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(11) | EP 0 409 429 A3 |
(12) | EUROPEAN PATENT APPLICATION |
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(54) | Loudspeaker drive unit |
(57) The invention relates to a constant current drive speaker system in which a dynamic
speaker is driven by a constant current amplifier. Generally, when the dynamic speaker
is driven by a constant current, it is frequently observed that the vibrational system
thereof cannot be damped satisfactorily near the low band resonance frequency. To
remove this disadvantage, a damping coil (23) provided bodily with the vibrational
system is terminated by a predetermined impedance and is provided within a magnetic
gap of a magnetic circuit (25) provided independently of the magnetic circuit (15)
of the vibrational system, thereby damping the vibration system. Alternatively, a
voice coil bobbin is formed of a conductive material to form a short-circuited ring
on which there is wound a voice coil. This speaker system is driven by a low frequency,
whereby the vibrational system thereof is damped without electromagnetic coupling.
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