DE1053571B - Magnetic frequency setting for electrodynamic loudspeakers - Google Patents

Description

GERMAN

The invention relates to a magnetic frequency setting for electrodynamic loudspeakers.

The loudspeakers known so far are due to the properties of the centerings and membranes the reproduction range and the resonance frequency are determined and cannot be changed. To at To obtain sound reproduction over a wide frequency range, several loudspeakers are generally required with different frequencies as tweeter or woofer required.

There are also known electromagnetically acting damping devices, which from the playback current to be influenced.

So z. B. is an arrangement for damping the natural vibrations of membranes for telephones, Microphones, gramophones and similar apparatus described in which one or more Selective damping adjusted to natural vibration frequencies of the membrane is attached the purpose of an elastic that is undamped or weakly damped with regard to forced vibrations System with no or only weak natural vibrations.

The movements of the membrane cause changes in current in the windings of an electromagnet which in turn have a three-electrode tube that is tuned to the natural frequency of the membrane affect the controlling oscillating circuit in the case of resonance. In the output circle of the tube there is a Membrane retroactive electromagnet that works in phase opposition with the magnet.

Another device relates to the damping of mechanically vibrating bodies, in particular in the case of acoustic devices, in which the energy taken from the vibrating energy of the body electromagnetically reacts back to the vibrating body via an electron tube system. In this device, the same electromagnetic system that transmits the damping force to the vibrating body is also used to either supply the external force that sets the body in motion or to take the energy used to generate the damping force from the body or, finally, to exercise all of them at the same time these functions to be used. It can use the Electromagnet-Magnetic Frequency Adjustment
for electrodynamic loudspeakers

Applicant:

Karl Schulz,
Berlin-Weißensee, Schönstr. 54

Karl Schulz, Berlin-Weißensee,
has been named as the inventor

system also has a bridge arrangement

switched on

in which the output circuit of the tube system is balanced with respect to the input circuit.

The object of the invention is now to magnetically with only one loudspeaker, d. H. taking advantage of the magnetic flux, the reproduction range and the fundamental resonance frequency change.

According to the invention, this is achieved in that one up to the membrane head inside the voice coil at the end of the coil reaching pin is provided, the free end of which is a rotatably mounted star-shaped, the disc forming the pole ends carries, and that at the same height of the pole ends on the oscillating Share the speaker, e.g. B. centering, voice coil or membrane, the pole ends with a small distance opposing metal parts are arranged, which get into the area of attraction of the pole ends when the disk is rotated, in such a way that the membrane held in their vibrations at high frequencies or released at low frequencies will. The diameter of the disk is kept smaller than the voice coil diameter.

In the drawing, the invention is illustrated in more detail in an exemplary embodiment. It shows

Fig. 1 the loudspeaker in partial section and

Fig. 2 is the top view of the same.

The magnetic flux of the magnetic core is continued through the pin 1 within the voice coil to the end of the coil on the membrane head. The pin 1 carries at its free end a star-shaped iron disk 2 which is rotatably mounted. The disk 2 forms the pole ends 3. It is kept smaller than the voice coil diameter. At the same height as disc 2 , the vibrating parts of the loudspeaker (centering

809 787/386

Claims (1)

tion, membrane or voice coil) small metal parts 4 are arranged, which have only a very small distance from the pole ends 3 . By rotating the disk 2 , the metal parts 4 are brought more or less into the area of attraction of the disk poles and are thereby held more or less firmly. In this way, the membrane is optionally held in its vibrations at high frequencies and released at low frequencies. Due to natural signs of fatigue in the centerings and membrane vibrating grooves in the loudspeakers known up to now, each membrane tends to sag and thereby push the voice coil out of the magnetic gap. However, this has the effect that the efficiency of the loudspeakers is considerably reduced. This is completely eliminated by the design according to the invention, since the membrane is repeatedly pulled into its original position by the small metal parts 4 attached to it, that is to say to the height of the rotatable disk 2. At the same time, the vibrating parts are balanced. Claim: Magnetic frequency setting for electrodynamic loudspeakers, characterized in that that within the voice coil a pin reaching up to the membrane head at the end of the coil is provided, the free end of a rotatably mounted star-shaped, the pole ends forming And that the pole ends on the vibrating parts of the loudspeaker are at the same height, z. B. centering, voice coil or membrane, the pole ends are arranged with a small distance opposite metal parts, which get into the area of attraction of the pole ends when turning the disc. Considered publications:
German patent specifications No. 430216, 497 251. 1 sheet of drawings • -iigMi © 809 787/386 3.59