US 2351904 A
Description (OCR text may contain errors)
Jme 20, 1944` J. o. BALLINGER ET AL 2,351,9G4 4 l TRANSLATOR Filed July 3l, 1941 2 Sheets-Sheet yl June 20, 1944.;A
J. o. BALLINGR ET AL. 2,351,904? l TRANSLATOR Filed July 3l, -1941 2 Sheets-'Sheet 2 `filed July 23, 1937.
Patented `lune 20, 1944 UNITED STATES PATENT OFFICE TRAN SLATOR Jesse Ora Ballinger, Batavia, and Edward B. Worthington, Maywood, Ill.; said-Worthington assignor to said Ballinger Application July 31, 1941, Serial No. 404,920
This invention relates to a translator, and more 'filed October ll, 1939, which was in turn a substitute for our application Serial No. 155,302,
Certain generators of musical sound Waves, particularly in the audible frequencies below one thousandcycles per second, generate sound waves containing certain undesired and unpleasat partials, so that true and faithful amplification of such waves to considerable volume results in a sound which is very unpleasant to the ear. Examples of such generators are free oating reeds, chime bars or tubes, and short piano strings of the type found in a spinet piano,. for example. A free floating reed produces a sound which is fairly pleasing so long as it is kept at very low volume levels, since the unpleasant partials are of much weaker amplitude than the true harmonic partialsbut if such a tone is considerably amplified, as to ill a church or hall, the
weaker unpleasant partiels make the tone a grat- Iing one, highly unpleasant.
We have devised means for translating sound `Waves from such tone generators as those mentioned above having certain undesired partiels, the translating means operating in such a manner as to practically wipe out all of the low amplitude undesired partials, also tending to eliminate sharp wave front impulses and to smooth the tone out to a wave form more nearly approximating a true sine wave. That is, the fundamental and desired harmonic partials are retained in the resultant electric current, so that the electrical waves are generally similar to the original sound Waves, but they are modified slightly by the practically complete elimination of the unharmonic partiels and by the smoothing out of slopes.
The resultant electrical waves or currents can then be amplified to any desired extent and transformed faithfully intov sound waves, these sound waves being adapted to ll a church or hall with a pleasing tone rather than what would have been an unpleasant tone. Tones from the base reeds of a reed organ, for example, lose all of their undesired partials, pop tones, and the motor boating or death rattle frequently occurring upon termination of the action of such reeds, and the musical sound delivered by the loud speaker is a mellow pleasant one, which has, where desired, flute-like characteristics such that the average listener cannot distinguish it from the tones of a pipe organ. Our translator. also finds great advantage with chimes, resulting in an output tone having the quality of that of a heavy bell; and with very short stringed pianos where, with proper use of a plurality of translators, tones can be achieved which are indistinguishable from those of a concert grand.
Our translator, therefore, is to be distinguished from the ordinary microphone or pick-up device in that it translates sound waves into 4electrical currents which, While they are generally similar, are modified by theelimination of very weak partiels and by the smoothing out of sharp wave fronts in the sound waves. We have found that such a translator can be madeby using a quite heavy diaphragm of material which is relatively dead vibrationally, and by supporting the diaphragm by means which is substantially devoid of characteristics tending to return the dia-v conical diaphragm is best` and when we speak of making it of material relatively dead vibrationally we mean that the material must be fairlyheavy and have a low modulus of elasticity, so that the diaphragm tendsto move as a unit, like a plunger, rather than to break up into various movements in various sections, as
occurs with the conventional loud speaker diaphragm. We have found very heavy blotting paper to be an excellent material for the cone diaphragm. When We speak of the diaphragm as being supported by means which is substantially devoid of returning characteristics, we contemplate the use of supporting annuli o f felt or very soft leather, as kid, not under any appreciable tension., During incidence of sound waves upon it the diaphragm of our translator is moved back and forth almost entirely by the portions of high and low air pressure in the sound waves. The ordinary diaphragm of a microphone, or -oi' a speaker used as a microphone, is snapped back to its original position by the spring-like resilience of its mounting, whereas our diaphragm merely tends to float back such waves, will tend to overrun or lag behind reversals in the sound waves, and will fail to move at all in response to the very weak partials. The usual pick-up diaphragm or vibrating member, on the other hand, is resiliently returned to its initial position, with spring-like snap, whenever it is displaced by the compression portion of a sound wave; and the vibrating member is usually made as light as possible so that, in combination with this snap return, it tends to faithfully follow all of the variations in the sound waves. While faithful reproduction is desirable in many circumstances, it is highly undesirable in the loud reproduction of tones given olf by certain generators, as reeds, short strings, and tubes,
One feature of our present invention is that it provides desirable modiiicatons in translating certain sound waves into electrical currents; another feature of our invention is that it is particularly adapted to be used as a pick-up in connection with free floating reeds, tubes, and short strings, enabling the production of highly amplifled pleasing tones from such sources; another feature of our invention is that it may be simply and cheaply constructed and used in association with conventional tone generating elements; other features and advantages of our invention will be apparent from the following specification and the drawings, in which:
Figure 1 is a diagrammatic view of our invention in combination with a reed organ; Figure 2 is a partial end view of the organ, partly broken away and with a reed cell in section; Figure 3 is a rear elevation of a portion of the reed organ with the back removed, showing two of the translating devices: Figure 4 is a front elevational view, partly broken away, of one of our translating devices; and Figure 5 is a transverse sectional view of the translating device, along the line 5 5 of Figure 4.
In the particular embodiment of our invention illustrated herewith a reed organ, indicated in general as I0. includesa rear mixing chamber I2 and a conventional shutter Il for controlling the volume ofv sound from the reeds. The mixing chamber of a conventional reed organ would be lined with sound absorbent material, and when the shutter is open, as shown in Figure 2, the sounds of the reeds pass out into the mixing chamber and are picked up by translating devices incorporating our invention.
Referring now more particularly to Figure 2, a rather schematic showing of a reed cell shows a free floating reed I5 mounted at one end in a base I6. in turn mounted on one part of the reed cell. the free end of the reed being over an ac tuafing opening II connecting to an opening I3 in the pallet board I9. 'I'his opening is controlled by a pallet 20 movably mounted and adapted to be actuated by a corresponding key on the keyboard of the instrument, so that depressing the key admits air from the windchest through the pallet board and the opening II to set-the reed I5 into vibration. The vibrationl of the reed I5 sets up sound waves corresponding to the pitch and voicing of the reed, 'and these waves pass out through the opening in the end of the reed cell, controlled by the shutter I4.
Within the mixing chamber and to the rear of the reed cells and shutter, are mounted a plurality of substantially similar translators, here indicated as 2|, 22 and 23. These translators include a conical diaphragm mounted for axial movement and carrying a voice coil near its apex, the voice coil being adapted to move in a fixed magnetic eld so that movement of the diaphragm generates corresponding electrical waves or currents in the output leads from the voice coil. A multistage amplifier 24 is provided. this amplifier preferably being provided with three separate input stages and separate volume controls 25, 2B and 21. Translator 2| has its voice coil connected by the leads 23 and 29 to the input circuit controlled by the volume control 25; translator 22 is connected by the wire; 3U and 3| to the input circuit controlled by the volume control 26; and translator 23 is connected by the wires 32 and 33 to the input circuit controlled by the volume control 2'I. It will be understood that these three inputs are combined in the amplifler 24, amplified to any desired extent (which may be controlled by a separate general volume control), and the resultant amplified currents translated as faithfully as possible into corresponding sound waves by the loud speaker 3d.
While the translator 2I is exposed to vibra tions or sound waves from any"reed which happens to be playing, it is located adjacent the base end of the reed cell and is particularly designed to receive and translate the low frequency bass notes. In a particular reed organ which we have built and which we find operates very satisfactorily we employ a translator with an eight-inch diameter diaphragm adjacent the bass notes, a translator with a six-inch diameter diaphragm for the middle range (corresponding to the translator 22 in the drawings), and a translator with a five-inch diameter diaphragm adjacent the high treble notes (corresponding to the translator 23 in the drawings). We find that an eight-inch l translator constructed in accordance with the details which we are hereinafter disclosing re sponds in a desirable manner to frequencies from thirty cycles per second up to and including about five hundred cycles per second; a six-inch diameter translator of our type gives the desired response to notes having a frequency in the range of one hundred fty cycles per second to about two thousand cycles per second; and a five-inch diameter translator of our preferred type responds as desired to frequencies from about one thousand cycles per second to about seven thousand cycles per second. Because "of the overlap In response ranges some notes would be picked up and translated efficiently by two of the trans- Iators, and very high harmonics of the lower notes 'might be translated by the translator designed for the high frequency range. In the main part, however, the low frequency notes are translated by the translator 2 I, the intermediate frequency notes by the translator 22, and the high frequency notes by the translator 23.
As may be best seen in Figure 3, the translators are preferably vibrationally insulated from the remainder of the organ, here being shown as mounted` on twisted rubber strands 35. These serve to isolate the translators from undesired vibrations in the organ console, as vibrations of the motor driving the blower, or the like. The translators are intended to pick up and translate into modified electrical Waves the sound waves which emanate from the reeds, and are as far as possible isolated from other vibrations. Any sound outside the organ is prevented from energizing the translators by the same internal lining of sound-insulating material which tends to keep the sounds of the reeds within the mixing chamber I2.
Inasmuch as all of the translators are preferadapted to be vibrated by the sound waves: annular supports for the diaphragm attached thereto near its base and apex, said annular supports being of flexible and inelastic material, whereby the diaphragm is only slowly returned to a neutral position when it is displaced therefrom; and a coil carried by the diaphragm near its apex and movable therewith, said coil being adapted to move in a xed magnetic field to translate movements of the diaphragm into corresponding electrical waves, the moving parts having a total weight in excess of one gram per inch of dlaphragm diameter, such weight being principally concentrated in the diaphragm.
2. Apparatus ofthe character claimed in claim 1, wherein the material of which the diaphragm is made is relatively dead vibrationally, whereby the diaphragm vibrates as a unit and discriminates against low amplitude and sharp wave front impulses.
3. A device of the character described for translating sound waves into generally similar electrical waves having somewhat modiiled characteristics, including: a relatively heavy circular diaphragm adapted to be vibrated by the sound waves: means for supporting the diaphragm for vibratile movement along its axis, said means being of such nature as to cause said member to only slowly return to a neutral position when it is displaced therefrom; and means carried by the diaphragm near its apex and movable therewith adapted to cooperate with flxedly mounted means to translate movements of the diaphragm into corresponding electrical waves, the moving parts having a total weight of at least one and one-half grams per inch of diaphragm diameter and such weight being principally concentrated in the diaphragm.
4. Apparatus of the character claimed in claim 3, wherein the moving parts have a total weight of approximately two and one-half to three gram per inch of diaphragm diameter.
JESSE ORA BALLINGER. EDWARD AB. WORTHINGTON.