Metal shoe "tone collector"? Effect on sound?

Hello Jake,

If I may add my own two cents from the standpoint of a piano tuner:  I am not in any position to say whether such a device has a positive effect on the sound (surely, any modification to a basic design has "some" effect, either positive or negative).  One of the techniques I use when tuning the bass notes of upright and grand pianos involves pressing my left knee to the piano's case below the keybed, and "feeling" for the presence or absence of a sense of vibrational undulations against my pressed knee.  Why?  From a tuning aspect, I can detect frequency differences (between two strings) of less than one hertz using this technique.[EDIT: This technique works only for the lowest octave of notes. End Edit]

With that information as an introduction, here is why I am chiming in to this thread:  Verticals and grands of less-than-finest quality tend to dissipate higher qualitative percentages of the strings' motions into the pianos' cases instead of entirely through their soundboards.  Stated differently, when you play a tone on the acoustic piano, and you can readily feel the entire case vibrating, then you "know" that not all of the strings' vibrations have been faithfully sent through the bridge to the soundboard.

I suppose (but admittedly do not know for certain) that the notion of strengthening the joints between beams in a piano's frame is to reduce (attempt to prevent, but we all know that is fallacious) the strings'/soundboard's vibrations from leaking into the rest of the piano. 

My conclusion?  The inclusion of a shoe or a tone collector or some other fancy marketing term in all likelihood does "change" the sound/tone, but no one can convince me it is always in a positive manner.

Here's an analogy from the health food field:  Just because a particular pill or medication is touted as giving "fast, FAST, F-A-S-T" relief, even if the product is made from "all natural" ingredients, how does the marketer know the effects are all positive?  (They can't.)  Just remember in this analogy, that being "all natural", so is deadly nightshade.

Cheers,

Joe

I'm interested in this subject partly because I wonder if the plate might increase projection, but increasing projection might not necessarily be a good thing. Certainly more projection is good when playing in a large hall, but for the player, keeping the sound inside the piano, if it"s true that plate-less pianos lose more of the vibrations to the wood bracings and cabinet, might be a good thing. According to Conklin, in his section in the "Five Lectures on Acoustics of the Piano," the case does a poor job of radiating sound. My question would be: Can the player hear those vibrations in the bracings and cabinet, even if only a little? Do they contribute to our sense of the sound emerging from a wide field while we sit at the piano? Do they contribute to what we sometimes call "wood," as in when we say we want more wood in the sound? (And of course, Conklin was writing after the introduction of this metal shoe or plate, so he was presumably measuring the vibrations of a modern case that was intentionally stilled, or unified, by the Steinway invention.)

I can imagine that the different woods in the casing and bracing would have their own resonances--they would vibrate at some frequencies more easily than others. Another effect of using dovetail joints instead of a plate might be that there would be a series of impedances and thus delays. There would also be ongoing feedback between the soundboard and these other pieces of wood.

This way of thinking comes partly from playing guitars, which are of course held together with glue, the neck of older guitars and better new guitars being attached with dovetail joints. Different types of wood are usually used and different timbres are created by using a spruce sound board with a mahogany back and sides, say, versus an all-spruce guitar. Of course, a  modern piano is intended to instead sound completely through the soundboard, but that's a modern, Steinway and after, piano, with the iron frame and the shoe\plate.  Before those additions, would a piano have functioned a little more like a guitar, with all of the wood contributing to the sound, reducing its amplitude, or its projection, if those are different things, but giving it a different tone as all of the vibrations intermingle? (Whether good modern pianos, such as older Baldwin grands, behave the same way, minus the plate, but with the iron frame in place, is another question.)

An interesting book on the subject:

http://www.pianosinsideout.com/constbig.pdf

In short, as pointed by Joe, everything is done to avoid as much as possible vibrations going elsewhere than in the soundboard. The piano manufacturer's ideal is that the soundboard collects 100% of the energy provided by the strings. The way for achieving this is to have everything else as rigid as possible.

The funny thing is that perfect is not necessarily equivalent to desirable. For example, another piano manufacturer dream is to reduce as much as possible the inharmonicity. That you can do in Pianoteq by setting the string length to 10m. Does it sound better? This is a matter of taste and habitude.

Back to the soundboard: you are right, it is indeed a matter of setting the impedance to infinite. But if you do so in a real acoustic piano, you won't have any sound because no energy is transmitted to the soundboard. In Pianoteq, we made the volume independent, so increasing the impedance doesn't affect the volume as it would do in the real world. Hence, increasing this impedance let's you get closer to this manufacturer dream: a very long sustaining sound. In Pianoteq, just move the impedance slider to the right .