| Celtic Harps, their levers and frets Frets on commonly fretted instruments |
It is often said that the levers for a harp are really nothing but frets, but when one sees frets on a guitar or mandolin (or any other commonly fretted instrument) they have an entirely different look and many far different properties. One of the primary differences, of course, is that for commonly fretted instruments, all the vibrating lengths of the strings (the distance from the bridge to the nut) are the same. This in conjunction with designing the strings to have relatively close diameters and similar tensions allows using the same formula for halfsteps for each of the strings. This is usually related to the 12th root of 2 with something of a correction factor added to compensate for the increased tension (and thus the frequency) in the string from depressing it against the fingerboard and creating a vibration node at the next fret*. This factor can only be the same for each string because of their identical vibrating lengths and similar construction and open string tension. For the above reasons, placing frets on the commonly fretted instruments is significantly more simple than on the harp. |
On the modern folk harp, each string is not only a different length, but may be any one of several constructions with variations in materials of wound strings, variations in core and winding diameters, and then variations in diameters of monofilament strings. Add to this that conscientious harpmakers will design their strings to maintain at least a similar tension to length ratio of the strings. With so many variables it would be totally impractical and probably impossible to determine a given formula for predicting the correct placement of sharpening levers for each string. Also, small variations in the construction, materials and string pressure equilibrium conditions of the harp would also influence correct placement of the levers. One very unfortunate misconception that has gained wide belief is that over time the vibrating length of the strings change even after the harp has come to pressure equilibrium requiring the levers to be retuned from time to time. THIS ACTUALLY HAS NO BASIS IN FACT WHATSOEVER. Later in this paper I will suggest a means by which anybody can prove this for themselves. It involves developing a practice I wish all harpers would develop, asking not the engineer or harpmaker, but to ASK YOUR HARP. It is amazing what your harp can and will tell you through the medium of tape measures and/or electronic tuners. Many years ago, when I was building the first harp I personally designed, and also, the first harp that I levered, and when I was using a modified form of the Caswell blade lever. The modification I had made to the lever was to have threaded the shank, and thus minimizing its tunability but significantly improving its durability. In these two things I was exceedingly successful. I thought to make things easy for myself by using the same fret placement factors as my guitar. That didn't work at all, and I found the levers all too sharp, but not consistently so. Since I was making the harp for my daughter, and since most were close enough or could be made to be close enough for her use, she kept that harp for several years until she sold it to Bobbie-Jo Curley as her first harp. This turned out to be fortunate since I was able to keep track of that harp. I learned a great deal from carefully following the intonation of each lever over a period of about 10 years. Surprisingly, they did not change in their intonation so long as I kept the shank of each lever in a fixed position. Let us take a look at one of the typical blade levers from circa 1980 Typical Blade lever of the 1970's/80's Two things are immediately apparent. First, that the shaft is not threaded in any way and thus can not be secured in any given position. The holes drilled for these levers allowed the shafts to be forced in rather tightly, but both rotatable, and moved in and out of the hole. The second thing to be noticed is that the blade itself is severely tapered from one end to the other. It can easily be seen that as the blade is pushed further into the hole drilled in the harmonic curve for it, the less the string will be displaced thus reducing the tension on the string lowering the intonation of the sharpened note. Of course, pulling the shaft out a ways will increase the displacement of the string increasing the tension on the string and raising the intonation of the sharpened note. This of course was a very primitive attempt to make the sharpening levers tunable. I had threaded the shanks of all the levers I had purchased from Caswell and so could screw them out and in, but if not screwed in and out they kept the same intonation. I soon found out why the shanks were left unthreaded by their maker. The reason was that as I got to the shorter strings, the broad end of the blade ran into the bridge pin and it couldn't be screwed in far enough to even displace the string. Also, even bringing the blades down to the minimum deflection of the strings was insufficient to lower the intonation of the levers of the first harp that I levered. There was a much larger problem with those levers also. Since the shank was unthreaded it relied wholly on the wood pressure to keep it positioned. Of course, the more it was used, the more the wood just plane wore out specially on the Fs, Cs and Gs. At this point, the lever would certainly not stay in tune and eventually would become so loose that they began falling out. Once that occurred, there was just no way to repair them. They were a disaster. I have a term for "adjustable" mechanisms which are not well thought out ahead of time I call them the SLIPPY/SLIDY syndrome of engineering. The old tunable blade levers did have two marvelous features and hose were their simplicity and their ruggedness. There were no moving parts to wear out, come loose or buzz. Unfortunately, that was not a saving grace. I believe in my engineering courses in college, every professor extolled the virtues of simplicity. One former engineer for the San Francisco water department made a worldwide name for himself by satirizing American engineering. And also saying something like "There is no limit to the American engineers capacity for exerting maximum effort to accomplish minimal results. You would know him better by his cartoons and his name, Rube Goldberg. The Woldsong Fret
Now I make a distinction. If a device for achieving sharps on a harp is tunable, I am quite content to always refer to it as a lever. However since such devices as I use are permanently installed, and demonstrably as trouble free* as any fret oh a guitar or banjo when properly installed in the first place, and will never require "regulation"** then they really do have the same care free characteristics as any other the frets and so I have thus named them. **I have letters from Woldsong harp users that use their frets constantly in playing from classical music to jazz and who have Woldsong harps dating back to the early 1990's whose frets are still well within the guaranteed intonation. (+/- 13 cents) Flip up levers
Two typical flip up levers To make matters worse, at least in some designs with the retaining screw getting a bit loose, or a small bump occurring, the lever can get out of alignment. Too, the flip up mechanism though I'm sure in most if not all cases is well designed with the most advanced materials, they are still very small very delicate and fragile. Even such similar mechanisms as light switches which are much larger and more ruggedly constructed occasionally fail, If a harper extensively uses the levers, these too will fail and being much small and far more delicate, probably far more rapidly than light switches. When seeking to purchase a new harp, don't ask talking heads, ask the harps. Comparing harps side by side and using simple means of testing will tell you more than all the harpers that are already committed to harps they have played or own. The harps themselves are the authorities and they will never misguide you. |