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.

Good Chinese violin circa 1980, labelled ‘Liberto Planas'

 This is a full size (4/4) “modern” Chinese violin that had a crack on the front that required removing the belly to repair the crack. It also had a thick coat of modern varnish that had craquelled, with thousands of tiny varnish cracks. I sanded much the varnish with wet and dry emery paper and put on several coats of boiled linseed oil to remove the craquelling effect.

So I removed the front (easy, as it had been put on with thinned animal glue) and removed the fingerboard, which was glued on with contact adhesive. My thicknesses for the back are shown in pencil above if you click on the photo.

I thinned the back twice ( with 3 years between the thinnings!) as I thought it could be improved: my sister in law borrowed it for a year, but was not that taken with it. I thought last year that there was too big a difference between the Stiffness Factors of front and back, and now it certainly it has been much improved by thinning the back and improving the shape of the bassbar.

The spreadsheet showing the Stiffness Factor calculation is shown in the table below, and is available as a spreadsheet (.xls) here.

 I emailed Liberto Planas in Paris to see if he had made this violin, but he mailed me that it was only a repair he had done.

So this is now a good violin - it's not a Strad - but an excellent instrument for someone who will play in a band or orchestra.

15 1/4” (387 mm.) Viola

   Ken, a violinist friend, wanted me to take custody of a rather sad old 15 1/4” viola he'd been given. It hadn't been played for 10's of years, and had telltale worm holes in the front and a bout.

Taking the front off, the belly had an intrinsic bassbar (click picture above) and worm along the centre line. I fitted 5 spruce patches (see below) and increased the gluing area of the land for the top block and thinned the plate to:  centre (between ffs) 3.1 to 3.3 mm, sound post area 3.5 mm, top and bottom areas to 2.8 - 2.9 mm thick. This gave a belly that was 88 gms, Mode 2 = 111 Hz, and Mode 5 = 241 Hz. This is very low indeed for Mode 5, but a good tall bassbar might just get it to a useable Stiffness Factor, so I fitted and shaped a 17 mm (max.) bassbar. A Strad Magazine article (Jo Curtin?) in 2009 suggests a tall bassbar can be ok on a viola.

So the new bassbar looks like this ........, and it is shaped according to “The Art of Violin Making” by Courtnall and Johnson instructions for a good bassbar.

The back was thinned to a thickness pattern with a good thick area between the C-bouts to keep Mode 2 up, and the corner blocks were ‘filled in': see right. The back's Stiffness Factor was taken really low to 0.93: as low as I dare take it, as the front is at 0.82. I sanded the ribs down to 1.2 mm with a Dremel sanding bit.

The spreadsheet showing how the Stiffness Factors are calculated can be found here, and is summarised in the table below:

  With the viola reassembled - belly and fingerboard put back on, a new 47 mm. bridge, 6.5 mm sound post and strings fitted the first impression was that this is a very very good instrument, and well suited to a student for chamber and orchestral playing. The tone is even between the strings - even the G string where there is often a one-note boom. It has an amazing C-string, considering this is just a 15 1/4” viola! Bowing is so easy that Irish dance jigs etc. sound really good on it, and the notes can be articulated easily.

So even with such low Stiffness Factors this is the best viola I have played outside the BVMA exhibition in London!