Łukasz Martynowicz Posted September 8, 2021 Share Posted September 8, 2021 (edited) 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. Edited September 8, 2021 by Łukasz Martynowicz Quote Link to comment Share on other sites More sharing options...
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