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jdowning
Oud Junkie
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Impossible to judge isn't it?
Like you fernandraynaud I have never before heard the 'characteristic timbre' of an early design of fretted oud fully strung in silk (as was past
practice in earlier times prior to the 19th C).
To my knowledge there is no historical record that positively confirms silk strings were used on the European lute either (although gut strings get a
mention). Nevertheless, those of us who have been involved in 'hands' on research into historical silk strings (and do know what a lute fully strung
in silk actually sounds like) have our theories!
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jdowning
Oud Junkie
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After about a week at maximum pitch (Hadd @g' A440) during a period of fluctuating humidity, the core of one of the matched 4th strings (Mathlath),
for some unknown reason, broke at a point mid way into the peg box (about 6 cm from the nut). This was 'repaired' by tying a reef knot to rejoin the
string and has continued to give good service at a semitone lower pitch for another week or so until it failed again - this time at the nut - probably
because of the previous damage to the core. So far the other string remains in good order.
I have two other similar (used) 4th strings available so will test these alongside the surviving string for comparison.
Otherwise, the strings have proven to be quite stable in conditions of high and fluctuating humidity. One thing to note is that as silk strings
(unlike modern plastic strings) have only a small amount of 'stretch' when placed under tension, the tuning pegs on a silk strung instrument should be
made as small a diameter as is practical in order to minimise tuning sensitivity.
The oud will be used as a test bed for other silk strings of varying construction - as they become available.
I am encouraged by the response and tonal 'colour' and balance of this instrument with all silk stringing. When it was first strung with modern
plastic/ wire wound strings though I did have some doubts.
So now that the oud is not destined to become a decorative conversation piece I can proceed with making an 'authentic' protective case for it as time
permits.
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jdowning
Oud Junkie
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Apologies everyone - the audio clip previously posted is not that of the oud fully strung in silk but of one of my experimental Hadd strings on a
lute! That post has been edited but here again is the correct file.
This clip demonstrates the full range from the open Bamm (bass) string as far as the Hadd (treble) at the 7th fret position (at the neck joint).
String length 56 cm.
Attachment: Old Oud Silk String AudioTest 1.mp3 (314kB)
This file has been downloaded 693 times
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jdowning
Oud Junkie
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For the record, the audible response of the silk strings has been measured as
6 seconds.
This compares with 14 seconds on a lute fitted with Pyramid lute strings (PVF and metal over spun basses). Nevertheless, I consider this to be a good
performance first time around - especially for the thicker strings. I anticipate hearing a considerably enhanced sustain once I get around to making
some silk strings that are 'weighted' with adsorbed salts.
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jdowning
Oud Junkie
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For information, both treble Hadd strings broke overnight under 'heat wave' conditions of high humidity and temperature. The strings had been tuned
open to
f' sharp plus about 10 cents and broke not at the usual potential high stress positions (nut or bridge) but one at the 3rd fret (abrasion wear?) and
the other
23 cm from the bridge (material flaw?).
This is not unexpected. Unpredictable breakage - even under ideal conditions - is a well known feature of using both gut and silk top strings.
To improve top string longevity the first step is to drop the instrument pitch a little (say by a quarter tone) to reduce string stress - but not too
much as the consequent lowering of string tension can result in loss of acoustic performance of the bass strings.
Another step will be to review string construction - degree of twist, effectiveness of the binder etc. These aspect will later be examined as part of
the research topic on this forum 'Silk Strings - Making Sense of the Historical Data'
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jdowning
Oud Junkie
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The broken pieces of the Hadd strings have been subject to testing to determine the breaking load and stress - useful information in order to
establish optimum string design.
The broken string pieces were subject to a straight pull using a simple spring balance to apply a loading. The spring balance is not a very precise
piece of equipment so was calibrated (approximately) using standard weights from a commercial grocer's scale.
After several tests, the average breaking load was established at about 5 Kg (11 lbs).
The string diameter is 0.43 mm which gives a calculated breaking stress of about 35 Kg/sq. mm. (49,000 p.s.i.)
Interestingly this is about the same as the breaking stress for gut trebles of the 16th and 17th C (average value
34 Kg/ sq. mm. - source Mimmo Peruffo, 'The Lute in its Historical Reality').
Using the Mersenne-Taylor Law, if the strings were raised to a pitch of a' sharp @ A440 (frequency 466 Hz) the strings would be above breaking load
(5.24 Kg). Practically (historical experience), the pitch of the trebles should be set at about
2 -3 semitones below this theoretical value (for gut strings at least) in order to avoid frequent string breakage. This practical rule of thumb would
bring the maximum working pitch of the Hadd strings to a bit less than g' @ A440 (392 Hz).
So f' sharp @ A440 (370 Hz) should also be about the optimum pitch for the silk Hadd strings.
The degree of twist of the silk filaments in string construction affects the ultimate strength of a string - the smaller the angle of twist (low
twist) the greater the breaking load and ultimate breaking stress. The attached macro image of the Hadd strings indicates a twist angle of about 30
degrees. Further reduction of this degree of twist (consistent with producing a uniform cylindrical string) would produce a string of higher tensile
strength.
String durability will also depend upon the abrasion resistance of a string - as individual filament are broken by the action of a mizrab or risha -
or by localised wear on a fret - then the strength of a string is reduced accordingly.
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danyel
Oud Addict
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cf: http://www.mikeouds.com/messageboard/viewthread.php?tid=10010&p...
The Kitâb al-adwâr illustration on which this oud appears to be based is found in Ms. Oxford, Bodleian Library, Marsh 521. it is dated 734 H = 1334
CE, 40 years after Urmawî’s death. It is entitled "Sifat al-’ûd" (characteristic/attributes of the oud). Its geometry is simplified.
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jdowning
Oud Junkie
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Thank you danyel. Yes I was aware that the illustration was in the Bodleian Library copy and that the illustration was a later addition around 1334
AD. No matter it is the only accurate representation of a 14th C oud.
As you are new to this forum and to save me going over old ground again I would refer you to this topic that precedes this Urmawi oud project.
http://www.mikeouds.com/messageboard/viewthread.php?tid=7745#pid485...
Note that the drawing - apart from the pegbox representation - is an accurate representation of the geometry made by the scribe (or engraver) using
compasses to define the geometrical outline - just as an early oud or lute maker would have done to lay out the design of an oud or lute. It is
clearly not some kind of freehand drawing as found in the early Persian miniature paintings.
Note also that the geometry is replicated in the mid 15th C drawing of a lute and its bracing layout by Arnault de Zwolle.
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FAYSSAL
Oud Admirer
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hi.
please if any one know the high between the nut and the neck for floating bridge oud thankyou
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