The 5th Element #27

What has happened will happen again, and what has been done will be done again, and there is nothing new under the sun.—Ecclesiastes 1:9

The author of Ecclesiastes was a world-weary chap. He beat the existentialists at their own game, and he did it nearly three millennia before they even suited up. (As Mark Twain noted, those dead guys stole all our best ideas.) I think that the reason the author of Ecclesiastes' writing still resonates with so many people is that, over the run of human experience, he ends up being right enough of the time that you can't discount his attitude out of hand.

However, every now and then there is something new under the sun. In rare cases, that something new appears to be genuinely worthwhile. In this installment, I want to tell you what I have learned about an Australian company that is relatively new (research projects undertaken in 1983), and that has developed and implemented a fundamental technical advance in piano building (first production piano released in 1994).

A technical explanation follows. But, to cut to the chase, based on the half-dozen or so recordings I have heard, this new piano sounds absolutely fabulous, producing extraordinarily clear, sustained tones without any glassiness or tinniness. If the piano is the center of your musical life, you owe it to yourself to hear at least one of the recordings listed at the end of this column.

The Stuart & Sons concert grand piano is manufactured by Piano Australia Pty Limited. Designer and builder Wayne Stuart, OAM (Order of Australia Medal), was born in Tasmania. After Stuart learned enough piano-playing technique, he played for local dances in rural areas. He soon discovered that he would have to learn at least the basics of the craft of being a piano technician, because most of the pianos he had to play were in poor repair.

Stuart enrolled in a conservatory program in piano technology. Upon graduation, he did a year of postgraduate study in Japan under the auspices of Yamaha, and later spent a year with five of the major piano manufacturers in Europe. However, Stuart grew frustrated with the inbred aversion to innovation he perceived in the piano industry. The basics of the concert piano were established in Beethoven's time; by the end of the 19th century, the grand piano had reached its modern form. Cumulatively, over the past 100 years, the pace of innovation has been glacial (footnote 1).

The elemental innovation of the Stuart & Sons piano is a radical rethinking of how the end of the string farthest from the keyboard is coupled to the piano's bridge. The bridge in both a traditional piano and in Stuart's redesign sits directly under the strings. It is made from laminated wood that is rectangular in cross-section, and is curved to follow the shape of the piano's end. The bridge, as its name implies, carries the string's vibration down to the piano's soundboard. But to appreciate Stuart's innovation, a little more background is in order.

Each note on the piano's keyboard is sounded by one string (the bass), two strings (upper bass and lower midrange), or three strings (midrange and treble). This is so because, as the pitch of the notes ascends, the strings become increasingly thinner and shorter. Maintaining an even loudness from note to note requires that the higher notes employ more strings, to make up for the strings' diminishing gauge and length.

At the keyboard end, the string ends first go through, then wrap around square-headed tuning pins. These protrude up from the pin block, through holes in the harp or plate, which is the iron framework that holds the strings in tension. From the lower midrange on up, two adjacent strings consist of one long piece of piano wire that is looped at the very farthest end around a hitching post of sorts (called a "hitch pin"), with both ends wrapped around adjacent tuning pins at the keyboard end.

Starting at the keyboard end, the strings pass over (by which I mean they are in contact with) a lateral element of the frame and (usually) through a flattened sort of eye-hook. The goal is to damp the vibrations of the string in the short segment where the tuning mechanism is, yet allow free vibration over the majority of its length, where the string vibrates after being struck by the hammer. At the far end, the challenge is to transmit the string's vibration through the bridge and on to the soundboard; in other words, to transmit the string's vibration while terminating its effective speaking length.

The reason there has to be a string segment beyond the bridge is that the bridge alone could not bear the horizontal pull of the tension of the strings, which in a large concert grand can total 40,000 lbs. The hitch-pin arrangement places the horizontal load on the iron plate while allowing the resting string tension on the wooden bridge to be mostly vertical.

The way grand pianos—up to the present—have terminated the string's effective speaking length has been to use two offset pins driven into the bridge as the string-coupling device. These offset pins make the string zigzag slightly on its way to the hitch pin. That is, the bridge pins couple and damp the string by means of horizontal deflection (fig.1).

What Wayne Stuart recognized, which apparently no one else ever had (or, if they had, had done nothing about), was that introducing an element of horizontal deflection into the string's energy path was essentially at odds with the string's dynamic behavior over its speaking length. This is because the hammer strikes upward at the string from below, and the string then vibrates in a primarily vertical manner. Stuart's experiments convinced him that this conflict between vertical and horizontal modes of vibration produced noisy transients, impaired pitch security, and resulted in a more rapid decay of the piano's sound (through destructive interference) than is desirable.

Once he'd grasped this insight, Stuart's work focused on designing a string-coupling device that would use vertical deflection to terminate the string's speaking length. (Over and above the requirement of vertical deflection, the new string-coupling device had to allow for the installation and replacement of strings without kinking or breaking them, which was a substantial challenge.)

Stuart's string-coupling device, which he calls a bridge agraffe (from the French word agrafe, for hook), has three removable lateral rods or pegs, the middle of which goes under and is grasped by three upper, clawlike elements. In total, the string passes over a lateral rod at the rear, goes between two of the claws, under the rod held by the claws, and then over another lateral rod at the front. The Stuart string coupler therefore has three points of deflection, not two, and these are aligned in the vertical plane, not the horizontal (fig.2).

The string coupler itself has as a base a hollow post, which goes into a hole drilled into the bridge, and which provides for a woodscrew as well. During assembly, a silicone compound is placed in the trough between the claws and the front of the agraffe, to provide additional damping.

Because, under the Stuart system, the piano's bridge is no longer subject to the torsional forces of reaction to the horizontal deflections after the hammer strikes the string, the piano's soundboard—which is both an acoustical element and a structural element—need not be as thick and heavy as that required by a piano with conventional string coupling. A less massive soundboard has less inertia to overcome as it begins to propagate a musical note, which results in a greater dynamic range. Ah-ha!



Footnote 1: I am aware of grand pianos in which a lower "lid" acts as an additional acoustical reflector. However, I consider that a rather peripheral development, and more in the realm of acoustics than in the piano's playing mechanism itself. Furthermore, the lower-lid grand piano seems to be a dead end; neither players nor audiences are clamoring for them. In sharp contrast, the Stuart & Sons piano seems to have a major buzz going on about it. So to speak.—John Marks
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