----- Original Message ----- From: "ruud billenkamp" <rudyard@EURONET.NL> To: <pianotech@ptg.org> Sent: November 07, 2000 11:28 AM Subject: Re: RIPPEN soundboards > A vibrating wire gives a clear sound when it's hold strongly between the > tuning- and the hitch pins. Pressed down at V-bar's, by Capo's, wrenged > between the bridgepins. > These two pins are solid fixed in wood and iron construction. Yes, these are the essential characteristics of a taut-string vibrating system. First of all, the vibrating wire does not give a clear sound. (This may just be a question of semantics -- of wording -- but it is a good place to start.) Indeed, the string gives virtually no 'sound' at all. Without the soundboard we would hear very little sound coming from the piano. When the hammer strikes the string it sets up vibrating wave energy within the string, or strings, based on, but not restricted to, their fundamental oscillating frequency. In other words, there will be some vibrating energy at the fundamental frequency and some at the various harmonic partials of that fundamental. Exactly what the mix of that energy -- in other words, how much energy there will be at which particular harmonic -- is determined by the physical characteristics of the string, the hammer, the point at which the hammer impacts the string and the velocity of the hammer at impact. Yes, it gets very complicated -- and, with wrapped strings this mix can get pretty chaotic -- but the point is that, so far, the soundboard has had nothing to do with the energy mix in the string. Unfortunately, since the surface area of the string is so small very little air is disturbed. We don't hear much sound directly radiated from the string. To actually hear some usable sound from the piano we have to change the string's vibrating energy into sound energy. This is where the soundboard comes in. > The wire is in contact with the soundboard so the vibration is taken over by > the soundboard. There are a couple of other things to consider before we get to the soundboard. Even though energy appears in the string at a certain frequency, there is no assurance that this energy will make it through the system and end up as sound energy. If the backscale -- the scaling of the strings between the trailing bridge pin and the back termination point -- is very short, the mobility of the bridge at low frequencies will be impeded -- its motion will be restricted by the apparent stiffness of the backscale -- and very little of string's energy at those low frequencies will pass through the bridge to the soundboard. It will simply dissipate within the string, mostly as heat within the string itself. If the bass bridge has a cantilever, even more energy at the lowest frequencies will be lost; dissipated within the bridge itself -- i.e., the cantilevered bass bridge acts as a low-frequency energy absorber. It will also be absorbed into the system as heat. Only that portion of the wave envelope that is left after all this will actually reach the soundboard where it can be transduced into usable sound energy. In some designs there will be no measurable energy at the fundamental frequencies of the lowest octave or two all in the final sound waveform. That is, all -- or nearly all -- of the energy from 27.5 up to as high as 110 Hz is effectively filtered out before ever getting to the soundboard. > When the soundboard is glued around it's perimeter we have a copy of the > vibration of the string, here comes my points, > the vibration took place between two solid fixed points. > Exept the freefloating boards! They can move a little at one side so, in my > opinion, the Tone is not straight. I don't understand what is meant by, 'the tone is not straight.' The soundboard should track the vibrating energy coming to it from the string/bridge system. Preferably without altering it much, but this is not how the soundboard works. All soundboards, regardless of their design, break up into various resonances. In other words, all of them color the sound to some extent. In short scales, and all vertical pianos can be considered to have short scales, it is very difficult to get much of the low frequency energy -- energy at the fundamental frequency -- through the bridge/soundboard system and get it into the air as sound energy. Every part of the piano's design must be considered with this in mind. All to often, marketing considerations take over and one aspect of the scale design is overdone. Specifically, the speaking length is made longer than it should be in relationship to the overall design of the piano. This feature alone does more to destroy good bass tone than any other single element of the design. For our brains to clearly identify the pitch of a piano tone, especially in the bass section, our ears must furnish it with some minimal amounts of information. There must be some fundamental energy in the overall waveform. Lacking this, our brains can ultimately identify the pitch of a given tone, but it takes longer and we identify the sound as 'indistinct or 'muddy.' It must depend on energy coming from the harmonic partials which, in many bass strings, may also be indistinct. > The strobo of my tuner gives a 8 leds > wide screen instead of 5 normally. > There is some noise around it and I think that noise is made by the unknown > length of the vibration of the soundboard! The length of vibration -- the wavelength -- is determined by its frequency. This will not be affected by the soundboard in any way. I am not sure exactly what you mean by this. > When the soundboard is fixed you can measure the length of the vibration. > But not at freefloating ones. I am also not sure what you mean by this. It is possible to measure the vibration in any vibrating body, whether it be a piano soundboard or the earth's surface during an earthquake. In the case of the piano soundboard an accelerometer is placed on that portion of the soundboard you want to study and observe the level of vibration on some type of vibration analysis equipment. These days that would probably be some type of FFT analyzer. > Can you follow my thoughts.. Delwin? I think so, at least partly. If I have mis-understood parts of your explanation, let me know. I don't think it was the free-floating lower edge of the soundboard that is responsible for the tone character you are hearing and are bothered by. At least not fundamentally. I did think the lower edge of the Rippen soundboard could have used a bit more support, but the basic design concept was very good. There were some other aspects of the Rippen design that I thought could be improved. I did do some limited work on a couple of Rippen pianos that we owned, but it was a long time ago and I don't remember the details all that well. At one time I did approach the Rippen company with some suggestions, but they were not interested. The Rippen pianos had several interesting design features that I still think were good in concept, but which were not fully developed. With just a little more design work they could have given considerably better performance and been much more competitive. As may be, back to the question at hand ... we have now had a lot of experience with this design concept in many different types of pianos, including both vertical and grand pianos of various sizes. In every case we have been able to improve the tone quality of the low bass section when using it. Obviously, it is more successful in smaller pianos than it is in larger pianos. As the length of the piano increases, both the need for this design feature, and the tone benefit gained by it, decrease. Regards, Del Delwin D Fandrich Piano Designer & Builder Hoquiam, Washington USA E.mail: pianobuilders@olynet.com Web Site: http://pianobuilders.olynet.com/
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