end is an open end, and the other end is a closed end, and the high-order resonance sound pressure in a finite length acoustic tube with a main body speaker attached to the closed end is at its maximum and on the side surface of the position where the phase is opposite to that of the closed end. A horn-type speaker, characterized in that a cancellation speaker is attached that is driven in the same phase as the main speaker.