tapping belly 2 sml

A website for the serious amateur violin maker, restorer and tinkerer.  A violin front and back (the plates) can be tuned using tap-tones.  Use tap tones to adjust the 2 plates of a violin to get the best sound, the kind of sound you want, or make an instrument that is easy to bow.

This site has something for you if you are either making a violin or you want to improve a low cost violin or viola.

By tuning the top & back plates you can get a good instrument that responds well to the bow and that can sound like a 1500 instrument.

inside mould Inside of back of J Lavello

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 Last updated on the  3rd. Nov. ‘09

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JTL Medio Fino, Marked “Steiner”JTL medio fino label

BrandingThis is a JTL “Medio Fino” which is branded “Steiner” (not Stainer!) on the button.

It has a single piece back which is very plain. The front had a great big chunk missing bottom left when I got it, and for my first graft ever, I grafted in some good quality spruce as shown.

I took the front down from the original 3.8 and 4.0 mm thickness all overDSC01312_1 (i.e. unusually thick!), to 2.6 mm all over - to give me a Mode 2 of 162.5 Hz, and Mode 5 of 351 Hz measured as shown here. I left the original good bassbar in place. A belly at 2.6 mm is rather thin, but this is somewhat dense spruce of the belly, and it has shown no signs of splitting anywhere in 80+ years.DSC01337_1


So I thinned the back at the edges a little to make it more even, but the centre is already at a measly 3.3 mm: I didn’t want to take it down any more than that.

The [estimated] Mode 2 of the back is now 164.5 Hz, and Mode 5 at 374 Hz .

So taking 78 gms. for the front and 100 gms for the back, gives a “Stiffness Factor” of 1.01 for the front and ~0.96 for the back: quite a good match.Steiner 002_1

I hasten to add this was more by good fortune rather than good planning.

The tone of this fiddle is now superb! A very good G string. So far, matching stiffness factors for front and back has always yielded a superb G string tone.

I’ve played this now in quite a few Concerts and its good both at fff and ppp, and its a fine all rounder. Good balance between strings, a nice breathy A string, and it has no noticeable vices anywhere, other than the repair.

Steiner 004_1DSC01343_2



JTL Medio Fino violins don’t have purfling (the lines are inked in), and that made the repair simpler, as matching purfling is challenging. Colour match to the varnish is ok.

Here’s what it sounds like: showing G and D strings, “The Day before Easter” . This fiddle has an enormous G-string sound that’s easy to draw out.

The A and E strings are shown in “The Wind that Shakes the Barley” .  This is with a cheap mono computer mic, a 10 Chinese bow, and Corelli Crystal strings. Beware however of amateur violinist.

Note that most of the tone of a violin comes from the start or attack of each note, so I don’t find the long, legato demo stuff many demos do to be of any use at all. This fiddle has a strong B natural on the A string..

German “Bench fiddle”, circa 1800, unlabelled copy of D Hopf.DSC01214 smll

A couple of years ago I asked a friend of mine for his ‘worst fiddle’: I wanted to see how good I could make it sound by matching the stiffnesses of the front and back plates. And it’s turned out rather well, though it does look rather like Humpty Dumpty after his fall!

This is a ‘cottage’ or bench ‘transitional’ fiddle probably made in Germany in the early 1800’s, as the neck was too short by 10mm, but with the more modern neck angle. No machines whatsoever were involved in its making: it is strictly hand-made, and made in a hurry!DSC01213 smll The arching is somewhat crude.

As you can see right in the picture of the fiddle as received, the front had no bassbar and worse, it had a crack along where the bassbar should be. There were no upper linings at all, no purfling (it’s inked in), and the neck extended into the body to form the upper block, in the German tradition.

I thought I might end up using this as firewood, but with the bassbar crack glued up the front had a good tap tone, belly bench fddle smllso I used it as an experiment, taking the stiffness factors of front and back plates quite low, set the thicknesses right and added a bassbar to the belly(see right).

Then I took the back right out too: it got damaged, but it meant I could set the tap tones and back’s stiffness exactly where I wanted, and confirm the relationships of the tap tones of the back plate (both Modes 2 and 5) in and out of the bouts. Repaired and glued back onto the bouts, onto the sides and onto 6 new blocks it’s quite constructionally challenged.

 CIMG0416 smllThe bouts were 4 mm thick in places, so I reduced them with a Dremel-type grinder to about 1.2 mm. You can see the back’s thickness contours on the back plate here.

The neck had to be lengthened too with new maple, and set it into the new neck block.CIMG0415 smll  Not pretty, but effective. I haven’t got the skills (yet?) to do a pegbox graft, and it wouldn’t be worth the time on this fiddle.

CIMG0422 smllYou can see the lengthened neck here on the right.

What does it sound like? Great! for Irish or English dance music, with a strong A and stronger E string, with a good ‘bite’ to the sound using hard bowing. The G string is quite good, but the fiddle back is too light to have real G-string grunt, confirming what Dr. Harris says about the ratio of front and back plate weights. The D string is quite acceptable, but like all my fiddles so far, the D string lets the rest of the fiddles tone down: a little weak, and slightly ‘scratchy’ as each bowed note begins.

 Recently I put a proper Thomastik Dominant G string on it, and which is much more respectable now - it shows good strings can improve tone.

This fiddle is good enough to use on a recording, so it was used in a set of songs for a charity concert we put onto CD just before Christmas ‘07. This a part of Jane Gridley’s ‘Horace goes to London’ with this fiddle doing both the rhythm bowing in the background and the ‘descant’ over the voice.

Here is the response of this fiddle using the bowed ‘semitone loudness’ method described on this page. It shows the 3 main frequency responses are roughly right, but it’s a little weak on ‘G’s on both the D and E strings.



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