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Łukasz Martynowicz

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Chatty concertinist

Chatty concertinist (4/6)

  1. 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
  2. https://en.wikipedia.org/wiki/C_(musical_note)
  3. Great material! Does anyone know, by chance, where can I get the dots for "Un-noticed Waltz"?
  4. 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.
  5. For your convenience, here are audacity screenshots, first is the bad one.
  6. 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. The strangest thing is, this is not because of anything with the reed itself.
  7. 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. 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.
  8. 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). 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.
  9. 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.
  10. 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).
  11. Here is an audio source for the left part of the screenshot. 1st and 3rd is the bad reed, 2nd and 4th is the good one. ZOOM0001_MS120.wav
  12. 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.
  13. 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.
  14. 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.
  15. 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.
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