The Twelve Most Important frequency relationships for a successful violin...

I would like to approach this from two prospectives; from existing and new instruments: FIRST, from the prospective of the current owner of an existing violin (viola, or cello):

...Is your bridge adjusted (tuned) so that each string sounds rich and full when plucked? ...Do some of the strings sound better than others? ...If you tap down on each string just where it meets the bridge, is this the same tap tone (frequency) as the top plate of the violin (tap just in front of the bridge to hear this tone), and are all four of these string tap-tones the same pitch (frequency)?

... Are the open string notes the same loudness and intensity as the fingered notes when you play the instrument?

... As you play up the fingerboard, are all the notes of the same loudness and intensity? Are there certain areas or even individual notes that are more focused than others? Are all four strings equally strong and focused?

...Get all the strings in perfect tuning with the 'A' string tuned to 440 HZ. Pluck the harmonic note on the 'A' string (880 Hz) and immediately after the back side of the 'D' string {between the bridge and the tail piece}; if the second plucked string (the 'D' backside) sounds higher, then the tailpiece tailgut needs to be shortened. If the second plucked string sound lower, then the tailpiece tailgut needs to be lengthened. If however, it is in harmony (that is at 1,760 HZ) then the tail gut is already adjusted properly.

...I list them here in the order that you are likely to need to deal with them:

...The back plate frequency should be even all over the open (carved out) vibrating area. The ideal frequency for the back plate is 353.5 HZ after U.V.(Ultra Violet Light) curing effects and varnish drying effects. This means that the tuned frequency when making will need to be somewhat lower to begin with. Good record keeping and some experimenting should give you a close estimate of the plate frequency to start with inorder to end up with your goal plate frequency.. In general the back plate will be graduated to one full tone above the top plate {which, will eventually become 3/4 of a full tone [which is 1 1/2 semi-tones] higher when both plates are cured). This is because the top plate wood tends to increase more.

... The top plate frequency should be even all over and ideally 322 HZ after curing. Again, the plate must be made a bit lower than the goal you intend due to increases from U.V. light and its effect on the varnish ground and wood surface. ... The bass bass bar should be tuned so its tap tone (tapped down on from 'above' the bar) is even from end to end. It should be tuned to your goal frequency for the plate (322 HZ) as it will remain at this frequency, being sheltered from the sunlight. ...The top plates' frequency should be lower than the back plate by the above described difference.

...The next thing to tune is the glue liner strips on the completed rib structure, just before gluing the rib structure to the back plate (and later, the top plate). This is done by cutting a taper on the inside edge (away from the glue joint). What you want to accomplish here is to make the downward tap on the glue joint line to be the same as the final (goal) frequency of the plate it will be glued to. Thus the glue liner strips for the back plate should tap 353.5 HZ and the liner strip for the top plate (belly) should tap 322 HZ. This will allow the top of the rib structure to be acoustically matched to each plate. ...As the bevel cut is increased, the tone is decreased. It can be increased by lightly sanding or scraping the inside edge (try and leave the actual glue line surface if you must do this).

... The next very important item to tune is the fingerboard before it is attached. Do all the shaping and hollowing out on the underside and edges, bringing it to its finished shape. As you do this, keep in mind our goal of making the side tap down both sides, and all over the top surface, to be even and ideally the same frequency as the top plate's final frequency. The most important goal here is to make it even all along both sides and all over the top surface. The overtone series of the various tap tones will be different at the extreme ends, but the base tone of the taps do need to match. When this is accomplished, all the notes will be even all over the fingerboard when the instrument is played. ...This can also be checked by tapping down on the top surface of the fingerboard; the tone should be the same all over. Adjust as necessary before attaching (gluing) it to the roughed out neck shape.

...Once the fingerboard is glued to the maple neck, continue to refine the neck shape, gradually working the neck until it just comes even with the pre-tuned fingerboard. Tap just below the glue junction on the maple. Make the final adjustments to the neck shape so that the tap tone at the glue junction with the fingerboard exactly matches the fingerboard. {Removing maple from the neck side lowers the tone at the glue joint, and rounding the neck bottom corner shape more raises it.}

...About now the nut has been glued to the neck next to the end of the fingerboard. It is time to tune the nut to match the fingerboard. Its' side tap, as well as taps down from above at the string contact posints, should match the tap tone of the fingerboard. If it does, then the open and fingered notes will be even (match). Each side must be tuned separately. Remove wood from the side {the end of the nut} to lower that side. File or sand material from the top (sloping) side (toward the peg box) to raise the pitch on that side, or that string position.

...As you fit the tuning pegs, why not also tune them to the same pitch as the string that will be wound around them. Here is how to do this. Since the shoulder of the tuning peg should be 0.50" from the side of the peg box and the width of the peg box at the location of that peg is also known, cut the tuning peg off to this proper length. Then using your peg shaver, begin to turn down the peg shaft until the tone matches the proper pitch. Tap the small end of the peg vertically down on the taple top to hear its pitch.

...You may want to fit the end pin at this time. It is tuned to match the tap tone of the nut of the fingerboard (tapping straight down on to the center of the nut , which should just match the fingerboard tap tone). Tap the end pin from the side. Making its tapered shank smaller lowers the tone and shortening the end (inside end) raised the pitch of the end pin. If it is too high then the head can be sanded shorter (the part that stick out) and this will lower the tone. Matching this pair makes for a smoother, clearer sound.

...After fitting the bridge feet and shaping the bridge to get the proper string heights, it is time to tune the bridge to the instrument. As a general rule, shape the bottom curve of the bridge to closely match the curve (arch) of the top of the instrument. Adjust (tune) the bridge by shaping the front side (toward the fingerboard): ...Made the wood across the bottom be an even tap, the same tone as the back plate. Make the wood all across the top be the same tone as the top plate. Tap sideways against the face of the bridge to hear this tone. Removing wood from the face (the side towards the fingerboard) lowers the tone. If you go too far and the tone needs to be raised slightly, then file or sand the bottom arch slightly higher to again raise the pitch. Tiny adjustment here made a big difference so go slowly. The area just under each string can be raised individually by filing the shape of the top of the 'kidney' under the string slightly higher.

...The tail piece is probably ready to be installed now. It must be exactly tuned to the fingerboard tap tone. To hear this tap, tap down on the string contact point (right where the string support bar is). Again, each string position tailpiece must be tuned separately. When the tailpiece frequency exactly matches the fingerboard, the maximum power and clarity will result, and this effect amazing to experience!

...The tail piece gut is probably next to be tuned. As a rough estimate; adjust the tailgut so that the most rearward part of the tail piece is just even with the peak of the saddle (the ebony block the tailgut turns over). ... After the instrument is strung up and tuned, plucking the back side of the 'D' string {between the bridge and tailpiece} should produce a tone of exactly 1760 HZ. To hear this tone, compare it to the natural plucked harmonic of the 'A' string (880 HZ). Shorten the tail gut if too high pitched and lengthen the tail gut if too low pitched. {One of the very talented young violin makers from David Kerr Violins of Portland, Oregon taught me this technique, and I find it does seem to make a positive difference.}

...One of the last items to get in balance is the relationship between the downward tap on the end of the fingerboard (which is the same as the downward tap on the top of the scroll), and should match the tap tone of the center of the back plate. If the fingerboard tap tone is too low, then all that is required is to evenly sand (scrape) the end of the fingerboard until the tap tone down on the end of the scroll matches the back plate tap tone. Once this is accomplished, compare this "top of the scroll downward" tap tone with the upward tap tone under the scroll (just in the end on the neck to scroll transition ares). If this bottom the scroll tap tone is too high (compared to the tap tone down on the top of the scroll, which now matches the center tap tone of the back plate) then carefully sand; scrape material from the root of the neck support where it makes a shape transition to the rood of the neck to lower this tap tone. (see photo at right:)

Adjust here at neck root

...After accomplishing these twelve frequency adjustments I believe you will have crafted an instrument that you will be proud of and that will bring musical enjoyment to many for years to come!