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Łukasz Martynowicz

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Posts posted by Łukasz Martynowicz

  1. On 1/13/2022 at 4:49 PM, Stefan said:

    There are two small microphones under my palms, one left one right. They go into a guitar multi effect board that has two separate effect strings. So I can use different effects for the left and right side. 


    Thanks! But I do wonder - how are there no feedback loop problems? Sorry to ask so many questions, but I simply love the electrified concertina sound since I first heard your recordings few years ago, and wanted to try this myself, but I have no real experience outside of acoustic and MIDI environments.

  2. 59 minutes ago, Stefan said:

    Yes Geoff, it´s from 1916 and I am still greatful that you gave it to me. It plays and sounds like a dream. And yes, I take good care of it.

    Do you know where Alex West got it from? He is a member here, maybe I can ask him.

    If Concertinas could talk....

     

    I always wanted to ask you - how is it electrified? Is it a pickup, a microphone, a MIDI pickup? And do I guess correctly, that only a single side is electrified and the other is plain acoustic?

  3. 7 hours ago, Little John said:

    I envy your opportunity to try this out. I'm sure I would find it fascinating, but in the end I have to go with your later sentiment:

    but if I had come across it much earlier I would have been sorely tempted to make the change!

     

    I don't really think about it now, but in my earlier days I tended to think of it as right-to-left: D E F (up a row) G A B etc.

     

    I also wondered why the original design wasn't right-to-left: C D E (up a row) F G A etc.; ie why the "D" and "E" columns are interchanged to give the 1-3-2 pattern of fingering. My conclusion lay in the right hand accidental column. If you think of them as being related to the adjacent column then the CDE pattern would yield Eb, Ab, Db, Gb and Cbb (yes, C double flat). The actual CED pattern gives D#, G#, C#, F# and Bb which is much more intuitive.

     

    I actually played a mouth-blown version of this once. The keys were hexagonal so there were no gaps. However following the link and studying the layout makes it clear that you couldn't convert a Crane as even a single chromatic octave takes 7 columns.

    Ah, you’re right. I just remembered it exists, scanned through it briefly on musix when posting and my phone cut it to five chromaticized columns. My bad. I have clearly overdosed isomorphic layouts into one, big, isomorphic blur :D

  4. For those of you who would like to dabble with this or other regular layouts, there’s a great app called Musix, that let you arrange any isomorphic layout on either square or hex grid. 
     

    As to features of 5CC, any isomorphic layout gives you uniform triangles for triads, and in fact a single geometrical shape for all chord classes. But some of them strongly favour chordal play vs melody play, some get into „twisted fingers” problems, some have octaves stretched over so many columns/rows, that it is impractical or straigth impossible to implement on concertina… 

     

    The layout that seems to be best suited for Crane conversions is called Harmonic, spans over 5 columns of the hex layout and is pretty much a Crane turned inside out - black buttons in the center, white keys on the outside. It’s main feature is that with large enough buttons and small enough distances between buttons, triads can be played with a single finger. Great for singing accompaniment Cranes are often used for.

  5. I’m 100% positive, that they mean brass plate, steel tongue, and probably mean DIX range of reeds by Harmonikas.cz. The reason is very different tone, way closer to traditional concertina reeds, than standard accordion aluminium plate reeds. In last years harmonikas.cz extended their DIX range towards concertina world and now offer three grades of reeds suited for concertinas - fully traditional with straight screwed tongue; semitraditional with standard accordion shaped tongue on concertina shaped shoe; and their brass plated twin tongue accordion reeds. I have those reeds in my Hayden and they sound lovely. They have way more depth to their tone than standard accordion reeds.

  6. 4 hours ago, ttonon said:

    Lukasz, from my calculations, I see no possible resonance interference with the tongue vibration.  This applies to both Helmholtz and quarter-wave tube resonance.  

     

    I thus cannot make a suggestion here, only I'm still not clear on what the basic problem is.  Are you saying that all the F3 reeds you put into the "bad" cavity show the same problem?  Also, that when you put those same reeds into a different cavity but with the same dimensions of the "bad" cavity, there is no problem?  

     

    Best regards,

    Tom


    Exactly. Bad cavities are on the LH side of the instrument and good ones are on the RH, reeds are identical and it does not matter which one I mount where. The .wav file above is with endplates mounted, but this problem is present without the endplates as well. Endplates emphasise it further.
     

    Some parameter of reedpan is causing this but not simply inner vs outer chamber placement, as both initial chambers are outer ones. I suspect it is either amount of solid wood block left in the reedpan, differences in reedpan’s wood parameters between sides or the exact layout of surrounding voids, because I can get significant improvement in spectrum shape during tests by using tack to mount the reed to the reedpan instead of rigid screw connection and thus decoupling it mechanically. 
     

    But using tack is not a valid permanent solution so I’ve settled with increasing chamber depth to bring missing partial back as a way to rebelance this instrument. It is not ideal, as I loose some higher partials this way, but it sounds way smoother now.

     

    Perhaps it is now easier for you to understand why I said, that reeds seem to not care too much for our simplistic mathematical models :D 

  7. 2 hours ago, malcolm clapp said:

    In response to a couple of recent inquiries, I have today posted on my Soundcloud page https://soundcloud.com/klappo a number of recordings I made back in 1984 of talented Crane/Triumph player Polly Garland, who sadly passed away at the end of last year. (Just ignore my melodeon stuff 😎 ). Perhaps Daniel or Alan might like to add a link or two to the Duet Recordings Page if any of the tracks are likely to be of interest to members here. Thanks.

     

     

     

     

    Great material! Does anyone know, by chance, where can I get the dots for "Un-noticed Waltz"? 

     

  8. 1 hour ago, ttonon said:

    Hi Lukasz, I just now heard your wav file and I agree, the 1st and 3rd sounds seem restricted, and the 2nd and 4th more open or free.  In my experience, such a restricted sound occurs when the mounting of the reed - most often the geometry of the cavity - begins to acoustically interfere with tongue vibration.  For instance, if the port is too small, or even if the leather valve isn't opening completely enough.  Alternatively, there could be some defect in the construction of the reed, such as a burr, or other way to interfere with tongue vibration.  

     

    Your guess that the problem lies in a restricted second partial seems to be borne out by the spectrum.  In the bad note, that partial is about 13 dB below the fundamental, and in the good note, it's only about 5 dB below the fundamental.  I'm not sure there's evidence in the spectrum for your claim that the energy of that second partial is fed into the higher partials, which from my experience would be an odd occurrence, knowing what I know about the conversion of pressure pulses to audible sound. 

     

    We can notice that the bad note has also a greatly reduced 8th partial, compared to that of the good note, but I doubt that has anything to do with what we hear, since the pitch of that partial is about 22,000 Hz, far above our normal hearing range.

     

    However, your discovery of this reduced second partial may give us a clue.  If you'd go through the trouble of presenting here all the exact 3-D dimensions of the cavity and the size of the port, I'd be glad to take a look at it, possibly finding an identification of the second partial frequency with some way the cavity could resonate.  If it's a simple rectangular cavity, it should be easy to do.  

     

    Best regards,

    Tom 

     

     

     

     

     

     

    That's exactly the mystery though - ALL tested cavities (this is a hybrid, I have more than two cavities of same dimensions), good and bad are 39mm x 14mm x 10mm and ports are 10mm diameter (and I also tested it with 12mm, 9mm, 8mm and 7mm ports). Graphs you see above are identical if I switch the reeds side to side or if I test any other identical chamber on the LH. I have two reeds (four tongues, four valves) and the problem always stays with LH side of the instrument for F3 note, with or without endplates, in both airflow directions and with all possible flips and orientations of those four tongues. Some of those chambers identical chambers are outer (basic two in question are both outer, but one of them is perpendicular to the closest outer edge and one is at 45 degrees) others are more or less inside the reedpan.

     

    Regarding "feeding into higher partials" - audible volume of the bad reed is louder than the good one (though dB meter stays at +/- 1dB spread between sides), so I figured that this energy has to go somewhere and on those graphs you have bit different distribution of dB levels of higher partials. You're the expert though, I'm just a more and more confused amateur builder looking for solution even more than the cause.

     

    Now the trick with increasing depth of the bad side chamber by 50% does change the spectrum enough for those notes to blend into the accompaniment well enough to pass as a flavour instead of the right out interruption, but this is a not ideal workaround.

     

     

  9. 11 hours ago, ttonon said:

    Hi Lukasz, Audacity enables the calculation of a frequency spectrum showing a rectilinear graph, with sound intensity on the vertical axis and frequency on the horizontal axis.  I believe that such a representation is much more useful than the kind of spectrum you posted here.  If you can't figure out how to get that graph on Audacity, let me know and I can perhaps lead you through it.  

     

    More basically, I don't know what your "problem" is.  Apparently there's a problem with the sound of two different F3 reeds when alternatively mounted in the same cavity.  Is this correct?  If so, could you please explain in detail the problem in the sound?  Do you think you see the "problem" in the spectrum you posted?  If so, please explain.  In the "Bellows pressure and musical pitch" thread, if I recall, you thought that the poor sound was because of a pronounced harmonic and I suggested you do a spectrum analysis.   Do you still think the  problem is with a pronounced harmonic?  If so, the kind of spectral graph I describe will be most useful.  

     

    Regards,

    Tom Tonon

    www.bluesbox.biz

     

    For your convenience, here are audacity screenshots, first is the bad one.

    Screenshot 2021-09-12 at 13.50.24.png

    Screenshot 2021-09-12 at 13.50.41.png

  10. 10 hours ago, ttonon said:

    Hi Lukasz, Audacity enables the calculation of a frequency spectrum showing a rectilinear graph, with sound intensity on the vertical axis and frequency on the horizontal axis.  I believe that such a representation is much more useful than the kind of spectrum you posted here.  If you can't figure out how to get that graph on Audacity, let me know and I can perhaps lead you through it.  

     

    More basically, I don't know what your "problem" is.  Apparently there's a problem with the sound of two different F3 reeds when alternatively mounted in the same cavity.  Is this correct?  If so, could you please explain in detail the problem in the sound?  Do you think you see the "problem" in the spectrum you posted?  If so, please explain.  In the "Bellows pressure and musical pitch" thread, if I recall, you thought that the poor sound was because of a pronounced harmonic and I suggested you do a spectrum analysis.   Do you still think the  problem is with a pronounced harmonic?  If so, the kind of spectral graph I describe will be most useful.  

     

    Regards,

    Tom Tonon

    www.bluesbox.biz

    There’s a .wav file with this problem attached to one of my previous posts. I have now switched to real time app and indeed the freq/volume graph is what I’m using. The problem is with missing/reduced second partial and shifting this energy into 2-4 higher ones (how many depends on the note in question) and as I wrote in previous post, it turned out this affects not only F3 but few other notes as well. F3 was most audible because the endplate emphasised this further in case of this note. 
     

    And the problem is not with two reeds alternatively mounted in the same cavity, but a single reed alternatively mounted in two identical cavities. I just have two of those reeds, also identical, so I can swap them around. The problem stays with LH cavity. 

     

    1 hour ago, d.elliott said:

    From time to time I have experienced the this sort of problem on various instruments, I have never truly understood the issue but I have found that the following has helped. running a 400 frit file round the frame vent and across the top surface of the frame to ensure a clean edge around the reed vent, and the removal of any burr, then polishing the flanks, and tip of the reed tongue to ensure no burr or accumulation of dirt or even corrosion. Then re-centralising the tongue in the vent.

     

    I can recall changing the reed tongue in one instance because the reed had been filed in such a way that the filed surface was far from parallel to the under side and that the filing seemed to be closer the tip than I would have expected. This did work, emphatically!.

     

    I suspected that the reed was beating with a figure of eight path, and that there was possibly a slight secondary flex to the reed. I am talking an old and traditional reed here.


    The strangest thing is, this is not because of anything with the reed itself.

     

  11. Ok. I have revisited the problem with a proper real time spectrum analysis app and have some findings and a good enough workaround but I still have no clue about why the difference is there.

     

    So, the problem does not originate in the endplate/action box, it just so happens that with F3 it emphasises the problem so much that it was unacceptably large and could not go by as "flavour". Now that I know what exactly is happening I could check all notes and as it turns out it does affect not only F3 (it is just the most offensive note), but assorted other notes, mostly on the LH side, with just a couple on the RH side, because lower notes are generally more affected by this. What is happening is that some notes have 2nd partial reduced and this energy goes into several upper partials, creating a gap and a "trumpet like" timbre. Only a single note, A3 is affected equally on both sides of the instrument. My best guess about why those differences are there is that either the amount of leftover reedpan material or exact chamber neighbourhood (layout of surrounding voids) interferes with some frequencies. So Alex, it turns out that this is related to what you wrote earlier, but it is not directly related to distance to outer edge, or anything else that I could pinpoint. At this point I simply accepted this phenomenon and moved to finding a workaround.

     

    On 9/9/2021 at 7:42 AM, alex_holden said:

    I don't have a solution, but I have noticed on traditional-style instruments that you get similar tonal differences between chambers that have the pad close to an outer wall and ones that are closer to the centre of the pan (what I call "inner chambers"). I've not yet figured out why it happens or how to prevent it, other than making the instrument bigger and moving the chambers to the outside of the pan. The effect seems stronger when the affected reeds are lower in pitch.

     

    What I've found worked well enough was to increase the depth of chambers in question by 50% (I've tested this in 10% increments) which promoted lower partials just enough while not muffling too much upper partials. I've fixed three notes at this point so it's a reliable enough solution.

     

    So now I have an instrument that requires that chambers on each side of the instrument differ substantially in order for two identical reeds to sound uniformly enough. Odd.

  12. 1 hour ago, Geoffrey Crabb said:

    Being a simple concertina maker/repairer (now retired) and a technology Luddite, I am somewhat confused by the following part of your statement which seems contradictory:

     

    If,

        1. 'the problem stays with the note, not the chamber'. This suggests that there is some anomaly with that particular reed. 

     

       2. 'despite not being related to the reed itself.'  have you actually proved this by careful visual examination and comparison with the other ,non affected, F3 reed?

     

    If all the gaps etc are the same, perhaps the profiling is different. 

     

    Just a thought

     

    Geoff

     

     

    As I wrote above, there are two F3 notes in that box, one on each side. When I swap reeds between sides the problem stays with the side of the instrument, not any of those two reeds (four tongues, this is a hybrid).

     

    1 hour ago, dabbler said:

    I'm not a master builder but here's a thought.  Maybe the resonance of your fretwork is tuned such that it absorbs energy from the F3 frequency.  That is, the fretwork is acting like a tongue drum tuned in a way that interferes with the F3.  You could probably test this by sticking hard modeling (plastalina) clay or mounting putty to the fretwork to alter or eliminate the resonances.


    That is my current theory, and I have made mass tests by adding putty to both sides, to either fix LH or recreate the problem on RH, but to no avail (but perhaps I have simply used too little added mass, such composite system probably acts differently to solid wood and I only added enough to cover the difference in geometry). But I figure this is a geometry issue if the endplate rather than mass of the endplate (the area of the „tongue drum” part). My current plan is to 3d print temporary endplates of the same geometry and work from there with carefull alterations in hope to pinpoint the cause and then apply results to the real endplate. But first I’ll try to butcher the endplate on this other box showing the same symptom, as it is a „single serving” 3d printed travel box made for this year’s vacations, now sadly behind me. I’ll report results of this butchering in a day or two.

     

  13. 1 hour ago, alex_holden said:

     

    Do you mean, if you put an F3 reed in a particular chamber it sounds poor, but if you swap an E3 or F#3 reed into the same chamber without changing anything else it sounds fine?

     

     

    I don't know. I have tried adding chamois gasket material to the back wall of an inner chamber (on the theory that maybe the bellows frame lining is absorbing some harsh harmonics), and I couldn't hear any difference. Also @Dana Johnson's reed pans seem to be routed from a single block and have solid back walls, even on the outer chambers.

    http://www.kensingtonconcertinas.com/photo-album/5-inch-reed-pans.html

     

    My current best guess is that it has something to do with how the sound resonates inside the action box. I tried fitting a small dummy wall inside the action box next to an inner chamber pad, with again no noticeable difference.

    Only F3 reed and maybe G3 reedto lesser extent behave like this and perhaps F2 and G2 are affected but those do not have direct counterparts on the RH side so I can’t easily verify this. If I move this F3 reed to other four chambers of same dimensions the problem stays with the note, not the chamber, despite not being related to the reed itself. As I wrote, this problem stays with the instrument side, nothing else seem to affect this particular rouge frequency spike. Of course moving the reed around changes the tone as you would expect, but more on the bright-vs-cassotto dimension. 
     

    Dana’s reedpan design indeed falsifies my intuition. 
     

    Same as you, I have also tried fitting a dummy wall behind this pad, and same as you got no results.

     

     

    • Confused 1
  14. 4 hours ago, alex_holden said:

    I don't have a solution, but I have noticed on traditional-style instruments that you get similar tonal differences between chambers that have the pad close to an outer wall and ones that are closer to the centre of the pan (what I call "inner chambers"). I've not yet figured out why it happens or how to prevent it, other than making the instrument bigger and moving the chambers to the outside of the pan. The effect seems stronger when the affected reeds are lower in pitch.

    At first I thought so too, as I remembered discussions from years ago about those tonal differences you write about. But this particular quality does not change when I move this note around four different chambers on the LH reedpan. 
     

    Now regarding what you describe I always wondered if it is because in traditional concertinas the back wall of the chamber is decoupled from the pan, while with inner chambers all walls are connected (either glued or carved from a single block altogether).

  15. In the pitch stability thread I’ve mentioned my misbehaving F3 note. I’ve done some more tests and I’m fairly certain that I’ve managed to norrow down the likely cause/causes. Attached is a screenshot of spectum analysis from Audacity: on the left are two repeats of LH/RH comparison (I have two F3s) with endplates mounted (a complete instrument) and on the right is LH/RH comparison without the endplates (only bellows and single reedpan/action board on the bench. It is the LH note that is problematic. Volume difference in the bench part is only partially caused by my failure to recreate exactly same pressure (this is large box, 8 2/3”, and is as such is VERY responsive), this note does sounds percievably louder during normal play, but the 2khz problem persists after decreasing the volume by decreasing padhole diameter.

     

    First a comprehensive list of all manipulations that do not affect this problem:

    reed and valve: this problem does not follow the reed when I switch reeds between sides

    chamber volume and coupling: chambers on both sides are the same and introducing a controlled airleak does not change anything

    chamber placement on the reedpan/relative to the fretwork: since this is hybrid Hayden I have 4 chambers of this size all over the reedpan and moving the reed around does not alter this particular tone quality.

    padhole size only affect overall volume

    baffles, of any kind, outer, inner, partial, full, even nearly airtight, do not alter this particular tone quality. This also includes antlers/hand placement.

     

    Now, the only manipulation that switches the side of the problem is switching endplates. But as I wrote above, it has nothing to do with reed placement relative to fretwork/hand. 

     

    So, if I did not ommit something else, there is only one (and a half :) ) possible culprit. Both endplates share the same pattern, except for number of button holes and thus a volume of solid wood left in the LH endplate (this also means larger continuous (I’m not sure about the word here, entire endplate is obviously continuous, what I mean is „without any hole in it”) area in the center of the endplate). Other than that („and a half” :) ) there might be a slight difference in the thickness of shellac coating on the LH as I had to make some revisions to it. When tapping on the endplates they do make different sound, with LH being slightly lower.

     

    Now three questions to more experienced builders:

    have I forgot to test something else

    have you encountered a similar problem

    do you think that removing wood on the inside of the endplate will suffice or I have to bore another hole through the surpluss continuous area.

     

    This problem is the most audible with F3s, but I now think it also influences other notes slightly, up to G#3, just not to the point of dominating the chord/octave/side ballance so it have slipped my ear before yesterday’s investigation. It might also be a part of the reason why my F2-A2 range has a clear trumpet quality to it.

     

    One last curiosity, I have encountered the same problem of F3 standing out on entirely different box, a 7”, 3d printed hexagon with normal alluminum accordion reeds and not brass DIX reeds as in the box in question.

    D14661DB-9CCE-49AF-A638-87B1EACDEFDA.png

  16. 2 hours ago, pierstitus said:

    Nice handle design @Łukasz! I'd be curious to try something like that with the Striso.


    Thanks! But as David wrote, I don’t see a benefit of this type of handle on an instrument without the bellows, especially when my handle is designed for sitting position. You already have the „flying hand” I was trying to achieve.

    That is unless Striso has accelerometer capabilities. In such case trading thumb freedom for additional degree of expression might indeed be beneficial and my handle leaves other 4 fingers virtually unconstricted. 

  17. Currently I’m using Zoom iQ7 mic with iphone (I have been using Tascam im2 in a-b setup before). This is mid-side mic, so it gives a nice option to controll how much stereo/room reverb you want in your final recording. Depending on your iphone model you may need to use lightning extension cord due to interference with power supply. There are other such „field recorder” iphone mics, in a-b, x-y or mid-side configurations and with different price tag, so read some reviews/rankings first if you like such portable option.

    • Like 2
  18. 11 hours ago, soloduet said:

    Thank you David and Don! The technical topics are always a little difficult for me and even more difficult as it's always written in English, but I intend to explore little by little all the potential of the instrument.

    To switch between both instruments is another difficulty but I think that it's possible to memorize both, like between violin and viola or cello. Actually I feel that the spacing and diameter of the buttons is a little more comfortable on the striso (about 14 mm between the centers of the buttons and about 1 cm for the diameter), so I wonder if it would be possible to make duet concertinas with a little larger buttons and spacing between the buttons even if I don't have very big fingers.

    With the striso duet you loose the expressivity of the bellows but you win the freedom of the hand on the keyboard without any hand straps...


    Regarding hand freedom without the strap, take a look at my handle design here: 

    I’ve now tested it on two boxes, 66 button you see above and 45 button, 7 1/3” box. I’m nowhere near your level of play, but I’m now learning a piece that uses almost entire RH range of the 45 and it poses no fingering problems even when jumping from Bbs to G#s and D#, all while giving normal bellows control of a hand strap.

  19. 3 hours ago, Dana Johnson said:

    Lukasz,

      especially for lower reeds (B3 and lower) and especially if the press and draw reeds are close in pitch,  ( and or have a harmonic component near the paired reed ) I often experience an odd coupling where the flap valve adjacent to the active reed slightly opens and closes causing a burr adding to the reed pitch.  This also happens at low to medium pressure when the valve is cupped ( touching at tip but not in center ) even for high reeds, where it opens and closes with the pressure variation, making the burr related in frequency to the active reed.  I can usually solve the low reed condition by using a valve that is thicker but not stiffer so it has a lower ability to vibrate at the activating pitch.  The noise isn’t valve noise, but rather how the driving pressure on the active reed is caused to vary by the slight bypass of the vibrating valve.  I don’t know if this will help your particular case.

    Dana

    Thank you very much for this hint, it might be a part of the problem, as this is a duet concertina, but as I wrote earlier, this problem does not follow the reed when I swap them between sides of the instrument. But maybe it is a significant enough part to it. 
     

    What you wrote about wall height influencing the spectrum is in line with what I have observed with my lowest reeds when trying to improve response and pitch stability (this is when I had to and could go creative with chambers in an already built instrument). 
     

    @Tom, yes, those were the conclusions on initial tongue oscilation mechanism. Without allowing it to happen by overblowing the reed, tongue acts as a simple pressure valve, exactly as I wrote before. I also second what Dana wrote about too thin/soft/weak tongues being prone to choking. I have a set of russian reeds from a cheap accordion, which are apparently made from a chopped tin can :D. Those are near impossible to set properly, they either choke if you play staccato or are so air hungry that it is pointless mounting them in concertinas.

  20. Exactly as Alex wrote, you can choke any reed, over any cavity, if you overblow it during the first half cycle. We have long ago established in discussions on this forum, that initial oscilation happens and has to happen entirely above the reedplate, otherwise the tongue sinks in the plate as you would expect from a simple valve and cavity resonance has nothing to do with it. 

     

    Another question about irrelevancy of chamber shapes - aperture location relative to tongue tip makes all the difference for both reed response and strength of the tone. With long, thin chambers, location of the reed along the wall and aperture location also play significant role. In a simplified model of „only volume matters” those should not have any impact.

     

    But I think I know why we missunderstand eachother - for me the isolated pitch question is not really all that important or interesting, because I can tune deviations happening due to say valve choices or anything else with a simple file. It is the response problem, the timbre problem and the volume problem that is trully important when building an instrument, and with those, everything matters to lesser or greater degree and simplistic models don’t usually provide meaningfull clues when you encounter a problem.

     

    Now about burr/beating - it may help to know in this context that I’m not a native english speaker and finding an adequate translation for sound phenomena is difficult. But when I say that one partial gets amplified, I say that after looking at the spectrum in my tuning app (which sadly has no scale, only graphical representation). The spike is not present when testing without the endplate and is present with the endplate.

  21. I agree that „beating” is confusing. What I mean is that one higher partial is so emphasized that the reed burrs.

     

    I only ever encountered Helmholz calculations in free reed context in orthogonal form, so my bad here, but in this case it is even less acurate for free reed physics because cavity shape matters and matters a lot. Sorry, but you are trying to convince me, that when theory contradicts experience I should rely on theory instead of practice. When working to improve my largest reeds’ response I had to work within confines of available space, so I had to work with shapes I could fit in. Simply creating a cavity of calculated (and then verified on variable length cuboid tuning chamber) volume and mounting the reed on it did not work well. The response was better (but still not ideal) than small volume, but the sound was muted and nasal. Reshaping the cavity (with near constant volume) changed the tone completely, with different shapes having different exact result, ranging from soft and muted to powerful and deep). Moreover, changing the angle of completely constant cavity (to fit another one) relative to action board/padhole also significantly changed the response and tone. So I’ll stick to my experience for now and wait for a model that can explain those variations.

  22. I know this table and I know Helmholz model. What I try to tell you is that you can make the reed work perfectly well with non-orthogonal cavities that do not follow this model, thus the model is overly simplistic. Another example - I’m currently trying to solve the following problem: I have two F3 reeds in the box I’m building, both cavities have exact same geometries (classic Helmholz orthogonal), one causes beating, the other does not. The problem is not reed related nor valve related, as it doesn’t follow the reed when swapped. It is also not air leak decoupling related as you imply above in similar context. What is different between those sides is position on the reedpan relative to outer border and surrounding endplate geometry. Since you seem to understand reed physics way better than I do, maybe you can point me in a proper direction here? I have encountered the same problem in the other box and have indeed thought at first that introducing cavity leak will solve it, but it didn’t. This particular case has different reed, different valve, different cavity dimensions (coincidentally it is the same note, F3) and the spectrum is ok up until I secure the enbox screws. Any suggestions?

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