GB1525561A – Magnetic recording apparatus and method
– Google Patents
GB1525561A – Magnetic recording apparatus and method
– Google Patents
Magnetic recording apparatus and method
Info
Publication number
GB1525561A
GB1525561A
GB2981774A
GB2981774A
GB1525561A
GB 1525561 A
GB1525561 A
GB 1525561A
GB 2981774 A
GB2981774 A
GB 2981774A
GB 2981774 A
GB2981774 A
GB 2981774A
GB 1525561 A
GB1525561 A
GB 1525561A
Authority
GB
United Kingdom
Prior art keywords
signal
khz
filters
recorded
passed
Prior art date
1975-10-02
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB2981774A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
EMI Ltd
Original Assignee
EMI Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
1975-10-02
Filing date
1975-10-02
Publication date
1978-09-20
1975-10-02
Application filed by EMI Ltd
filed
Critical
EMI Ltd
1975-10-02
Priority to GB2981774A
priority
Critical
patent/GB1525561A/en
1978-09-20
Publication of GB1525561A
publication
Critical
patent/GB1525561A/en
Status
Expired
legal-status
Critical
Current
Links
Espacenet
Global Dossier
Discuss
Classifications
H—ELECTRICITY
H03—ELECTRONIC CIRCUITRY
H03G—CONTROL OF AMPLIFICATION
H03G5/00—Tone control or bandwidth control in amplifiers
H03G5/16—Automatic control
H03G5/165—Equalizers; Volume or gain control in limited frequency bands
G—PHYSICS
G11—INFORMATION STORAGE
G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
G11B5/86—Re-recording, i.e. transcribing information from one magnetisable record carrier on to one or more similar or dissimilar record carriers
H—ELECTRICITY
H03—ELECTRONIC CIRCUITRY
H03G—CONTROL OF AMPLIFICATION
H03G9/00—Combinations of two or more types of control, e.g. gain control and tone control
H03G9/02—Combinations of two or more types of control, e.g. gain control and tone control in untuned amplifiers
H03G9/025—Combinations of two or more types of control, e.g. gain control and tone control in untuned amplifiers frequency-dependent volume compression or expansion, e.g. multiple-band systems
Abstract
1525561 Signal compressors EMI Ltd 2 Oct 1975 [5 July 1974] 29817/74 Heading H4R In a method of duplicating recorded magnetic tapes in which a master tape is replayed at a higher speed than recorded and duplicated on tapes which are proportionately speeded up relative their ultimate replay speed, the master tape is recorded after passing the signal through a circuit which limits the amplitude of a selected band of frequencies above 4 kHz to a level which is below that which, during the final recording, will cause saturation of the magnetic material on the duplicate tapes. As described the signal to be recorded on the master tape is passed through the apparatus of Fig. 1 in which the input signal at 1 is passed through a filter 10 having an m-type section 11 and a k-type section 12 to give a response which falls at 24 dB/octave above 14 kHz. The resulting signal is split into frequency bands centred at 51 Hz, 2 kHz, 4 kHz, 8 kHz and 16 kHz, by filters 21 to 24, the lower filters 24 having a fixed loss in the pass band, while the higher filters have a variable loss dependent on the signal level. The outputs of the filters are combined at the low impedance input of adder 30 before appropriate amplification and recording. In the control circuits the combined signal from the adder 30 is passed through an equalizer amplifier 44, which has a characteristic rising at 6 dB/octave above 5 kHz, to selective filters (411, 421, 431) Fig. 2 (not shown) having centre frequencies corresponding to those of the filters 21 to 23. The filter output pass through flat amplifiers (412, 422, 432) to rectifiers (413, 423, 433) to provide control signals which increase with the signal amplitude in the respective channels, and through differentiating amplifiers (414, 424, 434) to rectifiers (416, 426, 436) to provide control signals which depend on the rate of change of signal in the respective channels. The control signals in each channel are combined to provide a single control signal for each channel which is applied to a respective Zener diode network (415, 425, 435) to provide an adjustable gain control impedance in the respective filter.
GB2981774A
1975-10-02
1975-10-02
Magnetic recording apparatus and method
Expired
GB1525561A
(en)
Priority Applications (1)
Application Number
Priority Date
Filing Date
Title
GB2981774A
GB1525561A
(en)
1975-10-02
1975-10-02
Magnetic recording apparatus and method
Applications Claiming Priority (1)
Application Number
Priority Date
Filing Date
Title
GB2981774A
GB1525561A
(en)
1975-10-02
1975-10-02
Magnetic recording apparatus and method
Publications (1)
Publication Number
Publication Date
GB1525561A
true
GB1525561A
(en)
1978-09-20
Family
ID=10297659
Family Applications (1)
Application Number
Title
Priority Date
Filing Date
GB2981774A
Expired
GB1525561A
(en)
1975-10-02
1975-10-02
Magnetic recording apparatus and method
Country Status (1)
Country
Link
GB
(1)
GB1525561A
(en)
Cited By (1)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
FR2469829A1
(en)
*
1979-11-14
1981-05-22
Elap
Automatic gain control wide band amplifier – carries frequency multiplexed channels using sequential feedback through parallel filters with bandwidths matched to inputs
1975
1975-10-02
GB
GB2981774A
patent/GB1525561A/en
not_active
Expired
Cited By (1)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
FR2469829A1
(en)
*
1979-11-14
1981-05-22
Elap
Automatic gain control wide band amplifier – carries frequency multiplexed channels using sequential feedback through parallel filters with bandwidths matched to inputs
Similar Documents
Publication
Publication Date
Title
US3784749A
(en)
1974-01-08
Noise eliminating device
JPS57150285A
(en)
1982-09-17
Magnetic recording system of sound signal and recording and reproducing system
US4074204A
(en)
1978-02-14
Equalizing amplifier
GB1525561A
(en)
1978-09-20
Magnetic recording apparatus and method
US3067287A
(en)
1962-12-04
Stereophonic sound transmission systems
US2527463A
(en)
1950-10-24
Multicolored record and reproducing system therefor
EP0052415A3
(en)
1982-08-04
Frequency characteristic adjusting apparatus
US2748192A
(en)
1956-05-29
Reverberation generator
JPS57190477A
(en)
1982-11-24
Noise suppressing circuit
US3911370A
(en)
1975-10-07
Audio frequency amplitude compensator
JPS59105707A
(en)
1984-06-19
Acoustic effect device
GB871992A
(en)
1961-07-05
Improvements relating to stereophonic sound transmission systems
GB1011443A
(en)
1965-12-01
Magnetic recording and playback device
ATE12870T1
(en)
1985-05-15
EQUIPMENT FOR RECORDING AND/OR EDITING STEREOPHONE SIGNALS.
GB798948A
(en)
1958-07-30
System for reproducing signals from a magnetic medium
US2260717A
(en)
1941-10-28
Sound recording system
JPS5220801A
(en)
1977-02-17
Automatic voice frequency elimination and control system
JPS5446404A
(en)
1979-04-12
Noise reduction device
GB762928A
(en)
1956-12-05
Magnetic sound transduction
JPS578913A
(en)
1982-01-18
Magnetic recording and reproducing device
JPS5562509A
(en)
1980-05-12
Sound recording and reproducing system of tape recorder
JPS57195307A
(en)
1982-12-01
Magnetic recording and reproducing device
Burwen
1972
A Dynamic Noise Filter For Mastering
GB1462719A
(en)
1977-01-26
Amplifier arrangements for magnetic tape apparatus
NL7700385A
(en)
1978-07-18
Power amplifier with two output channels for electronic organ – has three cascade connected operational amplifier stages and filters
Legal Events
Date
Code
Title
Description
1979-01-10
PS
Patent sealed
1981-05-13
PCNP
Patent ceased through non-payment of renewal fee
