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Edward Powell
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well, according to the physics of it, I think it is pretty easy to see that with a fixed bridge there is more string tension directly applied to the
soundboard. The amount of tension that the tailpiece must sustain with a floating bridge is not insignificant.
but, one major difference, as you mentioned, is the DIRECTION of this tension. With a floating bridge, the force is directed DOWNWARD, whereas with a
fixed bridge it will TWIST the soundboard. How this changes the sound's character is something I would like to know more about.
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theodoropoulos
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as i have made some experiments with tap tuning i have seen that when i we increase the pressure in one part of a SB ,then the frequency there
raises.
So, i believe that we have more treble in the "soundcolour" of an instrument if we have more pressure in the bridge ....
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corridoio
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hi
anybody knows wich is the matematical formula to calculate the string tension in floating bridge models?
I used always arto's calculator mentioned several times here in the forum but I think it refers at classic glued bridge ouds, in floating bridge we
should have 2 different tensions to considerate, one between bridge and nut and one between bridge and tailpiece, right?
the 2 lenghts, the height of the bridge should be the elements (or maybe better the angle in case of angled soundboard in the bottom like some old
Fadel and also others ouds that share the same "mandolin" design)
thanks
Ale
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Edward Powell
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| Quote: | Originally posted by theodoropoulos
as i have made some experiments with tap tuning i have seen that when i we increase the pressure in one part of a SB ,then the frequency there
raises.
So, i believe that we have more treble in the "soundcolour" of an instrument if we have more pressure in the bridge .... |
sure! more tension/pressure means tighter wood which always results in more highs and less bass. Raise the tension of something and it's pitch goes
up --- like "bending" a string... raises the pitch.
on the otherhand, there needs to be sufficient pressure to "drive" the bass. There is a lot of talk about certain areas of the soundboard being
responsible for producing certain frequencies. My understanding is this:
-the top nylon is produced behind and near the bridge (the first brace)
-2nd nylon is around the bridge and the second brace
-first wound string is the entire area infront of the bridge up to the soundhole
-the remaining bass notes come from the entire soundboard pumping in totallity.
---keeping in mind that the first brace and the area around the bridge will ALWAYS be resonating, either with fundamentals (if you are playing very
high notes), or various harmonics.
---just my opinions
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theodoropoulos
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edward how did you find all these things??
has anyone mention that??
i believe that with the help of the stiffness of the braces we can modulate the frequency of each area.
it's not neccesary this correspondence you mention.But honestly i dont know ....
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Edward Powell
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i think in fact, it is obvious when you think logically about it. As you say, the stiffer something is, the higher it's frequency, so therefore the
area around the bridge and behind the bridge are the most stiff - so this is where the high frequencies predominate.
actually it was Faruk who first pointed this out to me --- THANKS FARUK! --- and the obviousness of it was immediately appearant although I had never
realised it before on my own.
simple logic also tells us that a high frequency only needs a very small/tiny area (look at a tweeter), midrange needs medium size areas, and deep
bass needs LARGE areas.
furthermore, the SOUND IS ROUND theory will apply to the oud --- the bridge being the center of the frequency circle, and therefore the larger and
larger the circles going out from the bridge will produce lower and lower frequencies - BUT since the oud's bridge is so close to the rear of the
soundboard, that means that the larger frequency "circles" are not complete circles - that are just "arches" from part of the circle - - - but anyway,
they go outwards AWAY from the bridge producing deeper and deeper frequencies the further you go out. Again this is logical because the further from
the bridge, the looser the soundboard and more space the soundboard has.
Finally to get DEEP bass obviously (!) is NOT concerned with any specific region of the soundboard but can only be produced by the WHOLE THING PUMPING
AIR. (look at a bass bin and reflect on that)
I remember one day sitting with Ramazan who was telling me the same thing, the each string has it's brace. We even tested this right there. I played
the top nylon and he put a tuning fork where the first brace is (behind the bridge), and tested other areas as well with the tuning fork.... sure
enough it was the first brace area that energised the tuning fork the most... same for the second string/second brace etc etc.... all the way to the
fourth string, but after that it didn't work because those lowest notes don't correspond to any small locality - obviously.
Again, I am not claiming to KNOW all of this --- they are just my opinions. Acoustics and luthiery are extremely complex subject, and nothing is ever
as simple and straightforward as we would like to guess 
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theodoropoulos
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all things you say make sense and seem very logical to me.
but we must not focus on 6 strings only,but to the whole range of frequencies.
for example,perhaps you mean that the area behind the bridge resonates in a range that involves the fist nylon string,AND NOT JUST THE NYLON STRING
ONLY.
anyway thanx for this very usefull info
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Edward Powell
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yes... that's it exactly! When you start with the very high notes you only get very high frequency resonance and this happens near and behind the
bridge... then when you play slightly lower notes the resonance area starts to more in front of the bridge - BUT THE HIGH FREQUENCY AREAS WILL STILL
BE ACTIVATED BY THE OVERTONES! Then as you play lower and lower notes to FUNDAMENTAL is generated further and further from the bridge (but again,
all the mid- and high- frequency areas will still be activated by the overtones of those low notes)
When finally you end with playing the oud's lowest note which excites the WHOLE KIT AND KIBUTL!
- - -
I wanted to share also my opinion about my understanding of Faruk's method:
Personally I have my own opinion about how and why Faruk's brace tuning system works so well. I also struggled for a very long time trying to
understand this - and also had many questions in my head, such as: how do these frequencies get 'untuned' by extraneous factors such as gluing on the
bridge, pick guard, and soundboard to sides etc.
I think that the main reason why people have a hard time understanding Faruk's method is because of this idea of "tuning" the braces to a specific
pitch. This TUNING TO A PITCH concept immediately sets our brains in motion thinking about musical notes and tunings etc and we find ourselves somehow
imagining the soundboard that is supposed to be like a xylophone or something and that if you tap one part you will get a C and a little bit higher
you will get an F... etc etc and that finally this leads us totally in the wrong direction of thinking - - -
The point is not at all about having specific pitches tuned into the soundboard - the point is about making optimum use of the very limited space
available on the soundboard in order to get ALL the desired frequencies represented in the desired proportions. This means that the strength/stiffness
of the soundboard must be distributed in the optimum way.
In my opinion Faruk's method offers him a way of measuring strength/stiffness very very accurately and scientifically. Most oud makers simply have
wood measurements to guide them - for example 1.8mm thick soundboard - first brace 10X5mm - second brace 12X5mm and so on. The better than average oud
maker will use these measurements as a starting point only, and then 'fine tune' using other methods such as flexing and/or voicing the soundboard.
Faruk's tuning (compound tuning to be more accurate) method allows him to guage very precisely the REAL strength properties of the soundboard area
around each brace. Because the resulting frequency characterises the REAL CRITERIA we need to know in order to judge that area's strength --- a simply
measurement of 5X10mm is a very rough guide because it is assuming that all wood shares the SAME stiffness properties, which is not true.
Faruk's method allows him to overcome and "read-thru" the differences in different wood's stiffnesses. Therefore determining the brace sizes according
to their compound frequency when coupled with the soundboard, truly gives you the REAL strength characteristics of a particular soundboard area. After
that it is only a question of experimentation to 'get to know' which combinations of "frequencies/strengths" will give WHAT result. Faruk has done so
many experiements and made so many ouds - and with each one he has a computer read-out sheet which reminds him of exactly what frequencies were tuned
into what areas. . . .
So after a while he knows what will be the result of even a tiny change to one single brace, and he is able to custom tailor the sound of each oud.
Only my opinions by the way.
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theodoropoulos
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overtones
as far as the overtones concerns,take a look at a FFT analysis of a brace tone.
As you see the highest pick corresponds to the resonant frequency of this brace .All the others are overtones.
Problem is that tuning one brace ,gets out of tune the other in the neighborhood.So,its very difficult to maintain all the target frequencies.
So,its important to tune the braces about 20 Hz upper in order to have this margin of correcting.
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farukturunz
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| Quote: | Originally posted by Edward Powell
Only my opinions by the way. |
Yes! Here is my sincere opinion:
I need to add neither a single period nor one comma to your explanation my friend. Of course there is no need to say that designations such as "brace
tuning" and "tuned soundboard" may be misleading in many cases. But if the real desire of someone is "to understand" what it is, truly, there is no
harm in it to cause to miss the whole point.
I neither presented my tecnique with some illusory definitions just like in a spot announcement "how to make magic braces" nor called my ouds'
soundboards as "incantation soundboards"
I just wanted to share something really working with the "oud world". Solely with a single condition I have always taught all my technique who ever
demanded. My single condition is this: To deserve my "secrets" one must be ready to grasp and apply it )
After some little joke I want to felicitate you for your vast apprehention, KURNAZ!!!
Congratulations. I am sure that you can make any wooden musical instrument perfectly) through a few experimental ones. Many may not accept this truth: Even without constructing a corporeal instrument, a "luthier" may be capable to
construct at least one insubstantial applicable method which is really perfect... many of the contemporanous theories of the Physiscs was and is made
in that way)... why should we put a condition in front of our ability of
imagination!
CHEERS!!!
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Edward Powell
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| Quote: | Originally posted by farukturunz
KURNAZ!!!
Congratulations. I am sure that you can make any wooden musical instrument perfectly) through a few experimental ones.
CHEERS!!! |
now if I could only figure out how to apply this method to my sarod/oud combo double-necks! 
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farukturunz
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| Quote: | Originally posted by Edward Powell
now if I could only figure out how to apply this method to my sarod/oud combo double-necks! |
Why should we put any condition in front of our ability of imagination!
I just suggest you imagine the most possible good sound of the sarod/oud combo double-necks within the limitations it has in its soundboard's physical
entity.
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Edward Powell
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yes... this is what I have been trying to do this last 9 months, ...the new one sounds completely different than the first two.
I just can't help but wonder if there might be a way to get more scientific as you have done with the oud. The problem with two instruments in one is
that it is not DEDICATED to just one sound - - - you must accommodate for BOTH somehow. This can be done to a certain degree, but there is this
"cross-over zone" in which the characteristics of both MUST be shared to a certain degree - even though each "instrument" has totally different tonal
requirements.
gotta think some more on this one
http://www.youtube.com/watch?v=_WPzBI4h0l4&feature=channel_page
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farukturunz
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| Quote: | Originally posted by Edward Powell
gotta think some more on this one
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It will not be in vain. Maybe you had better widen the oud side to be exactly the same width as an oud's soundboard.
Take it easy
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Ararat66
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Hey Edward
Maybe you are thinking too much I can almost see the steam coming out of your
ears ... what would your instinct tell you?? (BTW we have just got a cat)
Leon
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Edward Powell
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| Quote: | Originally posted by farukturunz
Maybe you had better widen the oud side to be exactly the same width as an oud's soundboard.
Take it easy |
Yes for sure this would bring out the oud's depth of low-mids... I really tried to do this on my new version, as you see the soundboard shape is no
longer symetrical --- it got "pregnant" on the oud side 
I used lattice bracing because this way I could 'taper' the strength gradually from the low-tension oud side - to the high-tension sarod side.
Also with the original design I was having serious ergonomic problems because the bridges were so far forward - with the new design the bridges are
right at the back and allow for very comfortable "wrist flapping" technique.
I didn't bring this axe with me to Cairo and before leaving Czech had only got thru about 90% of the voicing process. Already the oud part sounds MUCH
MUCH deeper and warmer! ...but it is too early to hear exactly the final result of this experiment, and therefore what exactly to do next on the
next one.
Here are some pics
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Edward Powell
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| Quote: | Originally posted by Ararat66
Hey Edward
Maybe you are thinking too much I can almost see the steam coming out of your
ears ... what would your instinct tell you?? (BTW we have just got a cat)
Leon |
Yes!
...and also to follow up on what Faruk was hinting at with his suggestion to simply IMAGINE the best possible sound.
In fact, during the building process I realised that I really did not want again to go thru this incredibly LONG process of building, and NOT end up
with the result I really want - which is A VERY DEEPLY AND BEAUTIFULLY RESONANT INSTRUMENT.
So I decided to use visualisation, and before sleeping every night I simply imagined the finished instrument in my hands giving incredibly resonant
tones... then I was surprisingly from time to time getting little pictures in my head of what to do---- it told me to DRAMATICALLY (!!!) reduce
the mass of the bracing that I had on there . . . and a few other good ideas, more difficult to explain.
the instrument now in fact does seem very resonant... but the final result will take a while to judge.
- - -
One of the stumbling points of this instrument is what kind of pick to use.... to get it sounding more like an oud it really needs a very soft
mizrab. And the sarod side likes a very hard pick (sarods use coconut shells!).
On the other hand - it is not my intention to imitate oud or sarod... otherwise why not just play oud/sarod. I am trying to come up with something new
- but if it doesn't sound great, then what will be the point. Of course oud/sarod is the inspiration.
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Edward Powell
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This would bring the oud soundboard size about as wide as a regular oud's...
what you think?
Does it make the instrument TOO big and bulky? Ungraceful looking?
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Edward Powell
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or this...
shows a much deeper cutaway for the sarod --- actually when I moved the bridges BACK this created a problem with the sarod of not being able to reach
the very very high notes which sound so great on a sarod... with this new cutaway design that problem is solved...
furthermore, as shown on the second pic, the oud side starts to actually take on the shape of an oud...
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Edward Powell
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Faruk, what is you opinion about the resulting sound when the oud's bridge is placed VERY far back and the first brace eliminated?
TESE KUR...!
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Edward Powell
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this extra WIDE body size would not affect oud side ergonomics since the instrument rests on the leg anyway - -
however the sarod side would now be very very high - - - but perhaps an AZERI TAR technique would suffice??
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