| Pages:
1
2 |
theodoropoulos
Oud Junkie
Posts: 177
Registered: 12-21-2008
Location: Greece
Member Is Offline
Mood: No Mood
|
|
brace location coincides with harmonics...
is it true that the braces location must not coincide with the location of the harmonic of a sting.????
i mean that if for a string's lenght of 60 cm the first harmonic is in the 20 cm for example....so we must not put a brace 20 cm away from the
bridge...is that correct???
|
|
|
Edward Powell
Oud Junkie
Posts: 1212
Registered: 1-20-2008
Member Is Offline
Mood: g'oud
|
|
Hi Theo
That is an interesting theory... where did you hear it?
I have never heard of such a theory but there might be some sense in it.
I think that in general you would not want the soundboard to have a definite strong pitch on exactly any note which for sure will be frequently
played because perhaps this might cause unpleasant sympathetic resonances (wolf notes) - and maybe you theory might connect with this theory, but as
Faruk always says: "to really know the answer you must TEST IT."
I wonder what Faruk would say to this question.
|
|
|
farukturunz
Oud Junkie
Posts: 569
Registered: 8-16-2005
Location: Istanbul, Turkey
Member Is Offline
Mood: hopeful
|
|
| Quote: | | Quote: | Originally posted by Edward Powell
Hi Theo
That is an interesting theory...
I wonder what Faruk would say to this question. |
I wonder what Faruk would say to this question. |
How could I stay silent while I'm invited to say something! I don't know should I thank you Eddi for your credence upon my thoughts in this issue;
although by some of the prestigious members of this forum I have been pushed to a great doubt dealing with the association between my theoretical
approach and the oud sound coming out as the result of my approach and the technique I apply to the soundboards of my ouds. May it (my ouds’ sound)
be controlled by a collective awareness or some powers(!) in my unconscious!
Thank you any way for your interest in what I am thinking on this issue. Let me start to my expositions with a generalization:
Every particular state of a body puts forward its specific conditions and represents a unique entity and all the physical phenomena in it take place
in accordance with the known physics laws but in a specific way which fits to the conditions acquired beforehand by the said unique entity. If you
make your brace locational pattern as an original one then this pattern determines the resonance areas pattern as a new model and this begets a new
harmonic composition in the sound.
The “ladder type bracing” divides the soundboard into areas whose ranges are different from the others through the difference in the distances
between the braces and the curvature of the soundboard. The stiffness of an area can be controlled and calibrated by changing the rigidity of the
braces confining that area. The “eigenfrequency” comes out as the derivative of the “stiffness”.
Once you make a template with the braces you determine the lines (the lines that the braces are glued) where the vibration will be the least… The
areas (not the braces) confined by the braces will vibrate but when and how?
When?
- When a frequency generated by the inciter vibration (any of the overtones of the vibrating string) happens to be identical with one of the
eigenfrequencies of that area, a vibration takes place(resonance).
How?
- Either together with the other areas scattered onto the soundboard or form into a line along all the area parallel to the braces. I posted some PNG
pictures showing vibrating areas on the soundboard (ıt was a soundboard vibration analysis made on ANSYS program) I am posting those PNGs once
more to capture attention on how one and the same area vibrates under different inciter frequencies.
- Of course, again we have to take into account all the other parameters that take place in the action like the soundboard material, thickness of it,
the heterogeneous character of the wood etc.
Every theoretical modeling can be denied by a better one just like every theory is accurate until a more accurate one is proposed.
|
|
|
farukturunz
Oud Junkie
Posts: 569
Registered: 8-16-2005
Location: Istanbul, Turkey
Member Is Offline
Mood: hopeful
|
|
I am posting those PNGs once more to capture attention on how one and the same area vibrates under different inciter frequencies.
The same area is vibrating under both a 146,634 Hz and a 881,652 Hz inciter frequencies.
|
|
|
farukturunz
Oud Junkie
Posts: 569
Registered: 8-16-2005
Location: Istanbul, Turkey
Member Is Offline
Mood: hopeful
|
|
| Quote: | Originally posted by farukturunz
Either together with the other areas scattered onto the soundboard |
All the vibrating points are scattered in the areas confined by the braces. There is very few slightly vibrating point just on the braces. Compared to
the majority of the area vibration their effect is minimum.
|
|
|
theodoropoulos
Oud Junkie
Posts: 177
Registered: 12-21-2008
Location: Greece
Member Is Offline
Mood: No Mood
|
|
hallo!!
edward in a greek forum called Rembetiko they mention it as a rule with no proof.....as a dogma.
Mr .Faruk its is my honour that i have an answer to my question,as i my opionion you are not just a luthier but a scientist.
As having studied Physics and have started m aking ouds this was my question with a doubtfull answer .
Having studied your answer i have some positions to mention.
1)i understand that every inciter frequency shifts the 3D shape of the plate (often resembles to that mexican hat.BUT there are no 7 areas-lines which
remain still IN MOST FREQUENCIES , in order to but the braces there...
2)if there where these 7 lines ,would it be correct to put there braces...as this is a zero point,which means it doesn't vibrate.
3)i have not understan and please forgive me Mr.Faruk..... the answer to my question, is yes or no???i mean that i see that in specific frequencies
there are determined some areas-lines but what is the relationship whith the harmonics????do we get those distances by a division of the string's
lenght???
4)i use in my construction the tap tuning method to tune my braces.Please give me your lights in this question....what are the target frequencies of
every brace??i mean the target are certain frequencies of the braces or just a harmonic relation between the frequencies of the braces...
thank you for your interest my friends ...
|
|
|
theodoropoulos
Oud Junkie
Posts: 177
Registered: 12-21-2008
Location: Greece
Member Is Offline
Mood: No Mood
|
|
tuning process
that' my tap tuning process
|
|
|
farukturunz
Oud Junkie
Posts: 569
Registered: 8-16-2005
Location: Istanbul, Turkey
Member Is Offline
Mood: hopeful
|
|
Congratulations my friend. It is a very well organized testing mechanism.
Of course I am not a scientist but a luthier who has smelled the scientific base of his work.
Let me try to give the answers to your questions in the original order:
1-These PNG pictures I’ve posted are only three of two hundred pictures. Of course some areas confined by some braces do not vibrate with the
Frequency Mode In Range. At the top left of all pictures a definition takes place like that: (x)th Frequency Mode In Range
Perhaps we should not assume all parts or all areas to vibrate with every frequencies. The braces are there but there is no vibration at that area!
True! This is what this analysis made by this engineering program is. We can only interpret but not demur it.
2- The seven lines are not there due to the pictures show those lines are there vice versa because the braces have been glued on some particular
lines, those lines are there. If I had put them in different places the vibration patterns or let me say in the terms used by the program: Frequency
Mode In Range would be different.
3- No! The answer to your question is “no”. Harmonics consist of the harmonic vibration of the strings. There is no proportional relationship
between the string length or its any fractional sizes and the soundboard’s physical features.
4- Target frequency of a brace is not a constant. You can change it by changing the material of the brace, using different wood whose densities are
different, changing their specific frequencies by several applicable ways. The reason I am dealing with the brace specific frequencies is at just this
very point: I am using a formula to determine the target frequency. I have made a data bank: I record every numeric and measurable features of the
ouds I make. Specific frequencies of the braces are some numerical values that function in the vibration movements of the vibrating areas, and I can
solely trust on some unchanging values. The metric sizes (hight, length, shape of a brace) does not give an unchanging calibration. Only by the help
of a statistical data I can anticipate the stiffness range of an area, I do not deal with the brace specific frequencies as a consequent target. I
need to know the stiffness of the braces (or the frequencies of them) but by means of this information I try to anticipate the stiffness (or specific
frequencies=eigenfrequencies) of the areas. In practice I design the soundboard with its braces’ specific frequencies. Then I prepare and glue the
braces on the soundboard. After all I tap on the areas enclosed by those braces. Because the vibration takes place there.
With my sincere respects.
[file]8740[/file]
|
|
|
farukturunz
Oud Junkie
Posts: 569
Registered: 8-16-2005
Location: Istanbul, Turkey
Member Is Offline
Mood: hopeful
|
|
| Quote: | Originally posted by farukturunz
I am posting those PNGs once more to capture attention on how one and the same area vibrates under different inciter frequencies.
The same area is vibrating under both a 146,634 Hz and a 881,652 Hz inciter frequencies. |
I should add this:
881.652 Hz has a diversion from 880Hz at the range of %0,18 that means 18 over 10.000 so we can accept it as the fourth overtone (harmonic) of
A2=110Hz, third harmonic of A3=220Hz and the second harmonics of A4=440Hz.
The harmonics rather than the fundamental frequencies are in the scene.
|
|
|
theodoropoulos
Oud Junkie
Posts: 177
Registered: 12-21-2008
Location: Greece
Member Is Offline
Mood: No Mood
|
|
dear Mr.Faruk its my honour that you reply to my questions...As i read more your reply ,i want more and more to discuss with such lovely and experts
like you,
I have read all your presentetions ,your mathematical formulas and i try to see them in my experiments.
As i read your replies its been generated a question..What is the distribution of frequencies you plan for an excellent soundboard??Which areas are
apropriate to uphold certain frequencies?
and one last thing..There is much difference from theory to practise.If i tune the sound board excellent (well balanced) and glue it on the bowl and
string it the tuned frequencies change.....
So,as i have constructed the tuning mechanism i did not estimated the stress of the strings.An area counted befor stringing the oud was for example
184 Hz and after gluing and stringing raised up to 220 Hz.
how do you measure your brace's frequencies..?The soundboard free??secured around as mine without string stress???secured around with
stress????how??
with all these i mean that how can we be sure that our frequencies will remain the same after the final set up??
with my best regards and great respect
Dimitris Theodoropoulos
|
|
|
Edward Powell
Oud Junkie
Posts: 1212
Registered: 1-20-2008
Member Is Offline
Mood: g'oud
|
|
| Quote: | | Originally posted by theodoropoulosThere is much difference from theory to practise.If i tune the sound board excellent (well balanced) and
glue it on the bowl and string it the tuned frequencies change..... |
This is something I have also wondered about a lot.
My guess is, and what I think Faruk tried to explain to me is that by tuning the SB and the braces to a series of compatible pitches which will spread
over the ideal range consistently what you end up with is a BALANCED soundboard - which finally is the ultimate goal.
It seems that it is the BALANCE (relative) that is the desired result - not specific frequencies. Afterall we do not want any specific and strongly
individual frequencies represented on the soundboard - we want a BALANCED SMOOTH RANGE, right? If we have a strong specific frequency this will cause
some pitches to have unpleasant sympathetic resonances, while other pitches (far from that tuned pitch) will be weak...
...Anyway, this is my current understanding....
|
|
|
Ararat66
Oud Junkie
Posts: 1025
Registered: 11-14-2005
Location: Portsmouth, UK
Member Is Offline
Mood: mellow yellow
|
|
Hello Faruk and the others
Have you ever tried other bracing patterns on ouds such as those found on guitar such as fan bracing or 'X' bracing. I have a very wonderful handmade
acoustic guitar by an English luthier called Nick Marchant with a very unusual bracing pattern - somewhere between fan and 'X' but with very shallow
thicknesses.
I know the old Gibson mandolins and probably guitars, tuned by Lloyd Loar were tuned using C256 as reference making A to be 430.6 Hz instead of 440 Hz
as is concert pitch for A now. Apparently this quarter tone difference created an amazing and unique sound and 'colour' to the instrument when tuned
to A440 ... and luthiers still copy this.
There is also the problem of 'wolf' notes that occur as a result of sympathetic frequencies within the air chamber of the instrument. The quarter
tone difference was beneficial in the case of these old Gibsons but could potentially be a sonic disaster in other instruments causing interference
patterns that set up oscillations throughout the instrument that could be pretty hard on the ears (and possibly even the instrument).
There are some really interesting books on this subject by Roger H. Siminoff.
I don't have the hands-on experience of a luthier but have seriously thought about taking the plunge so I find the subject and your collective
expertise fascinating.
Leon 
|
|
|
Edward Powell
Oud Junkie
Posts: 1212
Registered: 1-20-2008
Member Is Offline
Mood: g'oud
|
|
I build an oud (first I ever built) with an X bracing. I had just heard that X was "ultimate" so I gave it a try...
The background tune of this clip used this oud (a tune called SUDAN, from you CD "Spiritdance").
|
|
|
theodoropoulos
Oud Junkie
Posts: 177
Registered: 12-21-2008
Location: Greece
Member Is Offline
Mood: No Mood
|
|
ararat ,
all things i mention are based on Siminoff methods of tuning,but all things that i ask Mr. Faruk are not explained in details in his book.It's a good
book for beginning but it does not has a purpose....Just says how he tunes them .Good for starting!!!!
in Greece all luthiers i have asked about tap tuning noone uses this method.All work by experience or i don't know.
they don't admit that it works....
sad but true...
|
|
|
WFBustard
Oud Addict
Posts: 31
Registered: 3-7-2009
Member Is Offline
Mood: No Mood
|
|
HI folks, this is just my first or second post here. I have been checking in to learn about Ouds and decided to get involved in the site.
I am an experienced luthier and from my experience with designing over 100 instruments -
-No, the placing of braces while in some instance may help to contirbute to a faulty tone or 2 but most often it doesnt matter.
The bracing is there to prevent the top ffrom collapsing.
Now Ouds are different and Ive never built one, they have many braces whereas Ive only ever used 2 or 3 on my various mandos, bouszkis, & viheulas
and guitars.
I beleive that too many braces increase the chance for the deterioration of precise tone and sustain.
But thats just my opinion. Tap tuning can come into play to rectify any inherent unwanted distortions caused by bracing.
Im going to try an Oud soon...I have the wood.
|
|
|
spyrosc
Oud Junkie
Posts: 405
Registered: 9-18-2003
Location: Northern California, USA
Member Is Offline
Mood: Grateful
|
|
Kyrie Theodoropoule,
Tha eimai stin Ellada ton Iounio kai tha eithela na sas synantiso, eho kapoies idees gia to thema sas pou mporei na sas endiaferoun.
Steilte mou email i U2U
Euharisto
Spyros C.
|
|
|
Luttgutt
Oud Junkie
Posts: 578
Registered: 1-10-2009
Location: Norway
Member Is Offline
Mood: Curious
|
|
Hi to all!
Wanderful that you share your knowledge with us!
WFbustard,
Very nice to hear that you want to try to build a oud! Jamell Khalaf have a wanderful step by step guidence to oud making!
Another thing you might be aware of, is that in Oud, unlike buzuki, mandolas, guitar etc. the traditional oud bridge is built such that all the
tention is LATERAL. So that braces role might be different. And my guess is that is why the braces are deep in the oud. They are there to insure
sustaine. not just to protect the sound board.
P.S. I am in no way an expert, and I don't make ouds. And I might be wrong in what I wrote. But I thought you should anyway NOTICE the difference in
the bridge structure :-)
So my question to Mr. Turunz and Mr. Jameel (and others:-)
- Do you think it is necessary to have deep braces in "floating" bridge ouds?
- And shouldn't the braces on such oud be designed defferently from the standard oud?
With all respect, admiration and best regards
|
|
|
theodoropoulos
Oud Junkie
Posts: 177
Registered: 12-21-2008
Location: Greece
Member Is Offline
Mood: No Mood
|
|
spyrosc,
to mail mou einai shadowsdance@iname.com
den ta katafera me u2u na steilw .perimenw nea.menw kriti kai 8a itan megali mou xara na bre8oume kai na ta poume apo konta!!!!!!!
|
|
|
WFBustard
Oud Addict
Posts: 31
Registered: 3-7-2009
Member Is Offline
Mood: No Mood
|
|
Thanks to you Luttgut I am sure of my ignorance of such matters.
I do beleive that I must do more research on oud construction, I was thinking I would just build a lute and put a different neck set up on it. A kind
of off the cuff, but I can see that there is more to ouds than meets the ear.
I will investigate further-
thanks for the comment
cheers-
|
|
|
farukturunz
Oud Junkie
Posts: 569
Registered: 8-16-2005
Location: Istanbul, Turkey
Member Is Offline
Mood: hopeful
|
|
| Quote: |
So my question to Mr. Turunz and Mr. Jameel (and others:-)
- Do you think it is necessary to have deep braces in "floating" bridge ouds?
- And shouldn't the braces on such oud be designed defferently from the standard oud?
|
Floating bridge ouds must have the typical sound of its kind, I believe. For any other reasons such as appearance only, for instance, do you want to
obtain it? Of course some may want
Sound is characterized and determined by the bracing predominantly.
|
|
|
Luttgutt
Oud Junkie
Posts: 578
Registered: 1-10-2009
Location: Norway
Member Is Offline
Mood: Curious
|
|
Well, I am not interrested in floating bridge ouds as such, but I am curious from the scientific point of view :-)
To my knowledge (and please correct me if I am wrong) floating bridge oud makers use the same bracing technique as the fixed bridge ouds (maybe with
some modification to make the face stronger), but it is still the same bracing place and shape. And I was wandering wether they should be
experimenting with other structures that could fit better to that kind. Because I believe that the two kinds of ouds vibrates in a different way! Am I
wrong?
P.S. Thank you for answering, Mr. Faruk.
|
|
|
Edward Powell
Oud Junkie
Posts: 1212
Registered: 1-20-2008
Member Is Offline
Mood: g'oud
|
|
anyway, one thing must be pointed out and that the bracing on a floating bridge oud must NOT be heavier than a fixed bridge soundboard - it must be
lighter. The reason is that with a fixed bridge the pull of the strings is absoluted direct on the soundboard and therefore stresses the soundboard
much more than a floating bridge.
in order for a floating bridge to DRIVE the soundboard enough (and on an oud the string angle from tail to bridge-saddle is not sharp - which
compounds the problem) the bracing must be made even lighter.
i have never seen a floating bridge oud being braced but the other day I saw a braced soundboard which looked completely normal except the 2nd brace
was totally absent! I wondered about that, then concluded that it must be for a floating bridge oud.
anything with a floating bridge needs to be braced LIGHT as possible, as opposed to a fixed bridge - and the angle from the heal to bridge should be
as great as possible (within reason).
|
|
|
theodoropoulos
Oud Junkie
Posts: 177
Registered: 12-21-2008
Location: Greece
Member Is Offline
Mood: No Mood
|
|
in fixed bridges there is a torque which tends to lift the soundboard with an angle.in a way it moves part right and another left..In floating
bridges the stings push down the strings.I dont know where is more stress but i dont see reason of high depth in braces.Maybe they must be more strong
by adding width...
|
|
|
Edward Powell
Oud Junkie
Posts: 1212
Registered: 1-20-2008
Member Is Offline
Mood: g'oud
|
|
well, it is pretty obvious that a fixed bridge puts more tension on the soundboard, simply because 100% of the strings stress is attached directly to
it. On a floating bridge much of the strings tension is absorbed at the tail where the strings are attached - therefore only a part of the tension
gets transfered to the soundboard - therefore the bracing must be much lighter in order for it to respond.
|
|
|
theodoropoulos
Oud Junkie
Posts: 177
Registered: 12-21-2008
Location: Greece
Member Is Offline
Mood: No Mood
|
|
edward
i dont think you are right...the part of the string from the bridge to the tail is very small and needs much energy to resonate.I think only in high
frequencies we have this transfer of energy....Of course we have a small transfer of energy as a loss but i think it's not worth to mention...
it'smy opinion...
|
|
|
| Pages:
1
2 |
![[*]](images/xmbprobrown/default_icon.gif){kind=icon}
