U.S. Philips Corporation

Adrianus J Kaizer

Cornelis A Wesche

Joris A Nieuwendijk

Nico V Franssen, Deceased

Cornelis D Van Dijk

Georgius B Sanders

Gerrit Hendrik Van Leeuwen

Frederik Leonard Sangster

Friedrich J De Haan, Administrator

Wiert Kopinga

A bass-reflex loudspeaker system in which, by the addition of a corrective network (7) to an arrangement of a transducer (1) accommodated in a bass-reflex enclosure (2), which transducer is dimensioned such that it cannot be bass-reflexed by means of the bass-reflex enclosure, it is possible to simulate a set-up of an imaginary transducer which is housed in the said bass-reflex enclosure and which has a much greater frequency range H.sub.f (f) than the aforesaid arrangement.

Bass-reflex loudspeaker system

An arrangement for converting an electric signal into an acoustic signal (y/t) or vice versa, comprises an electroacoustic transducer (2) and means (3) for reducing distortion in the output signal of the arrangement, which distortion is caused by the electroacoustic or acoustoelectric conversion performed by the transducer. The means comprise a non-linear network (3', 3' or 3'' in FIGS. 3; 43', 43' or 43'' in FIG. 4). The non-linear network is arranged for reducing non-linear distortion by compensating for at least a second or higher order distortion component in the output signal of the arrangement. The network may comprise at least two parallel circuit branches (15a, 15b in FIG. 3; 47a, 47b in FIG. 4). At least one of the circuit branches (15b in FIG. 3; 47b in FIG. 4) compensates for non-linear distortion of the second or higher order.

Arrangement for converting an electric signal into an acoustic signal or

A device for converting an electric signal into an acoustic signal, which comprises an electro-acoustic transducer unit (2) having a quality factor (Q) less than unity. The device further comprises an amplifier circuit (3) for driving the transducer unit. The amplifier circuit has a frequency-dependent gain characteristic (6) which increases towards the lower frequencies, starting from f.sub.2, in a frequency range between a first and a second frequency (f.sub.1 and f.sub.2), f.sub.1 being the resonant frequency of the transducer unit (2) and f.sub.2 being greater than f.sub.1. The efficiency can be increased if amplifier the circuit includes a special amplifier such as a switched amplifier, for example, a class-D amplifier, or an amplifier with a power supply that provides a DC voltage that depends on the drive level of the amplifier.

Electro-acoustic converter with compensated frequency response

An electroacoustic transducer comprises a diaphragm (1), a magnet system (4) and a voice coil (3) arranged on a voice-coil former (2) in an air gap (5) of the magnet system. The movement is transmitted between the voice-coil former and the diaphragm via a lever mechanism comprising n lever devices (6) arranged at an angle relative to each other (n.gtoreq.2). A lever device (6) comprises a lever arm (9) coupled to a fulcrum (11) at the location of a first position (10) on the lever arm, to the voice-coil former (2) at the location of a second position (13), and to the diaphragm (1) at the location of a third position (14). The lever mechanism multiplies the excursion of the voice-coil former by a factor greater than unity. This results in an electroacoustic transducer with a long stroke which provides large excursions of the diaphragm. The lever mechanism may also be employed in other types of transducer, such as piezo-ceramic transducers. A compliant element (25) formed as a zigzag bellows secured both to the outer circumference of the diaphragm and to the chassis (26) to permit the large excursion of the diaphragm, is constructed so as to reduce the acoustic contribution of the compliant element to the transducer output signal, which contribution forms a distortion component in the output signal.

Large-excursion electroacoustic transducer

A device for driving an electroacoustic transducer (1) comprising a feedback amplifier and a pickup (2) whose output signal is a measure of the acoustic output signal of the transducer. A by-pass network (4) bypasses at least the transducer and the pickup and produces an output signal that for frequencies outside the operating range of the transducer is large and for frequencies in the operating range (f.sub.1 to f.sub.h) of the transducer is small relative to the pickup output signal. The sum of the output signals of the pickup and the by-pass network serves as a feedback signal. This widens the transducer frequency range and reduces distortion. The device may include a limiter (11) and a network (5) before the transducer. The network has a frequency response inverse to that of the signal path from the electroacoustic transducer to the pickup to provide an additional reduction in the distortion.

MFB system with a by-pass network

An electrodynamic transducer having a mechanical filter as a coupling element between a voice coil former (3) and cone (1) in order to obtain a frequency characteristic whose high frequency roll-off begins at a lower frequency, in which a part (7) of the centering diaphragm (4) situated within the periphery of the voice coil former is used as the mechanical filter.

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Eindhoven, Netherlands

Adrianus J Kaizer