If you're a piano rebuilder, you've undoubtedly experienced the frustration of carefully and meticulously rebuilding a fine grand piano only to be disappointed with the acoustic results. Sure, it looks great. The finish and detailing are better than the original. The new soundboard looks great. The bridges were never notched better. The action is regulated perfectly. The old ivories are buffed and lush.
The only problem is that it just doesn't sound like we hoped it would. The bass is still a little muddy. The bass/tenor break is still uneven and no amount of voicing will bring it together. The tone "color" of the bass is different than the tenor which, in turn, is different from the treble. And in the "killer octave"-the upper tenor/lower treble-sustain falls off no matter how much "super-turbo-power voicing" we do. No matter how we shape and lacquer the treble hammers, the tone is still weak and thin.
So, where did we go wrong? Well, in most cases, we didn't. None of these tone problems are necessarily the result of poor materials or shoddy workmanship either in original construction or in our rebuilding work.
Certainly, mistakes like improper downbearing or incorrect strike point can aggravate these problems, but more often they result from basic limitations in the piano's original design. In other words, the piano once again has the same tone problems it had when it was new!
At the opposite extreme is the non-descript piano of vague origin that, after a quick rebuild-It's not a Steinway or a Mason-Hamlin so it surely wouldn't do to invest too much effort into it, would it!- we find ourselves with an instrument having a quite marvelous sound.
The sound of any piano is determined by an almost infinite number of tightly inter-related design and structural elements, many of which have very little to do with the commonly heralded benchmarks of manufacturing "quality." Let's take a brief look at some of the most basic of these and see how they contribute to a piano's overall performance.
| Details & Specifics of Piano Remanufacturing |
| The Action & Keys-The link between the pianist and the sound. |
The link between the pianist and the sound of the piano is the action and key mechanism. By subtly varying the striking force on the keys the pianist should be able coax sounds of great expression from the piano. Gentle force on the keys should create sounds of low volume and soft, sweet tone. Greater force should elicit louder, more powerful and aggressive sounds. Up to a certain point, this does happen with all pianos, but with many -especially with some larger pianos-we soon run into the limits on the power available.
Unfortunately, the action is often the limiting factor
in determining a piano's total output power. This is especially true of
some modern grands. Many early pianos-at least the larger ones-used keys
25 mm or more tall that were fitted with a bottom foot and/or a top plate,
increasing the overall height even further. Sadly, many modern piano makers
have switched to thinner keys-often in the neighborhood of 22 to 23 mm-and
have foregone the use of the foot and top plate entirely. (A few years ago,
while requesting bids for a keyset to fit a high-end grand piano I had designed,
I was told by a well-known German keymaker that they had determined that
the bottom shoe and top plate were unnecessary and they no longer built
keys that way. They informed me that piano makers didn't want keys of that
type any more. Well, I did. And they should.)
As a result, some pianos today have keys so flexible that even with a moderate blow the front of the key bottoms out on the keyframe before the hammer even begins to move.
[This phenomenon is called action saturation. It is defined as the point beyond which there can be no further increase in output sound power regardless of the energy input to the key. Since I've written two recent Journal articles about this subject I'll not go into it further here. -DDF]
| Hammers-Restoring the "Piano" in Pianoforte. |
The hammer has been blamed for nearly every tone problem ever found in the piano. Often viewed as the sole nemesis to good piano sound, they've also been treated like the sorcerer's talisman which, if only rubbed with just the right witch's brew, will cure all sorts of tone maladies. They are, of course, neither. They're simply one component of the total package. The hammers function is to excite or suppress specific harmonics in the strings. What happens beyond that is not influenced by the hammer.
Pianos were originally called piano-fortes because they could be played both softly and loudly. With the wood and leather hammers used on early instruments, volume was the primary variable. When pressed felt hammers came along more tone subtleties became possible-tone quality could also be controlled with the strength of the hammer blow.
The spectrum of harmonics excited in the strings depends, in part, on the resiliency of the hammers. The greatest dynamic range being available only from instruments with relatively soft and resilient hammers. Hard, dense hammers can not give the same results despite the most heroic attempts at voicing them. Over the past thirty years I have watched with dismay as piano hammers have gotten heavier and harder in misguided efforts to make pianos "more powerful" and "brighter." At some point it was decided by some marketing guru that if a little loud was good, a lot louder would be even better. "Just listen to the power of our new and improved Super-Colossi Model GLTñZ piano, Mrs. Jones! Why, this piano uses special hard-pressed 28-pound hammers (Alas, no. I didn't make this up. ddf) and they are brighter and more powerful than anything built by our competitors." While this trend started with cheap, low-quality pianos, it has sadly influenced even some of our most prestigious makers, who really should have known better. Nonetheless, the race was on to build ever louder and brighter pianos. Along the way, tone quality got lost.
This trend also affected the piano rebuilding industry, where we've seen available replacement hammers also becoming harder. Only recently has there begun a swing back to softer after-market hammers. Many rebuilders are now putting softer hammers on pianos originally built with so-called "hard-pressed" hammers. Unfortunately, while this may help a little, it can't solve the fundamental design problems that lead to the use of hard-pressed hammer to begin with.
Besides the quest for "power," there are several other reasons driving the trend toward hard-pressed hammers. First, they are easier to make in high production. The process does involve the use of high heat, pressure and humidity-a combination not particularly good for felt-but the finished hammer will look good and it will be inexpensive to make. Soft hammers take more care. More attention must be paid to the many subtle details and more care must be taken to control the process.
Second, the soundboards and ribs on most mass-produced pianos tend to be relatively heavy and stiff. They respond poorly to the complex energy spectrum developed in strings struck by soft hammers. Reasonable sustain is possible, but to get acceptable power it's necessary to use fairly hard and heavy hammers and forget about tone dynamics. The combination of hard-pressed hammers and stiff, heavy soundboards produces sounds having a limited energy spectrum. These pianos can be played at low volume and at high volume, but soft, mellow tone cannot be found at any level. Even at triple pianissimo the tone will still be edgy and thin.
Most pianists want to control both volume and tone. They want an instrument that can produce quiet tones that are soft and lush, as well as loud tones that roar and crash.
To do this the soundboard assembly must be responsive to the most subtle vibrations of the strings. To create these subtleties, the hammers must be soft and resilient, having a mass that is well matched to the stringing scale and the soundboard. At PianoBuilders NW, we've found that our ClarityÆ soundboard and rib designs are so responsive that we usually have to voice down even the softest hammers.
A further advantage of soft hammers is that because they are naturally
resilient they are much easier to voice and they will maintain their voice
longer. §
Top of page.
| Strings & Stringing Scales The Speaking Voice of the piano. |
Early stringing scales were mostly laid out by guess and by hope. Samuel Wolfenden's book, A Treatise on the Art of Pianoforte Construction, has a good section describing the process. Relatively simple calculations would be made to determine the length of just a few strings. The rest were drawn in by scribing a line along a wood "spring lath" that was bent to connect as many of the the points as possible. It was hoped that the lath would bend uniformly and that the intermediate scale points lined up properly. Many errors crept into those early scales, and many of those same errors are today being faithfully copied into computers.
At the time, concepts like inharmonicity or string impedance were not considerations in the development of stringing scales.. Mathematical tools for designing bass strings were completely unknown until well into the 1900's. Viewed in this historical context, it should come as no surprise that older stringing scales beg for improvement! Unfortunately, some of the worst examples are found in the seven and nine foot pianos that have since become industry standards. Warts and all. That these designs were the best that could be done in 1880, or even in 1930, does not mean that they cannot be improved upon today.
The configuration of the plate often prevents us from correcting some of the most glaring scale defects. For example, we cannot change the the location of the bass/tenor crossover in a short piano. Nor can we greatly change a strings' speaking lengths. Still, many improvements are possible.
Sometimes slightly re-locating a bridge will make substantial improvements in a piano's tone. In some cases-our "Killer B" conversion of the Steinway Model B is an example-we can make a new tenor bridge that will clean up both string scale and strike point problems. In re-designing one Yamaha model, we were able to correct a poor hammer strike point problem at the bass-tenor break by changing the configuration of the bass bridge. And, of course, we can improve every old string scale design by carefully manipulating the core and wrap sizes of the bass strings.
I should say here that I'm very conservative with string scale modifications. I don't make gross changes. Caution and subtlety are key words when it comes to re-designing string scales. I rarely raise the over-all scale tension above the original. My goal is not to add "power" but to clean up the sound; to smooth out and unify the tone throughout the scale. Usually we can improve the keyboard's entire range:
-The bass will be clearer and more accurately defined. The low bass will be more articulate. The inharmonicity curve will be much smoother for easier and smoother tuning. Power response will be more uniform.
-The bass/tenor break will be smoother. It will have more consistent color, power, and sustain. The harmonic content of the wave envelope will be more uniform from note to note.
-The upper tenor and treble will be brighter, cleaner, and when combined with our soundboard designs, more powerful. §
| Plates-Defining & Supporting the Stringing Scale |
The plate-along with the shape and structure of the
rim-is the major limiting factor in how far an existing design can be taken.
It defines the scale, the hammer strike points, and the overall string lengths.
It determines whether tuned duplex string segments must be retained and
establishes the practical maximum length of the strings' back sections.
Usually, tuned front duplex designs can be converted to a more efficient system with improved deflection angles providing better speaking string termination. In extreme cases where we find gross strike point problems, we can grind off the V-bar and fit new bronze castings. An added benefit is a much better bearing surface for the strings. Yes, it's a costly procedure, but very effective!
On a more practical level, we can often improve a bass/tenor break by changing low tenor plain-wire tri-chords to wrapped bi-chords.
In some cases we can convert the hitch pin system over to one of several
types of vertical hitch pin styles. Please note that we are very cautious
with this conversion, carefully analyzing the strength of the plate until
we're satisfied that the plate will handle any possible added stress. Fortunately,
most plates are quite strong along the bass hitch pin riser where the vertical
hitch pin design is the most helpful. Many "muddy" low bass sections
can be made clearer and more defined this way. §
Top of page.
| Soundboards & Ribs-Defining & Developing the Voice of the Piano |
The soundboard was, and still is, one of the most misunderstood components of the piano's tone production system. Yet it is one of the most important links in the chain. No matter what is done to the rest of the design, all is lost if the soundboard design is poor.
As indicated by the quote from Pianos and Their Makers by Alfred Dolge (1911), basic soundboard physics and design principles were poorly understood by the designers of our early pianos. It was mostly empirical (i.e., hit or miss) and often based on flawed science. Empirical design is not necessarily bad design; many very good pianos have been designed this way. Most pianos built today have soundboards that are direct descendents of those early designs. However, empirical design often leaves lots of room for improvement when more sophisticated technology is developed and applied.
Understanding soundboard acoustics and design principles has long been a subject of study and experimentation for me. Designing, building and installing custom soundboards has become a specialty of our shop.
My goal in soundboard design is to improve the overall performance of the piano. Yes, I want to increase output power (remember Mrs. Jones?) but first I want better sustain (especially in the upper-tenor and treble) and, most importantly, I want improved dynamic range. Without an elastic and responsive soundboard design, no action and no hammer can give a piano the wide dynamic range required by the sensitive musician.
We've encountered very few limitations in fitting our improved soundboards into original rims. Since many of the specifics of what we do are proprietary, I really can't describe our soundboard designs in detail. I can tell you that we design and install soundboard cut-off bars, we re-calibrate ribs (i.e., we specify new cross-sections, crown, and feathering), and we re-calibrate soundboards (thickness, tapering, and grain angle). In our more involved jobs we plug rim notches and start over with a completely new rib layout, usually in the radial pattern I've been developing for the past fifteen years. §
| Rims & Bellyrails- The structure of the piano. |
The piano rim must be acoustically dead. It must provide a solid support for the soundboard and reflect as much energy as possible back into the soundboard. Most wave energy transmitted from the soundboard to the rim is lost forever. Despite what some manufacturers seem to believe, piano rims do not make good soundboards. They do not efficiently convert wave energy from the soundboard into sound energy.
The most obvious method of achieving this is to make the rim as massive and stiff as possible. Both the inner and outer rims of older American pianos were pressed from thick maple or oak veneers. Some lower grade pianos used poplar in their outer rims, but most manufacturers used some sort of acceptably hard wood. Most reasonably good pre-1950 pianos still used some maple in their rims.
Not much needs to be done to these earlier pianos. Occasionally, we find strong resonances on the straight-bass-side, so we add one or two braces as stiffeners.
Many of the grand pianos I've examined from Japan and Korea often have both inner and outer rims made from not-so-hard "select hardwoods." These rims can require a lot of engineering to calm them down.
The rims of European pianos can be at either extreme and I can't really
comment on the rims used in pianos built in China or Russia as I've not
yet examined any of them all that closely. §
Top of page.
| Summary |
So, that's a general overview of our "Value Added Rebuilding" concept. This work is applicable to both older and more modern pianos. And yes, some of this work is done on fairly new pianos.
We're using this newsletter as a means to announce this new direction for our company (actually, confirming a reality that already exists) and to explain just what Value Added Rebuilding is all about.
Over the past several years an increasing number of pianos have come to our shop with redesign as an integral part of the re-manufacturing process.
Although we will surely continue to do traditional ("authentic") piano restoration work when requested, it's clear that the VAR pianos leave with substantially better sound. So much so that we have to admit to some frustration after listening to an "authentic" rebuild knowing we could have gotten so much more performance out of it.
We've had good success improving the performance of existing pianos from all points of the size and quality spectrum. We've worked on pianos of all ages and types, including pianos from Steinway, Mason & Hamlin, and Yamaha and through a variety of no-name wonders of various vintages.
The results have been consistent and encouraging. We're able to strengthen
most of the weaknesses of these pianos while enhancing their strengths.
§
Top of page.