Plate Acoustical Tuning

... According to to Author and researcher Isaak Vigdorchik in his book 'The Acoustical Systems of Violins of Stradivarius and Other Cremona Makers', this is the method faithfully used by both Stradivarius and Guarneri del Gesu.
... If you gently tap down the center of the marked diagonal strips, the tone will be as marked; and if you were to cut the plate apart along the diagonal lines, each strip would still give the same tap tone as when part of the whole.

According to author Vigdorchik, Stradivarius made this central strip wider so that the sound post actually rests on the strip; also there is just one octave between the highest and lowest tone along the back, going from A#3 up one octave to A#4.
. ..Notice how this contrasts to the top plate tuning: there the central tone strip is D4 and the extreme tones are G#3 and G#4 so that at each point the top is just one whole tone (two semi-tones) below the back plate.
... The actual process of tuning these plates is well described in Mr. Vigdorchik's fine book .

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...I want to add this idea to the above (2014/ 2017):
... Mr. Vigdorchik's tuning system involved listening to the high overtones of the wood to tune the various tone strips.
..My system involves listening to the lowest part (fundamental) of the tap tone {Kind of like listening to the lowest bass note of an orchestra performance} and tuning to that. It has the advantage that I can use this technique to tap tune all the parts of the violin.
..So, if you tune your violin plates so that they produce an even (fundamental) tap tone all over their vibrating surfaces: 176 HZ for top plate and 198 Hz for back plate, you will have achieved an ideal plate tuning.
..Along with this plate tuning we must understand that the weight of the plate wood and actual graduation pattern are important elements; and all three, working together are necessary for best results. (see other areas on those subjects).
... Please see related subject articles elsewhere at www.violinresearch.com...