US1588788A - Piano sounding-board bridge - Google Patents

Description

June 15 1926'. 1,588,788

6. s. WEBER PIANO SOUNDING BOARD BRIDGE Filed Sept 18, 1922 rim! INVENTOR' Patented June 15, 1926.

UNITED STATES CHARLES S. WEBER, OF HANFORD, CALIFORNIA.

PIAITO SOUNDING-BOARD BRIDGE.

Application filed September 18, 1922.

This invention relates to piano bridges. supported by the sounding board; its object is to obtain from the primary strings aclear tone; furthermore, to enrich this with sympathetic unisons derived from additional strings.

In annexed drawings Fig. I shows a crested bridge supported by the sounding board of a grand piano.

Fig. II shows the portion of strings under a section of bridge, encompassing seven notes.

Fig. III shows the portion above same section of bridge.

Fig. IV shows the preceding section in a front View.

Fig. V shows an improved stringing of the highest octave in an upright piano.

Figs. VI, VII, and VIII show a modification in the way of passing the strings from under the bridge. 7

Figs. IX and X are diiferentviews of a double crested sounding board bridge supported by the main sounding board.

Fig. XI shows different forms of crest.

As shown in the drawings there are on both sides of the sounding board bridge A holes for strings to pass from under to above it; the holes m are on the side farthest from the wrest pins; on the nearest side being the holes 7L In stringing the piano, a string bent double may have one strand passed through a hole m, the other through a as shown in the notes F3 and G, Fig. 2;

' or it may have both strands passed through holes on the same side, as in the notes Git and A, also in Fig. 8 showing a modification of the holes. All strands for each note, emerging on the side m farthest from th wrest pins in, cross the crest c in the direction oi said pins. and form unisons in the main section 9 between 0 and the wrest bridge 2'. Strands emerging from holes n cross the crest directed to hitch pins Z, and

form unisons in the counter section between 0 and the hitch bridge j.

To prevent the portion of string under the bridge slipping whilst being tuned, I twist together two adjoining unisons, as close as practicable to their exit from under the bridge, as shown in the note A of Fig. IV, also in Fig. VII.

T '0 provide for the contingency of a broken unison, I have an eye 2,, Fig. IV at the end Serial No. 589,009.

of said twist, for attaching a new unison without the trouble of replacing the rest of the strings.

To secure two unisons at the point of their bearing on the crest, I use the spreader 8 Figs. IV and VIII; a slight elevation on the slope of the bridge, having divergent sides to engage both unisons and hold them the proper distance apart. Improvement in tone is noted with the use of this device.

To prevent strings cutting the base of the bridge, I use bottom shields f, Figs, I, II, IV, VI, and VIII. Where sounding board ribs 9 Fig. 2, make the surface uneven, I place along the holes m and n the required number of short blocks 6, equal in height with the ribs.

Means for equalizing the pull on opposite s des of the sounding board bridge are shown in a patent granted to me July 4th 1911 Ser. 557,538; other means subsequently discovered will be described in the follow ing. Fig. V on its left shows five notes in the highest octave of an upright piano. In the counter section of said notes, besides the multiple lengths, the primary note is also given, that would result, if the string, held at any of said marks, were sounded by a direct impulse. Thus C held at the 6th 'mark will sound F at the 7 th it will sound a note between Eb and D, (not a step in our scale); at the 8th mark, the note will be C although, when influenced solely by sympathetic action of its main string the note will be C no matter at which mark the counter strino' may be held as by a temporary bridge. IVhilst the removal of this device will leave equality of pull undisturbed; the two sections, with proportions of length altered, will have lost the ability to vibrate in unison. To avoid the complications that might result from a number of individual bridges made permanent; I use a principle so far new in stringing pianos and similar instruments. This allows expanding or contracting the lengths at which sympathetic action results in two strings. To this effect I sustain the pull of a main string with a counter string of diflerent thickness. The thinner string pulling against a thicker will have the greater tension, requiring a greater length for having both to sound in unison.

Thus in the highest notes of a piano to oppose the size 18, I may successively try sizes l2, and 1.1; and select whichever should come near -t to placing the lowest marl; in the of the hitch bridge 1 "1 in c trings two sizes thinner than those in the main may be chosen in the counter section, his not being reached by the blow of an action hammer. To select the proper sizes and indicate pitch to wh ch the counter strings should be tuned, is left to the manufacturer. This task will be easiest in the highest octave of an upright piano where the relative length may exceed 16 to 1; in the truncated frame of a grand, towards the middle notes of an upright, the proportion may not exceed three to one it may even fall to par. Heretofore said task has encountered new obstacles. I overcome these by varying besides the sizes the number of opposing units also shown in Fig. III, where the note B has two main strings opposed by four counter strings; in the note C the number of opponents is six. There being no less than 16 sizes of steel wire manufactured thinner than the thinnest now used for main strings in pianos; so many combinations between numbers of units and their different izes are at the disposal of the piano maker, that, no difficulty should be encountered for having at least in the treble notes efliciency in sympathetic action combined with equal pull on both sides of the sounding board bridge.

To extend this improvement to the notes of the bass I use the double crested auxiliary sounding board cZ shown in Figs. IX and X.

Here the bass string g instead of going from the crest 0 directly to the hitch bridge y" is led under the auxiliary sounding board back to 0 to obtain sufficient length in its counter section between 0 and j for a correct estimate of its tone and thereby of its tension, thus avoiding the alternatives of cutting short the main section, or deadening its tone by short hitching.

Since the counter section in the bass notes is shorter than the main section, sympathetic action only results in overtones being heard in the shorter section, although indispensable for establishing equal pull, they are not needed for acoustical efiect in this invention, therefore the counter strings in this part are muted in any convenient way, to be open only during the act of tuning.

The four auxiliary notes to the right of Fig. V, C,, B,,, Bb,, 1%,, may be contained within a strip two inches wide beyond the higest octave of a piano, even if their counter strings should be double the number, or more, than those shown in the drawings. Not being reached by the action hammer the length of the main section is increased. The object is to further strengthen the often barely audible top notes of a piano. Reversing the order of succession places the weaves corresponding auxiliary at the side of the presumably weakest note of the usual scale, as shown in C and G,, Fig. V.

Sympathetic unisons derived from a short string may have no less amplitude than those originated in a long string; but the latter persist more, and may be heard for some time after the short string has ceased to vibrate. To gain in volume of tone an increase in the number of sympathetic units, as shown, has been found effective.

To control the vibrations in the counter strings I have invented the legato pedal; as shown in Fig. V, this consists of two boards a and u, hinged on the frame of the piano and operated by the performer in any convenient manner. strip of felt to silence vibrations when not needed. The lower board it holds the harmonic divisors 2. Instead of placing these at the first or at the last mark of multiple lengths as shown in a patent granted to me on April 19, 1887,No. 361,38 l, Charles S. Weber, in the present improvement I place the divisor at the farthest mark found within a distance of 18 inches from the hitch bridge. Thus in the counter set of The upper board holds a C,, the removal of the divisor from a dis-' tance of 2 ,4; inches to one of 16 inches, (the length of 0,) enables not only C, but C C and 0 also to obtain sympathetic unisons from said counter section altho by this limitation of lengths, six or eight central notes below A, may lose their share in sympathetic unisons; forty upper notes, more in need of assistance, should profit by the change.

A slight pressure on the legato pedal lifts the upper board off the strings, and leaves the lower board with the attached divisors to regulate vibrations in said strings. Besides what already has been stated, the efiect on the performers play will be to smooth with sympathetic vibrations any break or incoherency, often involuntary, between two consecutive notes; thereby creating an impression as if the notes were correctly held down. This position of the pedal therefore may be used to compensate for a deficiency in legato playing. Increased pressure on the pedal will lift the divisors off the counter section. WVith all lengths open sympathetic action is increased, but, not being controlled, some blur may occasionally be noticed in the melody; not to a degree, however, as what may appear with the loud pedal we so often hear. In pianissimo parts, therefore, the second position of the legato pedal may be used as a substitute, or in fortissimo passages, as a complementary to the loud pedal; one acting on the upper,

' the other on the lower notes.

In tuning the counter section, I sound the string with a pick, and stop turning the pin just before the pitch is fully attained; In

fully stretched it may need no repetition, unless in replacing a broken string.

Having described my invention, what I clann is:

In a piano, :1 bridge having two crests in combination With strings having main and counter sections for each note, one of said sections being located nearer the Wrist pins than the others, the main sections of the strings for any one note resting on the crest farthest from the wrist pins, and the connter sections of the strings for the same note resting on the crest nearest the Wrist pins. CHARLES S. VEBER.

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