US2892372A

US2892372A - Organ tremulant

Info

Publication number: US2892372A
Application number: US368427A
Authority: US
Inventors: Howard G Bauer
Original assignee: Wurlitzer Co
Current assignee: Wurlitzer Co
Priority date: 1953-07-16
Filing date: 1953-07-16
Publication date: 1959-06-30
Anticipated expiration: 1976-06-30

Description

' H. G. BAUER ORGAN TREMULANT June 30, 1959 zvsneets-sneet 1 Filed July 16, 1953 INVENTOR.

June 30, 1959 H. G. BAUER ORGAN TREMULANT 2 Sheets-Sheet 2 Filed July 16, 1953 l INVENTOR BY (www s@ B@ w AL United States Patent O 'ORGAN TREMULANT Howard G. Bauer, Tonawanda, N .Y., assignor to The Rudolph Wurlitzer Company, North Tonawanda, N.Y., a corporation of Ohio Application July 16, 1953, Serial No. 368,427 13 Claims. (Cl. 84-1.25)

This invention is concerned generally with an electronic organ, and more particularly with an electronic tremulant therefor.

Tremulant effects in musical instruments can be produced by various means. The normal musical tremulant is a pure pitch variation such as is achieved by a violinists hand. Various mechanical devices have been utilized heretofore to produce tremulant effects by means of pitch variations in electronic organs. Obviously, mechanical devices in electronic organs are undesirable as they are apt to be accompanied by electrical noise after a certain amount of wear. All-electronic tremulants in electrical organs heretofore have been devices causing a volume variation, rather than a pitch variation. The volume variation simulates a tremulant effect, but the results are not entirely satisfactory from a listing standpoint.

Accordingly, it is an object of this invention to provide, in an electronic organ, an all-electronic tremulant prodncing a tremulant effect by means of a pitch variation.

Another object of this invention is to provide, in an electronic organ, an all-electronic tremulant incorporating a pitch variation accompanied by a relatively low volume variation.

A more specific object of this invention is to provide, in an electronic organ, a phase shift tremulant or vibrato.

A further object of this invention is to provide, in an electronic organ, a phase shift tremulant or vibrato by relatively emphasizing first one and then the other of a pair of similar signals having a constant phase difference.

Another object of this invention is to provide, in an electronic organ, a pitch change tremulant automatically variable in pitch with the musical frequencies to produce a constant percentagewise tremulant at low frequencies.

An ancillary object of this invention is to provide reverberation in an electronic organ.

A further object of this invention is to provide, in an electronic organ, a tremulant which is variable in effect and in frequency.

`Other and further objects and advantages of the present invention will be apparent from the following description when taken in connection with the accompanying drawings wherein:

Fig. 1 is a fragmentary perspective view of an organ embodying the principles of my invention;

Fig. 2 is a block wiring diagram of the organ; and

Fig. 3 is a schematic wiring diagram of the tremulant.

Referring now in greater detail to the drawings, wherein like numerals are used to identify similar parts throughout, there is shown in Fig. 1 an electronic organ 10 embodying the principles of my invention. The organ 10 includes a cabinet 12 having suitable keyboards 14 and a pedal clavier 16. A volume control or swell pedal 18 is provided on the organ cabinet as is a loudspeaker 20 for converting electrical oscillations into audible organ tones.

The electrical circuit of the organ is shown in general in Fig. 2. A plurality of bass tone generators is indicated at 22. The output oscillations from the bass tone generators are connected in parallel through a wire 24 to a preamplifier 26. Similarly the output of a plurality of treble tone generators 28 is connected in parallel through a wire 30 to a preamplifier 32.. Preferably the bass and treble tone generators take the form of vibrating metallic reeds. As explained in Hoschke No. 2,015,014, remarkably realistic organ tones can be generated by using a vibrating reed and an associated pick-up as the plates of a variable capacitor which Varies in capacity with the spacing between the reed and pick-up and hence in accordance with the vibrations of the reeds. The reed is vibrated by means such as an air blast. In the present invention, all of the reeds preferably are continuously vibrated and suitable electrical connections are made t0 the various reeds and associated pick-ups when it is desired for particular musical notes to play.

The output of the treble preamplifier 32 is fed through a suitable circuit 34 to a phase inverter 36. The phase inverterp36 produces two output signals varying substantially linearly with frequency, but always with a predetermined substantially constant phase dilerence. Preferably, the two outputs differ in phase by These two outputs are fed through wires or

circuits

38 and 40 to

mixers

42 and 44.

A low frequency oscillator 46 is provided and the intensity of the output of the oscillator as well as the frequency are adjustable by means of depth and speed controls 48. The output of the low frequency oscillator 46 is suitably coupled to a phase inverter 50. The two outputs S2 and 54 of the phase inverter 50 are utilized to control the conduction of the

mixers

42 and 44 so that the

mixers

42 and 44 alternatively swing in accordance with the frequency of the oscillator 46 from cut off condition to conducting condition, the degree of conduction being determined by the depth and speed controls 48. The

outputs

56 and 58 are out of phase due to the phase inverter 36, and the alternate conduction of or emphasis on the

mixers

42 and 44 causes rst one and then the other to be emphasized. The

outputs

56 and 58 are combined at 60, and the alternate emphasis on rst one phase and then the other causes a phase shift tremulant or vibrato to be produced.

The combined output 60 is filtered by a low frequency filter 62 to prevent the oscillator frequency from appearing in the organ output. It might be well to state at this time that the frequency of the low frequency oscillator 46 preferably is on the order of six cycles per second. In a specific organ constructed in accordance with the principles of this invention, the oscillator frequency is either 5.7 c.p.s. or 6.7 c.p.s depending upon the position of the speed control 48. The output of the low frequency lilter 62 is fed through a suitable circuit 64 to a point 66 where it is combined with the output of the bass preamplifier, the combined outputs beingap- M76 .to a phase -inverter pull output vtubes 80. 1 point thatthe phase `inverter 78 could be replaced by a center-tapped transformer according to the usual pracvisvillustrated more specifically in Fig. 3. -inverter 36 is illustrated as 1/2 of a 6SN7 twin triode.

from `theplate 90 at 91 and from the cathode 92 f The-tube 864 is conventionally connected as a phase in- -verter with equal resistors-94 and Arr A additional `resistor `included in the cathode circuit for biasing `the junction of vrvalue. t As a specific example, kmicrofarad, while capacitor 104b is .0025 microfarad.

112a is .0002 microfarad and to the junction 122 between the networks 108a, and 112a, 114a. of the wire or circuit 40 including a capacitor 124 to the control grid 126 of the mixer l/ yof a 6SN7tube. half of .the,tube.

, halves iof .the tube are grounded through a cathode resistor 132. The lower end of the, resistor 106!) is connected by a wire 134 to the '-juncton'136' betweenthe networks '108b,' 110b and 112b,

H4pledto a swell control 68. The swell control 68 cornprises a resistor or potentiometer actuated by the swell pedal 18 for producing an organ swell.

The output of the swell control 68 is applied through a suitable wire or network 70 to a gate circuit 72. This gate circuit substantially eliminates all signals when no notes are played, but is rendered conductive by gate switches 74 which are closed whenever one of the keys of the keyboards 14 or one of the pedals of the pedal clavier 16 is depressed so that the musical notes may be amplified.

y The outputv from the gate circuit 72 is coupled at 78.which drives a pair -of push- It is to .be understood at vthis tice for driving push-pull output tubes, and that the tphase inverters-36 and` 50 likewise could be replaced by ,g transformers. -.output transformer 82 in ;;this transformer is connected to the loudspeaker 20. A t vfeed-back .former 82 tothe gate circuit 72 for improved linearity `tof amplification-and for reducing hum.

The push-pull output tubes 80 feed an the conventional manner, and

circuit 84 is connected from the output trans- The tremulant portion of the organ circuit of Fig. 2 The phase a triode tube 86, specifically The input 34 thereto is connected to the control grid 88, while the output is taken at 93.

96 connecting the plate the cathode to ground. 100 of relatively small value is purposes and a. grid resistor-102 is connected between the grid and the resistors 96 and 100.

, The output 91 from the plate of the phase inverter 36 to a B+ line 98 and 4connecting isapplied -to a pair of similar phase shifting networks comprising series connected capacitors and resistors, the 'capacitors being identified respectively by the numerals -104a and 104b, and the resistors being identified by the numerals 106a and 106b. The two phase shifting networks, although similar in appearance, differ slightly in capacitor 104a is .00056 Each of the resistors 106a and 10611 is 62,000 ohms.

The cathode output circuit 93 is connected in parallel to another pair of phase shifting networks that are similar to one another. These phase shifting networks comprise `parallel connected resistors andy capacitors respectively Aidentified by the numerals 108a, -These parallel connected resistors and capacitors are 108!) and 110a, 110b.

connected in series with grounded parallel connected :capacitors and resistors respectively identified as 112a,

112b and 114a, 11412. The cathode phase shifting networks appear similar but different somewhat in value.

= The resistors 108e and 108b are equal, each being 360,000

ohms. The capacitor 110er is .0001 microfarad, while the capacitor 11011 is .00047 microfarad. The capacitor the capacitor 112k is .00075 microfarad. The resistors 114e and 114b are each 180,000 ohms.

The lower end of the resistor wires 116 and 118, these Wires 106a is connected by having a junction at 120, 110a The junction 120 is connected by means 44, the latter comprising The mixer 42 comprises the other The cathodes 128 and 130 of the two connectedtogether and are 114b. A tap or connection 138 on the wire 134 is connected by means of the wire or circuit 38 including a capacitor 140 to the control grid 142 of the mixer 42.

The

plates

144 and 146 of the

mixers

42 and 44 are respectively connected through

plate load resistors

148 and 150 of equal value to a junction 152. This junction in turn is connected through a load resistor 154 to a dropping resistor 156 connected to the B-lline 98. A decoupling capacitor 158 is connected between the line 98 and ground on the high side of the resistor 156.

The low frequency oscillator 46 comprises a triode vacuum tube 160, specifically 1/2 of a 6SL7, having the cathode 162 thereof grounded through a self-biasing circuit comprising a resistor 164 and a capacitor 166. The plate 168 is connected by a wire 170 to a resistor 172, which is in turn connected to a resistor 174, the junction between these two resistors being grounded through a smoothing capacitor 176. The high side of the resistor 174 is grounded through another smoothing capacitor and is also connected to a resistor 178. The high side of this latter resistor is connected by means of a wire 180 to a junction point 182 which is connected through a resistor 184 to a B-lsupply line 186.

The grid 188 of the oscillator 46 is grounded through a grid resistor 190 and is connected to the plate by feed-

back capacitors

192, 194 and 196, and a resistor 1 198 grounds the connection between the capacitors 194 202 is `selectively engageable wtih any of three fixed

contacts

204, 2,06, or 208. The rst two-of these contacts are connected together to a grounded resistor 210 -while the third contact 208 is connected to another grounded resistor 212. The resistors 210 and 212 are of different values, by way of illustration, the resistor 210 may be 1.2l megohms and the resistor 212 820,000 ohms. When the movable contact 202 is in engagement with either of the fixed

contacts

204, 206 the frequency of the low frequency oscillator 46 is approximately 5.7 cycles per second, whereas when the movable contact engages the third fixed contact 208, the oscillator frequency is approximately 6.7 c.p.s.

The plate 168 of the oscillator is connected by a wire 214 to a voltage

divider comprising resistors

216, 218, 220 and 222, the lower end of the latter being grounded at 224. Three fixed

contacts

226, 228, 230 of the vibrato depth switch are connected to the voltage divider to provide progressively increasing oscillation voltage. The fixed

switch contacts

226, 228 and 230 are respectively connected between the

resistors

222 and 220, between the

resistors

220 and 218, and between the

resistors

218 and 216. It will be understood that a further contact could be provided on the high side of the resistor 216 for an even greater oscillation voltage, although the latter is not shown.

Three

fixed switch contacts

232, 234 and 236 are positioned oppositely to the vibrator speed fixed

contacts

204, 206 and 208. The first of these, namely the contact 232, is an open contact and represents the off position of the vibrato or tremulant. The latter two contacts, namely 234 and 236, are connected in parallel. by a wire 238 to a movable switch contact 240 selectively engageable with the three fixed

contacts

226, 228 and 230 of the vibrato depth control.

A movable switch contact 242 is ganged for movement with the movable switch Contact 202 as indicated by the dashed line 244 and is cooperable with the vibrato speed xed contacts 237., 234 and 236. When the movthe fixed contacts l234, 236, the

toscillator output as determined in magnitude-bythe vibrato depth control is applied by means of a vwire 246 connected to the movable switch contact 242, a resistor 248, and a capacitor 250 to the grid 252 of the phase inverter 50, the latter comprising a vacuum tube 254 which specifically is one half of a 6SN7. The tube 254 is connected as a phase inverter with equal plate and cathode load resistors, identified by the numerals 256 and 258 respectively. An additional and relatively small cathode resistor 260 is incorporated between the cathode load resistor 258 and the cathode 262, a grid resistor 264 being connected from the junction 266 of the latter two resistors to the grid 25.2. A capacitor 268 is connected from the junction between the resistor 248 and capacitor 250 to ground at 270.

A capacitor 272 connects the plate 274 of the tube 254 to a wire 276 leading to the junction 278 of a pair of resistors 280 and 282. The resistor 280 is connected at the other end to the wire or circuit 38, while the resistor 282 is grounded at 284.

The cathode output of the phase inverter 50 is taken from the junction 266 and is opposite in phase to the plate output. The cathode output is connected through a capacitor 286 and a wire 288 to the junction point 290 between a pair of

resistors

292 and 294. The resistor 292 also is connected to the grid 126, while the resistor 294 is grounded as at 296.

The outputs of the

mixers

42 and 44 are combined by means of the common load resistor 154 and the output is then transmitted by a wire 298, a capacitor 300, and a wire 302 to the grid 304 of a vacuum tube 306 comprising a part of the low frequency lter 62. The cathode 308 of the tube 306 is self-biased by means of the usual grounded resistor 310 and parallel connected capacitor 312. The usual grid resistor 314 connects the control grid 304 to ground.

The plate 316 is connected through a plate load resistor 318 to the junction 182 for supplying B-lpotential to the tube.

The low frequency filter 62 also includes a network connected to the swell control by means of the wire or line 64. This network includes a resistor 317 connected to the swell control and also to a capacitor 319, the latter being connected to a junction point 320. The junction point 320 is grounded through a resistor 322, and is also connected to a parallel connected resistor 324 and capacitor 325. This resistor and capacitor are connected in turn to a capacitor 326 which is connected to a capacitor 328 through a junction point 330. The junction point 330 is directly connected by means of a wire 332 to the plate 316 of the vacuum tube 306 for connecting the output of this tube to the network. The capacitor 328 is connected through

resistors

332 and 334 to the grid 304 of the tube 306, the junction 336 between the

resistors

332 and 334 being grounded through a capacitor 338.

Operation parts, but rather with the treble circuit and the tremulant or vibrato therein.

The oscillations generated by the treble tone generators are amplified by the'preampliiier 32 and are applied to the phase inverter 36. Referring now to Fig. 3, thel outputs taken from the output junctions V1207,and 138 vary substantially linearly with the frequency of the input oscillations, but maintain a constantphase angle relation between one another. Mathematical relations can be and have been worked out explaining the phase shifting. However, the mathematical relationships do not clarify the end result anymore than the simple explanation following immediately hereinafter.

Referring first to the circuits having the identifying numerals ending with the suliix a, it will be seen that at low frequencies the impedance of capacitor 104a is very high and practically the entire transmission from the phase inverter tube 86 takes place through the resistance 108a, the capacitor l10n also having practically infinite impedance. At higher frequencies the capacitor 104a passes the oscillations more freely than the

resistance

108a, and 180 of phase shift takes place in the voltage between the output terminals. On a further increase in frequency the impedance of capacitor 104:1 becomes low relative to that of the resistor 106g, and the latter controls transmission through this branch. At still higher frequencies the impedance of capacitor 110:1 gradually reduces and this capacitor finally passes oscillations more freely than resistor 108s, thereby producing a further phase shift. Thus as the frequency varies from the low end of the range to the high end, a

complete 360 phase shift takes place in the voltage at the output terminals.

The operation of the phase shifting network similar to that just described and identied by numerals ending with the suffix b is similar to that of the network just described except that diiferent values are chosen for the circuit elements as heretofore described and set forth by way of illustrative example so that the outputs of the phase shifting networks as applied to the wires of the

circuits

38 and 40 are at all times substantially 90 apart. The outputs, of course, are identical except for this phase difference.

The two signals 90,out of phase are combined in the common output of the

mixers

42 and 44. The 90 phase difference causes a slight reverberation in the tonal output of the organ, thus giving the effect of a large pipe organ installation.

The output of the low frequency oscillator 46 is converted into two signals 180 apart by the phase inverter 50, and these signals are applied to the grids of the

mixers

42 and 44 along with the musical oscillations which are 90 apart. The biasing of the mixers and Vthe magnitude of the amplified oscillations of the low frequency oscillator are such that each

tube

42, 44 is first conducting with relatively high amplification, and then is cut down to relatively low amplification. The tubes operate 180 apart so that first the output of one of the

tubes

42, 44 is emphasized, and then the other. The result is that the combined voutput of the mixers 42,

' 44 shifts back and forth between the 90 out of phase musical signals to effect a phase shift vibrato or tremulant. The degree of phase shift is determined by the position of the movable switch contact 240 of the depth and speed controls. When the greatest depth of vibrato is applied each of the

tubes

42, 44 is alternately highly conductive and substantially cut off. This effects a maximum phase swing and a substantial tremulant or vibrato. When the vibrato is applied with lesser depth, the relative conductivities of the two

tubes

42, 44 are not changed to such a great extent. Accordingly, the combined output does not swing as far, and the vibrato or tremulant is lessened.

The components in the phase shifting circuits are so chosen as to maintain a substantially 90 phase shift between 500 cycles and 15,000 cycles. Above and below these values the phase shift becomes progressively less as the frequency moves away from these values. When v the two signals 90 out of phase are controlled or modu- `lated in the mixers by the output of the low frequency oscillator, the modulation is uniform over the band between 500 cycles and 15,000 cycles. The percentage of the percentage of modulation) must remain substantially constant to maintain a uniform tremulant effect.

Accordingly, asv noted above,. the phase'shifting circuit components are chosen so that the phaseshift, and consequently the degree of modulation or vphase swing, progressively decreases below 500 cycles. As aresult the `percentage of modulation or phase swing remains *at` a constant percentage of the musical tone frequency below approximately 500 cycles.

It will be understood that the maximum .phase swing is somewhat less than the 90 between the two input signals to the mixer. By way of example, the maximum `phase swing for optimum results is approximately one radian, or about 57.

The combined output of the mixer is applied to the .low frequency filter 62 comprising the tube306 and kthe circuits associated therewith. This filter cutsV off sharply below 130 cycles per second to keep the low frequency oscillator signal from appearing inthe output of the organ. generated by the bass tone generators. .The output of the low frequency filter is applied to the swell control along with the base tone generators, and the bass and treble signals thereafter are handled together.

The inherent characteristics of the modulator or

mixer tube

42, 44 are such that some amplitude variation is introduced along with the pitch Variation. The amplitude modulation is relatively small, being on the order of and adds to the pleasing effects of the phase shift vibrato on the human ear. I

The specific structure herein shown and described is by way of example only. Various modifications can be made in the structure and are to be considered as forming a part of my invention insofar as they fall within the spirit and scope of the appended claims.

I claim:

l. An electronic organ tremulant comprising a tone generator, means connected to said tone generator for splitting the tones generated thereby into a plurality of signals differing in phase by a substantially fixed predetermined degree substantially less than 180, and electronic means connected to said splitting means for combining the plurality of signals produced and including electronic means for relatively emphasizing one phase and then the other at a tremulant frequency to produce a tremulant effect.

2. An electronic organ tremulant comprising a tone generator, means connected to said tone generator for splitting the tones generated thereby into a plurality of like signals differing substantially 90 in phase, and electronic means connected to said splitting means for combining the plurality of signals produced and including electronic means for relatively emphasizing one phase and then the other at a tremulant rate to produce a tremulant effect.

3. An electronic organ tremulant comprising a tone generator, means connected to said tone generator for splitting the tones generated thereby into a plurality of signals varying in phase with the frequency of the tones generated but having a substantially constant phase difference, electronic means connected to said splitting means for combining the plurality of signals produced and including electronic means for relatively emphasizing one phase and then another in a cyclic manner at a tremulant rate to produce a tremulant effect.

4. An electronic musical instrument tremulant comprising a generator of electrical oscillations corresponding to a musical tone, an electronic amplifying device having anode, cathode, and control element connections, said oscillation generator being connected to said control element, a pair of anode circuit phase-shifting networks rconnected in common at one end to said anode connection, a pair of cathode phase-shifting networks connected in parallel to said kcathode connection, `meansrminter- All musical tones under 130 c.p.s. are

network,` a pairof electronicY amplifying devices having common anode circuits and common cathode circuits, and having independent control elements, means connecting one of said interconnections to one of` said lastmentioned control elements and the other of said interconnections to the otherof `saidflast-mentioned control elements, an oscillation Vgenerator providing electrical oscillations atV a Vtremulant frequency, means applying the output of said tremulant` oscillation generator in opposite phase to said last-mentioned control elements whereby alternately to emphasize the musical tone oscillations applied thereto, kand means connected to said common anode circuit: for converting thel electrical oscillations in r.said common anode Acircuit into audible musical tones having a tremulant impressed` thereon.

5. An electronic musicalinstrument tremulant as set forth in claim 4 wherein each anode phase-shifting net- `work comprises a series-connected resistance element and capacitance element,; and` wherein each.` cathode phaseshifting network comprises a parallel-connected resistance element and capacitance element. i

6. An electronic musical instrument tremulant as set vforth inl claim 5 wherein anelement in one anode phase- `work comprises a second parallel connected resistance element and capacitance element in series with the firstmentioned parallel connected resistance element and capacitance element and connected thereto at a junction.

8. An electronic musical instrument tremulant as set forth in claim 7 wherein each anode phase-shifting network is connected to the junction of the corresponding cathode phase-shifting network.

9. An electronic musical instrument tremulant as set forth in claim 7 wherein each cathode control element is connected to ground through a pair of series connected resistors connected together at a junction, the junction of each pair of resistors being connected to the junction of the corresponding cathode phase-shifting network.

l0. An electronic organ tremulant comprising a tone generator, and a tremulant producing device acting on the tones produced by said tone generator, said device comprising a vacuum tube having a cathode, a plate, and a control grid, means connecting the tone generator to said control grid, a pair of resistance-capacitance phase shifting networks each having components connected to said plate and having components connected to said cathode, the plate components of the two networks having similar elements, but `of different values, and the cathode components of the two networks also having similar components, but of different values, electronic mixing means, means differentlyy connecting the two phase shitting networks to said mixing means, ysaid phase shifting networks providing signals `to said mixing means, which are outof phase relative toone another, and means connected to said mixingrmeans for successively relatively emphasizing the signals from one phase shifting network and relatively minimizing the signals from the other phase shifting network.

ll. An electronicworgan, `tremulant asvset forth in claim luwhereinujthe plate-connected components* of each phased-shifting network comprisewseries connected 9 resistance and capacitance elements and the cathodeconnected components of each network comprise parallel connected resistance and capacitance elements.

12. An electronic organ tremulant as set forth in claim 11 wherein the cathode-connected components of each network comprise a rst combination of a parallel connected resistance element and capacitance element, and a second combination a parallel connected resistance element and capacitance element, said first and second combinations being connected at a junction and serially connected between said cathode and ground.

13. An electronic organ tremulant as set forth in claim 12 wherein the plate-connected components of References Cited inthe tile of this patent UNITED STATES PATENTS 2,048,900 Usselman July 28, 1936 2,148,478 Kock Feb. 28, 1939 2,233,948 Kock Mar. 4, 1941 2,300,999 Williams Nov. 3, 1942 2,382,413 Hanert Aug. 14, 1945 2,534,342 Daniel Dec. 19, 1950 2,583,566 Hanert Jan. 29, 1952