Abstract:
A device is arranged for driving a transducer unit (20) comprising at least one transducer (21) accommodated in an enclosure (22). The device comprises mapping means for mapping input signal components having a first audio frequency range onto a second audio frequency range. The second audio frequency range is narrower than the first audio frequency range, and the second frequency range contains the Helmholtz frequency of the transducer unit (20). A transducer unit (20) for use with the device is optimized for operating in a narrow frequency range at or near the Helmholtz frequency ( ƒ H ).
Abstract:
A loudspeaker arrangement comprises an acoustic enclosure (101) which is divided into at least two subchambers (103, 105). An audio radiator (109) is mounted in a first subchamber (103) of the at least two subchambers (103, 105) such that it radiates outwardly of the acoustic enclosure (101). A port (107) is included for pneumatically connecting the first subchamber (103) and the second subchamber (105). The system is designed such that a Helmholtz frequency of the first subchamber (103) and the port (107) is at least five times higher than a resonance frequency of the audio radiator (109). The loudspeaker arrangement may provide an improved trade-off between sound pressure levels, audio quality and size and may in particular provide improved low frequency performance without introducing disadvantages typically associated with conventional ported speaker and passive radiator designs.
Abstract:
A vented loudspeaker system comprises a cabinet (CA) with a bass port (BP) and a loudspeaker (LS) creating an air pressure in the cabinet (CA) in response to an audio signal(DS). At least part of the bass port (IP) is moveably arranged with respect to the cabinet (CA) to vary a frequency response of the vented loudspeaker system. The air pressure causes an alternating airflow through the bass port (BP) thereby generating an alternating force acting on the at least part of the bass port (IP). The system further comprises means (AS, RE) for applying a direction dependent passive force or for modifying the alternating force on the at least part of the bass port (IP) to obtain a total non-zero average force acting on the at least part of the bass port (IP) in one direction for moving the at least part of the bass port (IP) in the one direction.
Abstract:
A loudspeaker protection system comprises filter means for defining one or more frequency bands of an audio signal, controllable amplifier/attenuator means coupled to the filter means, and processing means coupled to control the amplifier/attenuator means, such as to determine audio power in at least one of said frequency bands representing relevant loudspeaker protection information used for selective audio power control in said at least one frequency band. This system has the features for a fast and/or slow thermal protection, as well as for a cone excursion protection all for a loudspeaker in such a system.
Abstract:
A cooling device (1) using pulsating fluid for cooling of an object, comprising: a transducer (2) having a membrane adapted to generate pressure waves at a working frequency (f w ), and a cavity (4) enclosing a first side of the membrane. The cavity (4) has at least one opening (5) adapted to emit a pulsating net output fluid flow towards the object, wherein the opening (5) is in communication with a second side of the membrane. The cavity (4) is sufficiently small to prevent fluid in the cavity (4) from acting as a spring in a resonating mass-spring system in the working range. This is advantageous as a volume velocity (u 1) at the opening is essentially equal to a volume velocity (u 1 ') at the second side of the membrane, apart from a minus sign. Thus, at the working frequency the pulsating net output fluid can be largely cancelled due to the counter phase with the pressure waves on the second side of the membrane resulting in a close to zero far-field volume velocity. Thus a low sound level is achieved, at a low cost, without requiring mechanical symmetry.
Abstract:
A cooling device (1) using pulsating fluid for cooling of an object, comprising: a transducer (2) having a membrane adapted to generate pressure waves at a working frequency (fw), and a cavity (4) enclosing a first side of the membrane. The cavity (4) has at least one opening (5) adapted to emit a pulsating net output fluid flow towards the object, wherein the opening (5) is in communication with a second side of the membrane. The cavity (4) is sufficiently small to prevent fluid in the cavity (4) from acting as a spring in a resonating mass-spring system in the working range. This is advantageous as a volume velocity (u1) at the opening is essentially equal to a volume velocity (u1 ') at the second side of the membrane, apart from a minus sign. Thus, at the working frequency the pulsating net output fluid can be largely cancelled due to the counter phase with the pressure waves on the second side of the membrane resulting in a close to zero far-field volume velocity. Thus a low sound level is achieved, at a low cost, without requiring mechanical symmetry.
Abstract:
A device is arranged for driving a transducer unit (20) comprising at least one transducer (21) accommodated in an enclosure (22). The device comprises mapping means for mapping input signal components having a first audio frequency range onto a second audio frequency range. The second audio frequency range is narrower than the first audio frequency range, and the second frequency range contains the Helmholtz frequency of the transducer unit (20). A transducer unit (20) for use with the device is optimized for operating in a narrow frequency range at or near the Helmholtz frequency ( H).
Abstract:
A device (30) for adapting an audio input signal (V1n) to a transducer unit (20) comprises: mapping means (10) for mapping input signal components from a first audio frequency range onto a second audio frequency range so as to produce a mapped audio signal (VM), wherein the second audio frequency range is narrower than the first audio frequency range, and wherein the transducer unit (20) has a maximum efficiency at the second audio frequency range, filter means (31) for filtering the input signal (V1n) so as to produce a filtered input signal (V1n') having a third audio frequency range, and combination means (32) for combining the mapped audio signal (VM) and the filtered input signal (V1n') so as to produce a transducer signal (VT). The first audio frequency range is preferably contained in the second audio frequency range, while the third audio frequency range may be adjacent the first audio frequency range. The second audio frequency range preferably extends within 5% of the Helmholtz frequency of the transducer unit (20).
Abstract:
An enclosure (1) for an acoustic transducer (2) comprises a first chamber (11) for accommodating the acoustic transducer (2) and a spaced apart second chamber (12), which first and second chambers are acoustically coupled by a coupling section (15). The coupling section may have a smaller diameter than the first and the second chamber. An optional further coupling section (16) may acoustically couple the first chamber (11) to an optional third chamber (13). The volume of the enclosure is distributed over the various chambers, thus providing a relatively large enclosure, even when the first chamber (11) is small. Any non-fundamental resonances induced by the coupling sections (15, 16) lie outside the active region of the transducer (2).
Abstract:
An audio driver comprising a diaphragm (101, 103) with a first side and a second side. The diaphragm (101, 103) is coupled to a transducer element (109, 111) on the second side and is arranged to radiate sound. The transducer element (109, 111) converts an electrical input signal into movement of the diaphragm (101, 103). The diaphragm (101, 103) is arranged such that a part of the diaphragm (103) at least partly forms a cavity (113) at the second side and an air conduit (115) is coupled to the cavity (113). The air conduit (115) has a first opening (117) into the cavity and a second opening (119) outside the cavity (113). The air conduit (115) and cavity (113) form a resonator which has a resonance frequency that is less than half a free air acoustic resonance frequency of the audio driver. The invention may allow simultaneous sound production and an acoustic air flow generation while maintaining an efficient decoupling between the two functionalities.