Plates for ‘Cellos
It has been possible to use data that Carleen Hutchins, Dr. Nigel Harris and particularly John Osnes Violins (Anchorage, Alaska) have provided to estimate the Stiffness Figures required for ‘Cello plates too. Carleen strongly recommends that the plates have matching Mode 2’s, and they are ‘octave’ plates (Mode 5 = 2 x Mode 2) in the range: Mode 2 = 60 to 65 Hz, and Mode 5 120 to 130 Hz.
Using Harris’ stiffness figures and not Davis’
Not surprisingly the ‘cello Stiffness Figures are very similar to those for violin and viola plates. For normal ‘cello ‘Orchestral Tone’ the belly unvarnished but with ff’s and bassbar should have a Stiffness Figure of 4.03E6 (4,030,000 ) and the back unvarnished 6.0E6. Varnished this rises to 4.44E6 for the ‘cello belly (note it is almost identical to the violin figure) and 6.16E6 for the ‘cello back, which is 19% less than for violins.
You should change the Stiffness Figures say 5% lower to 15% lower for a ‘student’ tone (3.78E6 and 5.24E6) for easy bowing, or increase it by up to 15% for a ‘Solo’ tone (5.1E6 and 7.08E6). Note that plates still need to have matched Stiffness Figures, as for violins! This is summarised in this table: click on it ....
In the CAS Journal III there is a particularly interesting example of a ‘factory’ Mittenwald ‘cello that has been rethicknessed. Thomas King did the work under Carleen Hutchins’ supervision, and the article is here.
I strongly recommend you get the full set of CAS articles. The ‘cello has a low but matching Mode 2 in front and back plates (57 Hz): the back has a standard ‘orchestral’ Stiffness Figure, but the belly is 20% low, assuming standard plate weights. The tone apparently is outstanding and is easy to bow.
Alan Carruth published and article entitled ‘violin plate tunings’ but has some good ‘cello plate data in it too: have a look