US2501172A - Electrical musical instrument - Google Patents

Description

d m H fig WWW W 2, QMW f L HAMMOND ET AL ELECTRICAL MUSICAL INSTRUMENT March 21, 1950 Flled May 15 1946 wAAA u AAAA A: I @@@w March 21, 1950 L. HAMMOND ET AL ELECTRICAL MUSICAL INSTRUMENT 3 Sheets-Sheet 2 Filed May 15, 1946 WWM Mww 0 T l H mm MM 2 T M L wmw Q MN T LT //?V/? 20/19 1a are/25 Hammond M A ffler f March 21, 1950 HAMMOND E AL ELECTRICAL MUSICAL INSTRUMENT 5 Sheets-Sheet 5 Filed May 15, 1946 Patented Mar. 21, 1950 Laurens Hammond, Chicago, and John Hanert, Park Ridge, 111., assignors to Hammond Instrument Company, Chicago, 111., a.

corporation of Delaware Application May 15, 1946, Serial No. 669,991

16 Claims. 1

Our invention relates generally to electrical musical instruments and more particularly to improvements in means for producing and controlling organ bass tones.

In the conventional pipe organ the pipes for the production of bass tones are necessarily very large and thus expensive, and they require a greater amount of air supply than the smaller treble register pipes, thereby making necessary the use of relatively large power consuming blowers. Similarly in electric organs the production of the bass tones imposes somewhat greater loads upon the electronic components than is imposed by the generation and transmission of tones in the treble register and greater difficulty is experienced in producing bass tones of pleasing quality and of the desired intensity.

Furthermore the bass tones of an electric organ are usually controlled by the pedal clavier, and since one of the player's feet is usually required for the operation of the swell pedal, he is usually forced to depress the pedals in a detached or nonlegato manner. This results in the production of bass tones which are discontinuous. In the rendition of many musical selections this effect is not desirable. This undesirable eiiect may be partially remedied by the reverberative characteristics of the room in which the instrument is being played, or by the provision of means for introducing the reverberation effect artificially, as for example, by the mechanism disclosed in the prior patent of Laurens Hammond, No. 2,230,836. The addition of such reverberation mechanism adds to the cost of the instrument and does not completely satisfy the musical requirements, because when two pedals are depressed in rapid succession the reverberant decay portion of the tone controlled by the first depressed pedal is heard simultaneously with the initial or attack portion of the tone controlled by the second depressed pedal, so that unless the two tones are harmonically related, a certain amount of dissonance or muddying effect is obtained. This undesired simultaneous adding of the two bass tones limits the undistorted output of the amplifier, thus greatly increasing its cost for a given acoustic power output.

To overcome all of these diliiculties and disadvantages and high cost encountered in the production of organ bass tones, we have provided an improved bass tone generating, controlling, and producing apparatus which may readily be incorporated in a conventional pipe organ so as to be controlled by the console keys, pedals and registration controls, and may with equal facility be 55 incorporated in electric organs to produce the bass tones thereof in a more satisfactory and economical manner than was previously possible.

It is therefore a primary object of our invention to provide an improved organ bass tone enerating, controlling, and producing apparatus which is of relatively simple construction, which is reliable in operation, and which is capable of producing musical effects not heretofore attainable by the largest pipe organ or by electric organs.

A further object is to provide an improved organ bass tone generating and controlliwng apparatus whereby the tones may be sounded with predetermined attack and decay characteristics.

A further object is to provide an improved bass tone generating and controlling apparatus Wherein upon the release of a depressed pedal of the pedal clavier the tone will continue sounding at a predetermined decay rate until another pedal is depressed, whereupon the note corresponding to the second depressed pedal will commence sounding with a predetermined attack.

A further object is to provide an improved bass tone generating and controlling apparatus which may be connected for operation from the console or the customary pipe organ, in which the electronic portions of the instrument may be located in the pipe loft, or swell chamber, and in which a minimum number of wires is required to connect the bass tone generating apparatus with the organ console.

A further object is to provide an improved bass tone producing electrical musical instrument having an improved relay system for controlling the instrument.

A further object is to provide an electrical musical instrument particularly for the generation of bass tones in which there are three master sources generating, frequencies at octave intervals, in which there are a series of cascaded frequency dividers, the output of which may be selectively utilized for the acoustic generation of the tones, and in which relay means are provided to select which of the three frequency generators is to control the frequencies generated by the cascaded series of frequency dividers.

A further object is to provide an attack and decay apparatus which is direct current operated and in which the high frequencies are caused to decay more rapidly than the low frequencies.

A further object is to provide a pedal clavier controlled multi-octave electronic tone generating system of the oscillator and cascaded frequency divider type, in which the tuning range of 3 the oscillator is small in comparison with the pitch range of the pedal clavier, in which th sig-- nal utilization circuits are permanently coupled to a single frequency divider generating system, and in which the several auxiliary frequency dividers associated with the oscillator provide input signals to the main frequency division generating system of sub-octave frequencies relative to the master oscillator frequencies. By this means the tones derived from the mainfrequency divider generating system are prefectly uniform over the entire range of the pedal clavier and simple single pole signa1 throw switches may be employed for the various stops.

A further object is to provide an electric bass tone producing and controlling apparatus in which a plurality of tone qualities may beselectively utilized either one at a time or in any desired combination.

A further object is to provide an inexpensive electric bass tone generating unit which may be incorporated in a pipe organ in the place of the large bass pipes and which will produce tones equivalent to those obtainable by several ranks of pipes.

Other objects will appear from the following description, reference being had to the accompanying drawings in which:

Figures 1a, 1b and 10 together constitute a schematic wiring diagram of the complete instrument.

Referring to Fig. 1a, the instrument is controlled by a pedal clavier comprising a plurality of pedals IO illustrated as 32 in number to cover the frequency range (3:32.703 to G2=196.U0 C. P. 5. when playing at 16' pitch. These pedals constitute the conventional pedals of a pipe organ which has been constructed and installed or may be the pedal clavier of a, new pipe organ or electric organ. As in a conventional pipe organ, each of the pedals I operates a switch I2. The switches Him the first octave are adapted, upon depression of their associated pedals to connect a bus 26 respectively to conductors I4 to 25 respectively, while the pedals ID of the middle octave of the clavier through their switches I2 connect a bus 21' respectively to the conductors I4 to 25, and the switches I2 for the pedals I0 representing the notes C to G of the highest octave connect a bus 28 respectively with conductors I4 to 2I respectively.

The bus conductor 26 is normally connected through relay windings 30 and 3| and switches 35.I and 39.I to a source of energizing current indicated as a +24 v. terminal. Similarly the bus conductor 21 is connected through relays 34 and 35 and switches 3|.I and 39.2 to the +24 v. terminal. The bus conductor 28 is likewise connected through a pair of relay windings 38 and 39 and switches 35.2 and 3L2 to the +24 v. terminal.

Each of the conductors I4 to 25 is connected to ground through relay winding 40. Thus when any of the pedals III is depressed to close its switch I2, a circuit will be completed through one of the relay windings 40 and through the relay windings 303'I, 34-35"or 3839, depending upon the particular key depressed.

When any of the relay windings 40 is energized it closes its associated switch 42 thereby completing a circuit from ground through a holding Winding 44, switch 42, a conductor 4'6, resistor R48 to a source of operating potential, indicated as a +24 v. terminal.

Energization of one of the relays 40 also effects closure of a tuning switch 50. One pole of each of the tuning switches 5|] is connected to a grounded conductor 52 while their other poles are respectively connected to the junctions between a series of tuning capacitors 054. These capacitors 054 are connected in series between ground and a terminal 56 of a variable tuning inductance L58, the other terminal of which is connected to ground. Inductance L58 forms part of an oscillator comprising a pentode 69 having its control grid BI connected to the terminal 56 through a capacitor CB2 which is shunted by a grid leak resistor R64. The cathode of pentode 59 is connected to ground through an inductance L66 which is in mutually inductive relation with L58. The suppressor grid of pentode 60 is connected to the cathode thereof while the screen grid "I0 is connected to a conductor I2. The plate I4 of pentode 50 is supplied with plate current from a suitable potential source indicated as a terminal +300 v. through load and voltage dividing resistors R15 and R16 connected in series. the junction of these resistors having a signal conductor connected thereto.

A pulse sharpening and rectifying triode 84 has its grid 86 connected to the plate I4 through a blocking capacitor C88 and is connected to ground through a grid resistor R90. The cathode of triode 84 is connected to conductor I2 while the plate thereof is connected to the suitable source of plate potential indicated as +300 v. through a load R92. Cutoff bias is provided by a parallel resistor R9I and capacitor C93 connecting conductor I2 to ground. (Fig. 1b.)

The negative pulses appearing at the plate of triode 84 is impressed upon the control grids of alternate pulse responsive frequency dividing triodes 94 and 95 through capacitors C96 and C91. The grid of a triode 94 is connected to the plate of triode 95 through a mesh comprising series resistor R98 and capacitor 099 having a resistor RIM in parallel therewith. Similarly the grid of triode 95 is connected to the plate of triode 94 through a mesh comprising RIIJI and CI03 in series and RIOZ in parallel therewith. The grids of triodes 94 and 95 are connected to ground respectively through RI D6 and BI 01. The plate of triode 94 is connected to a +300 v. source of plate potential through RI08 and RIOS, the junction point of these resistors having a signal conductor IIil connected thereto. The plate of triode 95 is connected to a source of plate current shown as +300 v. through a load resistor RI I2.

A pulse sharpening and rectifying triode H4 is coupled to the output of triode 95 in the same manner as the triode 84 is coupled to the output of pentode E0, and the triode II4 supplies sharp unidirectional negative impulses for the operation of an alternating pulse responsive frequency dividing triodes '6 and H8, which have associated circuit elements similar to the triodes 94 and 95, and function in the same manner. The signal from the triode H6 is obtained through a conductor I20 connected to the junction of plate load resistors RI22 and RI23 of the triode IIB.

When the relay 30 is energized by the depression of a pedal in the lowermost octave of the clavier it closes its switch 3D.I and thereby completes a circuit through a holding winding I30, this circuit being traced from the grounded pole of switch 30.I through the winding I30, conductor 49, R48 to the +24 v. terminal. Similarly, energization of relay winding 34, upon depression of a pedal in the middle octave, by closure of its switch 3'4.I energizes a holding winding I34, and

holding winding I38 is similarly energized through closure of switch 38.I upon depression of a pedal in the incomplete highest octave. Energization of the relay 30 also results in closure of its switch 30.2 thereby connecting signal con ductor I to conductor I40. Similarly, energization of relay 34 by closure of a switch 34.2 connects signal conductor IIO to the conductor I40 and energization of relay 38 by closure of switch 38.2 connects conductors 80 and I40.

Energization of the relay 3| also effects closure of switches 3L3, 3L4 and 3I.5. Similarly energization of relay 35 causes closure of switches 35.3, 35.4 and 35.5, and energization of relay 39 causes closure of switches 39.3, 39.4 and 39.5. The function of this latter group of switches will be explained hereinafter, it being necessary merely to mention here that the relays 3I, 35 and 39 are fast operating, that is, they close rapidly and open rapidly relative to the speed of operation of the relays 4044, I-30, I34-34, and I38-38. The time differential in the operation of these relays is sufficient that when a pedal I0 is released to open its switch I2 the relay 3I or 39) will be deenergized and the switch contacts 3| and 3| .2 will close and its switch contacts 3L3, 3I.4 and 3L5 will open, all before the associated relays 4044 and I30-30 become deenergized to permit opening of the switches operated thereby. Thus, whichever of the switches 3I.3, 35.3 and 39.3 was closed by the energization of its relay will, upon release of the depressed key, open, and thus disconnect the ground from conductor 46 so that potential will be available to retain the holding relay Winding 44 of the last depressed pedal in energized condition and the switches 42 and thereof will remain closed, and thus the oscillator will remain tuned to the frequency represented by the last pedal which was depressed.

It will be noted that the relays 40, 44 for the two B pedals are not provided with a switch 50, so that upon initially supplying current to the instrument as a whole the oscillator 60 will be tuned to the frequency of the note B.

From the foregoing it will appear that when a pedal in the lowermost octave is depressed the signal from the lowest alternate pulse responsive divider stage comprising the triodes H6 and H8 will be impressed upon the conductor I40 by closure of switch 30.2, that when the pedal depressed is in the middle octave range, the signal from the intermediate frequency divider stage comprising triodes 94 and 95 will be impressed upon the conductor I40 by closure of switch 34.2, and that when a pedal in the highest octave range is depressed a signal from the oscillator 60 will be impressed upon the conductor I40 due to closure of switch 38.2.

Since each of the divider stages divides by the factor 2, the signals produced thereby will be in octave relationship. These .signals when im pressed upon conductor I40 are supplied as the input signal to a rectangular wave distorting triode I50 through a blocking capacitor CI 5I and series gridresistor RI52. The grid of the triode I50 is connected to ground through the series resistor RI52 and a resistor RI54. The cathode of this triode is connected to ground, while the plate thereof is connected to a suitable source of plate potential, indicated as +300 v., through series voltage dividing load resistors RI56 and RI 51, the'junction of these resistors having a conductor I58 connected thereto.

The signal supplied by the triode I50 is im-'- pressed upon the grid of triode I60 through a blocking capacitor CIBI, and this grid is connected to ground through a grid resistor RI62. The rectifying triode I60 functions in the same manner as the triodes 84 and H4 and is similarly connected to a pair of alternate pulse responsive triodes I64 and I66 constituting the first stage of an alternate pulse responsive frequency divider system. The second stage of this system comprises a pulse sharpening and rectifying triode I10 which supplies a signal pulse to the pair of triodes I14 and I16 which constitute the second stage of the frequency dividing system. The third stage is indicated by a block I while the fourth and last stage is indicated by a block I82.

The output signal from the first divider stage is impressed upon a conductor I85, that from the second dividing stage upon a conductor I86, that from the third and fourth stages upon conductors I81 and I08 respectively. The signal appearing on the conductor I88 will thus have a fundamental frequency corresponding to that of the note of the depressed pedal while the signal appearing upon the conductors I81, I86, I and I58 will have fundamental frequencies corresponding to the second, fourth, eighth and sixteenth harmonics respectively of the depressed pedal. The fundamental frequencies appearing upon the conductors I88, I81, I86, I85 and I58 will therefore be, in pipe organ terminology, of 32 foot, 16 foot, 8 foot, 4 foot, and 2 foot pitches:

The signal appearing on a conductor I58 is impressed upon the inputs of three triodes I90, I9I and I92 respectively through blocking capacitors CI94. These triodes have associated with their input circuits different types of meshes, the mesh associated with the triode I90 being a simple grid resistor RI96, that associated with triode I9I comprising a grid resistor BI 98 having a capacitor C200 in parallel therewith, while the mesh associated with input of pentode I92 constitutes a resistor R202 in parallel with a capacitor C204.

The plate of the triode I90 is connected to a suitable source of plate potential through voltage dividing load resistors R206 and R208, the junction of these resistors being connected to ground through a high frequency by-pass capacitor C2 I 0 and connected to a pole of a switch 2I2 through a blocking capacitor C2I4 in series with a resistor R2I6. A capacitor C2I8 also serves as a second stage of high frequency by-pass from the plate of triode I90 to ground. The switch 2I2 forms part of a relay 220 energized from the suitable stop tablet operated switch forming part of the organ console. In electrical musical instruments the switch 2I2 may be located at the console and manually operated.

The switch 2I2 for the output of triode I90, when closed, forms a path for the transmission of the signal to an output conductor 222. Thus upon closure of this switch 2I2, a very bright trombone-like tone having both odd and even harmonics will be impressed upon the conductor 222. It will be noted that the cathode of triode I 90 is at a relatively high positive potential, being connected to a +20 v. terminal, thereby rectifying its current-limited symmetrical input wave (composed of odd harmonics only) to produce an assymmetrical output wave having both odd and even harmonics.

The triodes HM and I92, similar to the triode I90, are adapted to have their plates connected tothe signal conductor 222 upon closure of relay a switches 2I2, completing a circuit from theplates of these tubes through resistors R216 and block ing capacitors C2I4. The cathodes of triodes I9I and I92 are connected to a source of negative potential, indicated as .a terminal -100 v., through self-bias resistors R224, having capacitors C225 in parallel therewith. The values of the circuit elements associated with the triodes I90, I9I and I92 are such that the signal output appearing on the conductor 222 from the triode I90 is a very bright trombone-like tone, that from the triode I9I is intermediately bright diapasonlike while that from the triode I92 is a much less bright flute-like tone.

In a similar manner the symmetrical oddharmonic signal supplied by conductor I85 may be modified through selective utilization of triodes and associated meshes similar to the triodes I90, I9I and I92 and their connected circuit elements, these tone modifying meshes being represented by blocks 226, 221, 228. Similar tone quality and modifying meshes 230, '23I and 232 are connected with the conductor I86. The signal supplied by the conductor I81 may be modified by selective utilization of meshes 234, 235 and 236, while the signal supplied to the conductor I88 may be selectively modified by utilization of meshes 238, 239 and 240.

The tone modifying meshes 226,230, 234 and 238 are similar to those associated with the triode I90. The tone modifying meshes 221, 23I, 235 and 239 are similar to those associated With the triode I9I, and the meshes228, 232, 236 and 240 are similar to those associated with triode I92.

The :amplifying system 256 for the signals appearing upon the conductor 222 comprises a triode 254 operating as a phase splitter with its cathode 256 connected to 'ground through series voltage dividing resistors R258 and R259. The junction of these resistors is connected to the grid through grid resistor R260 and this junction is also connected through a blocking capacitor C262 with the input of a remote cut-off variable mu pentode 264. The plate of triode 254 is supplied with current through plate load resistor R266 and the signal is transmitted through a blocking capacitor C268 to the control grid of a second variable pentode 210. The pentodes 264 and 210 are thus supplied with the signalin push pull. The cathodes of these pentodes are connected to ground, as are their suppressor grids, While the grids thereof are connected to a terminal 214 through grid resistors'R216 and R211. The terminal 214 is connected to ground through an attack and decay capacitor C218 which is adapted to have a capacitor C280 connected in parallel therewith upon closure of a switch 202 which may be relay operated. The terminal 214 is connected to a suitablecutoifbiasing potential source, indicated as a terminal -60 v., through a resistor R284. The terminal 214 is'also connected through an attack resistor R206 with a conductor 288 which, it will be noted, is connected .to one pole .of each of the switches 3L5, 35.5 and 39.5.

The other poles of these switches are connected to a conductor 290, the potential of which is determined by the position ofa three-position switch 292 cooperating with taps on a voltage divider R294 for providing graded voltages such as 5, 10 and volts. The screen grids of pentodes 264 and 210 are connected to a terminal +B through a voltage dropping resistor R296 and areconnected to'ground through series fixed resistor R291 and variable resistor R298, the adjustment of the latter determining the cut-off of the'pentodes 264 and .210, so as to prevent the transmission of a signal when :no pedal is depressed. The plates of these pentodes are supplied with operating potentials in the customary manner and the output signal thereof is impressed upon the input of a push-pull power amplifier 300 which supplies current to a speaker 302.

The amplifier 253 for the signals appearing on the conductor 252 from meshes 2'36 and 240 is similar to the amplifier 250 except that the values of .the various components are different so as to permit more efiicient transmission and amplification of the lower frequencies.

The amplification system 253 differs from the amplification system 250 in several important respects. As shown in the diagram the signals supplied to the amplifier 253 comprise the Bourden 16 foot tone as well as the sub-bass 32 foot tone. These extremely pure loW frequency tones require a very great amount of acoustical energy to radiate the sound at an audible level. If an attempt were made to combine electrically tones such as the diapasons and trombones with these deep tones, cross modulation would occur unless an extremely linear and powerful amplifier, as well as a very extensive speaker system, were supplied. By means of the arrangement shown in Fig. 10 these low frequencies are produced through a separate amplifier and loudspeaker system. This amplifier and loudspeaker system produces a considerable of harmonic distortion (especially the loudspeaker system) which is of no importance musically as it merely introduces a small quality modifying effect.

Another important reason for providing two independent bass tone amplifying systems is to make it possible to have the twoBourden tones associated with amplifier 253 decay at a rate approximately one third that of the bright tones produced by the amplifying system 250. This is extremely important musically as otherwise the car would interpret the tone quality as changing as it decayed away. In order to produce uniform quality of tone during the decay period it is important that the very low frequencies decay much more slowly than the high frequencies. Furthermore, it is desirable that the low frequencies in the bass tones decay slowly relative to their high frequencies so that the clarity of the music being played on the manuals of the organ shall not be blurred by the persistence of the high frequencies in the bass tones. On the other hand, it is highly desirable that the low frequencies of the bass tones persist for a relatively long period of time so as to facilitate legato pedal playing.

The sizes of the amplifiers 250 and 253 will vary, depending upon the size of the auditorium in which the bass tones are to be radiated. In general the amplifier 253 will be approximately four times as powerful as the amplifier 250. Similarly the speakers for the amplifier system 250 may be adapted for high frequency radiation and have relatively low power acoustic output as compared to the bass speakers for the amplifier system 253. The latter are preferably of heavier construction and may be operated with a considerable degree of non-linearity for the sake of increased efficiency.

In view'of the similarities, the amplifier 253 will not be described in detail and similar reference characters have been applied to some of the corresponding parts. The potential on the terminal 214 of the amplifie 253 is determined by the potential on conductor 304, which is connected to one pole of each of the switches 3i .4, 35.4 and 39.4 while the other terminals of these switches are connected to the conductor 290.

As previously stated, the apparatus of the invention is to be utilized in conjunction with the pipe organ or electric organ to provide means for producing and controlling the bass register tones thereof. Thus the instrument is played by the musician using the same technique as is employed in playing pipe organs and electric organs. Whenever a pedal is depressed, as for example pedal A in the lowermost octave, the closure of its switch 12 results in the energization of its associated relay windings 40, 44 thereby closing the associated switches 42 and 50. The closure of its switch 50 results in tuning the oscillator 60 to the required A frequency. As a result divider stages 94-35 and ll5l l8 successively divide the frequency of the oscillator 60 by 2, and these sub-multiple frequencies are impressed upon the conductors 80, H0 and I respectively.

Closure of the switch l2 also results in energization of the relay -l30 and relay 3|. The energization of relay 30 establishes a holding circuit through the winding I30 by closure of switch 301. Energlzation of relay 3| results in opening the circuits for relay windin s 34, and 38, 39 by opening switches 3H and 3L2. Therefore if any pedal in the middle or highest octave of the clavier is depressed the closure of its switch I! will be incapable of completing circuits through the latter relay windings or through the relay windings 40, 44 associated with the tuning circuits.

The energizaticn of relay 30, by its closure of switch 30.2, selects the cutout signal from the frequency divider H6, H8 by connecting conductor I20 to the input of the box wave pulse sharpening tricde I50. Therefore the four stages of frequency dividers controlled by the triode I50 will operate at the frequency A of the four lower octave pitches corresponding to the 4, 8, 16 and 32 foot pitches. The signals supplied by these four frequency dividin stages to ether with the out ut of t e 2 foot out ut o triode I50, are impressed uoon their tone modifying meshes, and depending upon which of the stops on the organ console are operated to energize the circuits of the relays T ll. the si nals will be supplied to conductors 222 and 257. and impre sed on the input circuits of amplifiers 250 and 253.

Energizeti n of t e relay 3| by closure of its switches 3|.4 and 3L5 im resses a potential, pre term ned hv t e adi t nent of the vol me control voltage divider R294, upon the control grids of the push ull amplifier pentodes 264 and 21 i in the manner previouslv described. The potential on these control grids builds up gradually due to the attack resistors R286 and attack and decay ca acitors C218 and optionally connect d ca acitor C289. The tone is thus pro duced by the speakers associated with the amplifiers 250 and 253 with a tonal intensity envelcpe havi g gradual attack and gradual decay ch racteristics.

The control of the overa l intensity of the output of the instrument is effected by operation of the swell shutters of the pipe organ swell box in the customary manner, since the speakers 302 are located in the swell chamber of the pipe organ. When the instrument is used in conjunction with an electric organ the volume control may be eiiected in any suitable manner. as. by

10 varying the potentials applied across the volume control voltage divider R2 94.

If as above assumed, the A pedal of the lower octave is depressed, and if this pedal is held depressed and another lower pedal depressed, the only effect will be that the tuning of the oscillator 60 will be changed to accord with the pitch associated with the second depressed pedal. The tonal output of the instrument will thus be changed in pitch but unchanged in volume and the tone produced upon depression of the second depressed pedal will not have slow attack but will merely continue at the same steady intensity level. If a higher pedal in the same octave as a previously depressed pedal is operated, it will not have any effect.

While we have shown and described a particular embodiment of our invention, it will be apparent to those skilled in the art that numerous modifications and variations may be made in the form and construction thereof, without departing from the more fundamental principles of the invention. We therefore desire, by the following claims, to include within the scope of our invention all such similar and modified forms of the apparatus disclosed, by which substantially the results of the invention may be obtained by substantially the same or equivalent means.

We claim:

1. In an electrical musical instrument having a source capable of supplying signals of musical scale frequencies throughout a range of several octaves, and a tone signal generating system controlled by the source and including a plurality of cascaded frequency divider stages, each of the latter operating to halve its input frequency; the combination of a plurality of pedals constituting a pedal clavier of a range of several octaves, means operable upon the depression of one of the pedals to cause a signal of corresponding frequency from the source to be impressed upon the first stage of the tone signal generating system thereby to control the frequency at which the latter operates, an output system including electroacoustic translating means, and means for selectively coupling one or more stages of the tone signal generating system to the output system.

2. In an electrical musical instrument, an 05- cillator for supplying signals of musical scale frequency throughout the range of several octaves, a tone signal generating system including a plurality of cascaded frequency divider stages, each operating to halve its input frequency, several octaves of playing pedals, means operable upon the operation of any of the pedals to cause a signal of pitch corresponding to that of the operated pedal to be impressed upon the first stage of the tone signal generating system to control the pitches at which the latter operates, an output system including electroacoustic translating means, and means for selectively coupling the stages of the tone signal generating system to the output system.

3. In an electrical musical instrument having a plurality of groups of playing keys, a plurality of relatively slow-operating note relays of num ber corresponding to the number of keys in a group,'a holding circuit for each of said relays, switches respectively operable by said keys, energizing circuits for each of the note relays completed respectively upon closure of the switches of the different groups of keys corresponding in position in their groups to the position of the relay in its group, a fast-operating group relay associated with each group of keys, circuits for :asnmzz energzing the group zrelays Ein response 'to the operation of any of the keys in its associated roupya source of electricaltone signalspmeans controlled by the slow-operating n te relays to cause said source to provide t ne'signals o'f octtavely related frequencies, an output system in-- cluding an amplifier :and electroacoustic translating means, and means controlled bythe'group relays to cause the amplifier to transmit the tone signals. provided by the source.

1-. .Inan electricalxmusical instrumenthaving an output system including an amplifier and electroacoustic translating means, the combination-ref a keyboard comprising a plurality of keys, a plurality'of switches, one for each of thekeys and operable thereby, a plurality of firstrelays anda plurality of second relays-energized upon the operati"n .oihthe" switches, circuits connecting the "swtches and relays to cause .one "of the Ifirst relays to be energized upon-depression of corresponding note designation keys in different octaves 'andto cause one of'th'e second relays to be .energ zedupon operation "of any of the keys in a given octave, said first relays being o'f'slcw release type and the'second relays beng of the F fast'release type, an electrical tone'signal-generating'system, 'meanscontrolled by the firstrelays to determine the pitch of'the tone signal produced by the generat ng system. means operated by-the secondrelays to control the gain of trolling means associated with reach of the amplfiers, the envelope controlling means "for the amplifier of the lowest frequencies producing .a relatively slow decay while that for the higher frequency ampl fier produces arapid decay, and

means controlled by the keys for rendering effective both ofthe tone intensity envelope .controlling means.

6. In an electrical musical instrument, the combination of anoscillator, a plurality o'f'cas caded frequency halving'stages coupled to the l output of the oscillator, a second group creascaded frequency halving stages, a pedal clavier comprising several octaves of pedals, means operable .upondepression of one of the pedals to tune theroscillator to a frequency corresponding .with the pedal in note designation butnot necessarily in the same octave range,;means operable upon depression of a pedal to couple the cutput .ofeither the oscillator or ;of:one :o'f its-associated .freguency halving stages to "the input :of :the 1 second group of .frequency halving stages, an output system including an amplifier and electroacoustic translating means, and means for selectively coupling the outputs of 'said second group of frequency halving stages .to the :output system.

7. The combination set forth in claim '6 in which means are provided .to maintain the oscillator tuned to the frequency to which .it was tuned bya depressedpedalwuntil the depression 12 of a second pedal which requires that 'it be tuned to adiiferent frequency.

8. In an electrical musical instrument, the

"combination of an oscillator,.a plurality of cascaded frequency halving stages coupled to the output of the oscillator, a second group of cascaded frequency halving stages, a pedal-clavier comprising several octaves of pedals, means operable upon depression of one of the pedalsto :tune the oscillator .toa frequency corresponding with the pedal in note designation but not neces- .sarilyin the same octave range, means operable .upon depression of a pedal tocouple the output of 'either'the oscillator or of one of its associated frequency halving stages to the input of the second group of frequency halving stages, an output system includingtwo'ampliflersand two electroacoustic translating means, means for selectively coupling the lowest'frequency output of said second group of frequency halving stages to one of the amplifiers of the output system and for couplingthe highenfrequency output to .the other amplifier, slow decay control means forming a part of the amplifier for the lowest frequencies,vrelatively rapid-decay control means for the other amplifier, *and means controlledby the depression of a pedal to render eflective both of said decay control means.

9. An electrical musical instrument for the production of organ bass tones and having an outputsystem'including an amplifier and electroacoustic translating means, the combination or a'pedal clavier having pedals extending through more than one octave ranga'a switch associated with each of the pedals and operated thereby upon depression of the pedal, an electrical 'tonc signal generating system having means for tuning it to generate 'anv musicaltone signal within the range of'an'octave togetherwith a signal an octave lower in pitch, an octaveseries of tun- .ing relays each having a holding circuit and connected to be energized upon the closure of axpedal switch of corresponding note designation in any octave of thepedal'clavier, said tuning relays including means operative to tune the generating-svstem,'an octaveselecting relay for each octave of pedals connected to be energized upon the operation of any ofthe pedal switches in 'its associated "octave of pedals, clrcuits associated'vvitl'i saidoctave relays to prevent-enchgization of more than one of them at one ti; c, said octave'relays operating ra idly with respec to the speed of operation of the tunim relays. whereby the tuning :relavs will remain in energized condition after the octaverelays have re-- leased. and means'controlledby theoctave re ays .tocausetransmission of the-signal to the output systemwith controlled attack and decay.

10. In an electrical musical instrument having a pedal clavier consisting of a plurality of octaves'of pedals, an'electrical tone signal generating system providing a plurality of signal frequencies "in .octave relationship and tunable .to frequencies of the notes of the musical scale throughout ranges 'of "an "octave, note relays operated upon depression of'a pedal in any octave to tune the generating s stem to apitrah corro- :sponding.in note designation'with that of the de ressed pedal octave relay means associated with each octave of pedals and o erable to sele t the proper octave tone si nal from the generating systern,an output svstem includingan amplifier and electroacoustic translating means, and means operable by the octave relavs to couple the generating system .to the output system and to render the amplifier capable of transmitting the signal.

11. In an electrical musical instrument having a pedal clavier consisting of a plurality of octaves of pedals, an electrical tone signal generating system providing a plurality of signal frequencies in octave relationship and tunable to frequencies of the notes of the musical scale throughout ranges of an octave, note relays operated upon depression of a pedal in any octave to tune the generating system to a pitch corresponding in note designation with that of the depressed pedal, a holding circuit for each of the note relays, octave relays associated with each octave of pedals and operable to select the proper octave tone signal from the generating system, means associated with the octave relays to prevent energization of more than one of them at a time, an output system including an amplifier and electroacoustic translating means, and means operable by the octave relays to couple the generating system to the output s stem and to render the amplifier capable of transmitting the signal.

12. In an electrical musical instrument. the

combination of a frequency source capable of producing the frequencies of the notes of the musical scale th oughout the range of an octave, a series of cascaded frequency halving stages, a pedal clavier comprising several octaves of pedals, means operable upon depression of one of the pedals to cause the frequency source to impress a frequency, corresponding with the depressed pedal in note designation but not necessarily in the same octave range, upon the input to the series of frequency halving stages, an output system including an amplifier and electroacoustic translating means, and means for selectively coupling the outputs of said series of frequency halving stages to the output system.

13. In an electrical musical instrument, the combination of a frequency source capable of producing the frequencies of the notes of the musical scale throughout the range of several octaves, a series of cascaded frequency halving stages, a pedal clavier comprising several octaves of pedals, means operable upon depression of a pedal to cause the frequency source to impress a frequency corresponding with that of the note designation of the depressed pedal upon the input of the series of frequency halving stages, an output system including a normally cut-off amplifier and electroacoustic translating means, means for selectively coupling the outputs of said series of frequency halving stages to the output system, and means controlled by the depressed pedal to render the amplifier capable of transmitting a signal.

14. A bass tone producing system for organs comprising a pedal clavier, an electrical bass tone signal generating system capable of simultaneously producing complex wave signals of several pitches octavely related to the nominal pitch of a pedal of the clavier upon depression thereof, said generating system having a first output circuit for the lower pitch bass tone signals and having other output circuits for the intermediate and higher pitched bass tone signals, a high power output amplifier for the bass tone signals of lower pitches, a speaker coupled to the output of the amplifier and constructed for efficient radiation of the lowest frequencies, a second amplifier and speaker constructed for efficient amplification and sound radiation of the intermediate and higher pitched bass tone signal, and a plurality of tone quality modifying meshes for coupling the first output circuit of the tone signal generating system to the high power amplifier and for coupling the other output circuits to the second amplifier.

15. A bass tone producing system for organs, comprising a pedal clavier, an electrical bass tone signal generating system capable of simultaneously producing complex wave signals of several pitches octaveiy related to the nominal pitch of a pedal of the clavier upon depression thereof, said generating system having a first output circuit for the lower pitched bass tone signals and having other output circuits for the intermediate and higher pitched bass tone signals, a highpower output amplifier for the bass tone signals of lower pitches, a speaker coupled to the output of said amplifier and constructed for efficient radiation of the lower pitched signals, a second amplifier and speaker constructed for efficient amplification and radiation of the intermediate and higher pitched bass tones, selectively operable means effective to couple the first output circuit of the generating system to the highpower amplifier and to couple the other output circuits of the tone signal generating system to the second amplifier, and means connected with said amplifiers and operable upon the release of a depressed pedal to cause slow decay of the tone signals transmitted by the first amplifier and relatively rapid decay of the tone signals transmitted by the second amplifier.

16. In an electrical bass tone generating musical instrument, the combination of a plurality of pedals constituting a pedal clavier, a tone signal generating system capable of simultaneously producing tones of different octavely related pitches, a first amplifier for the lower pitched bass tone signals, a second amplifier for the higher pitched bass tone signals, the first of said amplifiers having a slow attack and slow decay control circuit associated therewith, said second amplifier having a relatively fast attack and fast decay circuit associated therewith, means controlled by the depression of a pedal to effect transmission of the lower pitched bass tone signals to said first amplifier and transmission of the higher pitched tone signals to the second amplifier, and means controlled respectively by the depression and release of a pedal to render effective the attack and decay control circuits of both amplifiers.

LAURENS HAMMOND. JOHN M. HANERT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,877,317 Hitchcock Sept. 13, 1932 2,254,284 Hanert Sept. 2, 1942 2,301.871 Hanert Nov. 10, 1942 2,310,429 Hanert Feb. 9, 1942 2,357,191 Hanert Aug. 29, 1944

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