GB2153187A - A method of processing audio information - Google Patents

A method of processing audio information Download PDF

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Publication number
GB2153187A
GB2153187A GB08401589A GB8401589A GB2153187A GB 2153187 A GB2153187 A GB 2153187A GB 08401589 A GB08401589 A GB 08401589A GB 8401589 A GB8401589 A GB 8401589A GB 2153187 A GB2153187 A GB 2153187A
Authority
GB
United Kingdom
Prior art keywords
right hand
low
audio information
left hand
channel output
Prior art date
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.)
Withdrawn
Application number
GB08401589A
Other versions
GB8401589D0 (en
Inventor
Martin James Dalgleish
William Miller
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.)
Linn Products Ltd
Original Assignee
Linn Products 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.)
Filing date
Publication date
Application filed by Linn Products Ltd filed Critical Linn Products Ltd
Priority to GB08401589A priority Critical patent/GB2153187A/en
Publication of GB8401589D0 publication Critical patent/GB8401589D0/en
Publication of GB2153187A publication Critical patent/GB2153187A/en
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R5/00—Stereophonic arrangements
    • H04R5/04—Circuit arrangements, e.g. for selective connection of amplifier inputs/outputs to loudspeakers, for loudspeaker detection, or for adaptation of settings to personal preferences or hearing impairments
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00992—Circuits for stereophonic or quadraphonic recording or reproducing
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/24—Signal processing not specific to the method of recording or reproducing; Circuits therefor for reducing noise

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Stereophonic System (AREA)

Abstract

Stereo audio signals are processed by filtering low-frequency signals from each channel in a low- pass filter 10, amplifying the low-frequency signals at 12, and adding the resulting signal to the opposite channel. It has been found that this eliminates or reduces low-frequency noise caused by low- frequency vertical modulation, e.g. record warpage. <IMAGE>

Description

SPECIFICATION A method of processing audio information The present invention relates to the processing of audio information.
Generally, when a recorded disc is being played on a turntable the desired audio information subjects cartridge and headshell to lateral modulation as the stylus follows the groove of the disc. However, they are also subject to vertical modulation, i.e. up and down movement at low frequency, in the stiffness controlled region due to record warpage and other effects. It is desirable to remove this low frequency noise from the audio output, and this is usually achieved by using a high pass filter to cut off the low frequency components. However this cuts off the wanted low frequency components as well as the unwanted low frequency components.
Although the audio spectrum for the human ear extends from 20Hz to 20KHz, there are frequency components below 20Hz which enhance the sound quality perceived by the listener.
It is an object of the present invention to mitigate or obviate the aforesaid disadvantage.
The invention is based on the realisation that the wanted low frequency audio information is in-phase in the left and right hand channels, while the unwanted low-frequency noise is substantially antiphase.
The present invention accordingly provides a method of processing audio information by cross-feeding the low frequency components of the right hand and left hand channel output signals from a stereo cartridge in order to eliminate unwanted low frequency components and maintain the wanted low frequency components.
From another aspect the present invention provides apparatus for processing right hand and left hand audio information from a stereo cartridge, the apparatus comprising signal paths including low-pass filter means from the right hand channel to the left hand channel and vice versa, such that the substantially out of phase output signals due to vertical modulation are eliminated and the substantially in phase output signals due to lateral modulation are added.
Preferably, said means comprises a low pass filter, an amplifier and a resistor connected in series between the right hand channel output and the left hand channel output and a low pass filter, an amplifier and a resistor connected in series between the left hand channel output and the right hand channel output.
An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings; in which:~ Figure 1 shows the right hand and left hand channel output responses due to lateral modulation; Figure 2 shows the right hand and left hand channel output responses due to vertical modulation; Figure 3 shows the combined output response of both channels; Figure 4 shows a schematic diagram of the apparatus according to the present invention; and Figures 5 and 6 show the right hand and left hand channel output responses after the audio information has been processed according to the present invention.
With reference to Fig. 1, as the stylus follows a record groove it is subject to lateral modulation. This this side to side oscillation produces RH and LH channel output signals as shown in Fig. 1. These output signals are in phase with each other and are predominant above the arm/cartridge resonant frequency of approximately 1 OHz (Fig. 3).
The output signals due to lateral modulation contain low frequency components which are of interest.
With reference to Fig. 2, the stylus and corresponding cartridge and headshell are also subject to vertical modulation. This up and down movement produces RH and LH channel output signals as shown in Fig. 2. These output signals are out of phase with each other and produce distortion at the loudspeaker. It is therefore desirable to eliminate the low frequency components due to vertical modulation.
With reference to Fig. 5, the apparatus for processing audio information according to the present invention comprises a low pass filter 10, an amplifier 12 and a resistor 14 connected in series between the RH channel output and the LH channel output and similarly between the LH channel output and the RH channel output.
The output signals from each channel are therefore cross-fed and therefore added. The out of phase signals due to vertical modulation are effectively eliminated and the in phase signals due to lateral modulation are increased.
This is represented by the voltage/frequency characteristics of Figs. 5 and 6.

Claims (3)

1. A method of processing audio information by cross-feeding the low frequency components of the right hand and left hand channel output signals from a stereo cartridge in order to eliminate unwanted low frequency components and maintain the wanted low frequency components.
2. Apparatus for processing right hand and left hand audio information from a stereo cartridge, the apparatus comprising signal paths including low-pass filter means from the right hand channel to the left hand channel and vice versa, such that the substantially out of phase output signals due to vertical modulation are eliminated and the substantially in phase output signals due to lateral modulation are added.
3. Apparatus for processing right hand and left hand audio information from a stereo cartridge, in which said means comprises a low pass filter, an amplifier and a resistor connected in series between the right hand channel output and the left hand channel output and a low pass filter, an amplifier and a resistor connected in series between the left hand channel output and the right hand channel output.
GB08401589A 1984-01-20 1984-01-20 A method of processing audio information Withdrawn GB2153187A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08401589A GB2153187A (en) 1984-01-20 1984-01-20 A method of processing audio information

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08401589A GB2153187A (en) 1984-01-20 1984-01-20 A method of processing audio information

Publications (2)

Publication Number Publication Date
GB8401589D0 GB8401589D0 (en) 1984-02-22
GB2153187A true GB2153187A (en) 1985-08-14

Family

ID=10555310

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08401589A Withdrawn GB2153187A (en) 1984-01-20 1984-01-20 A method of processing audio information

Country Status (1)

Country Link
GB (1) GB2153187A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0546619A2 (en) * 1991-12-09 1993-06-16 Koninklijke Philips Electronics N.V. Low frequency audio doubling and mixing circuit
US6920224B2 (en) * 2000-10-20 2005-07-19 Rohm Co., Ltd. Deep bass sound booster device

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB845958A (en) * 1958-01-06 1960-08-24 Erie Resistor Corp Binaural phonograph system
GB1564547A (en) * 1976-12-03 1980-04-10 Sacks J Noise reduction system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB845958A (en) * 1958-01-06 1960-08-24 Erie Resistor Corp Binaural phonograph system
GB1564547A (en) * 1976-12-03 1980-04-10 Sacks J Noise reduction system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0546619A2 (en) * 1991-12-09 1993-06-16 Koninklijke Philips Electronics N.V. Low frequency audio doubling and mixing circuit
EP0546619A3 (en) * 1991-12-09 1994-04-20 Koninkl Philips Electronics Nv
US6920224B2 (en) * 2000-10-20 2005-07-19 Rohm Co., Ltd. Deep bass sound booster device

Also Published As

Publication number Publication date
GB8401589D0 (en) 1984-02-22

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Legal Events

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)