Johann
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Posts posted by Johann
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Hi Dana,
thanks for your reply. You are the native speaker and i full agree with all you did explain!
Have a nice day an keep healthy. i keep working, because we should stay indoors anyway.
Johann
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Hi all,
i can only speak about accordion reeds and dont have much experience with Concertina reeds.
The shaping of tongues can vary and was used in reed organs to give a distinct tone character. And special bendig tools ware in use. On Accordions i find it in most cases best to set the curve to a nice parable lice set. Learn to here the difference in sound with different settings and shapes. It is the key of understanding in respect of talk reaktion and more. The way how do the bending varies depending on the size of the reeds. Usually you get along with just using the thin shim and the fingers. Best would be to demonstrate this in a video or have a person that can show it. Is not as easy as one may think because depending on the size of the reed and the material for the tongue all is a bit different. very little differences in setting may cause different results. Best Regards, and greeting from Austria i hop my english is good enough. Johann Pascher
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Hi Tom, i have red some of P. Cottigham's publications now. especially "Analysis of free reed attack transients " Since it is quite a long time as i was talking about additional modes in reed motions in some forums. I am surprised that this letter now more or less confirms my hypotheses i made years ago. Then i was criticized about my theses. Over time i even was not sure anymore, since i could not find a real prove expect that i could hear some of this mode related pitches. I have found some way to control low reeds, without special tool only by hearing and changing the profile, but not as good as i would like to be in control off this. I will read more of P. Cottigham's Publications. Takes time. I am quite happy that there is some research done on the subject. As far as i can see his research are made under comparable conditions as mine. He also uses Matlab and similar equipment. I did not have high speed camera i used strobe light and sycron photography about 20 Years ago. As i told you i am now more in the practical phase of work.
Best regards Johann
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18 hours ago, ttonon said:
When I chastised Johann for spreading false concepts, I didn't mention that higher harmonics of the acoustic reed sound can be coupled to the air in the cavity, affecting the harmonics, and thinking back on it, that may be all he was referring to. But this is a very weak form of coupling, and it's far different from the "acoustic coupling to an air column" usually referred to with such terminology.
Hi Tom, yes Tom exactly, still if we look deeper into the subject it may be important to remember that the western reed still behaves comparable, even we can get away with a much simplified model. Sure there are differences in the reed and in the cavity and where the reed is mounted. The circumstances remain the same, we still have a cavity and a reed and a mounting point of the reed all differs dramatically but the reed needs the air to sound. With the western reed, the reed is the dominant part and the cavity, it is nearly neglectable. I also like to point out again on very low reeds it is even more important how this cavity is formed and how big the cavity is. On the very high pitched reeds we all know that we have to take measures to improve the speaking of the reed. All my thinking is influenced by building helicon boxes now for about 20 Years and optimising the sound. My theoretical influence is strongly influenced from may former profession working and teaching in the field telecommunication. I never would say i can't be wrong if someone comes up with other explanations that fit better. The usual models and explanations are for me always a bit to much simplified.
Best regards Johann
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23 hours ago, Wolf Molkentin said:
Possibly a feature of real good brass reeds (not entirely sure about the George Case in this respect, but the reeds of my Wheatstone model 6 are fantastic, definitely TOTL (and quite loud as well; only the model 24 is positively exceeding the volume) - however it might be in accordance to @ttonon's findings (that the significant difference was in the higher, but not the very high harmonics), might it not?
High Wolf, it is really difficult how we charge sound and timbre. The main key is for me the human vocal tract how we form speech. The frequencies that count to distinguish vocals. So the answer for me, as with most things is somewhere in the middle. Read about https://en.wikipedia.org/wiki/Speech_recognition. This is a part from the german wiki can't find the same in the engisch: "Auf akustischer Ebene spielt insbesondere die Lage der Formanten eine Rolle: Die Frequenzanteile gesprochener Vokale konzentrieren sich typischerweise auf bestimmte unterschiedliche Frequenzen, die Formanten genannt werden. Für die Unterscheidung der Vokale sind insbesondere die zwei tiefsten Formanten von Bedeutung: Die tiefere Frequenz liegt im Bereich von 200 bis 800 Hertz, die höhere im Bereich von 800 bis 2400 Hertz. Über die Lage dieser Frequenzen lassen sich die einzelnen Vokale unterscheiden." Here is the link to the topic in englisch: https://en.wikipedia.org/wiki/Formant To get on we would should think about this.
Best regards Johann
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Hi tom, we keep on thinking and doing our best, but in the end we never know how others hear the same sound. For me spectrum carts are not as informative as the actual sound i hear. I wish we would have better tools to visualise sound and timbre. But in the end well trained ear is more precise. That's what i realised.
I also would like to to some dow back on my opinion about additional mode frequencies, and how much the cont in the resulting sound. I still think such frequencies are more or less present especially under transient conditions, but when a reed is sounded constantly i can't say that i hear or cn measure this additional mode frequencies. Don't trust this single test that all would need much more intense investigation. Especially on very low pitched reeds i have the impression the are noticeable but i don't have a practical way to influence the sound by profiling the reed. My be i am completely wrong with my hypotheses in this respect. As with all as time goes by the opinion on subjects may change especially if no one could come up with a prove. Still i hope younger people will put time in this subject. Unfortunately it is not of major interest to scientists. Still it is good to talk about it so it may be some one will get on it as well.
Best regards, Johann
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15 hours ago, ttonon said:
But I think this indeed explains why titanium to me sounds brighter than steel. It's that fifth harmonic, which dominates all except the first, by at least a factor of 50 in amplitude. It's often very difficult to make guesses about how different spectrums will sound unless there's clear dominance among enough harmonic amplitudes, but in this case, and you may not agree, if I saw that spectrum, I'd be confident to guess that titanium would sound brighter.
Tom i have the real sound not only the recording, and i think it depends strongly on the individium how we charge the sound. I had my hearing cuve checked some Years ago and then the test showed that i don't have any dropouts and i here quote high tone very well. Other my manly hear the lower components of the sound. So it may be well so that for you the titanium sounds brighter and for me it is the steel. Quite explanable with this 5th harmonic. 5th harmonic is 5:4 major 3rd (c to e1). If the 5th gets dominant it is more like a 3rd mayor is present. You may experiment with the sound by using equalizers try to inforce just the 5th or on the other hand enforce a wider range on the high end. I is common practice to brighten a sound by enforcing Frequencies above 1 khz.
Best regards, Johann
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3 minutes ago, ttonon said:
I can see that you simply reversed the colors for steel and titanium, and now, titanium is red.
No Tom see the index on the right. I did not change anything just the lins are now drown ble on top of orange.
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18 minutes ago, ttonon said:
I don't see much filing, so I'd guess that the tongue thickness is constant (no profiling) and that guesses about modal frequencies are probably reasonable. I apologize for not looking at that picture more closely.
Tom the tongue thickness is not constant it has the usual profile and the tongue bends in a smooth curve similar to the steel profile. But the titanium alloy reed is approximately 1/3 less stiff to get to the same pitch. So your theoretical model uses different parameter, with the same stiffness but different length. To get to the same pitch with nearly equal reed dimensions stiffness mast the different what results in less strong higher harmonics. That is for me a known circonstance if i make reedsets with different stiffness. Johann
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10 minutes ago, ttonon said:
Since there's no red color on the bump - or at the base of the bump - I assume that particular harmonic shape is duplicated by steel and titanium, since all other harmonics show a dark color whenever the values for steel and titanium overlap. I think you'd agree that this puts into question the accuracy of that harmonic measurement, because it's unlikely that both steel and titanium would have an identical 5th harmonic response.
Hi tom, the are not equal. I have attached the same chart but this time with blue line on top.
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45 minutes ago, ttonon said:
As interesting as Johann's data is, it cannot be decisive. Important information is left out. Most importantly, what kind of a microphone was used, where was it placed in relation to the reeds, is that relationship the same for both, was the same microphone used for both, what is the pressure level, what are the thicknesses and lengths of the tongues, what is the width and is it constant with tongue length, is there any profiling, etc. All these can have important influences. I'm struck by the very large 5th harmonic. In my experience, it seems exceptional. I notice that around the 6th harmonic, there's a blip that might suggest a slight contribution from the second bending mode of the beam. There's also a blip around the 16th and 17th harmonic, suggesting a third bending mode, however, we can't say for sure because we don't know if the geometry conforms to that of a simple constant area cantilever, for which such conclusions can be made. Additional blips might be contributions to torsional modes, though that's not too likely, but if pressures are high enough, maybe so. Then we have to wonder about the quality of the recording equipment and the software used to calculate the Fourier coefficients.
It's clear that theoretically, experimentally, and practically, a full understanding of tongue material would require considerable effort.
Please look at the attached pictures i also mentioned that test condition is totally equal and air pressure was 500 PaN/m2. Reeds were mounted equally on the same tunningtabel on exactly the same place. Nothing special about the microphone is an electrede micro. I don't say this are ideal test condition but enough to see differences in the chart. It my be you war mistaken steel has much more higher harmonics look at the chart and listen again. Don't take the blips to seriesly the my be caused by the wind machine i would need to repeat the test again with different pressures so i could tell for sure if the are from the windsource or not. The test condition should be carried out in a special noce damped room as well, i could do this in the sound laboratory at my former workplace. But this test was made on may workplace. All together would be a fillings subject for a dissertation. For now i don't have more. Best regards Johann
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I may be well wong on how the final instrument with titanium alloy reeds sound, i only know small accordions with brass or bronze reeds. All would need intense verifying and making complete sets with titanium alloys. Also keep in mind we only talk about reed sets my experience is that the instrument itself has also influence on the resulting sound and with "typical formant range" in the spectrum. We have et list some different filtering depending on the instrument. Comparing ist therefore alway not so easy. Best regards Johann
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" Listening to Johan’s sound files of a steel reed vs a titanium one, I really couldn’t tell the difference. The chart does show the different strengths of the harmonics, but our ears probably aren’t designed to distinguish between sounds that are proportionally so similar, especially since both seem to have strong odd harmonics as the defining feature of the tone. [...]
Tom doesn’t’ agree with Benade’s explanation and convinced me it may not be correct, but that is as far as I got.
Dana"
Hi Dena use headphones and you should hear the difference. Is not as much as one would expect and under real conditions it may be even less. Still i expect a more mellow sound as brass. This are all hypothesis that need to be proven in real Instruments. Also it is not so important for people who build instruments to understand way the different sound are produced. Important is that we know we can influence the sound by changing Profile and reed length. We just have to accept that reed produce beside the "normal" harmonics, that are more or less in a known relationship to each other, also harmonic frequencies that are in amplitude much less but don't fit into this scale. Changing profile will result in varying this frequencies and amplitudes of this so called inharmonic frequencies (additional mode frequencies). Relay on your ear by making reeds there is no real practical mathematical background that would really help in making reeds sounding more pleasant to our ears. Please point me to the differences of Bernard's explanation. Best regards Johann
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On 6/16/2019 at 12:26 PM, ttonon said:
Hi Tom my survey is surely not representative further observations would be need. Also be aware that the two sound files are with some background nice from the wind machine. Recordings war made with constant air pressure of 500 PaN/m2 Dimensions of bothe reeds are absolutely the same only the filing profile is a little be different to tune to the same pitch. Best regards Johann
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1 hour ago, ttonon said:
Hi Johann, I was maybe not clear enough. I respect your conclusions on observation and I'm eager to hear about them. It's when you try to explain the physics behind them that I sometimes cannot follow, and it's in the latter area where documentation would help.
Best regards,
Tom
Ok Tom i think it is mostly because it is very difficult for me to explain it not in my native language. This is why i would prefer that you ask question. You are on a very good way but things are often simplified to much. I know we have to do so to get on. But to understand all a bit better we have to proceed and think about it in a more complex scenario. For the simplified approach you are right, but once you have the simplified modul right you have to take more in account. Best regards, Johann
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4 hours ago, ttonon said:
The calculations I'm doing confirm that dissipation increases with amplitude, due to their nonlinear nature, and show that frequency drops can be as high as 50%!
Hi Tom, i am well aware of this as well, also keep in mind that not only with increase of volume the amount the pitch trops with increase of volume depends strongly on the spring stiffness off the reed. Also think in witch way dissipation comes noticeable what is causing the damping? Inertia material dissipation of the reed? No it is the air surrounding of the reed within a cavity that is more or less resistant compatible with bass sound boxes. But this is also in relation with resonance and coppeling. Don't see this as a completely different subject. I am electronic telecommunication engineer as well and i know how things are working and i know very well how LC or RC circuits or series of circuits behave and can be calculated and acoustic circuits don't behave completely different. For me it is not a matter that i have to prove it. It is or more less well known design knowledge. My be i can't explain it quit well enough because my english is not as good as it should be. Don't put it away think about it. If you have questions i will tray to explain. But i am not prepared to present more explanation without detailed further questions. Also is not for me to get a more intense understanding of this circumstances. At this time in my live (i am 68 Years old now) i am more in building of accordions especially the last teen years. I am retired from my professional work as telecommunication engineer and academy teacher in this field. Johann
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Tom i still don't know what your theoretical model includes, only the the reed as vibrating single side mounted beam? Or also the cutting of the air beam through the slot? The western reed is an impulse generator more like sirens not so much like a tuning falk. Johann
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Sorry Tom i cant agree, the same ist true for the western free reed as it is to a bigger extent on the eastern type with tuned resonators.
Think about it again. The only fact that it is possible to sound a western reed with a resonator that is very mistuned still does not change the fact that the reed on its own cant produce a sound. It always needs the air. Also keep in mind that the pitch can be varied by changing chamber parameters as well. In the eastern type the main sound generator is the air column and the reed is the rather passiv coupled part. With the western type it is the other way round, the reed acts as the main impulse generator and the misstuned resonator as coupled resonator. Johann
The dimensions of the cavity are small compared to the wavelengths of the vast majority of the musical frequencies - all except for the very lowest notes.
Ok agree but i think you mean the higher notes. Still you agree that we do have a miss tuned cavity. I do a lot of practical tests up to now. Especially on very low notes. Helicon Bassreeds with nots as low as 31 Hz. And changing cavity geometry is one of the major way to change the timbre. And iven on this very misstund situation pitch can be change up to semitone by changing geometry of the cavity. Johann
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1 hour ago, ttonon said:
Hi Johann, I believe you're under the mistaken impression that I experimentally measured different reeds that I made. This is not the case. I'm presenting theoretical results from a physical model and mathematical solution. The plots I present are the results of calculations from this analysis.
If it helps, I present the geometric parameters I used in these calculations, below'
Width of tongue = 3/16 inch
Thickness of tongue = 0.010 inch
Thickness of plate (shoe) = 0.125 inches
Length of steel tongue = 1.4 inches
Length of brass tongue (same pitch as steel) = 1.19 inches
Length of titanium tongue (same pitch as steel) = 2.77 inches
Length of carbon tongue (same pitch as steel) = 2.75 inches
Best regards,
Tom
Hi Tom, yes you are correct i did mistake the info in this respect! Ok this explains all. For me it is obvious that changing only the length be keeping all other dimensions the same for the same pitch must result in timbre change. So are my practical experiences. Johann
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2 hours ago, ttonon said:
"The docx file linked to below presents instructive plots comparing the harmonic amplitudes of titanium and steel. The results are most interesting in that, for low bellows pressure, titanium harmonic amplitudes are in general significantly less than those of steel, suggesting, if these amplitudes translate to the acoustic sound we hear, that titanium should have a mellower or less bright sound than steel. The prediction is that the sound should be even mellower than that of brass, in comparison to steel."
As i think you should know i did make sample reeds years ago with titanium and the measured and heard sound is as you described it here.
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10 minutes ago, ttonon said:
Hi Johann, what's the confusion? What would you like to know?
Tom
Hi Tom, the complete test condition described. How did yo make the reed? Dimensions off the reeds. that were compared. Johann
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I personal think it is a waste of time to to make reeds with Carbon (CFK) it is impossible to bend a carbon reed to set it correctly. This is important it is not enough to be able to sand the reed. And i personally would not like to do the job with this carbon dust. I did use carbon sheet material for some time not for rees but oherer parts.
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36 minutes ago, ttonon said:
Greetings. In my first post in this series, I forgot to mention the fact that in the comparison plots between brass and steel, the tongue lengths are adjusted so that the brass and steel vibration has the same frequency. In my second post comparing carbon and steel, the two tongues have equal length, and in this post, I give results for carbon and steel tongue lengths having the same frequency.
The amazing thing in this comparison is that the carbon normalized harmonics are enormously larger than those for steel. I honestly didn’t expect such dramatic results. And they show large difference even for the smallest bellows pressure. For me, this increases my curiosity over what a carbon fiber reed tongue would sound like. Notice also the dominance of the 5th harmonic over the 4th, for all but the lowest bellows pressures. I've noticed before the contentious battle between these two harmonics, and here it's well displayed.
The docx file for this case is the same: https://app.box.com/folder/79305691686
Best regards,
Tom
Tom this is a bit to less info how you set up the test condition.
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We never cover all aspects, main difference of DIX is the fact that the reed gup or precision is less narrow. A tighter fit of tongues to frame results always in more higher overtones.
I only can speak off acordeon DIX reeds the have in average shorter tongues on the comparable tone of modern reeds. Less stiff, thinner frames and geometrie is also different. All of this different dimensions have effects. Some or all have effects on overtone including modes, but the main difference is the reduced precision. Still if we copy old DIX as good as possible the never sound exactly the same. It is really difficult to copy old reedsets. If we only would need to know the type of steel and the dimensions then it should be possible but it isn't possible to copy this way. Even if we also copy the shaping the sound not quite equal. Most modern copies are to tight in fitting, so the sound brighter. But there are other factors what makes it difficult to copy DIX or other reedsets. Tom is right that modes do contribute to timbre but we are far away of calculating reed sound by setting up reed material and dimensions and stiffness. I agree that reeds made of different material do sound different because we have to use different length for the same pitch what results in a different mix of modes and overtones. I also disagree that carbon would be a good material for reed tongues. Carbon conbund is difficult to machine not easy. We also don't know how carbon compound behaves over longtime.
Reed setting tips?
in Instrument Construction & Repair
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Hi Tom, a friend of mine had two reed organs for repair and the did not have this shape of the reed tongue. The shape was as usual in accordions, but i know from other instruments, that it was in use quite a lot. Talk rektion is very slow on this reed organs. I have the impression that it was far more important to get a special sound as to have very good talk reaktion. Best regards Johann