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|The violin, the mandolin, and acoustic optimization
copyright 2005 Stephen Perry
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|A Brief History of
|1. Violin and Mandolin: A Brief History (below)
2. Observations: Violin and Mandolin Research and Construction
3. Acoustic Blueprinting and the development of Mandovoodoo (tm) optimization
Both the violin and modern carved mandolin are functionally and historically related.
These short sections briefly summarize violin and mandolin history, violin research
applicable to the mandolin, and my development of acoustic blueprinting (the
mandovoodootm process) from my research on and practical techniques for optimizing
The violin is older than the mandolin and has enjoyed the attentions of researchers,
amateur experimenters, and practical technicians for generations. Thus most work I'm
familiar with concerns the violin Research focuses, more or less, into:
1. The wood and its treatment
3. Graduating top and back including free plate tuning
4. Finishing systems
5. Acoustic adjustment via structural modification
6. Acoustic adjustment via dedamping
7. Acoustic adjustment via whole instrument tuning
I'm not going into a detailed treatise on each of these, just enough to provide context. I
invite readers aware of related mandolin research or additional violin research to let me
know. This discussion includes my personal observations and commentary. Have an
opposing opinion? Let me know, I'll put it in here.
|The wood and its
|Several commentators point to wood treatment or special wood as part of the "secret" of
the great makers of the past.
With violins, it is special magic trees that the commentator has usually located and is using
or selling pieces of. Or a special period of time. That we can buy virtually identical wood
from the same regions and of the same age the old masters were using escapes
comment. Thus I generally discount such claims. Except for hints by Michael Darnton.
Wish he'd just come out and say what he knows about that! Regardless, violin wood is
usually Acer pseudoplatanus and Picea abies in European classical instruments. US made
instruments can be found in silver, red, big leaf, and sugar maple. Poplar and sycamore.
Even walnut. Tops are in engelmann, Sitka, and red spruce. Probably other things.
Successful fiddles spring from all these. Successful classical violins seem to come mainly
from European woods, although this may be a function of wood selection habits of
successful classical violin makers.
Mandolins seem to come in all kinds of woods, too. Red spruce and sugar maple seem to
be popular and the holy grail of mandolins and guitars. The combination makes mellow
and powerful fiddles, too.
But very successful instruments spring from a wide range of woods. At least for mandolins
wood seems to be a small part of the equation. An important part, but not overwhelmingly
Another theme is special treatment. Soaking (ponding) the logs. Baking the wood first.
Baking the wood afterwards. Treating the wood with chemicals. Photomicrographs show
the long tubes opening up with soaking. Resins in the wood may well harden with baking. I
have no personal experience with these effects, but they may have played a role in past
masterworks. I'm not betting on it.
Good old violins often seem resistant to wood worm and rot. Water beads up on the inner
surface. This suggests a treatment, or perhaps multiple treatments. My only direct
experience with this is in application of a weak solution of historically available antifungal
stuff. It does indeed result in beading up of water and has a distinct broadening effect on
the tapped plates. Interesting. Wonder what it would do for mandolins.
I consider that wood treatment has potential for mandolins and violins. But I don't have
time to investigate it any more than I already have.
||Violin design has been talked to death, but is interesting here because of its possible
application to mandolins. Aspects I look at are construction, geometry, and graduation
At first glance, violins and mandolins appear to be constructed the same, but they aren’t in
a couple of important ways. First, violin rib garlands rely on relatively thin linings (2 mm
width), keeping the structure very light. In contrast, mandolins rely on thick kerfed linings. I’
d like to see mandolins built with bent linings. Second, violin plates overlap the ribs, while
mandolin plates terminate shy of the ribs against binding. Other than the problem in
repair, vibration from the top has to reach the ribs indirectly through other materials.
Whether this is a problem or not depends on the working model one has for mandolins.
Are the ribs most effective as a rigid barrier, keeping energy in the top, with the back
acting as a reflector (banjo model)? Or does the whole instrument vibrate and project
(violin model)? I like the violin model. The frequent exceptional performance of wood
bound and unbound mandolins lends some anecdotal support for this position.
Glue. Why are mandolins made with rubbery glues? Violins are made with hide glue. Hide
glue in best application pulls wood to wood with almost nothing in between. Titebond and
other things used by most shops seem to damp sound. I glued a bunch of strips together
with various glues. Then tapped and listened. I’ll stick with hide glue. Think of the organic
molecules as long springs with balls stuffed in to make them longer. And hooks on the
end. The hooks tie into the wood on each side of the joint. The water works its way out
and the glue cools, pulling the balls out. Bingo. Tight joint, sound goes right through. That’
s my story anyway!
Fortunately, arched plates and curved bent ribs are incredibly strong and rarely present
Arch shape is crucial in contouring the response and tone of an arched instrument.
Exactly why this is so remains a bit obscure. In both violins and mandolins bridge motion is
lateral, back and forth along the instrument’s axis, and up and down (pumping). String
vibration changes string tension and thereby changes tension on the tailpiece and neck.
Hit the instrument strings hard and the tension on the neck and tailpiece increase while
the push down onto the top increases. The instrument bows up at the ends in response.
What do these forces do?
My working concept for violins might prove interesting. I think of the center of the top as a
cylinder section, free at the edges between the F holes. A cylinder section can twist easily,
but is quite strong. Lateral movement twists the top. Changes in down force push the top
down. In a violin this force is transmitted to the back through the soundpost. In both violin
and mandolin reinforcing braces distribute the downward push through a larger area of
the top. How much of this matters I don’t know. I do know that making the center section of
a violin more of a cylinder and less of a dome helps generate easy response and intense
In a violin, the nature of the transition from the cylindrical center section to the domed
ends seems rather important. I’ve got some working models on this, too. I’ll keep them
under my hat for the moment. Mulling over many many details.
The bowing up of the ends of the instrument as string tension seems an often neglected
component of sound generation. These impulses move into the top and back from the end
and neck block areas. I think of them as pumping the upper and lower bouts in a violin.
Seems that this would be important in mandolins as well. Certainly the difference between
oval hole mandolins that have a suspended neck versus those with the fingerboard
flowing out over an elevated segment of top is quite distinct. Even if hard to describe.
Suspended neck models have much less impingement on the top and would appear to
allow excitation of the top more effective than mandolins where the fingerboard runs over
a strong arched section of the top material, limiting major top motion to the area below the
soundhole. Gibson’s prototype oval hole with suspended neck extension certainly
reflected the added power and punch. I don’t see why the structural issues wouldn’t be
minor or negligible.
Why don’t mandolins have a cylindrical center section of the top?
Another crucial element of design for both violins and mandolins is the relationship of
thickness to arching in the channel area around the edge and up into the dome of the
arch. I’ll simply point out that many very good instruments have no shelf or sudden
thickness change near the joint with the ribs and lining, that these instruments have a well
formed channel, and that this channel smoothly flows through a transition to the arch, the
recurve area, without any straight stretches. I see many mandolins without much channel.
These don’t seem to me to work as well.
The thickness of top and back in general seems quite important. Mandolins appear to rely
on bullseye thick center, thin edge models for graduation. Violins have the thick center on
the back, although this usually shows up as a lens in a membrane rather than a uniform
taper to the edge. In contrast, tops tend to be membrane (uniform thickness), thick
centered (similar to the back and very traditional in the trade violin world), or reverse (thin
spot in the very center).
Of much more interest is the final step in graduation: free plate work. This is covered in
the next section
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