How tight should a sound post be

[LCF]

7 hours ago, Dr. Mark said:

Maybe this: Someone may have noticed that a sound board coupled to vibrating strings is louder and resonates in a pleasant way .

It's only a short step from the prototypical stringed instrument, an archery bow, to finding that, while supporting one end on a convenient fallen log, the increase in sound power of the release scares off the prey. That leads in short order to something like the Egyptian naviform harp where one end of the bow is attached directly to a skin head stretched over a carved box, with multiple bowstrings.  In 1400 BC we have this remarkable ensemble of harp plus long neck lute plus reeds plus lyre played with a plectrum, all the prototypes. And dancing girls. But no sound post yet.

https://www.metmuseum.org/art/collection/search/557727

 

The Germanic lyre --- there are tuning pegs, thicknessed soundboard, maple construction, high modern looking bridge, probably some sort of floating tailpiece arrangement, and typically horsehair strings acvordung to some sources. It was so close to being bowed and needing a soundpost that as soon as the idea of bowing arrived it turned into the northern bowed lyre.

 

[Chris Anderson, PhD]

5 hours ago, martin swan said:

Of course, but that's an effect not a function.

I suppose I'm questioning the way a modern scientific mind attempts to quantify and sytematize soundpost adjustment, starting from the (false) premise that tonal balance and response are somehow a function of the post rather than a by-product.

I don't believe that changes in post position have predictable or reliably measurable or perceptible results across different instruments.

Do you mean - moving a post from one instrument to another? 

I recently had to do this because of the precise situation provided.  I had moved my daughter's soundpost on her violin (we call him 'Arthur') southward to give her a warmer tone - which was working great until she evolved and was called out in a clinic by the orchestra director - "Bring your violin to a Luthier and get the sound post adjusted, you're too quiet and sounding dull!".  (I called her clinician an unbecoming and inappropriate word...)

So I moved the post back to the optimum position and the difference in volume was perciptible by our ears (so around 3 - 6db).  I did not take measurements of the volume difference.  Perhaps my 'conventional wisdom' isn't always applicable (Sound simply can't be saved on a VSO or a low-quality hardwood instrument -  you have to have 'enough' broad frequency acoustical performance from the instrument to tell the difference - or you are turning a knob that does nothing). 

Let me give you an electrical engineering comparison.  Maximum power transfer occurs at a consistent transmission line impedance (50 Ohms is 'perfect').  This impedance is frequency dependent - as some frequencies (and harmonics) will transfer in different proportions.  My moving the post position further away from the foot of the bridge, you introduce a frequency-dependent impedance mismatch between the top and bottom plates.  Higher or lower frequencies (and their harmonics) will transmit more/less power as a result of this mismatch - depending upon the position.  This is probably why the post isn't RIGHT UNDER the bridge - because the acoustical energy transfer is maximized from the top plate to the bottom plate - and human ears don't like the way it sounds... The 'antenna' that is your ear is much more subjective than electrical engineering systems regarding power transfer.  

Tonal balance may be a 'by-product' of the position - but the human ear cares not for science: but beautiful music. 

'Meat sacks gonna meat sack'.

-Chris Anderson  

[Mark Norfleet]

5 hours ago, Chris Anderson, PhD said:

So I moved the post back to the optimum position…

Can you please share where that is?!  I’ve been looking for it for over 50 years and have yet to find it.

[VicM]

9 hours ago, Chris Anderson, PhD said:

Let me give you an electrical engineering comparison.  Maximum power transfer occurs at a consistent transmission line impedance (50 Ohms is 'perfect').  This impedance is frequency dependent - as some frequencies (and harmonics) will transfer in different proportions.  My moving the post position further away from the foot of the bridge, you introduce a frequency-dependent impedance mismatch between the top and bottom plates.  Higher or lower frequencies (and their harmonics) will transmit more/less power as a result of this mismatch - depending upon the position.  This is probably why the post isn't RIGHT UNDER the bridge - because the acoustical energy transfer is maximized from the top plate to the bottom plate - and human ears don't like the way it sounds... The 'antenna' that is your ear is much more subjective than electrical engineering systems regarding power transfer.  

Let me give you an electrical engineering comparison.

Electrical and mechanical impedances do not "compare" directly. 

 Maximum power transfer occurs at a consistent transmission line impedance (50 Ohms is 'perfect').  

Nope. Max power transfer occurs when the impedance of the load matches the source. Transmission line matching results in no reflections. In theory.

This impedance is frequency dependent - as some frequencies (and harmonics) will transfer in different proportions.

The idea of a transmission line is that the resistance and shunt conductance are much smaller than the inductive impedance and shunt capacitance i.e. the imaginary component vanishes. The characteristic impedance does not depend of frequency. In theory.

 My moving the post position further away from the foot of the bridge, you introduce a frequency-dependent impedance mismatch between the top and bottom plates.

The impedance mismatch is always there. You might add or subtract to it.

 Higher or lower frequencies (and their harmonics) will transmit more/less power as a result of this mismatch - depending upon the position.

Transmit where ????

 This is probably why the post isn't RIGHT UNDER the bridge - because the acoustical energy transfer is maximized from the top plate to the bottom plate - and human ears don't like the way it sounds...

Sometimes it is right under the bridge and human ears like how it sounds. Sometimes is not straight - needs to be tilted to do it's job satisfactorily.

The 'antenna' that is your ear is much more subjective than electrical engineering systems regarding power transfer.

What does that mean ??

[VicM]

4 hours ago, Mark Norfleet said:

Can you please share where that is?!  I’ve been looking for it for over 50 years and have yet to find it.

What do you hope the soundpost will do when in "optimum position" ?

[HoGo]

On 10/29/2024 at 9:06 PM, Marty Kasprzyk said:

Attached is a photo of an experimental  light weight adjustable soundpost.  It was taken from the attached dissertation "The Mechanics of the Soundpost in the Violin" by Myles Nadarajah written in 2018.  See Section 7.4 "Experiments with an adjustable soundpost" on page 165.

also see Section 3.5.1 "The effect of adding mass" (to the soundpost) 

 

I wouldn´t want that screwhead to touch top of my fiddle.

[Marty Kasprzyk]

34 minutes ago, HoGo said:

I wouldn´t want that screwhead to touch top of my fiddle.

Nadarajah wrote his PhD dissertation back in 2018 which summarized his work which probably took several years to complete. The Anima Nova screw adjustable soundpost was introduced in 2017 and Nadarajah might have used it instead of his own experimental screw adjustable soundpost had it been available earlier.

I witnessed some soundpost length experiments done at an Oberlin Acoustics Workshop back in 2018 using the Anima Nova soundpost and my impression was each violin has its own optimum soundpost length and that the Anima Nova was great for screwing around.  

Attached is a an old Maestronet discussion.

 

[Chris Anderson, PhD]

I'll respond to the first question by Mr. Norfleet

15 hours ago, Chris Anderson, PhD said:

So I moved the post back to the optimum position…

Can you please share where that is?!  I’ve been looking for it for over 50 years and have yet to find it.

CA: I am unsure if you are making a joke - but for the sake of those who may not be aware, the 'optimum position' when placing the soundpost is normally centered south of the right foot of the bridge (which is placed correctly between the f holes) and about 1.5 - 2mm below, edge to edge. (to quote Edgar Russ).  From here, slight adjustments can be made by loosening the smaller strings, modifying the post position by tapping it with that "funny s-shaped metal stick", re-tightening the strings and bowing all strings again.  Repeat until the volume/tone combination is satisfactory for the player.  Each instrument has slightly different construction - and so this position is modified to optimize volume balance between strings, overall instrument volume, and frequency response. You *CAN put the sound post next to the left bridge foot - but the orchestra director gives it back and says 'please try again'. 

 

Let me give you an electrical engineering comparison.

Electrical and mechanical impedances do not "compare" directly. 

CA: Why? Their units are ' A Force / fundamental unit / second'. Electrical impedance is V/A = Volts (electro-motive force)/Coulomb/second) and acoustical impedance is 'Pascals/ meter /second'. Acoustical impedance correlates directly in the solution to its differential equations.  Both are fundamentally governed by the 'Wave equation' and have various contributions of waves and harmonics at a combination of frequencies. Seems a bold statement when the mathematical theory is nearly identical.  I started walking through "The Acoustics of the Violin" - a heavy math Physics textbook  - and got just far enough to realize - 'I've read all this already...' I would recommend it if you *REALLY want to dive into the mathematical modeling.  Personally, I got bored.  

 Maximum power transfer occurs at a consistent transmission line impedance (50 Ohms is 'perfect').  

Nope. Max power transfer occurs when the impedance of the load matches the source. Transmission line matching results in no reflections. In theory.

CA: Agreed - I mis-spoke.  My apologies. In EE, 50 Ohms is nominal for wave transfer and a realistic, obtainable value for impedance as a result of native cable geometries and materials.  (Like - old TV Coaxial cable  is '75 Ohm' impedance... today, most high frequency transmission lines are designed for 50 ohms).  

This impedance is frequency dependent - as some frequencies (and harmonics) will transfer in different proportions.

The idea of a transmission line is that the resistance and shunt conductance are much smaller than the inductive impedance and shunt capacitance i.e. the imaginary component vanishes. The characteristic impedance does not depend of frequency. In theory.

CA: Acoustic impedance still has inductive and capacitive parts.  True enough -  'characteristic impedance' does not depend upon frequency.  However, most transmission lines (whether for power or any frequency) are not ideal at all frequencies.  This is the same for acoustical impedance, which has a complex value in the frequency domain.  These problems are solvable with simple geometries using computer FEM solvers - however, violins are by-no-means simple in their constituent parts, materials, nor in their geometries.  Perhaps moving the sound post is akin to 'bending the coat-hanger on the old television'. VSA actually did a paper for FEM solving on Violin/Cello bridges that is fascinating.  Even such a small piece of the instrument creates a VERY complicated math problem.  

 My moving the post position further away from the foot of the bridge, you introduce a frequency-dependent impedance mismatch between the top and bottom plates.

The impedance mismatch is always there. You might add or subtract to it.

CA: Correct.   

 Higher or lower frequencies (and their harmonics) will transmit more/less power as a result of this mismatch - depending upon the position.

Transmit where ????

CA: Transmit from the vibrating string, transversly from the top of the bridge to the bridge feet, through the top plate, down the sound post (and through the air-filled body) and induce vibration in the bottom plate. Since waves do not change direction without reflection and power loss, and the waves of different frequencies are interacting all together - adding and subtracting to one another, even a slight change in geometry can realize a frequency-dependent change in acoustical output.  (FYI - old Navy guys "tune" the rectangular waveguides for the ship Radar systems by adding dents to the metal walls with a hammer -  *bong!* "Larry! do we have 25db yet?".  These 'transmission lines' look like AC air ducts.. ) 

 This is probably why the post isn't RIGHT UNDER the bridge - because the acoustical energy transfer is maximized from the top plate to the bottom plate - and human ears don't like the way it sounds...

Sometimes it is right under the bridge and human ears like how it sounds. Sometimes is not straight - needs to be tilted to do it's job satisfactorily.

CA: I cannot comment here.  I would welcome Luthiers with more experience than me on whether they have found a sound post that is 'directly under' or 'North of' the bridge foot. I have yet to find a Luthier book that recommends this as an acceptable position.  If so, I would imagine the f-hole placement relative to the body might be slightly different from tradition?  I'm afraid that most of the instruments I've worked on have had fallen sound posts. 

The 'antenna' that is your ear is much more subjective than electrical engineering systems regarding power transfer.

What does that mean ??

CA: It means the 'tone' as we hear it is not purely scientific.  If you have seen a violin output through a microphone, it is a rather random looking jumbled combination of frequencies.  True - you can pick out the 1st order, 2nd order and 5th order mode peaks.  These peak mode frequencies move around and are used as guides for many Luthiers to match resonance between the top and bottom plates. John Mangum in this video gives the most 'practical' explanation of this evaluation that I have found.  "Tone" also has a fair amount of subjective nature - what sounds nice to one person is not the same as another.  And not all people who like violin like the same tone("fiddles" vs "classical violin").  You, as a listener, are hearing a different combination of vibrations than what the violin is producing, which sounds different from what the player is hearing, which will sound different to someone listening across the auditorium.  If we are using the 'Electrical Engineering' comparison - the violin is producing a signal which travels through the air, inducing a similar vibration in the bones in your ears, which your nervous system translates into sound.  In that way - it is the 'receiving antenna' of the signal.  I have heard stories that the classical Cremonese instruments can sound a bit 'harsh' and 'loud' in the ear of the player - but soften as they travel through the air to the hearers apart from the Orchestra.  Several professionals have observed this phenomena - which means that 'something' in the characteristics of the sound is changing. I hope that helps...  

Wonderful discussion.  

Thank you!

-Chris Anderson 

 

 

[LCF]

The idea of "mechanical circuits", of sketching simpler mechanical systems via the same types of mesh/node diagrams as we use for electrical circuits, is very useful. ( see J.C.  Schelling," the Violin as a Circuit", or his paper on the soundpost.) But acoustical circuits are different from mechanical circuits. They can be inter-related to each other, but some aspects of both are extremely subtle. AC electrical circuits are also extremely subtle eg filter design about which many weighty tomes have been written, and that's the tip of the iceberg as far as modelling violins is concerned. 

Acoustical and mechanical circuits and impedances do not have 'inductance and capacitance', they just use those symbols and principles. However, to confuse matters it is possible to write them in two forms which are dual to each other- force as voltage (resistive model) or force as current (conductance model) --- alternatively pressure as voltage, and so on. 

The only area of violin studies where the concepts of transmission lines, the "Telegraphist's Equations" are useful is with respect to strings. 

[David Burgess]

23 hours ago, Chris Anderson, PhD said:

So I moved the post back to the optimum position

 

18 hours ago, Mark Norfleet said:

Can you please share where that is?!  I’ve been looking for it for over 50 years and have yet to find it.

Chris, it appears that you have your electrical engineering metaphors, and maybe some theories derived from possibly sketchy (though prolific) internet posters, and maybe some experimental sample sizes of around one, but almost nothing in violin training or experience.

Norfleet is far from stupid.  I consider him to be among the best in our business, so it might be better to listen up than argue.

[VicM]

1 hour ago, Chris Anderson, PhD said:

but for the sake of those who may not be aware, the 'optimum position' when placing the soundpost is normally centered south of the right foot of the bridge (which is placed correctly between the f holes) and about 1.5 - 2mm below, edge to edge. (to quote Edgar Russ).

Just call it "standard position".

[Chris Anderson, PhD]

31 minutes ago, David Burgess said:

 

Chris, it appears that you have your electrical engineering metaphors, and maybe some theories derived from possibly sketchy (though prolific) internet posters, but almost nothing in violin training or experience.

Norfleet is far from stupid.  I consider him to be among the best in our business, so it might be better to listen up than argue.

Mr. Burgess - I never presumed anything wrt Mr. Norfleet.  Nor did I say so. I honestly did not understand if his comment was one of derision or earnestly seeking information.  I don't even know if I was 'arguing' with Mr. Norfleet. And if I insulted anybody in my tone, I apologize - it was not my intent. 

I have nothing to prove here - just trying to be helpful. But if you have some specific interpretation or insight on how the position of the soundpost might affect the sound produced by the violin from your practical expertise - I would welcome the information and edit my post to correct any misinformation. 

 

Mr. Norfleet - if I came across as disrespectful - I earnestly apologize.  

-Chris 

1 hour ago, LCF said:

The idea of "mechanical circuits", of sketching simpler mechanical systems via the same types of mesh/node diagrams as we use for electrical circuits, is very useful. ( see J.C.  Schelling," the Violin as a Circuit", or his paper on the soundpost.) But acoustical circuits are different from mechanical circuits. They can be inter-related to each other, but some aspects of both are extremely subtle. AC electrical circuits are also extremely subtle eg filter design about which many weighty tomes have been written, and that's the tip of the iceberg as far as modelling violins is concerned. 

Acoustical and mechanical circuits and impedances do not have 'inductance and capacitance', they just use those symbols and principles. However, to confuse matters it is possible to write them in two forms which are dual to each other- force as voltage (resistive model) or force as current (conductance model) --- alternatively pressure as voltage, and so on. 

The only area of violin studies where the concepts of transmission lines, the "Telegraphist's Equations" are useful is with respect to strings. 

I agree with you whole-heartedly regarding the complexity of modeling violins.  Thank you for the response.  I'll look up Schelling. 

(None of my posts have utilized sarcasm - I'm here to learn)

-Chris 

 

[Marty Kasprzyk]

24 minutes ago, Chris Anderson, PhD said:

 

I agree with you whole-heartedly regarding the complexity of modeling violins.  Thank you for the response.  I'll look up Schelling. 

(None of my posts have utilized sarcasm - I'm here to learn)

-Chris 

 

George Bissinger described the limitations of the early method of mechanical network analysis for violins.  These simple simulations were done before modern computers were in widespread use which allowed modal analysis to be done.

 His 2014 paper is attached and in the last ten years further progress has been made.

sem.org-IMAC-XXV-s35p01-Networks-Normal-Modes-Evolution-Understanding-Violin-Dynamics.pdf

[LCF]

4 hours ago, Chris Anderson, PhD said:

(None of my posts have utilized sarcasm - I'm here to learn)

-Chris 

 

I have tried using sarcasm on my posts but they are still just as hard to get right. 

[LCF]

4 hours ago, Marty Kasprzyk said:

George Bissinger described the limitations of the early method of mechanical network analysis for violins.  These simple simulations were done before modern computers were in widespread use which allowed modal analysis to be done.

 His 2014 paper is attached and in the last ten years further progress has been made.

sem.org-IMAC-XXV-s35p01-Networks-Normal-Modes-Evolution-Understanding-Violin-Dynamics.pdf 429.93 kB · 0 downloads

Marty I still find a nice diagram with some lumps of mass and stiffnesses and damping depicted which are related to things I can alter and understand, aids my understanding of how things work.  FE analysis deals with the exact same physics and the same boundary problems between the different domains, just a lot more tiny bits of them all at once. More than my brain can contain. 

Otoh mechanical and acoustical 'circuits' can be quite hard to come to grips with at first. I think J C Schelleng was an old fashioned seat-of-the-pants genius when it came to understanding how the various bits of this instrument work. 

 

PS I use electrical circuit modelling software on my pc, QUCS, to explore my mechanical network models, so there's that ...

[Randall The Restorer]

9 hours ago, David Burgess said:

 

Chris, it appears that you have your electrical engineering metaphors

When I have time, i will offer Respirology metaphors especially  auscultation (listening to lung sounds with a stethoscope) and chest percussion techniques. 
I think my metaphors apply better.

I’m glad my son is a practical electrician - I can understand when he speaks the lingo.

Randy O’Malley 

Respiratory Care Practitioner
 

[VicM]

10 hours ago, Chris Anderson, PhD said:

I'll respond to the first question by Mr. Norfleet

15 hours ago, Chris Anderson, PhD said:

So I moved the post back to the optimum position…

Can you please share where that is?!  I’ve been looking for it for over 50 years and have yet to find it.

CA: I am unsure if you are making a joke - but for the sake of those who may not be aware, the 'optimum position' when placing the soundpost is normally centered south of the right foot of the bridge (which is placed correctly between the f holes) and about 1.5 - 2mm below, edge to edge. (to quote Edgar Russ).  From here, slight adjustments can be made by loosening the smaller strings, modifying the post position by tapping it with that "funny s-shaped metal stick", re-tightening the strings and bowing all strings again.  Repeat until the volume/tone combination is satisfactory for the player.  Each instrument has slightly different construction - and so this position is modified to optimize volume balance between strings, overall instrument volume, and frequency response. You *CAN put the sound post next to the left bridge foot - but the orchestra director gives it back and says 'please try again'. 

 

Let me give you an electrical engineering comparison.

Electrical and mechanical impedances do not "compare" directly. 

CA: Why? Their units are ' A Force / fundamental unit / second'. Electrical impedance is V/A = Volts (electro-motive force)/Coulomb/second) and acoustical impedance is 'Pascals/ meter /second'. Acoustical impedance correlates directly in the solution to its differential equations.  Both are fundamentally governed by the 'Wave equation' and have various contributions of waves and harmonics at a combination of frequencies. Seems a bold statement when the mathematical theory is nearly identical.  I started walking through "The Acoustics of the Violin" - a heavy math Physics textbook  - and got just far enough to realize - 'I've read all this already...' I would recommend it if you *REALLY want to dive into the mathematical modeling.  Personally, I got bored.  

 Maximum power transfer occurs at a consistent transmission line impedance (50 Ohms is 'perfect').  

Nope. Max power transfer occurs when the impedance of the load matches the source. Transmission line matching results in no reflections. In theory.

CA: Agreed - I mis-spoke.  My apologies. In EE, 50 Ohms is nominal for wave transfer and a realistic, obtainable value for impedance as a result of native cable geometries and materials.  (Like - old TV Coaxial cable  is '75 Ohm' impedance... today, most high frequency transmission lines are designed for 50 ohms).  

This impedance is frequency dependent - as some frequencies (and harmonics) will transfer in different proportions.

The idea of a transmission line is that the resistance and shunt conductance are much smaller than the inductive impedance and shunt capacitance i.e. the imaginary component vanishes. The characteristic impedance does not depend of frequency. In theory.

CA: Acoustic impedance still has inductive and capacitive parts.  True enough -  'characteristic impedance' does not depend upon frequency.  However, most transmission lines (whether for power or any frequency) are not ideal at all frequencies.  This is the same for acoustical impedance, which has a complex value in the frequency domain.  These problems are solvable with simple geometries using computer FEM solvers - however, violins are by-no-means simple in their constituent parts, materials, nor in their geometries.  Perhaps moving the sound post is akin to 'bending the coat-hanger on the old television'. VSA actually did a paper for FEM solving on Violin/Cello bridges that is fascinating.  Even such a small piece of the instrument creates a VERY complicated math problem.  

 My moving the post position further away from the foot of the bridge, you introduce a frequency-dependent impedance mismatch between the top and bottom plates.

The impedance mismatch is always there. You might add or subtract to it.

CA: Correct.   

 Higher or lower frequencies (and their harmonics) will transmit more/less power as a result of this mismatch - depending upon the position.

Transmit where ????

CA: Transmit from the vibrating string, transversly from the top of the bridge to the bridge feet, through the top plate, down the sound post (and through the air-filled body) and induce vibration in the bottom plate. Since waves do not change direction without reflection and power loss, and the waves of different frequencies are interacting all together - adding and subtracting to one another, even a slight change in geometry can realize a frequency-dependent change in acoustical output.  (FYI - old Navy guys "tune" the rectangular waveguides for the ship Radar systems by adding dents to the metal walls with a hammer -  *bong!* "Larry! do we have 25db yet?".  These 'transmission lines' look like AC air ducts.. ) 

 This is probably why the post isn't RIGHT UNDER the bridge - because the acoustical energy transfer is maximized from the top plate to the bottom plate - and human ears don't like the way it sounds...

Sometimes it is right under the bridge and human ears like how it sounds. Sometimes is not straight - needs to be tilted to do it's job satisfactorily.

CA: I cannot comment here.  I would welcome Luthiers with more experience than me on whether they have found a sound post that is 'directly under' or 'North of' the bridge foot. I have yet to find a Luthier book that recommends this as an acceptable position.  If so, I would imagine the f-hole placement relative to the body might be slightly different from tradition?  I'm afraid that most of the instruments I've worked on have had fallen sound posts. 

The 'antenna' that is your ear is much more subjective than electrical engineering systems regarding power transfer.

What does that mean ??

CA: It means the 'tone' as we hear it is not purely scientific.  If you have seen a violin output through a microphone, it is a rather random looking jumbled combination of frequencies.  True - you can pick out the 1st order, 2nd order and 5th order mode peaks.  These peak mode frequencies move around and are used as guides for many Luthiers to match resonance between the top and bottom plates. John Mangum in this video gives the most 'practical' explanation of this evaluation that I have found.  "Tone" also has a fair amount of subjective nature - what sounds nice to one person is not the same as another.  And not all people who like violin like the same tone("fiddles" vs "classical violin").  You, as a listener, are hearing a different combination of vibrations than what the violin is producing, which sounds different from what the player is hearing, which will sound different to someone listening across the auditorium.  If we are using the 'Electrical Engineering' comparison - the violin is producing a signal which travels through the air, inducing a similar vibration in the bones in your ears, which your nervous system translates into sound.  In that way - it is the 'receiving antenna' of the signal.  I have heard stories that the classical Cremonese instruments can sound a bit 'harsh' and 'loud' in the ear of the player - but soften as they travel through the air to the hearers apart from the Orchestra.  Several professionals have observed this phenomena - which means that 'something' in the characteristics of the sound is changing. I hope that helps...  

Wonderful discussion.  

Thank you!

-Chris Anderson 

 

 

Thank you for taking the time and effort to reply. One or two things might need clarification - I will double check with an expert and get back to you asap. I like the discussion-unfortunately I play cello and that seems to be an animal quite a bit different from violins.   And the two-three people I know who are at the cutting edge of violin research have zero interest in cellos. Just bad luck..... 

[Dr. Mark]

On 10/30/2024 at 5:39 PM, Chris Anderson, PhD said:

So I moved the post back to the optimum position and the difference in volume was perciptible by our ears (so around 3 - 6db).

Hi -  So what I've learned here on MN, if a customer and luthier are on good terms then the optimum position of the sound post is where the luthier puts it, which is also where the customer thinks he moved it to after expressing his initial dissatisfaction with the tone.  If they're not on good terms then the optimum position is anywhere except where the luthier puts it, after any number of trials.

I think that to define optimum position we would need to define a metric, like a tonal characteristic, loudness (as indicated), some trait noticable when playing.  What is that metric?

I used to own a book 'Electrical, Mechanical, and Acoustical Analogies' that described all of the circuit elements and equivalents in each of these domains.  I couldn't find it the last time I looked - hate to think that I might have let it go since I could use a refresher now.  Let me try anyway:

Something to keep in mind although it may or may not be relevant:  Maxwell's equations there are two sources of 'current' - the time derivative of charge density and the time derivative of the electric field.  The electrical current in a transmission line is a wave traveling at the speed of light (its group velocity) on the outside of the conductor, while the motion of electrons is induced by the change in local potential and is pretty slow by comparison.  An acoustic wave is a pressure wave traveling through the material (depending on mode), the group velocity is material dependent, and multiple modes may be excited by different geometries or inputs.  A mechanical wave is essentially an acoustic wave at a frequency well below the range of hearing. 

The point being that the analogies aren't complete so probably some care is called for in their use.

[martin swan]

2 hours ago, Dr. Mark said:

if a customer and luthier are on good terms then the optimum position of the sound post is where the luthier puts it, which is also where the customer thinks he moved it to after expressing his initial dissatisfaction with the tone.  If they're not on good terms then the optimum position is anywhere except where the luthier puts it, after any number of trials.

 

Never has a greater truth been spoken about soundpost position.

For me, understanding the implications of this is fundamental. Given the total impossibility of finding broad agreement on "optimal" sound, a science-based approach is pretty pointless.

 

[Michael Darnton]

My experience with adjusting is that the better the player the more they are concerned with adjusting functional behavior, less with tone once the obvious tonal defects are removed. Then when the behavior is optimized an interesting thing happens and the overall tonal quality seems better as a side-effect of the machine being optimized. Magic is like a bonus overlay on top of the overall state of better health.

To that end, I prefer to work with a player who's testing by playing real music rather than hunting for problems. I can hear the problems easily on my own, much easier in the context of a musical phrase, but I can't hear behavior in a musical situation except when I'm hearing normal music played normally--a musical situation.

It's the amateurs and terrible players who do things like coming in and playing slow notes one at a time, and the same on different strings, listening and comparing them to each other, looking for "beauty" and balance. Total waste of time, it's like working backwards with earmuffs on.

 

[Vafan]

2 hours ago, Dr. Mark said:

Hi -  So what I've learned here on MN, if a customer and luthier are on good terms then the optimum position of the sound post is where the luthier puts it, which is also where the customer thinks he moved it to after expressing his initial dissatisfaction with the tone.  If they're not on good terms then the optimum position is anywhere except where the luthier puts it, after any number of trials.

True. Let me add some recent anecdotal evidence, from a customer's/player's perspective... There are more than 10 luthiers in my city, and I frequent three of them occasionally for different reasons, i.e. one for rehairs and another one for tonal adjustments and repairs. I trust him. He is trusted by professional musicians as well. He solves problems. He has that feeling of how to get the best out of an instrument. It's simply that.

The first bigger job he did for we was getting my decent fiddle from teenage years in shape again, as I wanted to sell it - which was so successful in the end that I keep it in my office today for practicing a bit in between when it gets later there.

Just some weeks ago I went to him with a fine French fiddle, because it did not respond as well any more as they did. He measures your violin's plate thickness first, measures and weighs your bridge, notes all values, starts easy changes to get a feeling how the violin behaves, like moving the bridge before touching the sound post. He usually brings the sound post to a N-S position in a distance to the bridge which is usually equals more or less the thickness of the top, or a little less (with cellos it's a different value, he says). He goes on with several other steps in a very analytical way, goes forward and sometimes backward, which also involves trying different position of the sound post, and in between he tests the instrument, and his customer as well, and just sees how things change to the desired result, and how they influence your problem. - Well, in the end, he made a slightly longer sound post to get it a bit tighter inside, and I agreed to get some 100 mg of weight off the bridge. Well, the violin sounds great again, a bit different though than before (not better or worse), is in tonal equilibrium and is probably more responsive than it ever was before (it seems to play itself).

Problem solved. Luthier happy. Customer happy. Isn't it more about finding the right overall compromise? :-)

[Vafan]

21 minutes ago, Michael Darnton said:

My experience with adjusting is that the better the player the more they are concerned with adjusting functional behavior, less with tone once the obvious tonal defects are removed. Then when the behavior is optimized an interesting thing happens and the overall tonal quality seems better as a side-effect of the machine being optimized. Magic is like a bonus overlay on top of the overall state of better health.

That's funny, Mr Darnton, I might be erring, but you seem to have formulated from a luthier's perspective, what I was similarly about to formulate from an (amateur's and, hopefully not a bad,) player's perspective :-)

[Dr. Mark]

2 hours ago, martin swan said:

Never has a greater truth been spoken about soundpost position.

You are complementing yourself and numerous other contributors to MN.

1 hour ago, Vafan said:

Isn't it more about finding the right overall compromise? :-)

Yes, that's probably a reasonable summary.  My intent was to capture the principal idea in a concise anecdote, since I don't think I can choreograph all of the various dances that makers and dealers go through with their clients.  It seems I was taking for granted a well-trained and experienced sound post adjuster:

1 hour ago, Michael Darnton said:

My experience with adjusting is that the better the player the more they are concerned with adjusting functional behavior, less with tone once the obvious tonal defects are removed. Then when the behavior is optimized an interesting thing happens and the overall tonal quality seems better as a side-effect of the machine being optimized.

So closing in on two principal metrics: 1. remove obvious tonal defects. I'd guess some defects are commonly agreed upon while others depend upon the violinist/fiddler's taste - coupled with some more-or-less subtle pressure from the luthier; 2.  Functional behavior - is this playability or...and...?

[Michael Darnton]

2 hours ago, Dr. Mark said:

1. remove obvious tonal defects. I'd guess some defects are commonly agreed upon while others depend upon the violinist/fiddlers taste - coupled with some more-or-less subtle pressure from the luthier; 2.  Functional behavior - is this playability or...?

1/ People mostly have the same list. Bad notes, wolves, bad strings or a range on a string that's misbehaving, overall balance, that kind of thing. It's not a really long list, basically. I guess you could call them local problems.

2/ And with that in mind, you could call the second type the global problems. How notes start and stop and how the sound moves between start and stop in response to changes in bowing. This kind of thing only shows up when actually playing strings of notes, trying to be musical. Basically moving behavior you won't discover if you just play a slow scale holding every note for a second or two, which is how I see some players "testing" instruments.

The absolutely worst example of this fixation on #1 that I ever saw was a kid playing single notes for several seconds each and grading them while Dad wrote the grades down. Every note on four or five instruments. I guess the one with the highest total won. Never was a single line of actual music played. It wasn't my customer so I didn't have to hang around for the answers.

Everything falls under the heading of "playability". If any of the things on either list is not working the player has to divert concentration off the music onto dealing with that problem, and that can detract from the performance. The really great musicians can apparently cover everything without a whole lot of distraction where for beginners who've gotten past the initial pains into some basic level of discrimination every twitch in the instrument, real or not, can a distraction and impediment. This is why some people prefer the most bland instrument possible--magic is wasted on them because they're totally focussed on and fatally distracted by every tiny "flaw" in the instrument--the things that better players call texture--and they never look higher up to the music itself.

There's a good market for "flawless" instruments for this type of player buying their first "good" instruments who are looking for an instrument that makes them sound pretty OK with the least amount of pain. Musical sophistication may not be as big of a consideration at that point because they haven't yet experienced what a really sophisticated tool might offer. You can't fault people for wanting to sound as good as possible as soon as possible.

Most players are somewhere in the middle, obviously. 

[VicM]

22 hours ago, Chris Anderson, PhD said:

If you have seen a violin output through a microphone, it is a rather random looking jumbled combination of frequencies.  True - you can pick out the 1st order, 2nd order and 5th order mode peaks.

When you look at the output of a microphone with an analog oscilloscope you see a mess of "frequencies" because the oscilloscope can't trigger. A digital storage scope will allow you to go back and reply the signal at your convenience and all you will see is a single dot corresponding to the total pressure of the air on the microphone diaphragm at that moment. Any sound card can process a piece of that signal and display an "interpretation" of the frequencies it is assembled from.