EP0546619B1 - Low frequency audio doubling and mixing circuit - Google Patents

Low frequency audio doubling and mixing circuit Download PDF

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Publication number
EP0546619B1
EP0546619B1 EP19920203748 EP92203748A EP0546619B1 EP 0546619 B1 EP0546619 B1 EP 0546619B1 EP 19920203748 EP19920203748 EP 19920203748 EP 92203748 A EP92203748 A EP 92203748A EP 0546619 B1 EP0546619 B1 EP 0546619B1
Authority
EP
European Patent Office
Prior art keywords
frequency
circuit
low
signal
audio signal
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.)
Expired - Lifetime
Application number
EP19920203748
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0546619A2 (en
EP0546619A3 (enrdf_load_stackoverflow
Inventor
Wayne c/o Int.Octrooibureau B.V. Schott
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.)
Koninklijke Philips NV
Original Assignee
Koninklijke Philips Electronics NV
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Filing date
Publication date
Application filed by Koninklijke Philips Electronics NV filed Critical Koninklijke Philips Electronics NV
Publication of EP0546619A2 publication Critical patent/EP0546619A2/en
Publication of EP0546619A3 publication Critical patent/EP0546619A3/xx
Application granted granted Critical
Publication of EP0546619B1 publication Critical patent/EP0546619B1/en
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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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H04R3/04—Circuits for transducers, loudspeakers or microphones for correcting frequency response
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S1/00—Two-channel systems

Definitions

  • the subject invention relates to a circuit for augmenting the bass reproduction of speaker systems according to the pre-amble of claim 1.
  • High fidelity reproduction of audio signals ideally requires sound transducers capable of reliably reproducing sounds throughout the listening range of human beings. This has been determined to be 20-20,000 Hz. However, realistically, most high fidelity speaker systems are capable of reproducing sounds in the frequency range of 40-20,000 Hz. These high fidelity speaker systems include small transducers (tweeters) for reproducing the high end of the frequency range, and relatively large transducers (woofers) for reproducing the low end of the frequency range. Naturally, these speaker systems are large in size and take up a substantial amount of space in the listening area.
  • An object of the present invention is to augment the apparent bass reproduction of small-sized speaker systems without introducing distortion in the sound emanating therefrom.
  • an electronically augmented stethoscope which includes a circuit for raising the audibility of inaudible sound by multiplying or doubling their frequencies.
  • the Philips et al. circuit processes signals below 20 Hz., i.e. below the threshold of human hearing, and raise them to an audible level.
  • the Philips et al. patent does not address the problem of inadequate speakers which are incapable of reproducing low frequency audio signals, albeit that these signals are already audible to human beings.
  • a left channel of a stereo signal applied to input 10 passes through a low-pass filter 12 to one input of a full-wave rectifier 14.
  • a right channel of the stereo signal applied to input 16 passes through a phase inverting low-pass filter 18 and is applied to another input of full-wave rectifier 14.
  • the low-pass filters 12 and 18 are arranged to pass signals below the frequency of 100 Hz. while attenuating signals above this frequency at 6 dB/octave.
  • the full-wave rectifier 14 combines the signals from the low-pass filters 12 and 18 and effectively doubles the frequency of the combined signals.
  • the output from the full-wave rectifier 14 is applied to a narrow-band filter 22 having a pass-band of, for example, 100-200 Hz.
  • the output from the narrow band filter 22 is applied through a resistor 24 to a left channel output 26, to which the left channel input 10 is connected by a resistor 28.
  • the output from the narrow-band filter 22 is also applied through a resistor 30 to a right channel output 32, to which the right channel input 16 is connected by a resistor 34.
  • the low frequency signal components in the left and right channels are separated from the main signals, combined and frequency doubled.
  • the resultant signal is then frequency limited to a pass-band of, for example, 100-200 Hz. and is then recombined with the original left and right channel signals.
  • FIG. 2 A practical embodiment of the circuit of the subject invention is shown in Fig. 2.
  • the left input 10 is shown connected to ground via a resistor R1 and, through the series arrangement of a capacitor C1 and a resistor R2, to the left output 26, which is connected to ground by a resistor R3.
  • the right input 16 is shown connected to ground via a resistor R4 and, via the series arrangement of a capacitor C2 and a resistor R5, to the right output 32, which is also connected to ground by a resistor R6.
  • the left input is further connected, via the series arrangement of a capacitor C3 and a resistor R7, to the inverting input of amplifier A1, to which the right input 16 is also connected via the series arrangement of a capacitor C4 and a resistor R8.
  • the inverting input of amplifier A1 is connected to the output thereof by the parallel arrangement of a resistor R9 and a capacitor CS, which is, in turn, connected to the inverting input of amplifier A2 by a resistor R10, this inverting input of amplifier A2 being connected to the output thereof by a resistor R11.
  • An 18 vdc supply is connected to ground via the series arrangement of a resistor R12 and the parallel arrangement of a capacitor C6 and a resistor R13, the junction J1 between the resistor R13 and the parallel arrangement being coupled to the non-inverting inputs of amplifiers A1 and A2.
  • the output of amplifier A1 is connected to the series arrangement of a capacitor C7 and a diode D1, the junction therebetween being connected to ground via a resistor R14 and to a B+ voltage source (which may be the 18 vdc supply noted above) via a resistor R15.
  • the output of amplifier A2 is connected to the series arrangement of a capacitor C8 and a diode D2, the junction therebetween being connected to ground via a resistor R16, and to the B+ voltage source via a resistor R17.
  • the purpose of resistors R15 and R17 is to bias the diodes D1 and D2, respectively, into conduction so that a wider range of signal levels will be doubled by the full-wave rectifier, thus making the circuit more effective.
  • the diodes D1 and D2 are then interconnected and connected via the fixed resistance of a potentiometer P1 and resistor R18 to ground.
  • the slider of potentiometer P1 is connected to a resistor R19 and then, on the one hand, through a resistor R20 to the non-inverting input of amplifier A3, and, on the other hand, through a capacitor C9, to the output of amplifier A3.
  • the potentiometer P1 is used to allow adjustment of the amount of doubled frequency signal level that one desires to be mixed in with the straight through signals depending on the size of the speakers used in a given application, since larger speakers, in general, require a lesser amount of doubled signal. It should be noted that these doubled signals may become obtrusive if present in too great an amount.
  • the non-inverting input of amplifier A3 is also connected to ground via a capacitor C10 and via a resistor R21 to the junction J1.
  • the inverting input of amplifier A3 is connected to the junction J1 via a resistor R22 and to the output of amplifier A3 via a resistor R23.
  • the output of amplifier A3 is connected to ground via the series arrangement of a capacitor C11, a resistor R24 and a further capacitor C12, the junction between the resistor R24 and the capacitor C12 being connected to the left and right outputs 26 and 32 via respective resistors R25 and R26.
  • the components R7, R8, R9, C5 and A1 form the low-pass filters 12 and 18, the components R14, R15, R16, R17, R18, D1, D2 and P1 form the full-wave rectifier 14, and the components R19, R20, R22, R23, C9, C10 and A3 form the narrow-band filter 22.
  • the values of the components are as follows: R1, R4 1OOK ohms R2, R3, R5, R6, R10, R11 lOK ohms R7, R8 15K ohms R9 180K ohms R12, R13 1K ohms R14, R16, R18 3.3K ohms R15, R17 39K ohms Rl9, R20 lSOK ohms R21 2Meg. ohms R22 27K ohms R23, R24, R25, R26 47K ohms C1, C2 0.1 uf C3, C4 0.3 uf C5 O .

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Stereophonic System (AREA)
  • Circuit For Audible Band Transducer (AREA)
  • Tone Control, Compression And Expansion, Limiting Amplitude (AREA)
EP19920203748 1991-12-09 1992-12-03 Low frequency audio doubling and mixing circuit Expired - Lifetime EP0546619B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US80535691A 1991-12-09 1991-12-09
US805356 1991-12-09

Publications (3)

Publication Number Publication Date
EP0546619A2 EP0546619A2 (en) 1993-06-16
EP0546619A3 EP0546619A3 (enrdf_load_stackoverflow) 1994-04-20
EP0546619B1 true EP0546619B1 (en) 1998-09-23

Family

ID=25191353

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19920203748 Expired - Lifetime EP0546619B1 (en) 1991-12-09 1992-12-03 Low frequency audio doubling and mixing circuit

Country Status (3)

Country Link
EP (1) EP0546619B1 (enrdf_load_stackoverflow)
JP (1) JPH05328481A (enrdf_load_stackoverflow)
DE (1) DE69227091T2 (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE38822E1 (en) 1996-05-08 2005-10-11 Koninklijke Philips Electronics N.V. Circuit, audio system and method for processing signals, and a harmonics generator

Families Citing this family (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0746083A (ja) * 1993-07-27 1995-02-14 Toshiba Corp 音声合成兼帯域制限回路及び低音増強回路
JPH08237800A (ja) * 1995-02-27 1996-09-13 Matsushita Electric Ind Co Ltd 低音増強回路
FI105522B (fi) 1996-08-06 2000-08-31 Sample Rate Systems Oy Järjestely kotiteatteri- tai muussa äänentoistolaitteistossa
US5930373A (en) * 1997-04-04 1999-07-27 K.S. Waves Ltd. Method and system for enhancing quality of sound signal
US6792119B1 (en) 1997-05-05 2004-09-14 Koninklijke Philips Electronics N.V. Audio system
JP2001507911A (ja) 1997-11-07 2001-06-12 コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ オーディオ信号処理回路を有するオーディオシステム
DE69825422T2 (de) * 1997-11-07 2005-07-21 Koninklijke Philips Electronics N.V. Audiosystem mit tonsignalverarbeitungsschaltung
WO1999026454A1 (en) * 1997-11-17 1999-05-27 Srs Labs, Inc. Low-frequency audio simulation system
US6285767B1 (en) 1998-09-04 2001-09-04 Srs Labs, Inc. Low-frequency audio enhancement system
EP1044583B2 (en) * 1998-09-08 2007-09-05 Koninklijke Philips Electronics N.V. Means for bass enhancement in an audio system
JP2002540697A (ja) * 1999-03-24 2002-11-26 コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ 帯域消去フィルタ
US7031474B1 (en) 1999-10-04 2006-04-18 Srs Labs, Inc. Acoustic correction apparatus
US7277767B2 (en) 1999-12-10 2007-10-02 Srs Labs, Inc. System and method for enhanced streaming audio
EP1168296B1 (en) * 2000-05-30 2004-10-27 Yamaha Corporation Waveform signal generation method with pseudo low tone synthesis
CN1274184C (zh) 2001-09-21 2006-09-06 西门子公司 在电声变换器中控制音频信号的低音放音的方法和装置
US7474752B2 (en) * 2003-09-16 2009-01-06 Koninklijke Philips Electronics N.V. Audio frequency range adaptation
US8050434B1 (en) 2006-12-21 2011-11-01 Srs Labs, Inc. Multi-channel audio enhancement system
WO2013101605A1 (en) 2011-12-27 2013-07-04 Dts Llc Bass enhancement system
WO2014190140A1 (en) 2013-05-23 2014-11-27 Alan Kraemer Headphone audio enhancement system

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS518551B1 (enrdf_load_stackoverflow) * 1970-07-09 1976-03-17
GB2153187A (en) * 1984-01-20 1985-08-14 Linn Prod Ltd A method of processing audio information
US4607381A (en) * 1984-10-05 1986-08-19 Sony Corporation Signal mixing circuit
JPS61248602A (ja) * 1985-04-26 1986-11-05 Toshiba Corp 周波数２逓倍器

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE38822E1 (en) 1996-05-08 2005-10-11 Koninklijke Philips Electronics N.V. Circuit, audio system and method for processing signals, and a harmonics generator

Also Published As

Publication number Publication date
EP0546619A2 (en) 1993-06-16
DE69227091D1 (de) 1998-10-29
JPH05328481A (ja) 1993-12-10
EP0546619A3 (enrdf_load_stackoverflow) 1994-04-20
DE69227091T2 (de) 1999-05-20

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