Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Tone of light soft hammers

Modern concert grands developed to have heavy and hard hammers for volume in large halls with large orchestras.
Can anyone comment on how light and soft hammers should affect the overtone spectrum, the attack, the control over shades of tone production? Furthermore would a light hammer profit from lower string tension or thinner strings in the treble? Finally has anyone compared conventional copper wound with steel wound bass strings in terms of sound?

Do you have a particular application in mind or is this a speculative, academic debate type of question?

There are more factors that affect a valid answer than what you specify. The more detailed and real-world you can make your inquiry, the more worthwhile an answer may be.

If you are looking for some universal principle of what "light/soft hammers do", there may be no definitive answer. In any event, the assumption that hammers have to be heavy and hard in order to achieve volume may be fallacious.

I was more interested in a general discussion of how these factors influence sound also in light of the sound of historcal instruments versus modern instruments.

+1 That question encompasses limited aspects of piano building that would require a book-length response, and it's likely that 20 books would produce 20 different opinions.

Glue up samples of different hammers on shanks.
Lift the damper and try to strike the string as close to strike point as possible.
Listen to differences.
It's not a perfect example but it is an example of what different hammers can do.
Easier and more effective in the bass for tone color, not so much for power.

If you can find a Steinway, Bosendorfer, Beckstein, Chickering, Baldwin or Mason & Hamlin grand from prior to WWII in still original and good condition you can hear lighter, softer hammers.

"If you are looking for some universal principle of what "light/soft hammers do", there may be no definitive answer."
As a scientist I was very much hoping that at least a limited and manageable set of rules have been identified hopefully explainable by physics derived empirically by piano builders and technicians over the years -after all pianos have been around for a while.
This could initially come as a simple list or technical elements with increasing and decreasing parameters and their potential effects. If one wanted to be more scientific about it one could eventually draw it as a 3D network with values.

Do a google search for dr Russell at Kettering university
He has some piano hammer studies
Can't recall if it was heavy or light but some good info and maybe a good place to start investigating

The primary physics of the hammer string interaction is the relation between the periods of the string and the inertia of the hammers. The secondary thing is the non-linear elasticity of the hammer felt.

This is complicated by the wide frequency range of the compass, the psycho-acoustics of musical perception, and the feel of the action. These physical elements must be graduated across the compass in a way that maximizes the production of musically intelligible sound. And the feel of the action must allow the pianist rapid, reliable feedback regarding dynamic output and repetition. The action needs to have an "intuitive" feel that allows for maximum feedback to the fingers about what the hammer is doing and when it is doing it.

The first class I took on tone-regulation was given by Fred Drasche at the 1972 PTG convention. Fred was head tone-regulator at Steinway NY. He was in his early 60's than and had been working at Steinway since he was about 16, if I remember correctly.

The first words he said was, "the hammer has got to get away from the string". He next said, "the voicer puts the tone in the hammer with the shape".

I have spent many years working out the relationship between the inertia of the hammer and the feel of the action. The result is a tone-regulation protocol I call, LightHammer Tone Regulation, (LHTR).

The simplest description I can give of LHTR is that that the tone regulators job is to shape the hammers to reduce dimensions on every surface, (except the strike surface), to reduce the mass enough that the feel of the action becomes very precise when playing softly. This feel has to be achieved with almost no leads in the keys so as to avoid too high hammer inertia. In essence the hammers are made oversize and must be fit to the piano. There is no magic perfect hammer weight for any particular note, the weight must be proportioned both to the string periods and to the leverage of the action.

The first pianos of Cristofori had extremely light hammers. There was open space between the striking surface and the wood moulding. These hammers did not wear well and most of his pianos got converted to harpsichord actions because the techs concluded it too much bother to duplicate them. (This is an assumption on my part as I don't have any historical references to prove this. But being a tech gives me some intuition on how they may have been thinking).

Where too heavy hammers most obviously impede the tone of a piano is in the treble. When the fundamental frequency hits four digits hammer inertia become critical. You can recognize the sound of heavy hammers in the treble by the PFFTHHAT sound at impact. The tone sounds like a singer with a lisp! This sound is the string "buzzing" against the hammer felt through several periods before it rebound fully. Also the heavy hammer imparts a more "woody" knock during impact that is carried by the plate and action parts. Heavy hammers also wear faster and brighten up faster.

Most pianos have hammers that are heavier than they need to be.

If the hammer is too heavy, the tone chokes. The tone is also slower to develop, and you will hear more of the percussive element at the attack. Heavier hammers dampen higher partials, but harder hammers bring out more of the higher partials.
If the hammer is too light, the sound is weak and thin. If the hammer is too soft, you get a weak/dead sound. If the hammer is too uniform in hardness ( or softness) you get less color variety.
Sometimes the hammer weight may sound great for one piece of music but be too heavy/light for something else, so ideal hammer weight, as with most things piano, is the best compromise one can come up with.
The ideal hammer weight is also a function of the acoustic of the room. In a dead space you may want one hammer weight and voicing, and in an extremely live space something entirely different, on the same piano, may work much better.
This is an extremely complex subject because there are so many variables separate from hammer weight that affect the sound and perception of sound.

But: that heavy hammer can move the string more efficiently giving more power and definition of partials. Heavy don't mean excessive.
Also the felt quality makes a huge difference giving the hammer that nonlinear spring that assists getting it off the string so it don't mute partials.
Isaac hammers are great for this.

I have seen no evidence that the spring rate of the felt plays any role in the rebound of the hammer from the string. The spring rate for hammer felt is much slower than the spring rate of the strings. You can watch hammer felt return from compression, string movement is a blur of motion.

A spring is a spring.
Soak it with lacquer and it's gone and that's not really voicing.
Slow is better than no.
It all counts.
For no or musical noise especially in treble it becomes a fine line between getting 88 to sound like note 88 or hitting the plate with the hammer. Spring don't matter much up there.
I can do it with a variety of hammers without too much difficulty.
Some capos are suspect of casting flaws too - air bubble can kill a nore.
In general a big heavy soft resilient springy hammer will push the string and a small rock hard hammer will bounce off and the result sound extremes are mush and ear piercing brilliance
Neither are desirable.

Thank you all for your insightful comments. Does anyone want to comment on the thickness of strings, tension and copper vs. steel wound base strings?

I am curious why you need to know these things? What are you trying to accomplish?

This site and a whole host of others are available through an online search.

Ed's question is pertainant.

For a given length and pitch, the thicker (heavier) the string, the higher the tension. Also, the thicker the string, the higher the breaking strength, in proportion so the percentage of the breaking strength remains the same. The sound that you get changes quite a bit as the tension changes, so any correlation between the percentage of breaking strength and changes in sound is dubious, at best.

Most of what people say about piano sound and the relation to physics and math is not well grounded.

BDB is completely out of the mainstream regarding consideration of break-point and tone. Many piano technicians have independently come to a different conclusion.

Which confirms what I said: Most of what people say about piano sound and the relation to physics and math is not well grounded.

BDB, are you sure it's directly proportional? Given the cross section of a wire is a circle, that would suggest that the wire gains mass at an exponential rate as you increase the diameter. It seems counterintuitive to me that the breaking strength remains in identical proportion to the tension. And if it doesn't, that lends credence to all this new-fangled scaling business. I studied this many years ago, but I've forgotten it. When I get time I'll look up the equations for wire strength and tension. But I'm pretty sure tension increases faster than diameter because of the square of the radius of a circle. I'll have to look into the calculation for wire strength to confirm this - I recall it's something to do with Young's modulus.

If you already know the calculations and can show that everything remains proportional, it would be helpful if you can show the equations.