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Showing results for tags 'rocking frequency'.
I have been puzzled by the sound qualities of different bridges on a violin I recently have glued the top and back plate back on. It is an oldish French, a bit oversized, instrument I have studied in detail many years ago in my master thesis work and I set it up at that time with not much experience (1993). Its bridge from that time was very light 1,37g and its rocking frequency was just below 3kHz. It has sounded good, according to a player I was cooperating with at that time. The top plate and the back has come loose in some places so I opened it recently and reglued it. At the same time I wanted to try a new bridge for it more in line with later experiences. I wanted to try a heavier bridge and a higher rocking frequency. The strings also needed to come a bit higher. In my documentation I play scales on the instruments and record the 1/3rd octave band spectra in the same mic position in the same room. This is repeated three times and the avearage spectrum and the standard deviations are plotted for each situation I want to document. The light blue curve is a test from 2008 or 2009 before I reglued the plates. It also had Dominant strings at that time. Now I have tried three new bridges for it. The first sounded brightest and was made of a low density maple, but the bridge was still too low and I did not reach the high rocking frequency I was aiming for (3,6kHz) so I tried a new one made of a heavier and stiffer material. I reached a higher rocking frequency, just below 3,5kHz but it became on the heavy side, 2,17g. Not by far as "sparking" sound. I tried yet another one, of really stiff wood and reached 3,6kHz and a more moderate weight 2,01g, not far from the average weight of merit bridges from violinbridges.com. now with the right height for the strings, but not the sparking sound I got out of the first new bridge. I sum up the data on the bridges below. No 1. is the original bridge from 1993, the rest are new now. No 1: 1,37g 2,97kHz No 2: 1,84g 3,27kHz No 3: 2,17g 3,46kHz No 4: 2,01g 3,64kHz The graph show bridge 2, with dark blue (the more "sparkling" one), bridge 3, in orange and bridge 4 in red. I am using a different measurement device for the three new bridges than the old. I should have tested it over with the original bridge, but I am afraid of doing too much harm to the new strings by doing too much changes. The setup for the new bridges are using what I believe is a "Tellefsen set" from wathing the photo of hs del Gesu from the Bergen exhibiton. A mix of brands, Pirastro Olive G 16, Priastro Tonica D, Dominant A and a Westminster 0,26mm steel E. The differences in the low frequencies might, by part, result from the difference in the strings used or it can also be changes to the body response after the reglueing and resetting the sundpost. However, I am very puzzled by these results. Why do the first new bridge sound so much brighter, even if its rocking frequency is quite moderate? I wonder if makers fit many bridges on their instruments before they are satisfied with the result? The pics show the bridges in sequence from above and down (No 1, No 3, No 4) with the bridge on the instrument being the first new one (No 2) in the table. Experiencces with Hardanger fiddle bridges also give the impression that the qualities of the bridges are very important. The body modes are important too, but does not influence the entire higher frequency spectrum of a violin like a bridge does.