sjgcit wrote:Jake Johnson wrote:One interesting thing about newish Baldwins is that they have adjustable hitch pins. You can change the height of each string individually, and thus change the down-bearing on the bridge for each string.
For people like myself (not at all versed in the details of piano mechanics), what I'd appreciate an idea as to what this means in terms of sound production, or indeed maintenance ?
I'm not qualified to give a thorough explanation, but I can try to convey my own understanding. The term itself describes the pressure that the strings exert on the bridges, which transfer the string vibrations to the wooden soundboard, which then transfers the vibrations to the air, and thus to our hearing. If the down-bearing of a string is too great--if strings push too hard against one of the bridges--they compress the soundboard, making it more rigid, and thus dampen the vibrations. The tone goes dead or the piano does not react proportionately to the strength of the key strike. Soft blows do not stimulate the soundboard enough; hard blows push the vibrations into the wooden soundboard too fast--hard strikes "break up" into a percussive sound. (The amplitude and tonal dynamics, in other words, are compressed.)
If the down-bearing is too light, the vibrations are not conveyed to the soundboard efficiently, and the energy is instead dissipated in the strings and in their movement over the bridge--the strings can slide around over the bridge very slightly with each vibration. Energy is lost before the vibrations even reach the sound board, in other words. So the ideal down-bearing is neither too heavy nor too light. It would seem almost simple to find this sweet spot, but other factors weigh into the equation--the soundboard is often not the same thickness all across its carved area, and its irregular shape, carved to best vibrate under the strings of various lengths and thicknesses above it, means that different pressures can be needed for different strings. And minute changes in the pressure at any spot can have large consequences on the tone. And all of the other physical elements of the piano weigh in--the string thickness and wire type, the hammer hardness and height, and almost everything else. So there is no single, ideal down-bearing pressure that can be applied to the bridges of all pianos. The makers instead calibrate all of the elements to create what they hear as the ideal sound.
(Steinway uses a low down-bearing, in the sense that it is calibrated to be exactly enough to convey the string vibrations to the bridge and sound board without dampening the sound. Steinway in other words, uses the terms "low" to mean "low in comparison to a too-heavy down-bearing.")
So...What Baldwin may make possible is more control over the amplitude and tonal dynamics of each key. But...
This note-by-note adjustment of the string height CANNOT be responsible, exactly, for "the Baldwin sound," if we mean the sound of the older grands. Baldwin only filed the patent in 1966. (See https://www.google.com/patents/US3478635 ) On the other hand, the company was surely experimenting earlier. The new hitch pins had to come out of research into varying string heights, or previous practice.
Last edited by Jake Johnson (07-08-2017 04:44)