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 can help if you are making a violin or you want to improve  a low cost violin or viola.

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

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tapping belly 2 sml

All you can ATE!

 A is for Arching,

   T  is for Tap-tones, &

      E  is for Edge-work.


‘Harrison’ Stradivarius violin plate thicknesses

email: webmaster @platetuning.org

 Last updated:                                 20 th. May. 2017                    Copyright  (C)                www.platetuning.org


Violin whole-body body resonances and modes

     This is for the brave!  Do not attempt to work on finding these ‘main body resonances’ until you are very familiar with using Audacity sound and FFT software and finding tap tones on the belly and back plates. It can drive you mad, .... but a good violin needs to have these key 7 resonances below 700 Hz put where they should be.

 It only takes about 5 minutes to find all the key body modes. These modes can also be seen at the Strad3D modal view site here.

  There is a website - John Schmidt Violins, Laurinburg, North Carolina, USA - that has two .pdf files (“Violin Mode Measurements 1 and 2” , half way down on the left and written by Don Noon). In them you can see how to measure A0, A1, B1- and B1+ body modes on completed, strung up violins: how to do it is also summarised below. And you can also see the  Maestronet chat pages about B1+ and B1 - for Don and Anders Buen’s discussions that lay out the basics. John McLennan has a useful web page describing and documenting the violin body modes here too.

How to do it ...

                             damp the strings and hold the violin at the top block with the left hand. Don Noon suggests you can see the individual body resonances by tapping and putting the microphone close to different places on the violin body, with the frequency peak of interest (usually) the highest of several in the recorded FFT for that microphone position and tapping point,

The microphone position and the tapping points are as follows:

For ........

  • A0      - close mic. at the upper part of an f-hole while tapping anywhere on the body,
    • a video of how to measure A0 can be found below, as it’s easily done when B1+ is measured
  • B1-    -  close mic near the center of the back, and tap at the centre of the back,
    • I have posted a video of how to measure the  ‘B1-’ body resonance here on YouTube .
  • B1+    - close mic the violin top, just above the f-holes, and tap the bridge with a light pencil,
    • I have posted a video of how to measure the  ‘B1+’ body resonance and A0  here on YouTube .
  • A1      - close mic at the lower eye or the lower ‘O’ of an f-hole, and tap a bout or tap the belly next to the tail-piece
  • B0     - hold the violin at the lower widest point, tap the scroll and place the microphone at the centre of the back.
  • CBR or C21  - on the violin’s back close mic at the edge of a C-bout, and tap the opposite C-bout.

You will then see that

  • A0   (the Helmholtz) peak about 270 - 280 Hz,
  • B1-   is at about 410 - 460 Hz, and
  • B1+  is at 510 - 550 Hz, and also
  • A1    is usually between B1- and B1+ at 450 - 485 Hz,
  • B0    is at about bridge tapped with pencil, mic over rt f hole270 Hz if there is a good ebony fingerboard.

      The example right is an Audacity FFT plot for my red  ‘Juzek’  Czech (Shonbach) violin, tapped on the side of the bridge with a pencil.

   There is 50 Hz hum (as always in the UK),

  • A0 is at 265 Hz (a very high peak),
  • ‘B1-’ is at 449 Hz,
  • there is a little of A1 visible at 465 Hz, and then there’s
  • ‘B1+’ at 540 Hz.
  • ‘CBR’ (C2) should be at 400 Hz.

The extract of this plot with these peaks is here.

You can see the exact same Audacity FFT curves/plots in the 2 papers by ‘Don Noon’ on the Schmidt website mentioned above.

  First, the A1 resonance, and this is a resonance mostly of the air column along the violin that is also linked to the air volume within the body and the f-holes, that is  to A0. This is found like this:-

    With the strings damped, hold the violin at the upper block and tap the belly next to the tailpiece with your finger or knuckle. Position the mic. so it is right at the lower ‘O’ of the right hand f hole - or right in it if possible! Then you will see clear resonances at A0 (~270 Hz) and also A1 (~450 - 485 Hz) as distinct peaks.upper bout tapped, mic at lower O of rt f hole

     With this method you can see the very strong A0 at 263 Hz for the ‘Juzek’ . If you click on the picture right the A1 mode frequency also shows up as a strong peak at 462 Hz. The extract of this plot can be seen here. The B1+ and B1- mode peaks are at a very much lower amplitude.

   If you look at Patrick Kreit’s site (or better, get his book!) you will see he strongly recommends that the relationships between these key body resonances should be as follows for a concert quality violin:

    - a delta of 75 to 95 Hz between modes B1+ and B1-

    - a delta of 60 to 90 Hz between modes B1+ and A1

    - a delta of 0 to 16 Hz between modes A1 and B1-.

   But be aware too that when the tailpiece and chinrest are added then B1- and B1+ both drop by 10 to 15 Hz!  Their weights affect the body resonances.  A1 is unaffected.

 Using the instructions given in Don Noon’s paper on the Schmidt website you can also easily find the ‘CBR’ or C2 mode* which lies between 350 and 420 Hz, but sometimes you may get 2 of them very close! The ‘Juzek’ has the CBR at 370.5 Hz.


  Footnote 1:  This “CBR” mode (called  "C Bouts Rhomboidal" by Bissinger:) was also labelled "C2" by Jansson, and "Vertical translation of C bouts" by Marshall .

Body resonance targets

  There is a useful artiBest Violins 1 smllcle available on the web on ‘ideal target body resonances’ titled  “Measurements of 10 Preference-Rated violins”  paper given at  ACOUSTICS 2012 on (page 3608), written by C. Saitis, C. Fritz, B.L. Giordano, & G.P. Scavone.

    If you click on the picture right it will bring up the data from that article for the key body resonances of the best 3 of the 10 good violins they tested for sound quality, as perceived by a group of expert listeners.  Strad 3D project band averages 1

 The Strad 3D Project gives us good information about the body resonances of 3 good Italian violins: one diagram from the site is extracted right, so click on it. It shows the peaks of the body modes that are best radiated from these violins.

  There is also helpful information in a Probing the Secrets Of The Finest Fiddles” article from the Science Magazine, June 2010.

     Carleen Hutchins recommended matching the B0 body resonance to the A0 (Helmholtz) resonance you have measured above. If it is at too high a frequency, reduce B0 by adding weight at the end of the fingerboard. For example, use blue-tack stuck under the end.

    You can look at Jo Curtin’s “Good Vibrations” papers in the Strad or on his website to see where these key resonances are for some of the world's great violins! So if you want to copy one - you can try to copy the main body resonances too!

 Ideally the tailpiece resonance, usually at about 125 to 135 Hz should be at half of A0 and B0.

Oberlin Acoustics has a glossary online of these key terms and abbreviations here

The article Mode tuning for the violin maker  by by Carleen M. Hutchins and Duane Voskuil is rather an advanced paper, but if you can understand it, it covers all the basics on violin body resonances.

  Now what do we do with this information on body resonances ? 

          Carleen M. Hutchins’ work showed that the difference or ‘delta’ between the frequencies ‘B1+’ and A1 dictate how a violin projects, and quoting from her CAS paper:

    A1 AND B1 FREQUENCY RELATIONSHIPS:  It has been found that the frequency spacing (delta) between the A1 cavity mode and the B1[+] body mode is critical to the overall tone and playing qualities, indicating whether a violin is suitable for soloists (delta 60-80 Hz), orchestra players (delta 40-60 Hz), chamber music players (delta 20-40 Hz), and below 20 Hz is easy to play but lacks power”    (Hutchins 1989).

Amongst my many violins I’d say that it is so!

  There are discussions among the experts on maestronet on just what the relationships are between the plate tap tones, weights and thicknesses. It is complex . Anders Buen has come up withB1+ and B1- relation to plates - Anders Buen a useful relationship I have reproduced here, where he says:

   I have developed a model (shown on the ‘Plate Tuning 4 Dummies’ page) that is based on the data from 25 violin samples. It follows each of the belly and back plates and their tap-tones right from the start of violin construction through to finished violins and the completed violin body resonances; all of these ~25 violins sound either good or very good.

 The data shows the most important factor for the important B1+ frequency is

1)     a) the back plate's Mode 2 frequency. A high Mode 2 frequency is likely to affect B1+ by up to 40 Hz, and

        b) the belly plate weight.  A heavy plate reduces B1+ by as much as 13 Hz.

 2) The next most important things are:-

        a) the back plate Mode 5 frequency,

        b) the belly plate Mode 5 frequency, and

        c) the back plate weight.

   These 2(a), 2(b) and 2(c) may affect the B1+ frequency by about 5 Hz each. A heavy back plate reduces  B1+.

    A very important element in what a violin sounds like is just how far B1+ is above the A1 body (or rather internal air) resonance is, the true ‘Delta’ given above.

    The back is often seen as the sound ’reflector’ to the belly’s ‘projector’, so do not take too much wood off this critical area between the C-bouts of the back plate, including the area of the channel next to the linings.

    So by making or adapting the belly and back plates, with  .....

  • good arching,
  • careful edge-work and edge thicknesses and
  • well chosen tap tones (Modes 2 and 5) based on
  • low plate weights - heavy plates need higher tap tones -

you can predict to an accuracy of 10-15 Hz the key violin body resonances and therefore be confident that your violin will sound excellent!

How the main body resonances depend on the plate tap tones HoVBRs-Rd V1.0 smll

    As mentioned above, Patrick Kreit gives a lot more detail (and I mean a lot) in his book “The Sound of Stradivari”.  He tells us that the sound, dynamics and clarity of a solo-grade violin, Strad or Guarnerius model, is based on the exact frequencies and ‘deltas’ of the B1+, B1-  and A1 body modes, and also on the frequencies of the A0, and the B0 and CBR (C2) modes.

   The diagram right (click on it) shows how important it is to get the plate tap tones right because they determine the main body resonances. The Mode 5 of the belly plate mostly sets the B1- frequency, and the back plate’s Mode 5 mostly determines the body B1+ resonance.

   For example, while reading Patrick Kreit’s book I modified a 40-year old, very cheap Chinese ‘Skylark’ violin to put the Mode 5 frequencies of the belly and back plates where Patrick said they should be, and with their Mode 2’s an octave below.  The key body resonances ended up where he said they would be (A0, A1, B1-, B1+). This ‘Skylark’ is now among the best sounding and easiest to play violin I have among my 12+ violins, which go up to ~$2.5k each.

   Apart from putting the Mode 2 an octave below Mode 5, his plate-tuning methods are based mainly on tuning Mode 5 of the plates, and also knowing what the wood’s moisture content is at all times. I have found with my data that Mode 2 measurements are actually more useful than Mode 5, but you do need to know both.

  Testing my violins I can find all of these body resonances / modes as good, clear peaks in their FFT (Audacity) plots, and they are of similar amplitudes.


    Getting the tap tones of the plates right, based on measuring the plate weights, goes a very long way to getting these key violin body resonances just where they should be for a good violin.   We do know that the plates’ tap tones need to be within a particular range for a decent violin: what I’ve found is that selecting them to give particular B1- and B1+ frequencies close to the A1 (internal lengthwise) air resonance, gives a better sounding violin.