US3562445A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Preamplifier for high fidelity system utilizing a moving coil stereophonic pickup cartridge
Assignee: PITS MUSIC CO
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Filing: 1968-09-23
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Granted: 1971-02-09
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Expires: 1988-09-23
Abstract
Abstract A preamplifier for a high fidelity system, which utilizes a moving coil, stereophonic, pickup cartridge, provides dynamic damping of the moving coils of that stereophonic, pickup cartridge by interposing an essentially resistive, low impedance, electrical interface between that cartridge and input of that preamplifier. Also, that preamplifier provides an overall gain which is greater than the desired overall gain, so an essentially resistive interface can be used between the output of that preamplifier and the input of the amplifier to which that preamplifier is connected.
Inventors
- 👤 Neil R Mccanney
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 20:30
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/181; H03F3/183
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
300 words
A preamplifier for a moving coil stereophonic pick up cartridge having two moving coils, one for each of two channels, which comprises: a first channel preamplifier section connected to one of the moving coils of said moving coil stereophonic, pickup cartridge to receive and amplify signals generated by said one moving coil; a second channel preamplifier section connected to the second moving coil of said moving coil stereophonic, pickup cartridge to receive and to amplify signals generated by said second moving coil; a resistive electrical interface connected across the input of said first channel preamplifier section and connected across the output of the first said moving coil of said moving coil, stereophonic, pickup cartridge to coact with said moving coil to form a closed loop, transducer-load system; said resistive electrical interface having an impedance smaller than the impedance of the first said moving coil of said moving coil stereophonic, pick up cartridge, whereby said electrical interface and said moving coil form a closed loop transducerload system wherein the impedance of the load is smaller than the impedance of said transducer; a second resistive electrical interface connected across the input of said second channel preamplifier section and connected across the output of said second moving coil of said moving coil, stereophonic, pick up cartridge to coact with said moving coil to form a closed loop, transducer-load system; said second resistive electrical interface having an impedance smaller than the impedance of said second coil, of said moving coil, stereophonic, pick up cartridge whereby said second electrical interface and said second moving coil form a closed loop, transducer-load system wherein the impedance of the load is smaller than the impedance of said transducer; and whereby said electrical interfaces provide dynamic samping for said moving coils and the stylus connected to said moving coils.
Claim 2
Dependent Claim
300 words
A preamplifier for a moving coil stereophonic pick up cartridge having two moving coils, one for each of two channels, which comprises: a first channel preamplifier section connected to one of the moving coils of said moving coil stereophonic, pickup cartridge to receive and amplify signals generated by said one moving coil; a second channel preamplifier section connected to the second moving coil of said moving coil stereophonic, pickup cartridge to receive and to amplify signals generated by said second moving coil; a resistive electrical interface connected across the input of said first channel preamplifier section and connected across the output of the first said moving coil of said moving coil, stereophonic, pickup cartridge to coact with said moving coil to form a closed loop, transducer-load system; said resistive electrical interface having an impedance smaller than the impedance of the first said moving coil of said moving coil stereophonic, pick up cartridge, whereby said electrical interface and said moving coil form a closed loop transducerload system wherein the impedance of the load is smaller than the impedance of said transducer; a second resistive electrical interface connected across the input of said second channel preamplifier section and connected across the output of said second moving coil of said moving coil, stereophonic, pick up cartridge to coact with said moving coil to form a closed loop, transducer-load system; said second resistive electrical interface having an impedance smaller than the impedance of said second coil, of said moving coil, stereophonic, pick up cartridge whereby said second electrical interface and said second moving coil form a closed loop, transducer-load system wherein the impedance of the load is smaller than the impedance of said transducer; and whereby said electrical interfaces provide dynamic samping for said moving coils and the stylus connected to said moving coils.
Claim 3
Dependent Claim
109 words
A preamplifier for a moving coil stereophonic, pick up cartridge as claimed in claim 1 wherein said first channel preamplifier section includes a plurality of stages of amplification, wherein said second channel preamplifier section includes a plurality of stages of amplification, wherein the first stage of amplification of the first said channel preamplifier section includes a transistor which has the emitter thereof directly connected to ground to obviate the thermal agitation developed within emitter resistors, and wherein the first stage of amplification of said second channel preamplifier section includes a transistor which as the emitter thereof directly connected to ground to obviate the thermal agitation developed within emitter resistors.
Claim 4
Dependent Claim
87 words
A preamplifier for a moving coil, stereophonic, pick up cartridge as claimed in claim 1 wherein said first channel preamplifier section includes a transistor and a coupling capacitor which directly couples signals, developed across the first said electrical interface by said one moving coil, to the base of said transistor, and wherein said second channel preamplifier section includes a transistor and a coupling capacitor which directly couples signals, developed across said second electrical interface by said second moving coil, to the base of the second said transistor.
Claim 5
Dependent Claim
63 words
A preamplifier for a moving coil, stereophonic, pickup cartridge as claimed in claim 1 wherein said first channel preamplifier section includes a transistor with a biasing resistor connected between the collector and emitter thereof to provide inverse feedback and wherein said second channel preamplifier section includes a transistor with a biasing resistor connected between the collector and emitter thereof to provide inverse feedback.
Claim 6
Dependent Claim
69 words
A preamplifier for a moving coil, stereophonic, pickup cartridge as claimed in claim 1 wherein said first channel preamplifier section includes a transistor with a biasing resistor that is dimensioned to provide an unsymmetrical, low noise Q point for said transistor, and wherein said second channel preamplifier section includes a transistor with a biasing resistor that is dimensioned to provide an unsymmetrical, low noise Q point for said transistor.
Claim 7
Dependent Claim
81 words
A preamplifier for a moving coil, stereophonic, pickup cartridge as claimed in claim 1 wherein said first channel preamplifier section includes a plurality of stages of amplification, wherein said second channel preamplifier section includes a plurality of stages of amplification, wherein all of said plurality of stages of amplification of the first said section are decoupled from said second section and wherein all of said plurality of stages of amplification of said second section are decoupled from the first said section.
Claim 8
Dependent Claim
183 words
A preamplifier for a moving coil, stereophonic, pickup cartridge as claimed in claim 1 wherein the total gain of said first channel preamplifier section is greater than the gain required to develop a usable output signal for said first section, wherein the total gain of said second channel preamplifier section is greater than the gain required to develop a usable output signal for said second section, wherein a third resistive electrical interface is connected across the output of said first section and is connected across an input of an amplifier to be driven by said preamplifier, wherein a fourth resistive electrical interface is connected across the output of said second section and is connected across an input of an amplifier, wherein said total gain of said first section is great enough to provide a usable output signal for said first section despite the signal attenuation caused by said third electrical interface, and wherein said total gain of said second section is great enough to provide a usable output signal for said second section despite the signal attenuation caused by said fourth electrical interface.
References Cited (Backward Citations)
US3079463A
Cited
US3213198A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-02-08 | 1974-08-10 | 1975-02-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-08 | 1978-08-10 | 1979-02-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-08 | 1982-08-10 | 1983-02-09 | $7700.00 | Window Closed / Lapsed |