Patent US3715501A successfully refreshed from Google Patents.
US3715501A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Loudspeaker system
Assignee: MCINTOSH LABOR Inc
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Filing: 1969-11-03
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Granted: 1973-02-06
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Expires: 1989-11-03
Abstract
Abstract A flat acoustic pressure response, compensating network, driver amplifier and loudspeaker system, the driver amplifier being an effective voltage source and the loudspeaker system containing multiple speakers including a low frequency loudspeaker mechanism which is both efficient and highly damped magnetically by providing a powerful magnetic flux field, and a many turn motor coil which is capable of enforcing wide cone excursions. The loudspeaker mechanism in the enclosure without acoustic damping has a higher Q than the same mechanism in the same enclosure with acoustic damping added. Response gradually rolls off below 150 Hz and down to system resonance approaching a rate of 6 dB per octave. Below system resonance rolloff gradually approaches 12 dB per octave. Rolloff prior to system resonance occurs due to a high flux density, long motor turns, low resistance, and low moving mass producing a Q at system resonance of 0.5 or less. The speaker is operated at high efficiency above 150 Hz and its rolloff is compensated to about 20 Hz by a compensation equalizer. This equalizer is connected to the input of the driving power amplifier and involves about 20 dB of boost at 20 Hz.
Inventors
- 👤 R Russell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:32
CPC Classifications
H; H04; H04R; H04R3/00; H04R3/04; H04R3/12; H04R3/14
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
372 words
A loudspeaker system including a compensation network, a power amplifier having flat response from 20 Hz to at least a mid-range audio frequency, a loudspeaker system arranged to maintain a level acoustic response down to 20 Hz, said loudspeaker system comprising at least one electrodynamic bass loudspeaker having a voice coil, said compensation network comprising an equalizer amplifier arranged to increase the drive of said power amplifier as a function of frequency so as to compensate for rolloff by about 6 db per octave to system resonance and thereafter by about 12 db per octave down to about 20 Hz with sharp cut-off thereafter, said power amplifier having a predetermined output circuit resistance as seen by said loudspeaker system which is sufficiently low that said output circuit acts as a voltage source for a loudspeaker load directly connected thereto such that said power amplifier provides essentially constant output voltage at all output currents, said power amplifier being capable of delivering its rated power with flat response down to said about 20 Hz, a loudspeaker system including said bass loudspeaker and a high frequency loudspeaker of acoustic efficiency equal to the acoustic efficiency of said bass loudspeaker, said loudspeakers being connected in electrical parallel to said power amplifier to be driven thereby, leads having resistance less than 5 percent of the dc resistance of said loudspeaker system connecting said power amplifier to said bass loudspeaker, said bass loudspeaker system comprising a sealed enclosure, acoustic damping material in said enclosure, said low frequency loudspeaker having concurrently sufficiently low effective moving mass, low resistance and high flux density, and said enclosure acoustic damping material providing adequate acoustic damping to provide a system Q at about 0.5 or less at a resonant frequency of about 60 Hz with consequent substantially smooth roll-off of acoustic pressure provided by said loudspeaker from about 150 Hz to 20 Hz, said loudspeaker system being mechanically capable of achieving uniform sound pressure response through its range down to 20 Hz, said compensation network being connected to the input of said power amplifier for compensating for said acoustic pressure roll-off of said loudspeaker system down to said 20 Hz, so as to provide flat acoustic pressure response down to said 20 Hz.
Claim 2
Dependent Claim
372 words
A loudspeaker system including a compensation network, a power amplifier having flat response from 20 Hz to at least a mid-range audio frequency, a loudspeaker system arranged to maintain a level acoustic response down to 20 Hz, said loudspeaker system comprising at least one electrodynamic bass loudspeaker having a voice coil, said compensation network comprising an equalizer amplifier arranged to increase the drive of said power amplifier as a function of frequency so as to compensate for rolloff by about 6 db per octave to system resonance and thereafter by about 12 db per octave down to about 20 Hz with sharp cut-off thereafter, said power amplifier having a predetermined output circuit resistance as seen by said loudspeaker system which is sufficiently low that said output circuit acts as a voltage source for a loudspeaker load directly connected thereto such that said power amplifier provides essentially constant output voltage at all output currents, said power amplifier being capable of delivering its rated power with flat response down to said about 20 Hz, a loudspeaker system including said bass loudspeaker and a high frequency loudspeaker of acoustic efficiency equal to the acoustic efficiency of said bass loudspeaker, said loudspeakers being connected in electrical parallel to said power amplifier to be driven thereby, leads having resistance less than 5 percent of the dc resistance of said loudspeaker system connecting said power amplifier to said bass loudspeaker, said bass loudspeaker system comprising a sealed enclosure, acoustic damping material in said enclosure, said low frequency loudspeaker having concurrently sufficiently low effective moving mass, low resistance and high flux density, and said enclosure acoustic damping material providing adequate acoustic damping to provide a system Q at about 0.5 or less at a resonant frequency of about 60 Hz with consequent substantially smooth roll-off of acoustic pressure provided by said loudspeaker from about 150 Hz to 20 Hz, said loudspeaker system being mechanically capable of achieving uniform sound pressure response through its range down to 20 Hz, said compensation network being connected to the input of said power amplifier for compensating for said acoustic pressure roll-off of said loudspeaker system down to said 20 Hz, so as to provide flat acoustic pressure response down to said 20 Hz.
Claim 3
Dependent Claim
372 words
A loudspeaker system including a compensation network, a power amplifier having flat response from 20 Hz to at least a mid-range audio frequency, a loudspeaker system arranged to maintain a level acoustic response down to 20 Hz, said loudspeaker system comprising at least one electrodynamic bass loudspeaker having a voice coil, said compensation network comprising an equalizer amplifier arranged to increase the drive of said power amplifier as a function of frequency so as to compensate for rolloff by about 6 db per octave to system resonance and thereafter by about 12 db per octave down to about 20 Hz with sharp cut-off thereafter, said power amplifier having a predetermined output circuit resistance as seen by said loudspeaker system which is sufficiently low that said output circuit acts as a voltage source for a loudspeaker load directly connected thereto such that said power amplifier provides essentially constant output voltage at all output currents, said power amplifier being capable of delivering its rated power with flat response down to said about 20 Hz, a loudspeaker system including said bass loudspeaker and a high frequency loudspeaker of acoustic efficiency equal to the acoustic efficiency of said bass loudspeaker, said loudspeakers being connected in electrical parallel to said power amplifier to be driven thereby, leads having resistance less than 5 percent of the dc resistance of said loudspeaker system connecting said power amplifier to said bass loudspeaker, said bass loudspeaker system comprising a sealed enclosure, acoustic damping material in said enclosure, said low frequency loudspeaker having concurrently sufficiently low effective moving mass, low resistance and high flux density, and said enclosure acoustic damping material providing adequate acoustic damping to provide a system Q at about 0.5 or less at a resonant frequency of about 60 Hz with consequent substantially smooth roll-off of acoustic pressure provided by said loudspeaker from about 150 Hz to 20 Hz, said loudspeaker system being mechanically capable of achieving uniform sound pressure response through its range down to 20 Hz, said compensation network being connected to the input of said power amplifier for compensating for said acoustic pressure roll-off of said loudspeaker system down to said 20 Hz, so as to provide flat acoustic pressure response down to said 20 Hz.
Claim 4
Dependent Claim
372 words
A loudspeaker system including a compensation network, a power amplifier having flat response from 20 Hz to at least a mid-range audio frequency, a loudspeaker system arranged to maintain a level acoustic response down to 20 Hz, said loudspeaker system comprising at least one electrodynamic bass loudspeaker having a voice coil, said compensation network comprising an equalizer amplifier arranged to increase the drive of said power amplifier as a function of frequency so as to compensate for rolloff by about 6 db per octave to system resonance and thereafter by about 12 db per octave down to about 20 Hz with sharp cut-off thereafter, said power amplifier having a predetermined output circuit resistance as seen by said loudspeaker system which is sufficiently low that said output circuit acts as a voltage source for a loudspeaker load directly connected thereto such that said power amplifier provides essentially constant output voltage at all output currents, said power amplifier being capable of delivering its rated power with flat response down to said about 20 Hz, a loudspeaker system including said bass loudspeaker and a high frequency loudspeaker of acoustic efficiency equal to the acoustic efficiency of said bass loudspeaker, said loudspeakers being connected in electrical parallel to said power amplifier to be driven thereby, leads having resistance less than 5 percent of the dc resistance of said loudspeaker system connecting said power amplifier to said bass loudspeaker, said bass loudspeaker system comprising a sealed enclosure, acoustic damping material in said enclosure, said low frequency loudspeaker having concurrently sufficiently low effective moving mass, low resistance and high flux density, and said enclosure acoustic damping material providing adequate acoustic damping to provide a system Q at about 0.5 or less at a resonant frequency of about 60 Hz with consequent substantially smooth roll-off of acoustic pressure provided by said loudspeaker from about 150 Hz to 20 Hz, said loudspeaker system being mechanically capable of achieving uniform sound pressure response through its range down to 20 Hz, said compensation network being connected to the input of said power amplifier for compensating for said acoustic pressure roll-off of said loudspeaker system down to said 20 Hz, so as to provide flat acoustic pressure response down to said 20 Hz.
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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) | 1976-02-06 | 1976-08-07 | 1977-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-06 | 1980-08-07 | 1981-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-06 | 1984-08-07 | 1985-02-06 | $7700.00 | Window Closed / Lapsed |