US3838216A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device to effectively eliminate the motion induced back emf in a loudspeaker system in the region of fundamental acoustic resonance
Assignee: Individual
•
Filing: 1973-06-14
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Granted: 1974-09-24
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Expires: 1993-06-14
Abstract
Abstract A loudspeaker system is provided wherein a circuit, including a second voice coil and a series LC resonant circuit, is connected in parallel with the conventional voice coil. The impedance of the second voice coil is lower than that of the conventional coil and the resonant circuit is designed to resonate at the fundamental acoustical resonant frequency of the speaker cone so that a low impedance path for audio amplifier drive current is provided in the region of resonance. The second coil is ineffective at frequencies off resonance and by proper choice of the impedance of this coil, the speaker response at resonance can be matched to that off resonance. A parallel LC resonant circuit connected in series with the conventional coil is designed to effectively remove this coil at resonance and hence eliminate the effect of the back e.m.f. generated thereby.
Inventors
- 👤 W Watkins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 21:23
CPC Classifications
H; H04; H04R; H04R3/00; H04R3/002; H04R3/04; H04R3/08; H04R9/00; H04R9/06; H04R9/063; H04R2209/00; H04R2209/041
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
149 words
In a loudspeaker system including at least one speaker unit comprising at least one voice coil adapted to be connected to an audio amplifier and an acoustical cone driven by the voice coil, the improvement comprising an electrical circuit connected in parallel with the at least one voice coil comprising a further voice coil having a lower impedance than the at least one voice coil and a resonant circuit, connected in series with said further voice coil, which resonates at the fundamental acoustical resonant frequency of the cone so as to present a low impedance path to the amplifier in the region of resonance such that current flow through the further voice coil is increased in said region and to effectively eliminate the motion induced back emf in the loudspeaker system in the region of fundamental resonance, said further voice coil being ineffective at frequencies outside of said region.
Claim 2
Dependent Claim
149 words
In a loudspeaker system including at least one speaker unit comprising at least one voice coil adapted to be connected to an audio amplifier and an acoustical cone driven by the voice coil, the improvement comprising an electrical circuit connected in parallel with the at least one voice coil comprising a further voice coil having a lower impedance than the at least one voice coil and a resonant circuit, connected in series with said further voice coil, which resonates at the fundamental acoustical resonant frequency of the cone so as to present a low impedance path to the amplifier in the region of resonance such that current flow through the further voice coil is increased in said region and to effectively eliminate the motion induced back emf in the loudspeaker system in the region of fundamental resonance, said further voice coil being ineffective at frequencies outside of said region.
Claim 3
Dependent Claim
43 words
A loudspeaker system as claimed in claim 1 wherein said resonant circuit comprises a capacitor and an inductor connected in series so as to present a low impedance path in said region and a high impedance path both above and below said region.
Claim 4
Dependent Claim
49 words
A loudspeaker system as claimed in claim 2 further comprising a further resonant circuit connected in series with the at least one voice coil for presentinG a high impedance to the amplifier in the said region, said further resonant circuit presenting a lower impedance above and below said region.
Claim 5
Dependent Claim
21 words
A loudspeaker system as claimed in claim 3 wherein said further resonant circuit comprises a capacitor and inductor connected in parallel.
Claim 6
Dependent Claim
20 words
A loudspeaker system as claimed in claim 1 further comprising a capacitor connected in shunt with said further voice coil.
Claim 7
Dependent Claim
22 words
A loudspeaker system as claimed in claim 1 wherein said further coil is wound on top of the at least one coil.
Claim 8
Dependent Claim
20 words
A loudspeaker system as claimed in claim 1 wherein said further coil is wound beneath the at least one coil.
Claim 9
Dependent Claim
21 words
A loudspeaker system as claimed in claim 1 wherein the further coil has fewer turns than the at least one coil.
Claim 10
Dependent Claim
29 words
A loudspeaker system as claimed in claim 1 wherein the wire size of the wire in the further coil is greater than that of the at least one coil.
Claim 11
Dependent Claim
21 words
A loudspeaker system as claimed in claim 4 further comprising variable resistor means for controlling the ''''Q'''' of said resonant circuits.
Claim 12
Dependent Claim
65 words
A loudspeaker system as claimed in claim 10 wherein said variable resistor means comprises a first variable resistor connected in series with said series resonant circuit and a second variable resistor connected in parallel across said series resonant circuit and a third variable resistor connected in series with said parallel resonant circuit and a fourth variable resistor connected in parallel across said parallel resonant circuit.
References Cited (Backward Citations)
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Cited
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-23 | 1978-03-25 | 1978-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-23 | 1982-03-25 | 1982-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-23 | 1986-03-25 | 1986-09-24 | $7700.00 | Window Closed / Lapsed |