The following article by the late J. G. Lively originally appeared in the February, 1999, Bulletin.
The topic of our May, 1999, meeting is to be asymmetric graduation of plates of the violin family. More specifically, this writing will concentrate on violins, however, the application is the same for violas and, with more difficulty, cellos.
I have prefaced most of my comments in the past by stating that asymmetry in plate graduation is not in any way an original method of mine alone. Perhaps the combining of several methods together might be considered original. I arrived at asymmetric graduation by academic, physical, and yes, accidental gathering of information supporting it. Through the process of elimination in making some 22 instruments, I developed a profound opinion that asymmetry is the better option for final graduation of both the belly and back plates of a violin. In making these instruments over several years, I gathered bits of information supporting this method of graduation and have continued it to the present time to include instrument number 63.
I have read historical narratives to state that some of the old masters had set up and played instruments in the white for long periods of time. They were alluding to the allowing the relaxation of being 'played in.' Perhaps that was a consideration but, maybe, and this is certainly speculation on my part, they were scraping them in acoustically from the outside on both the belly and back. This would possibly result in an asymmetric condition on both plates. The resultant renowned tone is still with us today. Woodwork and artistry of fabrication have varied from superb to ridiculous. The tone has seemed to survive intact over the centuries, probably not suffering greatly from repair attacks, re-necking, and possibly improving with mellowing or aging of the materials, we hope some of ours will be blessed with the same 'careful' circumstance. Re-measuring and cataloging of thickness of plates of some of the old important instruments has revealed a pattern of asymmetry.
Without rambling into some of the pitfalls of developing this profound opinion, I will list some of the background support for it. In the 80's, Jack Fry a physicist at the University of Wisconsin did a considerable amount of experimentation and research involving the alteration or destruction of some 60 instruments to arrive at the determination that asymmetrical graduation was indeed what affected and changed sound output toward a satisfactory tone. This was documented by a PBS-Nova production titled The Great Violin Mystery. When it was first aired locally on PBS, I ordered a transcript of the program and have re-read it periodically. It has become practically a textbook to me. Up until this period, I had not been aware of any methods of asymmetry except for an occasional statement in texts such as, "I like to leave an additional amount of wood at the sound post location," or "remove a small amount across the center away from the sound post location," which leaves an inconsistency with symmetrical graduation patterns. The symmetrical pattern is by far the most adhered to and stated academic way of graduation.
In the recent past and shortly after the passing of Harry Wake, our founder and in a few short days, Ray Doerr one of the founders of the Michigan Violin Makers Association, I realized that Ray Doerr was the author of a beautiful publication in our SCAVM library. I am particularly sorry that I didn't have the opportunity of meeting him. Prominently illustrated in his book is his diagram of an asymmetrically graduated back, very much the same as I had developed through practice. To me, it was a revelation that other makers had indeed opted to use this same method.
Just prior to the composition of this discussion, I received an E-mail posting from Leonard Showalter to pass along archival information from the SCAVM bulletin from March, 1990. It was passed along by him to help provide information for the up-coming subject of the meeting about asymmetric graduation methods. With permission I would like to comment that, with some small notable differences, it states much better than I the methods of asymmetric graduation put forth in a talk at a SCAVM meeting by George Awalt. I would like to quote Len's summary of what George had to say:
After tuning his plates using conventional methods, George adjusts his plates so that the acoustical center is at the sound post location. He first locates the acoustical center of the plate. He then moves the acoustical center to the sound post location. He does this on both top and back plates.
He finds the acoustical center of the plate by tapping it with a small leather tipped mallet and listening. In a symmetrical and well-arched, and tuned plate this will be centered laterally below the bridge line. There is only one spot per plate.
He uses this procedure on the top plate before the ff
holes are cut and the bass bar is in place and again afterward.
My procedure is a bit different on the belly because of working with a carved-in bass bar as noted later.
Here's the procedure:
Find the spot (acoustical center). It will have an unpleasant "solid" sound. Mark it. Also mark the sound post location. Draw a line that passes through the two marks. Remove a small amount of wood on the side of the acoustical center opposite from the post. A scraper stroke is enough. This will move the acoustical center along the line toward the post. Next, recheck for the acoustical center, and repeat the process as necessary. The final location of the acoustical center should coincide with the sound post location.
My comments: The description of the operation of locating and placing of the acoustical nodes (centers) is very brief and concise and should be memorized if one is to try this method.
There are a few notable differences in the method that I use
and one is that I usually locate the nodal point with "knuckle"
tap tones to be followed more precisely with a manual tuning fork,
A 440 Hz. The one main difference in locating the point
with a tuning fork, versus tap tones, is that in tapping, the
deadest, most solid sounding point is the acoustical nodal point
and with the tuning fork it will be the brightest, most amplified
sound available on the whole plate. This is a great aid for a
person who is uncertain of judging the thud and instantaneous
decay of a tap tone, and especially with an additional handicap
of bad hearing.
A manual tuning fork is usually adequate for a maker with near normal hearing. I knew that the method of checking with a tuning fork is not new.
Electronic tuning forks are used by some makers. I had once seen an electronic tuning fork being used in a PBS airing titled, John Brown Violin Maker. It was used in the same way a manual fork is usedto find nodal points of violin plates. It appeared to be an assembly of electronic components available from most supply houses. I searched several sources, including posting an inquiry on the violin makers' Internet web site thinking that a 'ready to use' version may be available. I received no responses. I had discussed it at some length with Larry Skertich. He 'juried' together a rudimentary version and it was obvious that the assemblage would be correct. I visited a local electronic parts house and from conversations with a sales technician managed to buy all the components to assemble one. It consists of a tone generator, the most expensive componentaround $150and a very small 9-volt self-powered amplifier for $22 which is 'piggy backed' to the larger tone generator. Also purchased were the output leads to lead from the tone generator to the amplifier input and the leads from the output of the amplifier to the speaker. I used a 2-inch diameter speaker from a throw-off drawer of my workbench and soldered a 3/16" diameter by 6" long brass welding rod to the steel coil housing of the speaker. The remaining end of the brass rod was ovaled and sanded smooth.This end functions as the haft of the tuning fork. It works quite well.
I usually set the tone generator to A 440 Hz. and set the amplifier output to an audible level. In using it much the same as a manual tuning fork there's usually a sudden burst of amplification of sound when a nodal point is located. This electronic tuning fork has become a necessity for the aural cripple that I am.
A maker has nothing to lose by asymmetric tuning of the plates. The steps are simple. Apply religious accuracy in following a graduation pattern and then make the recommended asymmetric changes.
The changes are so slight as to be within the spread of a tolerance band of conventional workmanship. Again, it's just that they must be in the correct locations.
A final note about graduation patterns: some patterns do note that the channel area, or track around the outer periphery and inside the purfling is to be 2.1 mm (.085) thick. The ones that do state this dimension, 2.1 mm, are the better choice, however, follow any pattern of your choice. The tonal output will be only slightly altered or moderated by having this region in excess of 2.1 mm. It will likely be a discernible amount less powerful if left heavier.
I do graduate the belly in much the same fashion as the back, holding closely, again to the demands of the graduation pattern being used. I make sure to place a nodal point over the sound post location, and on most instruments, since I carve in the bass bar from the virgin wood of the top plate, there will also be a nodal line over the bass bar, diminishing in strength either direction from the stop location. This reaction above the bass bar will occur under any circumstance. It is best to make sure the belly thickness on both sides of the bass bar in the stop region is 0.003 to 0.005 (0.1 mm nominal) thinner than at the sound post location.
An added statement to the graduation of the belly is that the small distance in front of and the back of the ends of the bass bar be the same thickness as that at the periphery channel. This allows for correct lower tones bassbar function.
As you may see, this method is not new but is a bringing together of several methods that produce asymmetric shape to both the back and belly, which when assembled allow equally phased function of the back with the belly. The back, coupled with the sound post continues amplification without interference from non-synchronous movement between the plates.
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