Violin Forum/Message Board

[jethro]

So far my Violins have seemed to me a little too loud - all things being equal. I am about to final graduate another top plate. I have been using Strobels graduation map and going for about 375 hz. I am wondering how to change the graduation a little to still have the same resonant freq.
but have slightly lower sound amplitude.....
Strobel's map is a thick center with a thin perrimeter. I am thinking this would respond (roughly) like a speaker which has a stiff rigid cone with
a soft flexible narrow border which flexes and allows the rigid center to
move in the Z axis. If I think of this as a spring - mass type system the
center is the mass and the thin perrimeter is the spring. To keep the
frequency the same : if I make the center heavier (thicker) that lowers the freq. so I would have to make the spring stronger to raise it back up.
So if I added about 1/2 mm everywhere on the belly's map should that
dampen the bellys response just a little do you think ??????
( I am just guessing at 1/2 mm being "a little" )

any thoughts?
Tim

[Dave Chandler]

While waiting on someone smarter and more experienced than me to weigh in, here's my take.

Half a mm seems a lot of adjustment, especially around the edges of the belly where you may be at around 2.2-2.5 in the channel already, that's a 20-25% difference, not small in my view. (I don't have strobels map, so not sure what he's calling for around the edges wasn't it about 2.8?). I think he calls for cutting the channel and then just blend it into the final arch, but I like to cut the channel as part of the final arching, and since starting this several violins back, I've noticed a difference in the clarity and quality of the sound. My final belly thickness in the bottom of the channel runs about 2.0 to 2.1 except along the c-bouts might go to 2.3 to 2.4.

Why not go back over an earlier instrument that you think is "too loud" and move the soundpost a bit more to the treble side and perhaps a bit closer to the bridge foot. You might try that before making a final decision on graduation which would be difficult to go back and rework.

Loud shouldn't be a problem unless it comes with a harsh tone. If thats the case, you can try a thicker bridge, leaving the heart of the bridge near say 4.2mm rather than traditional 4.0mm (per Strobel), even leave a little more on the feet, maybe 4.5mm thick. Then thin it down some more if it dampens the sound too much. It should filter out some harshness, which would make "loud" also unpleasant.

Thoughts from a novice -- for sure. I started with Stroebel, and have kind of wandered off on my own, although I still use his book on standard measurements for reference. I've spent a lot of time studying violin arching and graduations etc on the Luthierlibrary.com and a 2-sheet blue print for the "Messiah" which I was fortunate to find on ebay.
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[Michael Darnton]

I think that's all good stuff, and I'd add that another couple of coats of varnish would probably calm things down, too.
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[Jack H.]

Not familiar with Strobel's making book, but you are on the right track with adding mass all over. My bellies tend to be rather uniform in thickness with a few 10ths thinner up top and bottom. I do not measure for Hz but rather for flexibility/ stiffness. but more mass and as Michael says, more varnish should do the job.

[jethro]

I have tried seemingly all possible post positions, about 6-8 posts and have tried about 20 bridges each cut a little differently ( I was learning
the effects of bridge cuts and thicknessing )
I did not think of simply adding varnish ! I don't have a lot of varnish on the last one on the belly. I think I used 2-3 coats of varnish oil
(which is very thin by nature ) and about 3 of oil varnish.
It has a pretty heavy bass bar . ( Remembering Michaels post about the
bar geometry having relatively little effect )

I normaly cut the channel when I shape the top and then adjust the
thickness from the back when I plane/scrape the inside final grad.

Varnish would be an easy thing to try and see if it helps !
Thanks yall !

PS.
The output is really loud , and not unpleasant. It is just not
as "complicated" or "rich" or "textured" or something ...........
It is very resonant but just kind of plain and not as interesting as some I have heard. I think I should be able to do better !

Tim

[Mikes]

Is it loud to an audience or just under your ear when you play it? If it's just under your ear then then maybe a bigger dia. sound post or heavier bridge might be just right. If it's loud to an audience I would leave it alone unless it just loud with not much color.