Post subject: Response on the new Panart publication on the internet.
Hangblog.org published in the Hang Library a new PANArt communication.
On various forums and blogs on the internet I found reactions of people. Some of them are Hangplayers, some not.
I wonder, that a lot of people are experts in making Hang.
Otherwise I can not tell me that they say, the Hang goes out of tune, even if you dont play it.
The new PANArt communication is full of other informations. A lot of thougts direct from the Hangmakers to ponder.
But a lot of people talk only about that PANArt discontinuing their tuning service. Why?
Do they fear to have problems in the future with their Hanghang?
For me it is clear, that people who try to make copys from the Hang make such statements. This is simple to understand.
But, why are suddenly so many people experts in Hang making who own no Hang and never had an hammer in the hand ?
The Hangmakers have a long, long experience in tuning steelpans and making Hang.
I think after more than 30 years of beating metal sheet they know exact what they do. They work over 15 years with the new material called "Pang".
Since 10 years they make Hanghang from this material.
The result is an Hang what dont need a tuning in the future, if the Hangplayer play the Hang in the limit for which is was made.
I have no problems with out of tune Hanghang and I play my Hang every day since 4 years.
I know other Hangplayers and they have also no problem. If an Hangplayer plays his Hang as a drum or use sticks it is not in the responsibility from Panart to tune such an instrument. They clearly said again and again, that the Hang is not a drum!
Say it with numbers. There are round about 6000 Hanghang in the world.
The last few years every year Panart got circa 80 Hanghang for tuning.
(this is not estimative. I know it directly from Panart).
So, we can say that in 10 years maybe 800 Hang tunings are made.
Not 800 Hanghang! Some Hanghang need a tuning again and again.
Probably we speak about 700 Hanghang, maybe less.
Only a few Hanghang are accident victems. The most are only out of tune because the player has hit the Hang to hard.
That means in reverse, that 5300 Hanghang never need a tuning!
People who say a Hang goes out of tune in each case are totally wrong.
The most Hanghang are in tune and that for many years.
These facts made a tuning service unnecessary.
An Hangplayer could play Hang in confidence of the quality of his Hang. Dont worry about problems, if you play not to hard. Listen to the Hang. The Hang is crying before it goes out of tune!
I agree with you there Frank - I have played my First Gen C penta hang for 7 years and it is still in tune despite having been used in my Music Therapy sessions with heavy handed children and adults. I make sure that the Hang is never over hit, never in the direct hot sun and always in its bag when not being played. There are so many videos on YouTube of people 'abusing' the Hang and I am sure that it is these that need tuning - if you are going to beat the Hang then it will respond in such a manner!!
A good example, that Hangplayers could have confidence.
new Free Integral Hang. He returned his old first generation Hang to Panart.
in an open forum. Maybe he read this and want to confirm ?
By the way. Panart wrote in the new communication: " with time it matures to its full bloom, its sound space expands."
This means, not! that the tuning from the Hang is drifting.
For example. If you buy new Loudspeakers (I mean relative good Hifi-Speakers) they have not their full sound and potential from the beginning. After hours of playing they reached their full sound.
The same with musical instruments. An acoustic guitar sounds after a while better as new.
I dont know the correct englisch words and it is hard to explain.
oscillation ? The membrane from loudspeakers must oscillate. And with time the sound is better and better.
The same with the Hang. The new Hanghang in the workshop sound is relative "dry". They sound nice and are absolute correct in tune. But it is not the sound after long playing.
Sabina Schärer said to me as I picked up a brand new Hang for playing. These Hang are like "Frischkäse". (cream cheese).
Cream cheese is tasty, but a good cheese needs time. If the cheese is ripe he is delicious.
Ok. The Hang is not a cheese.
I hope you got what I mean?
A agree with Frank totally, when the hang is played softly without hitting it hard, it cannot get out of tune. I am playing the IH every day,for myself or with my patients - because of this thred- yesterday I took first time a look on the chromatic tuner for a check: and (of course) the hang is perfect in tune !
Dont get afraid, play with your soul, without forcing it, handle the hang like your girlfriend, your boyfriend or you baby: If you love it, do not strike it, be soft, patient and use all you social and spiritua competencies that you like to share with others by giving it also to your hang, that means also: give it to yourself.
Just try to get in contact with the hang and your inner self and be in love with the Hang.
The problem has been seen in many videos on YouTube, people smashing their Hang hard with their hands, using mallets, competing with Djembe, Cajon and other loud percussion instruments. As we all know the Hang is a delicate sound, soft, comforting, ethereal.
I've only had to send my Hang back to PANart once after it suffered an accident and the Ding was knocked completely out of tune. They have said in the event of an accident then a retune/repair is still possible so I do not see why there is a problem with the retune decision by PANart, unless someone can prove that the Hang goes so far out of tune by normal play - something I’ve not seen.
In fact a recent clean up with Biofa hard oil on my Hang actually made it sound clearer, whether that be a psychological thing or an actual thing, the amount of grease and dirt that was on the surface must play a small part in damping the sound.
These guys live and breath Hang, nobody knows the Hang like PANart do and as such their decision i'm sure has come from many years of research, knowledge and comfort that the Hang is a vessel that holds it's memory in tuning.
I think the large part comes that people are resentful towards PANart for many reasons, refusal to obtain a Hang, issues with selling on eBay, refusal for a retune due to repeated misuse of their Hang... a lot of issues build up over time, stories get told and others follow suit, whether it's a fear of being outcast by the PAN community or whether they have issues with PANart's unique way of business, people will persecute what they don't understand.
It is not our business, therefore we shouldn't judge their decisions, as has been proved already they make up their own minds and stick with it. Nothing anyone says or does will change that, as odd as it may seem to folk.
I dont know, if this is more an psychological thing. Could be. The appetite grows when food looks nice.
It is fact, that painting the Hang will have an negative effect.
I learned a lot of about the physical characteristics from the Hang in the last years. I read about steelpan tuning and I read the documents about the Hang on Hangblog. But most important I speak a lot of with the Hangmakers about their work. Felix show me a lot of aspects in hangmaking direct in his workshop. I only tell this, because people maybe wonder, why I think I could be part in this discussion.
On Handpan.org seems to be a lot of self-appointet experts in Hangmaking.
I am not an expert. I am far away to understand every aspect. Likely a lot of is incomplete and imperfect.
But what I understand perfect is, that the Hang has complete different physical characteristics as any copy or the so called Handpans.
Maybe Handpans go out of tune regulary. It is likely, that they do. Steelpans also go out of tune, if they are made with traditionell iron.
Why the Hang is different? The Hangmakers are working with high pre-stressing. I know, that for example in the Bells is not such a tension.
They use a special geometry to have the ability to control these tensions.
Also important is, that the Pang is aged artificially. It changed his characteristics not only because of time. It is technically an old material.
For sure. One day it is broken. Nothing is forever on this planet.
But in the meantime it will stay in tune.
Without high tension it is not possible to build long bridges. Think about that!
Please allow me to introduce myself. My name is Eric Ashworth. And, I am very likely one of the individuals Frank is referring to. I am posting here because a member of Hangforum sent me a link to this topic and I would like to clarify a couple things.
First, let me say that I am in no way an expert on tuning Hanghang. In fact I have never even seen one. But let me also say that I have indeed had a hammer in my hand. And, in the last two months I have learned a large amount about tuning steel. And the majority of that process has been documented publicly on handpan.org for anyone that would like to know more.
In my life I have had a wide range of experiences, some of which have helped me in understanding some of the basics of the science of Hanghang. There is much that I do not understand. But I do know that Hanghang are physical objects that are subject to the laws of physics like any other. This fact, Felix and Sabina have stated themselves.
That is a bit of a blanket statement. And I think you are overreaching in saying so. Now, I can not say that I have any evidence that Hanghang will drift in their tuning over time, but I can say that because of the nature of residual stress, changes will occur in steel, over a process of time, even in Hanghang—even after they have gone through the process of stress-relieving that Felix and Sabina have described. Because Hanghang are extremely sensitive to changes in stress, it is a logical conclusion that even if Hanghang are capable of balancing the stresses applied to them, that these natural changes will still have at least a slight effect on the tuning.
I am actually inclined to believe Felix and Sabina when they state that the latest generation of Hanghang can hardly be deformed when played normally. But, there have been accounts of first generation and second generation Hanghang owners who have been extremely careful and gentle with their instruments and those instrument have still drifted sharp in their tuning. Now you may not believe those accounts. But certainly not all of them can be lying, can they?
I believe that this is why many individuals are upset with Felix and Sabina's decision. Many of those individuals are Hanghang owners whose instruments, by their accounts, have shifted in pitch. And they now have no option for retuning other than to take their instruments to alternative tuners. Can you not understand how that would upset them?
Hi Eric, thanks for your contribution to this discussion. I would like to discuss concrete examples where Hang players say that their Hang drift sharp over time. Is there someone who is interested?
To understand PANArt's statement about Hang tuning you have to know something about the history of the steelpan and the Hang in Switzerland. The "PANArt Steelpan Manufaktur AG" was foundet in 1993 (as a successor of Felix Rohner's former steelpan workshop) by members of the steel band "Berner Oelgesellschaft". The target was to support the growing Swiss steelpan community with instruments and tuning service. That a steelpan needs a tuning twice a years was and is an important challenge for steelbands. Without a tuner a steelband is lost. This situation was one of the main reasons for Felix Rohner to start a comprehensive research in materials and techniques. The result was the Pang: Deep drawn rawforms that was gas-nitrided.
Summer 1995 was an important date: Except Felix Rohner the other tuners left PANArt in order to found a new company (Cosmopan) to build steelpans in the traditional way. And Sabina Schärer joined PANArt. The research on the Pang began. A number of instruments were developed, Steelpan like instruments (Ping, Peng, Pong), bells, gongs, cymbals, the Tubal and at last: The Hang. In this research process Felix Rohner and Sabina Schärer developed a new geometry and a systematical tuning process especially for the new rawform.
A new material, a new geometry, a new tuning technique which allows to systematically control the residual stresses separates Pang tuning from traditional steelpan tuning.
It was found that Ping, Peng and Pong the steelpans made of Pang stay better in tune than the traditional steelpan. But the tuner didn't become dispensable. These instruments needed a tuning from time to time and it was an important task for Sabina Schärer and Felix Rohner to support the Swiss steelbands who played their instruments with tuning service.
While the PANArt tuners concentrate more and more on the Pang development and new instrument concepts, the time consuming tuning service became a problem. On the other hand the costs for periodical tuning was a problem for steel bands. The PANArt tuners tried to find alternative solutions. They trained 50 members of swiss steel band members to empower the steel bands to support themselves. At the end of this period they canceled the tuning service for steel bands.
With the Hang, invented in 2000, the PANArt tuners recovered the new world of playing steel with the hands. They found that especial their Pang material had a great capability to be played with the hands. This was seldom done in the history of steel instruments. And the lighter touch of the hand became an new aspect that served the challenge to get an instrument that stays in tune.
As Frank told in a post above only a minority of Hanghang returned to the Hangbauhaus for tuning during the decade since the birth of the Hang. Obviously the majority of Hang players didn't need a tuner. Therefor Felix Rohner and Sabina Schärer felt more and more confident, that with the Hang they had found the musical instrument concept that makes it possible to play a tuned sheet steel instrument without needing a Tuner. Refinements in Hang tuning were made since 2005 when they began to use an oven to control the stresses. This new methods increased the capability of the Hang to stay in tune but even the older Hanghang were stable enough to stay in tune.
The concept of the Hang includes that it is an musical instrument made of a special processed sheet steel (Pang) that can be used by its player in the long run without needing periodical tuning.
This is something that steelpan tuners will find weird because they work in a world where periodical tuning is a must. Therefore they are often very distrustful when they listen to PANArt claiming that they have found a musical instrument concept that doesn't need periodical tuning. This distrust is reflected in the discussion we currently can observe at handpan.org.
The Hang ist not seperated from its player. While it is true that its material, geometries, and balanced residual stresses make its tuning very stable it is of course possible to detune a Hang if it is handled in an improper way. So the Hang needs a player who knows that it is an musical instrument that needs no periodical tuning. And it needs a player who understand how to handle it.
It's the task of the Hang player to handle his instrument in a way that his impact on the Hang doesn't reach the elastic limit. How can he do this? We have no sensory organ for the elastic limit of materials, but there is an easy method how the Hang player can control his impact by ear: If he plays his Hang in a way that he doesn't change the pitch in the moment of the impact of his hand on the tone field, he can be sure to stay away from the elastic limit.
If a Hang player usually or often plays in a way that his impact changes the pitch, he is not able to control his impact that it is not too high and could reach the elastic limit. Therefor this is a quite dangerous playing technique. But if we listen to all the many YouTube videos of Hang players we will find, that this dangerous playing technique is quite usual. These players seem to be clueless about a very important aspect of their instrument. To avoid misunderstanding: Changing the pitch is not the cause for detuning. The Hang can bear this in most cases if it is not too extrem. The problem is: The player loses control. Therefor it is dangerous.
We should understand PANArt's statement regarding the tuning service in "The call of iron" as a challenge for all Hang players. The tuners at PANArt say: We have done what we can do to develop a musical instrument that is able to stay in tune in the long run. Now it is up to you to understand how you can handle your Hang that this will happen in your concrete situation. It needs both the Hang maker and the Hang player to make it possible.
welcome on Hangforum. Please have in mind, that I am not an native englisch speaker and that it is likely that I use from time to time wrong words. My grammar is also bad.
Nice. You are on the beginning from a long journey. Do you know a little bit about the history from the Hangmakers? It is very interesting. They start to make Steelpans over 30 years ago. Felix Rohner told me, that an well known Steelpantuner from Trinidad sayd to him, that a man must learn and practice until he is 50 years old and maybe after that time he is realy a steelpantuner.
Of course. Hanghang are physical objects and subject to the laws of physics.
As I said before. Nothing is forever. But Hanghang are high quality instruments. I think they have a long life time.
Panart said, that Hanghang dont will go out of tune if you play the Hang in the limit they are made for.
I think one "problem" from people who make Handpans is, that they dont understand that the Hang is not only a reversed steelpan.
You could learn a lot , if you start to make steelpans. No question. There are similarities.
But a lot of inside the Hang is not to see with your eyes. I speak about tensions.
It is not a problem to copy the ratio of the tone fields. If you have a correct ratio you have done the most work. This is what you see on the BElls. There are nearly no hammer marks inside the Bells. Why not? Because there is no pre-stressing and the Bellsmaker work not with high tensions.
The tone fields are like seperate plates.
You can de-tune a Hang. But not with normal playing and not only because the material fatique. As I wrote before is the material technically an old material. There is no big changing over a lot of years.
The secret is the geometry. You have not enough power to deform the Pang only with normal playing. Not only because it is so hard. If you have a flat Pang plate, you could deform it relative easy.
For example an egg. It is easy to break an eggshell. But because of the shape it is not so easy to break an egg between thumb and indexfinger. Only because of the shape it is relative stable.
There are a lot of examples where geometry lead to very stable and strong constructions.
No, they dont lying. They only be at fault.
The Hangmakers know a lot of people who need a tuning in the foretime. A lot of streetmusicians for example.
At the beginning where I got my Hang I also where busking with my Hang from time to time. It is loud in the streets and if you need the attention from the audience you must play loud. Look on Youtube! A lot of examples.
Those people will say: "I was carefull with my Hang and I never hit it to hard".
Go to any big Hangmeeting and see what happens. Dont understand me wrong. I have nothing against festivals. I like jamming and session.
But by now I have learned for me personally, that my Hang is not a good instrument for such things.
A lot of people play together. Likely a few bongos or djembes join the circle.
In such a loud ambience and in ecstasy playing it is not easy for any Hangplayer to feel the point where the Hang is going out of tune.
All those Hangplayers will tell you, that they ever be careful and gentle with their Hang. And they dont lying. They believe it.
Another myth is, that Hanghang shift in tune equally. They shift and get higher, but it sounds not out of tune, because all notes are drifting. A lot of people beliefe that. How is this possible? This would be realy a wonder.
What do you say to over 5400 Hanghang who never need a tuning until now?
Thank you for the extensive information. I was already aware of much of it, but it is nice to read it again in summary.
I do know of individuals whose Hanghang have changed in pitch. And no, these particular individuals are not at fault as they have been exceedingly careful. However, I am uncomfortable referring to them by name. For anyone interested in reviewing the response and discussion of shifting pitch outside of this forum, you can read the discussion at handpan.org A quick note however, I had made a comment on that topic that implied derision of Felix and Sabina that I later apologize for in the thread. I wanted to say that up front so that any hangforum members not aware of the discussion already would not be turned away by that comment.
As for the stability of tuning, the instrument that I am currently working on, is utilizing very specific architectural principles that I believe will result in a significantly more stable tuning than most. This is actually the first time I have ever mentioned this publicly. But, I mention it here as it is one of the reasons that I have tended to believe Felix and Sabina's statements. Perhaps my approach is similar in principle to the geometry utilized by Felix and Sabina or perhaps not. I am not currently using case hardened steel, but I believe that will help—particularly as Michael points out that the yield point is a critical consideration. So I am quite aware of the need for careful playing in order to maintain the balance of stresses in one of these instruments.
My philosophical take on how an instrument should be played and whether or not a player is in control or not is likely very different from Felix and Sabina's. Primarily I view instruments as tools or means of human expression. To me, Manu Delago is an exemplary player. However, much of his percussive playing would still likely detune his Hanghang over time which would require retuning. And street musicians would obviously need to play at a level to be heard, which again might result in the need for retuning. This is quite similar to the need for retuning steelpans as a result of the style of playing with mallets. To me, that would be an understandable and normal use of the instrument. But I'm sure there are many who would disagree with me.
As for the myth of drifting, as a result of the testing I've done for my own instrument, I have found that my notes will drift higher in pitch and then stabilize due to the architecture of the instrument. I believe that a process of stress-relieving will reduce this drifting. But it is a logical and natural result of the stabilization of stresses in the steel. Because the entire structure of the instrument and the distribution of stresses in the instrument are involved, I can not force nature to stabilize fully. Thus there will always be a slight change in pitch. Most importantly, because the stabilization is due to a balanced ratio of structural and compressive forces, the shifting in pitch is extremely similar from one note to another. So I can verify from my own experience that it is not as impossible as it may seem for the tuning of an entire instrument to rise but stay in tune.
Michael, I do agree that the primary issue of discussion should be that of the stability of tuning for Hanghang that are played gently and carefully and not steelpans or handpans as they clearly are operating according to differing principles.
I do know of individuals whose Hanghang have changed in pitch. And no, these particular individuals are not at fault as they have been exceedingly careful. However, I am uncomfortable referring to them by name.
As I wrote in my last post, id doesn't make sense to discuss this topic without a concrete example.
There is one example I have no problem to call by name, because he made his statement in public: Saggio wrote that all of his three Hanghang had drifted sharp over the last years. Saggio, as you are a member of this forum I would like to discuss what you are meaning with this statement. After I read your statement I visited your website and listened to the sound clips of your latest CD. I compared the pitch of the Hang in the sound clip with my 2nd generation Hang which stays in tune exactly to A=440 Hertz for four years now. And I found out: Your Hang is perfectly in tune with mine. So your Hang cannot have drifted sharp. So I assume you mean something different. What exactly changed at all three of your Hang?
It's not the point whether this is normal use of an instrument. A normal use doesn't exist. You can use an instrument in any way you like. There are Bands who destroyed there E-guitars on stage. That's fine. The point is: If you destroy your instrument while using it, you need someone who is willing to repair it for you or you need someone who is willing to sell you a new one. If you don't find this person you have a problem.
PANArt don't want to be the servants for Hang destroyers any longer because they want to spend their time with other tasks.
So if you have the deep desire to play your Hang destructive, look for a tuner first who is able and willing to offer a tuning service for you. Than you can bang it as hart as you want.
It's not the point whether this is normal use of an instrument. A normal use doesn't exist. You can use an instrument in any way you like.
This said I have to add that this is only one aspect of the topic. It is also true that there are some important things to consider if you want a satisfating result when playing an instrument. For instance anybody is "allowed" to play his flute with the nose. But it is also true that in most situations using the mouth will be quite more satisfying.
In "The call of Iron" you find a formulation that can be missed but is the keypoint of the whole discussion. By now nobody has referred to this point: "A hot coal over which hands may safely glide – thereby serenely integrating Ding and Gu . . ."
"Integrating Ding and Gu" - If you understand this then you will not argue busking is a normal use. It is impossible to integrate Ding and Gu in a noisy place and in fact no busker does this. The same with almost all players on stage: No integration of Ding and Gu. This is a dimension of Hang playing that isn't discovered by almost all of the players who are applauded for their CDs, stage performances and YouTube videos. I call this playing a castrated Hang.
If you are used to integrate Gu and Ding, you will most likely automatically play in a range of forces that doesn't detune your Hang. In fact destructive playing is often done in the desire to get more intensity out of the Hang. If you have learned to integrate Gu and Ding, you will find the intensity in other dimensions of the Hang sound and you won't have a need for destructive playing any longer. And along the way this will solve your tuner problem because you don't need one.
My point in posting here was to clarify what Frank was addressing. I have provided the reasoning behind my logic and that is all I can speak to. As for concrete examples regarding Hanghang, that I will leave to others to address.
On this point I respectfully disagree. To me an instrument going out of tune or more accurately showing signs of wear are different matters than if it is physically destroyed. My guitar was built in such a way as to bring out the optimal intonation of the notes across the fretboard. However in the process of time, numerous factors can alter the intonation. The frets and fingerboard can wear down, the angle of the neck can shift. The end result is that eventually the guitar will "go out of tune" even if it is played "correctly." This is just a normal process of change that eventually will require that the instrument be fine tuned and restored to its initial state.
But clearly you perceive a Hang being detuned as a destructive act. And that is fine. We simply don't see eye to eye on this.
It is entirely their right to choose how they wish to do business and how to spend their time. And if they do not wish to retune instruments, then again, that is their right to choose not to do.
But then, there is going to be a logical response of frustration from those that were depending on their services which they have always provided. And thus the public response to their statements. So it shouldn't be a surprise that people have responded the way they have.
It is also true that there are some important things to consider if you want a satisfating result when playing an instrument.
While I understand that this is important to you, and very clearly so, it is a point of personal preference, just as playing in private or public is. As you have said, there is no right or wrong way to play an instrument. Correct?
If I am able to complete my instruments and begin selling them, I will always provide tuning services. PANArt has chosen not to. Additionally I intend to share all that I can with my players on how to maintain the tuning including teaching them how to tune the instruments themselves if they need to. PANArt has not.
Clearly their focus is completely different than my own. I am not an expert on the Hang. Instead I am becoming an expert at tuning steel for use by musicians. As a result there is clearly little else to discuss on this matter.
Not correct. Integrating Ding and Gu is as important as removing the resonance tubes under a vibraphone or let them in place. Yes, you can play a vibraphone without the tubes but no vibraphone player would do it because it is an important part of the instrument. Also a violin player would never remove the sound post in his violin because it has a necessary function for the sound of a violin. In a similar way the Ding-Gu-Integration has a basic function for the sound of the Hang. Did you ever hear the difference between a Hang played with and without Integration of Ding and Gu?
A normal use doesn't exist. You can use an instrument in any way you like.
For example, how does one go about integrating Gu and Ding when playing the Hang sideways and using percussive strikes on the Gu side? Or even more so, how does one integrate the Gu and Ding when playing upside down and the Ding is muffled or while activating the helmholtz effect which changes the pitch of the Gu?
Now, please, let's agree to disagree.
This can all be done. I think you never saw and listen to a player who understand what "Integral Hang" means and is able to play with the full potential of the Hang.
It is a quite limited approach to Hang playing if someone plays only the Ding side or only the Gu side or only "activating the helmholtz effect". These are all single aspects and integral means to play it alltogether in each moment.
This whole thread is really pathetically sad. There is not one shred of common ground between us. We are brothers in humanity, but in thought, utterly alien to each other.
As for your reply, you think wrong.
I am entirely open to the approach that you have mentioned, I understand the implications far better than you know, and I have a much deeper understanding of the acoustic science and phenomena of the Hang than I have even begun to hint at. However, I am just as open to exploring those areas that you feel are limited or destructive. But what is the use. Your mind is shut like iron. There is only one way for you and so many others here. And that is sad.
Meanwhile, a whole new world of musical possibilities is beginning, a whole new culture and community is growing and new joy, happiness and peace are being found. It is truly too bad that you and so many in this forum won't be joining us.
I will not be returning or posting here again. I wish you peace.
I asked a few times, what do you think about all the Hanghang who never need a tuning? More then 5400 Hanghang never came back to the hangmakers for a tuning. It is evidence, that Panart is right and no tuning regular tuning service is needed.
Maybe a few things are only matter of opinion. But these point is fact.
I understand the implications far better than you know, and I have a much deeper understanding of the acoustic science and phenomena of the Hang than I have even begun to hint at.
This is a bold statement for someone who wrote that he has never seen a Hang.
I don't know why, but I will try again.
Perhaps those instruments never needed tuning. Or perhaps they were simply never sent back to PANArt. As for proof, it is only evidence that those instruments were not sent back to PANArt for tuning. I am not saying that they aren't still in tune, perhaps they are, perhaps they are not. But you can not claim it is proof of their remaining in tune.
What I do know is that Felix and Sabina's techniques for tuning have changed in the last decade. They have gone from a less stable technique to a more stable one. Since you know them, then please ask them why the notes in early Hanghang have noticeable wrinkles in the steel around the domes. If they give you an honest answer, then I believe it may prove enlightening to you.