Originally posted by enescu:

How much is it the strings and the hammers, the scale design, the materials?
Thanks. [/b]
Any realistic answer to this question probably depends on your perspective.
As a piano tuner/technician about the only tools I have to work with are the hammers and the action. So the piano’s voice depends on the physical characteristics of the hammers and my ability to voice them to the clients pleasure. So the tone, or voice, of the piano is a function of the piano hammer. Of course, the hammer must be chosen to compliment the existing scaling of the piano — the string scale, the soundboard assembly, the rim, etc. So my hammer options for any given piano are some limited.
As a piano rebuilder/remanufacturer I have a few more options open to me. I can change the string scale somewhat, I can change the design and structure of the soundboard assembly. And to a limited extent I can change the plate. So now the voice of the piano is dependent on the string scale and the soundboard and on my ability to manipulate their characteristics within some very fixed parameters and I can tailor the sound of the piano a bit more. So, now the voice of the piano is determined by the string scale, the soundboard and the hammers. More options.
Still, I’m not going to be able to really change the string lengths all that much. And, while I can change the soundboard ribbing and shape, there is not much I can do with things like bridge placement or backscales, etc. As well, even though I still have a variety of hammers at my disposal they are going to be chosen with an eye toward the fixed-length scaling and the overall design elements of the piano that are beyond my ability to control. So my overall options are still limited.
Now, as a designer I (sometimes) have complete freedom to find my own way among a veritable maze of options. If you tell me you want a bright, powerful sound from a 7’ piano I know immediately where to begin. I’ll start by drawing a medium to long string scale and load it heavily. Or, if you tell me you want a 5’ 2” piano appropriate for use by an advanced player with limited space I’ll start by drawing a mid-length scale with relatively low tensions. In both cases I’ll follow up by matching an appropriate soundboard assembly to the chosen scale. Then I’ll develop a suitable rim assembly and plate. Finally I’ll specify appropriate hammers.
So, while all of the working elements of the piano are interdependent, it all starts with the string scale. If that is not suitable for the type of sound you want from the piano there are a limited number of things that can be done. (I’ve written on the difference among various string scale choices in other posts.)
And this is true whether you are an end user or a manufacture. I was once asked to “brighten up” the Baldwin L (a 6’ 3” grand) and “make it more powerful.” Now, this piano was designed to be a warm and dynamic chamber piano. It very appropriately has a relatively short, low-tension scale. With suitable hammers and nicely voiced it is one of the nicest solo and small ensemble pianos around. The only thing that can be done to make it brighter and more powerful without unacceptably distorting the sound is to make the scale longer. This would have called for a new, or at least significantly redesigned, plate and that was beyond the budget for the project. So, to satisfy the powers that were, we tried simply increasing wire diameters and smoothing out the scale. Needless to say, it didn’t work. The sound simply became hard and nasal.
The failure of this project illustrates just how important the string scale is in determining the overall performance of the piano. Once the characteristic of the string scale is chosen, the rest of the design is developed to suit. But that is where it starts.
Del