Micro Adjusting The Tap Tones, Once the Instrument is Playing...
(1/2022)
page AA_60
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...By David Langsather, Violin Acoustical Researcher www.violinresearch.com info@violinresearch.com
 These are the three tap tone goal tap references you can use in tuning these parts: [Click to hear frequency]:
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..Violin Top Plate...
  1. 0 HZ
..Violin Back Plate..... ......242.0 HZ
Violin FingerBoard
and Tailpiece:
  (227 1/2) HZ
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..Before gluing the plates I highly recommend that you use Dutch Rush to fine sand the inside surfaces (including the ribs and internal wood blocks), do this twice. See "Dutch Rush"
..If you decide to "Hematite burnish the inside of the plates; do that first (twice), and then the Dutch Rush.
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..Now for this to happen, the fingerboard and tailpiece must be perfectly matched and reacting to each other through the vibrating strings.
..Let us examine the fingerboard first: ...
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..Although the downward tap tone is 227 1/2 HZ...
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.....The side tap all around the perimeter is 242 HZ (which sounds in perfect harmony to the 227 1/2 HZ).
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E string
..Once our instrument is strung up and playing, we will want to micro tune the fingerboard. With constant bowing of each string: shift the stopping finger up the fingerboard in small steps listening to the tone response. At the point that you hear the sharpest, focuses tone, make a pencil line on the fingerboard across on both sides of the string. Do this all up and down the fingerboard; at first on the E string and then on the G string. (do the D and A strings later) ....
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..Now, tapping these focus points one after another, you will see that all these points are the same tap tone. Now we want to make all the areas of the fingerboard the same as these correct points.
..Next tap the areas to each side of each focus point line. You will discover that on one side the tone is higher and the other it is lower.
..You will also discover that the spaces between the focus lines alternate: high, low, high, low, high, low.
...With you pencil mark the high spaces with an + , and the low spaces with an --
+
+
+
--
--
--
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..Moving the string out of the way; and beginning with the + areas: tap along this space and listen to the tap tone to discover where the high point is. Begin scraping / sanding there moving in both directions to surrounding focus points (tapering amount removed in both directions).
..Continue to check tap tone and once the whole length between focus points, matches the surrounding focus points; that section is now tuned. Do the same thing with each + area.
{..when the top surface is +, you will note that the side tap in that area is low (below 242 HZ side tap tone)}.
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..Now we extend the top surface focus lines down the side of the fingerboard. We will raise the too low areas by removing wood on the side of the fingerboard. You will note that the side tap tone between the focus lines of the too low areas (--), is higher than our desired 242 HZ. Again tap along these areas and note where the highest tap sound is.
.. Begin scraping / sanding there moving in both directions to surrounding focus points (tapering amount removed in both directions).
..Continue to check tap tone and once the whole length between focus points, matches the surrounding focus points; that section is now tuned. Do the same thing with each -- area.
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..Now we turn our attention to the D and A strings. Repeat the steps for discovering and marking the focus note points and the + and -- low areas.
..We will only deal with the + gap areas; adjusting down to even 227 1/2 HZ tap tone (matching focus points on either side.
..Hopefully the too low areas will be close enough so as not to distract much.
..If however certain too low areas (--) are distracting, then these can be raised by scraping the nearest outside edge until they are even to focus points at either end. Now of course the outside string will be too high in that point and you need to scrape those areas back down to the focus note frequency.
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..The tailpiece is handled in similar fashion, also with a downward tap tone of (227 1/2) HZ on the upper surfaces and 242 HZ side ward tap tone around the perimeter horizontally.
 
..In general the tailpiece is responsible for the power produced (in conjunction with the fingerboard of course...).

..If some string, or strings of the fingerboard do not produce focus points, even though we know the tap tone is even all over, then this tells us that the tailpiece in line with that string is not in proper tune. So, adjust the tailpiece until focus notes are available on the fingerboard for that string.

..finally, on the tailpiece, there is a curved narrow block of ebony wood across the front end, recessed in a groove, that I call the "String Bar"... It is lightly pressed in place (possibly glued in as well).
..This String Bar is responsible for the response of the instrument and needs to have a vertically downward tap tone tuning of (227 1/2) HZ at each string contact point. If one or more strings does not have instant string bowing response; we know that that string contact location is out of tune at the string bar.
..If too high; lightly scrape the top surface where too high to reach the (227 1/2) HZ tap tone (compare to main surface of tailpiece.
..If too low; file the back side of the string bar at a slight angle at that string location until it is railed up to (227 1/2) HZ tap tone goal.
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..To raise string bar tap tone, file at an angle to back side, in the too low area.
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..Enjoy!

..I would welcome you comments and experience. You can E-mail us at: info@violinresearch.com .
David Langsather Salem, Oregon USA {(c) 2022}