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Aymara
Oud Junkie
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Location: Germany / Ruhr Region
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I just wanted to give a further example of veneer usage in instrument building.
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... I very much doubt if there would be any significant acoustic difference between one made from, say, ribs of thin Beechwood aircraft plywood and
one made of ribs from rosewood or any other materials all else ...
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When I bought my oud I had the choice between two ouds. Both had the exactly same bowl design, but one was made of rosewood, the other walnut. Both
soundboards were of the same spruce and had the same bracing, as far as I know. And both were strung with the same strings and had standard tuning
CFAdgc. Also important is that both ouds were built in parallel at the same time. The only difference besides the mentioned wood choice was the sound
hole design ... the rosewood oud had oval sound holes and the walnut oud had the typical round holes, both had no rosettes.
I think nobody will be astonished, when I tell that both ouds sounded totally different, but very nice. The most important difference was, that the
rosewood oud had a much deeper warm bass, which the walnut oud was totally missing.
I doubt, that the bowl wood choice didn't play a major role here, because the sound difference was huge and the only other design difference was the
sound hole shape.
PS: The bridges were also identical in design, but I don't remember, if they were of the same wood.
Greetings from Germany
Chris
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fernandraynaud
Oud Junkie
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Well, we have similar experiences. I suppose the "no effect from the bowl material" makes sense if you consider it mainly a reflector, but the whole
oud vibrates together, it does not have to be played with chords, because it makes its own harmony. And clearly some part of that comes from the bowl
itself.
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jdowning
Oud Junkie
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Well sound hole size shape and placement - together with bowl volume - can have an effect on bass response (Helmholtz Resonator effect) when comparing
two otherwise 'identical' instruments. No two sound boards are identical either - wood being such a variable material where there can be significant
differences in physical properties even when cut from the same tree.
Getting back to the environmental theme. Not to be forgotten as a potential bowl material is that perfectly engineered wood product - paper. Combined
with glue, paper can be hand moulded into practically any complex shape. Not new technology, as it was a very popular method used commercially for
creating household objects in the pre-plastic days of the 19th C (known as Papier Maché).
It is said that the great Spanish guitar maker Torres made a guitar body from this material in order to demonstrate that the material used to
construct the body made no difference to the sound produced and that it was the sound board material and bracing that was all important (not to
mention the skill of the luthier in being able to produce the optimum acoustic performance from a given set of sound board components).
A benefit of a moulded paper bowl is that there are no glued joints so the bowl might be made stronger and thinner with this seamless construction.
The method is to use a female master mold - similar to the procedure used today for moulding fibreglass by hand lay-up - the difference being that
fibreglass and its resins are costly, toxic irritants.
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Brian Prunka
Oud Junkie
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Plywood is often used in hollowbody archtop jazz guitars. An interesting specimen because they are both acoustic and electric.
A guitar is acoustically different from an oud because the top and back are both vibrating plates that work together. Of course the bowl of an oud
vibrates as well, but not to the same degree.
Very thin plywood (most often birch, sometimes a birch/maple combo) seems to resonate quite well, while thicker plywood exhibits noticeable damping
properties. As the plywood for a bowl would be expected to be quite thin (in order to facilitate bending), I would think it would work pretty well.
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Aymara
Oud Junkie
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That's interesting. Then it would be an interesting project to build an oud with a guitar like body, but still drop-shaped. A bit like the Godin
Multioud, but with a deeper body.
Did any luthier try that so far?
Greetings from Germany
Chris
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Brian Prunka
Oud Junkie
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I've seen a couple by Turkish luthiers, but haven't seen one in person and don't know what the sound is like.
Didn't Mav have one built?
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Edward Powell
Oud Junkie
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Quote: Originally posted by jdowning  | Well sound hole size shape and placement - together with bowl volume - can have an effect on bass response (Helmholtz Resonator effect) when comparing
two otherwise 'identical' instruments. No two sound boards are identical either - wood being such a variable material where there can be significant
differences in physical properties even when cut from the same tree.
Getting back to the environmental theme. Not to be forgotten as a potential bowl material is that perfectly engineered wood product - paper. Combined
with glue, paper can be hand moulded into practically any complex shape. Not new technology, as it was a very popular method used commercially for
creating household objects in the pre-plastic days of the 19th C (known as Papier Maché).
It is said that the great Spanish guitar maker Torres made a guitar body from this material in order to demonstrate that the material used to
construct the body made no difference to the sound produced and that it was the sound board material and bracing that was all important (not to
mention the skill of the luthier in being able to produce the optimum acoustic performance from a given set of sound board components).
A benefit of a moulded paper bowl is that there are no glued joints so the bowl might be made stronger and thinner with this seamless construction.
The method is to use a female master mold - similar to the procedure used today for moulding fibreglass by hand lay-up - the difference being that
fibreglass and its resins are costly, toxic irritants. |
To your first point, absolutely yes,- soundhole differences alter bass majorly, and it is a great mistake to assume that 2 soundboards are equal,
unless they are made by Turunz who has tuned them equally - because slight difference will result in different area frequencies - you can not consider
them equal unless you can prove that each resonant area is tuned exactly the same - otherwise each soundboard will produce a completely different set
of overtones.
Second point... regarding the papier mache and the Torres experiment --- I went down this famous road of reasoning for a long time and even built a
couple of paper backed ragmakamtars http://www.edwardpowell.com/rm6photos.html however, after some experimentation, I have to conclude that, on intuition only, I reject this
theory. I do in fact think that the material of the back makes a difference. As Fernie mentioned, when I play an oud or a guitar I can feel the back
vibrating strongly therefore this is obviously creating and filtering sounds... wood is special in that it has grain which makes it strong than
it's weight alone. Paper has no grain and is a really 'dead' material - it needs to be really thick and heavy to have any strength. . . . having
said that, i did not take the experiments too far, and it easily could have been due to other factors that those paper instruments left something to
be desired. . . the only way to find out would be to build an otherwise perfect oud, but with a paper back - - - it would be a good way to
finally know the answer to this question of how important to the sound the bowl material is.
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Edward Powell
Oud Junkie
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| Quote: Originally posted by Aymara |
That's interesting. Then it would be an interesting project to build an oud with a guitar like body, but still drop-shaped. A bit like the Godin
Multioud, but with a deeper body.
Did any luthier try that so far? |
http://www.edwardpowell.com/rm7photos.html
on my previous post i gave a link to ragmakamtar #6 which has a paper back... so then being a bit fed up with that sound after playing that
instrument for 18 months and many concerts and recordings http://www.edwardpowell.com/pg.html ....I decided to go completely the other direction and design a ragmakamtar which actually has two
resonating plates - top and back - and the sides very very thick and stiff.
The back resonating plate is of spruce also and lightly braced - and there are two large soundports on the side... it is an amazing sensation to
play this instrument because the sound comes right out of the side into your ear, and you can hear both plates resonating like crazy. Actually both of
these instruments #6 and #7 are now for sale if anyone is interested.
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jdowning
Oud Junkie
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Paper does not have a grain in the sense of wood but - dependent upon the type of paper and manufacturing process - can have a fibrous structure with
'grain' direction.
The 19th C commercial development of papier maché included a process where panels were made up from layers of paper saturated in hide glue and hand
pressed into a uniform thickness. These panels were often used in the manufacture of the then popular 'japan ware' by being saturated in a
bitumen/linseed oil based varnish and then dried in a furnace to produce a hard black smooth and durable product. Decorated trays, boxes and other
trinkets were popular but furniture was also made from this material.
So, it should be possible using this method, to make consistent thin, hard, light, durable and strong oud bowls from paper - with fluted 'ribs' if
required - using pre-plastic era materials. Choice of colour, however, would be limited to shiny black - like the model T Ford car (or french polished
ebony)!
Of course, if 'modern' phenolic resins and the like are used as binders then the possibilities are further increased. In this way even light weight
disposable fuel tanks on aircraft (drop tanks) used during WW2 were made from paper maché.
I have in the past made a few experimental 'fluted rib' lute bowls (with foam filled integral necks) from carbon fibre reinforced fibreglass - but
that is another story.
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Edward Powell
Oud Junkie
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| Quote: Originally posted by jdowning |
The 19th C commercial development of papier maché included a process where panels were made up from layers of paper saturated in hide glue and hand
pressed into a uniform thickness. These panels were often used in the manufacture of the then popular 'japan ware' by being saturated in a
bitumen/linseed oil based varnish and then dried in a furnace to produce a hard black smooth and durable product. Decorated trays, boxes and other
trinkets were popular but furniture was also made from this material.
So, it should be possible using this method, to make consistent thin, hard, light, durable and strong oud bowls from paper - with fluted 'ribs' if
required - using pre-plastic era materials. Choice of colour, however, would be limited to shiny black - like the model T Ford car (or french polished
ebony)!
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That would be great if you would give it a try. My paper mache was just packing paper and watered down white glue, and then (shame on me) a thin layer
of bondo on the outside for extra strength and smoothness.
the process you describe of layers of paper saturated with hide glue and pressed into uniform thickness sounds exactly like how them make trespa
except they saturate with poly-resin instead of hide glue....
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jdowning
Oud Junkie
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I am not familiar with Trespa or its manufacturing process.
I have no interest at present in making an oud bowl from paper (or fibreglass for that matter) as it would require all of the time consuming effort
and cost in mold making etc. but I might experiment at a later date with some small test strips of hide glue paper laminates 'japanned' and oven baked
in the old way - just out of curiosity.
Unfortunately I gave away my master mold for making fibreglass lute bowls some years ago before relocating to another country. This mold would have
been useful for paper bowl trials.
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Aymara
Oud Junkie
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Location: Germany / Ruhr Region
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Does that mean, you have once built a lute with a fiberglass bowl? If yes, please tell us more about it.
Greetings from Germany
Chris
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fernandraynaud
Oud Junkie
Posts: 1865
Registered: 7-25-2009
Location: San Francisco, California
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The writing's on the wall. Wooden instruments will soon be a rarity, like animals in Philip K. Dick's prophetic "Blade Runner". I got an inexpensive
Chinese Spanish Guitar recently that actually plays and sounds passable, though it's a bit heavy, and I'm currently hunting for an infuriating buzzing
loose brace. The sides and back are in a beautifully figured hardwood, heavily varnished. But it needed a better pickup and preamp. So, after removing
the tiny old preamp, I cut into the side with a Dremel. That was a hard hard wood, it took a while to cut through. Imagine my surprise when I looked
at the cut. Not hardwood. A laminate with a hard yellowish plastic inside. The wood grain is a photograph. After that, I started looking more
carefully at the instruments in the stores. Most of the acoustic guitars are made this way, including some very respected names that have garnered
rave reviews about their beautiful "mahogany". I haven't cut a soundboard yet, but I bet that spruce top isn't spruce. Though Faruk has shown it's
actually better than spruce, when I cut through that guitar I felt like I'd just discovered that my mother was a robot, and all the plants in the park
artificial.
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jdowning
Oud Junkie
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Location: Ontario, Canada
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I built and sold half a dozen of these experimental lutes during the 1970's before discontinuing because of the toxicity and irritant problems
associated with handling fibreglass and its resins. The objective was to built low cost lutes.
These instruments had a foam filled neck molded integral with the bowl (complete with decorative inlays cast in) and were fitted with cedar sound
boards, and wooden pegboxes with Brazilian Rosewood pegs (those were the days!). Two were fitted with extended wooden necks (small archlutes) - one of
these is currently being offered for sale on the Internet by the owner. The bowls have heavily fluted 'ribs'.
I may still have some images laying around somewhere so if I can find them I will post them for information just to show what can be achieved - but as
a separate topic - not on this thread!
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Aymara
Oud Junkie
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That would be great ... here we are too far off-topic right now.
Greetings from Germany
Chris
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