The information I have gathered/read regarding soundpost location is varied. Soundpost locations by various authors suggest the soundpost should be fractionally behind the right foot of the bridge and directly on the lateral centerline of the right foot of the bridge.
Others suggest a position 10 mm back of the right foot of the bridge and on the lateral centerline.
I have followed these directions and discovered the tonal qualities were far too harsh for my fiddle and consequently I positioned the soundpost 15 mm behind the right foot of the bridge and 8 mm towards the center of the violin. Is this an unorthodox soundpost position that is in a weakened part of the violin belly .
10 mm back of the right foot of the bridge and on the lateral centerline.
I have followed these directions and discovered the tonal qualities were far too harsh for my fiddle and consequently I positioned the soundpost 15 mm behind the right foot of the bridge and 8 mm towards the center of the violin. Is this an unorthodox soundpost position that is in a weakened part of the violin belly .
This location is in a thinner part of the the top plate. This may cause damage due to the stress the strings apply to the top plate. There may be some cracking in this area that will devlope over time.
I start with the sound post directly behind the treble foot of the bridge 3mm. To balance the base and treble side move the post tword the center this will increase the base tone moving it tword the sound hole will increase the treble once you have it balanced side to side then you can use the hammer end of the sound post setter and tap the top and bottom of the post tword the end block. This will lower the tone evenly with a more mellow sound reducing the harshness. Moving the post toward the bridge the sound will increase in volume and harshness. Always relieve the string tenson before making a sound post adjustment or you may damage the top plate.
Another factor would be the density of the post material, a lower density material will give a mellower tone, the higher density will have a brighter tone.
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Another factor would be the density of the post material, a lower density material will give a mellower tone, the higher density will have a brighter tone.
First off thanks for your input Carl and thanks to Harry for welcoming me aboard.
Would I be correct in understanding that an Adirondack Red Spruce soundpost would produce a brighter response as compared to Sitka and Engleman. Should the growth ring pattern in rings per inch on the soundpost resemble the tightness of the grain i.e. annular growth rings per inch on the top. When I have purchased sounds posts in the past I simply accepted whatever was handed to me…..or is this overkill to go to these extremes.
How critical is an 100 % even bearing at the top and bottom diameter of the soundpost. Upon viewing the soundpost through the end block/peg opening ( of course no tension on the top) I can see a small sliver of daylight at the top and bottom contact points. My guess is that with tension applied when the instrument is strung that the hairline space between the inner surface of the belly and back will close…..and if it doesn’t then what will be the telltale signs soundwise that the post is not fitted correctly.
Last edited by alt2ooning; 01-29-2009 at 08:10 PM.
Reason: Neglected a comment
First off thanks for your input Carl and thanks to Harry for welcoming me aboard.
Would I be correct in understanding that an Adirondack Red Spruce soundpost would produce a brighter response as compared to Sitka and Engleman.
Yes you are correct.
Should the growth ring pattern in rings per inch on the soundpost resemble the tightness of the grain i.e. annular growth rings per inch on the top.
The ring count should be equal to the top plate or greater then the top plate.
The ring wood of the sound post should be at 90* to the top plate.
When I have purchased sounds posts in the past I simply accepted whatever was handed to me…..or is this overkill to go to these extremes.
No it is not overkill this is another way of adjusting the tone of the instrument. The soundpost will transmitt the vibration at a different rate with the different density. I am very picky with the sound post material and have also made the sound post from left over scraps of the top plate.
How critical is an 100 % even bearing at the top and bottom diameter of the soundpost.
If the sound post is not 95-100% in contact with the top plate inside curviture, damage may happen and the post can kick out with the changes in humidity. Use a dental mirror to check the fit of the SP to the top plate after it is installed.
Upon viewing the soundpost through the end block/peg opening ( of course no tension on the top) I can see a small sliver of daylight at the top and bottom contact points. My guess is that with tension applied when the instrument is strung that the hairline space between the inner surface of the belly and back will close…..and if it doesn’t then what will be the telltale signs soundwise that the post is not fitted correctly.
Harshness of the tone and sometimes a slight buzzing that you may not be able to locate. The Biggest problem will be as the strings are tuned the top /belly compresses the the sound post. This will leave an indentation on the belly that will lead to a crack in a few seasons of weather change. Then the top would have to be removed and a patch placed over the location that the sound post was in. I have had to do a few of these repairs and the results are good. It is best to avoid the problem with a correctly fitted Sound post.
Carl
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Last edited by cfiddlemls; 01-29-2009 at 09:22 PM.
I now understand clearly why, as you informed me in your e-mail, the time consuming aspect of setting the soundpost to get the optimal tonal quality out of the instrument. I can see where several days are needed (allowing the instrument to undergo ‘tuned- to- pitch- structural- tension’ for several hours) to test tonal results and adjust and readjust as often as necessary using different density of spruce and positioning to attain a 100% bearing fit.
Does location of the soundpost have any bearing on the quality and strength of partials?
Little was I aware of the very real probability of causing serious cracks in the top from ‘loosy goosy’ fitting of the soundpost., needless to say your warning and red flagging errant soundpost installation/fitting is invaluable.
I realize the diameter of the sound post is governed by the largest access through the ff holes and having stated that , then what effect would a marginally larger diameter versus a narrower diameter sound post have on the tonal quality?. …….hopefully this isn’t interpreted as me trying to reinvent the ‘wheel’ (i.e ¼ in. diam. soundpost) that the masters Amati and Stradivarius invented.
Does location of the soundpost have any bearing on the quality and strength of partials?
Yes, it is also relevent to the position of the sound center of the top and back plates. The sound center of the plates must be in the area of the sound post location. If the sound center of the plates are of this location the partials will not me transmitted properly causing a reduction of energy applied to the back plate and a reduction of tonal output overall.
If these areas are out of position the partials will be lost.
I realize the diameter of the sound post is governed by the largest access through the ff holes and having stated that , then what effect would a marginally larger diameter versus a narrower diameter sound post have on the tonal quality?. …….hopefully this isn’t interpreted as me trying to reinvent the ‘wheel’ (i.e ¼ in. diam. soundpost) that the masters Amati and Stradivarius invented.
I have experminted with this aspect. My observations are that the larger diameter of the post (6.5mm) causes a higher mass value in the sound post. How does the higher mass effect the tone? With a higher mass the energy to set it in motion is greater. Where is the energy coming from? The strings, so more bow pressure and a longer bowing stroke are required to compensate for the extra drain of energy. It may not seem like much and it isn't, untill the player can not finish a set due to fatigue on the players part.
This is also true with the bridge material and tailpiece. In other words the response of the instrument is lowered and will sound muddy. Other factors that effect the size of the post is the material it is made from. Denser material can be smaller in diameter and still produce the same tone quality of a lighter material with a larger diameter.
__________________
Remember that with your skill
you sign your work
I have experminted with this aspect. My observations are that the larger diameter of the post (6.5mm) causes a higher mass value in the sound post. How does the higher mass effect the tone? With a higher mass the energy to set it in motion is greater. Where is the energy coming from? The strings, so more bow pressure and a longer bowing stroke are required to compensate for the extra drain of energy. It may not seem like much and it isn't, untill the player can not finish a set due to fatigue on the players part.
Your comments and direction/instructions are truly invaluable....you will most likely hear that often from this corner. Your comments are not only focused on the luthiery but also on the player.
The questions I pose are not likely to be answered via the textbook route . Thanks for sharing your expertise as a professional luthier and …...metaphorically speaking thanks for allowing me to ‘look over your shoulder’ in confronting the unknown (for me) in the art of luthiery …..I emphasize the word art as opposed to craft.
Soundpost location and fitting
Linear Mode
