US2846503A - Output stages for low-frequency amplifiers comprising two loudspeakers - Google Patents

Output stages for low-frequency amplifiers comprising two loudspeakers Download PDF

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Publication number
US2846503A
US2846503A US577113A US57711356A US2846503A US 2846503 A US2846503 A US 2846503A US 577113 A US577113 A US 577113A US 57711356 A US57711356 A US 57711356A US 2846503 A US2846503 A US 2846503A
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United States
Prior art keywords
low
loudspeaker
output
loudspeakers
grid
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Expired - Lifetime
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US577113A
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English (en)
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Kump Johann
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US Philips Corp
North American Philips Co Inc
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US Philips Corp
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/34—Negative-feedback-circuit arrangements with or without positive feedback
    • H03F1/36—Negative-feedback-circuit arrangements with or without positive feedback in discharge-tube amplifiers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
    • H03F3/22—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with tubes only
    • 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
    • H04R3/12—Circuits for transducers, loudspeakers or microphones for distributing signals to two or more loudspeakers
    • H04R3/14—Cross-over networks

Definitions

  • the present invention relates: toan amplifier output stage circuit arrangement. More particularly, the invention relates to output stages of' low-frequency amplifiers comprising two loudspeakers, which are preferably intended for the reproductionof low fequenciesand high frequencies, respectively, of the acoustic spectrum with the use ofone or more screen-grid tubes as output tubes.
  • the objectv of'the invention is. in such output stages to obtain a considerable decrease in distortion in the highfrequency range. It is commonknowledge that distor tion inthe high-frequency range is. subjectively very troublesome to the ear. Consequently, inthe. reproduction of an. acoustic. frequency-band, which. must comprise the whole acoustic. region. up. to about. kiljocycl'es. per second, the requirements in regard to freedom of distortion. must be much higher than in. the reproduction of an. acousticv frequency-band which is. limited in the direction of high frequencies.
  • the present types. of output. stages. of low-frequency amplifiers. substantially utilize screen-grid tubes and more particularly pentodes.
  • the new tones experienced therein. as distortion. substam tially comprise the third harmonicsand combination tones of higher order and hence high tones.
  • the loudspeaker suppresses part of this distortion. If use is made of aloudspeaker reproducing the frequencies up to 15 kilocycles per second,. or if two or more. loudspeakers. are used, which are'each.
  • the. high. frequencies. produced in the amplifier are. no longer suppressed and thusbecome manifest. with maximum effect.
  • triodes The behaviour of triodes ismore favorable. than that of screen-grid. tubes (pentodes) in. regard-v to distortion, but. their low. output constitutes a. great disadvantage.
  • the invention is basedonthe.consideration. that a decreased output. may be taken into the. bargain for/high. frequencies, if the output remains-unchangedin the low. frequency and. intermediate-frequency range, since thestrength of the subjective impression. of sound is determined substantially by the reproduction of this range. Ifthis range is reproduced by a. loudspeaker which is insensitive to high: frequencies and hence, by. a. low-tone loudspeaker, a higher distortion factor is permissible: for this.range, since, as: mentioned. before, the distortion which. consists of. very high tones is not audible. However, the highefrequency range, which must of. course not be. absent. in.
  • a:. low-frequency amplifier having: two loudspeakers preferablyintended" for the reproduction of lowfrequencies andhiglr. frequencies, respectively, of-the acoustic spectrum with the useof one. or more-screen-grid tubes as output tubes, the impedances; which are effected: by the loudspeakersinthe anode circuits of the; tubesare connected in series; The anode of each tubeis connected; to the. impedance: constituted by'the: low-tone loudspeaker, which impedance is shuntedby a capacitorrof a' value such that theresistance of the capacitor for high frequencies. is lowwith respect to this impedance.
  • the screen-grid for alternating voltage is. connected. between the: two im pedances.-
  • Fig. 1 is a schematic diagram of anembodiment of the circuit arrangement of the present: invention.
  • Fig. 2 is a -schematic diagram of another" embodiment of the circuit arrangement" of the present invention.
  • the alternating voltage to beamplified is; applied. to. control. grid 25- of pentode.
  • The: control: gridv receives: the.- requiredbiasing potentialiin the usual manner by connecting: cathode; 3; via; a resistor 4 and. acapacitor. 5,, toground. potential; Suppressor grid.6. is connectedto. thecathode.
  • The.-cir.- cuit leading from. anode 7 to battery 8 is completedvia the primary winding. 9. ofan output transformer 10,, the secondarywinding 11015 which is.conne.cted to.-a.low-tone loudspeaker 12, and via the primary winding 13,. con: nected'in.
  • the primary winding 9 is; shunted by a capacitor 17" having a value such that it constitutes a very low impedance forihigh frequencies and hence substantially short-circuits output transformer for these frequencies.
  • the screen grid 18 of pentode 1 isconnected directly to a point 19 of the anode circuit located between the two primary windings 9 and 13.
  • the primary impedance 13 may be comparatively low, since an output transformer for a high-tone loudspeaker is concerned.
  • the screen grid 18 is thus substantially connected to the constant positive potential determined by battery 8, so that tube 1 operates as a screen-grid tube for low frequencies. Its output is very satisfactory.
  • the distortion which is greater in screen grid tubes, is not completely heard in the loudspeaker, since the loudspeaker 12 is a low-tone loudspeaker.
  • the transformer 10 is substantially short-circuited by capacitor 17, which implies that the'anode 7 and the screen-grid 18 are substantially directly connected to one another for these frequencies.
  • the tube 1 thus operates as a triode for these frequencies and, while having a lower output for these frequencies, leads to a reproduction with a very low distortion factor. It is common knowledge in engineering to choose the proportioning such that the cooperation of the two loudspeakers yields the desired substantially rectilinear reproduction curve of the whole arrangement.
  • the i-mpedances are constituted by the transformers loaded with the loudspeakers.
  • the situation remains unchanged, if use is made of loudspeakers having impedances such that they can be included in the circuit without the use of transformers. Neither does a connection of the impedances free from direct current change anything in the fundamental operation.
  • Fig. 2 shows the use of the arrangement according to the invention in push-pull connection.
  • the two pushpull tubes 20 and 21 are shown only diagrammatically and the two halves 22 and 23 of the output transformer 24 for the low-tone loudspeaker 25 are not connected directly to one another. Each half is bridged by a capacitor 26, 27, respectively, for high frequencies.
  • the center tap 28 of the primary winding of output transformer 31 for the high-tone loudspeaker 32, which winding consists of two halves 29 and 30, is connected to the positive terminal of the source of anode supply.
  • the anodes 34 and 35 of the tubes 20 and 21 are each connected to one end of the primary windings 22 and 23, the other ends of these windings being connected to the primary winnings 29 and 30.
  • the screen-grid 36 of tube 20 is connected to point 37 between the windings 22 and 29, the screen grid 38 of tube 21 being connected to point 39 between the windings 23 and 30.
  • the operation of the circuit arrangement of Fig. 2 is similar to that of the circuit shown in Fig. 1.
  • a low'frequency amplifier output circuit arrangement comprising an electron discharge device having an anode, a cathode and a plurality of grids including a screen grid, a first loudspeaker system for reproducing sound in a substantially low audio frequency range, a second loudspeaker system for reproducing sound in a substantially high audio frequency range, means for applying an input signal to one of said grids, means connecting said first and second loudspeaker systems in series circuit arrangement and to said anode, said first loudspeaker system being interposed between said anode and IT;
  • a low frequency amplifier output circuit arrangement comprising an electron discharge tube having an anode, a cathode and a plurality of grids including a screen grid, a first loudspeaker for reproducing sound in a substantially low audio frequency range, a second loudspeaker for reproducing sound in a substantially high audio frequency range, means for applying an input signal to one of said grids, first and second coupling transformerseach comprising primary and secondary windings, means connecting said first andsecond primary windings in series circuit arrangement and to said anode, said first primary winding being interposed between said anode and said second primary-winding, means coupling said first loudspeaker to said first secondary.
  • a low frequency amplifier output circuit arrange- I ment comprising a pair of discharge tubes connected in push-pull arrangement each having an anode, a cathode and a plurality of grids including a screen grid, a first loudspeaker system for reproducing sound in a substantially low audio-frequency range, a second loudspeaker system for reproducing sound in a substantially high audio frequency range, means for applying an input signal to selected grids of said tubes, means connecting said first and second loudspeaker systems in series circuit arrangement between the anodes of said tubes, said first loudspeaker system being interposed between said anodes and said second loudspeaker system, a capacitor having a reactance value which is substantially low with respect to the impedance of said first loudspeaker system at said high audio frequency range, means connecting said capacitor in shunt across said first loudspeaker system, and means connecting said screen grid to a common point between said first and second loudspeaker systems in said series circuit arrangement.
  • a low frequency amplifier output circuit arrangement comprising a pair of discharge tubes connected in push-pull arrangement each having an anode, a'cathode and a plurality of grids including a screen grid, a first loudspeaker for reproducing sound in a substantially low audio frequency range, a second loudspeaker for reproducing sound in a substantially high audio fre quency range, means for applying an input signal to selected grids of said tubes, a first coupling transformer comprising first and second primary windings and a secondary winding, a second coupling transformer comprising primary and secondary windings, means connecting the primary windings of said first and second transformers in series circuit arrangement between the anodes of said tubes, the primary winding of said second'transformer being interposed between the first and second primary windings of said first transformer, means coupling said first loudspeaker to said first secondary winding and means coupling said second loudspeaker to said second secondary winding, a first capacitor having a reactance value which is substantially low with respect to the impedance of

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Amplifiers (AREA)
  • Circuit For Audible Band Transducer (AREA)
US577113A 1955-05-05 1956-04-09 Output stages for low-frequency amplifiers comprising two loudspeakers Expired - Lifetime US2846503A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AT791793X 1955-05-05

Publications (1)

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US2846503A true US2846503A (en) 1958-08-05

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US (1) US2846503A (en, 2012)
BE (1) BE547520A (en, 2012)
DE (1) DE1001327B (en, 2012)
FR (1) FR1152720A (en, 2012)
GB (1) GB791793A (en, 2012)
NL (2) NL206890A (en, 2012)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2980840A (en) * 1958-08-08 1961-04-18 Levy Lester Wide band, low distortion, high efficiency amplifier
US3060264A (en) * 1959-01-27 1962-10-23 Rojprasit Adisaun Amplifier
US3227962A (en) * 1959-03-06 1966-01-04 Siemens Ag Input stage for ultra high frequency amplifiers
US4856065A (en) * 1987-02-27 1989-08-08 Pioneer Electronic Corporation Power fader for a loudspeaker system
US4897879A (en) * 1986-04-09 1990-01-30 B & W Loudspeakers Limited Multi-way loudspeaker system

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1055839B (de) * 1957-10-25 1959-04-23 Loewe Opta Ag Verfahren zur Aufzeichnung von Tonschwingungen auf Magnettontraeger

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2084160A (en) * 1925-06-09 1937-06-15 Rca Corp Filter system for loudspeakers
US2612558A (en) * 1946-08-13 1952-09-30 Paul W Klipsch Crossover filter network

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2084160A (en) * 1925-06-09 1937-06-15 Rca Corp Filter system for loudspeakers
US2612558A (en) * 1946-08-13 1952-09-30 Paul W Klipsch Crossover filter network

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2980840A (en) * 1958-08-08 1961-04-18 Levy Lester Wide band, low distortion, high efficiency amplifier
US3060264A (en) * 1959-01-27 1962-10-23 Rojprasit Adisaun Amplifier
US3227962A (en) * 1959-03-06 1966-01-04 Siemens Ag Input stage for ultra high frequency amplifiers
US4897879A (en) * 1986-04-09 1990-01-30 B & W Loudspeakers Limited Multi-way loudspeaker system
US4856065A (en) * 1987-02-27 1989-08-08 Pioneer Electronic Corporation Power fader for a loudspeaker system

Also Published As

Publication number Publication date
NL89562C (en, 2012)
GB791793A (en) 1958-03-12
DE1001327B (de) 1957-01-24
FR1152720A (fr) 1958-02-24
BE547520A (en, 2012)
NL206890A (en, 2012)

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