I hope this page will help those making or improving their first violins: everything is new and so how can can tell good from bad?
If I had to name priorities on how to make a violin I would say you will need a coffee and a “L. A. TT. E.” :-
‘L’ stands for Light-weight plates,
‘A’ stands for Arching, it has to be right!
‘TT’ stands for Tap-Tone,so the violin will sound good, and
‘E’ stands for Edgework. Tap-tones do not measure the edges well, so edges need to be right too.
What is ‘TT’ or plate tuning?
Just as a violins are made to standard dimensions, plate tuning allows the stiffness, density and peculiarities of the particular wood of each back and front plate to be taken into account and compensated for: every piece of wood is different!
What a tap tone is, how to measure it and how to thin the wood to set or tune each one to get the Modes 2 and 5 where you want is shown in the Modes and tuning plates page.
What does plate tuning offer the violin maker?
Measuring tap tones and plate weights keeps us on the right track as they can enable you to create a violin with the 5 key body resonances in the right places.
The ‘model’ described in the right hand column of this page offers a way of predicting, with reasonable accuracy, where these resonances that largely define a violin's tone will be. So a maker can select a particular model and tone that they want, seeking after that elusive consistency, where every piece of wood is different. So if the wood you use (spruce for bellies, maple for backs) is not the best then that plate will turn out heavier than the plate reference weights.
Does it matter how heavy the violin plates are?
In general the data on the best violins shows that they have light plates, and often very light plates indeed. They are made of the best wood: so often the wood of factory violins is mediocre, so your plates will be heavier ... but they can still make a very good violin indeed! You will just need to leave the centre section of the back rather thicker, and therefore somewhat heavier.
The ‘radiation ratio’ of a plate improves dramatically if it is light, so there is a virtuous circle here: the best light but stiff belly means a light back plate, which means and excellent radiation ratio ...
The Mode 2 (and Mode 5) ring tones of both front and back plates.
Just as you make a violin with standard sizes, the plates need to have standard tap tones.
It is best to start with the belly:-
- The belly plate with its bass-bar needs to have a Mode 2 that is in the range 155 Hz (abs. min.) to 180 Hz: 160 Hz is ideal. A high figure achieves little but increases the plate weight.
- The belly plate needs to have a Mode 5 in the range 310 Hz to 385 Hz (abs. max.): ideal is 340-345 Hz. It appears to be better to keep the Mode 5 down below 385 Hz and those higher frequencies to keep the back plate weight down.
- The back plate Mode 2 ring tone needs to be in the range 160 to 190 Hz. If it is below 160 Hz start again: it is unusable.
- The back plate Mode 5 needs to be in the range 310 to 390 Hz: ideal is 360 Hz.
Choice of violin tone.
By setting yourself targets for B1-, B1+ body frequencies and the ‘Delta’ or difference between body modes A1 and ‘B1+’ then you can select the kind of tone you want from the violin. These ‘tones’ are shown in Table 2 in the next column as a choice of ..........
light green, (student tone),
green, (chamber tone),
orange, (orchestral tone),
purple ......... and
red (solo tone, requiring expert bowing).
The higher ‘B1+’ frequencies shown as ‘ideal’ on the page ‘Resonances of the Violin body’ give solo grade instruments. But selecting lower target frequencies for ‘B1+’will give a violin that is much easier to play and suitable for orchestral or chamber music.
Note that the A0 and A1 frequencies are mostly fixed by the dimensions of the violin body.
Tuning the body modes after assembly.
Once the violin is put together ‘in the white’, that is before varnishing, Stradivarius and many other makers used a technique of tuning the body resonances to what he wanted by finishing the channeling and purfling after the violin was assembled as it affects these key resonances a lot.
You can also make the plates a little too thick and then thin them ‘in the white’ by scraping or sanding the outside of the plates to get those resonances just where you want them, but this is not for your first violin! This is very hard to do. Start by walking before you run!
Alternatively I use the tables given here to estimate how much to take off the belly and back when I remove the belly for adjustments! (Use weakened glue to glue on the belly then!)
It is worth noting that there are limitations to this method because wood is organic, and because tap tones do not measure edge properties well.
(1) Moisture content (MC).
The violin plates measured here have low moisture content (MC) which is normal for wood in a heated workshop in winter. So tap tones change all the time (!) with the moisture content (MC) of the wood.
In a heated workshop in winter wood will have an MC of ~6% and the figures given on this website will apply. However in summer the wood MC will rise to ~12%, and the Mode 5 tap tone frequencies I give will need to be reduced by as much as 15 Hz! The plate weights also increase slightly with higher MC too!
(2) The plate edges 2
Unfortunately plate tap tones are hardly affected at all by the thicknesses of the plate edges, and yet these very edges matter a great deal because the plate is held firmly by the bouts and linings in the assembled violin 2 and the edges contribute a lot to the plate’s weight.
So take care with your choice of edge thicknesses, especially between the C-bouts on the back plate, and complete the edge thicknessing before tuning the plates. Never make the edges thin around the C-bouts.
I recommend thicknesses of 2.7-3.0 mm an all edges (just before the plate meets the linings) and 3.5 mm around the C-bouts 4 for both belly and back plates. Better wood needs thinner edges.
If you are making the plates from scratch
Cutting the f-holes on a belly reduces the Mode 5 by about 2 semitones (2 x 6% = 12%, about 38 Hz), but the original Mode 5 frequency is then restored to the same (or to a slightly higher frequency) by installing the bass-bar.
Making or modifying a violin for good tone.
I will now show how to get an estimate of the key body frequencies of a finished violin from the weights and tap tone frequencies of the plates that go to into making it.
A ‘model’ that uses weights and tap tones to predict key body resonances1.
By concentrating on the very important B1- , B1+ and A1 violin body resonances I have derived a model to predict the B1- and B1+ violin body resonances and hence help you make what can be a fine-sounding violin.
With regard to accuracy of the model, the prediction for the frequency of B1+ has a Standard Deviation (sigma) of 10 Hz. So there is a 68% likelihood that the actual ‘B1+’ frequency will fall within +/- sigma (+/- 10 Hz) of the predicted frequency.
The model described here predicts ‘B1-’ and ‘B1+’ body mode frequencies from the characteristics of the plates. It is derived by extending the work suggested in a paper by Alonso Moral (1984) outlining these relationships. My data looks for (assumed linear) relationships between ‘B1-’, ‘B1+’ and 7 aspects of the violin plates: Modes 2 and 5 in belly and back, their respective weights and the bass-bar height.
My results show figures similar to those of Moral, but importantly I have found that the two plate's Mode 2 frequencies and their weights have a much more important effect than Mode 5!
[continued in next column] -------------------------------------
1 This data also includes the data published in Patrick Kreit’s book and website that gives the ‘deltas’ between these (A0), A1, B1-, B1+ body resonances we should look for in a first rate violin. You may need to get Patrick Kreit’s book to get details.
2. See “The Art of Violin Making” by Courtnall and Johnson and the chapter on plate tuning. Tap tones do not measure everything about a plate!