As a pianist, I don't care what the action parts are made out of as long as I can get the performance (consistency, speed, dynamics, control, repetition) that I want. I've been very impressed with the M&H pianos I've played recently with the composite actions, as well as the rebuilt pianos I've played with WNG parts. Sure, aluminum rails pick up and transmit unwanted noises, and aluminum keybed supports may alter the resonance of the piano in an unpleasing way, but what does that have to do with composite action parts? It's a real stretch to cite those examples as justification for not liking composite wippens and carbon fiber shanks. Those parts do not generate or amplify unwanted noises, nor do they impact the natural frequency response of the piano. It would, however, be fair to say that a hammer shank's rigidity and spring response could influence the way the hammer interfaces with the string during impact and rebound, and this could change the tone of the piano since the partials might be excited differently between wood shanks and carbon fiber shanks. If you can consistently hear the difference blindfolded and prefer one over the other, then nobody can argue with that preference or with the reasoning behind it. I'm just saying, it's fine if you don't like composites, but if you're going to be negative about them, at least be fair. Personally, I'm enthused by the developments and intend to use those parts in my own personal pianos.
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