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  2. There are literature on htis on the web: https://research.cs.aalto.fi/acoustics/virtual-acoustics/research/room-acoustics-and-physics/74-seat-dip.html In an informal listening test with Claudia Fritz and a group of violin makers at a meet at Cambridge a few years ago, the players tended to prefer the softer violin and the listeners preferred the stiffer ones. Jim Woodhouse and Cliare Barlow have a set of six violins with a similar look, but with different building solutions inside, made by David Rubio. The only apparent difference as seen from putside are different coloured thin threads on the pegbox near the scroll for each of them. I think this observation is interesting.
  3. M Alpert


    Yes, of course, it's never simple ;-) Can you explain what is the seat dip effect? And could you possibly link to any of the studies you referred to in the previous post, about CBH and masking effects? I wonder if @Don Noon , @David Burgess , @Marty Kasprzyk or any of you possibly reading this have any insights on the perception of carrying power vs. under-ear loudness, and why these don't always seem to correlate directly? Something I suppose I'm not alone in wondering about...
  4. Recently acquired one, I have heard about the particular bass bar before but never managed to play one by myself. The sound is certainly interesting but hard to say if it has anything to do with the bass bar design. Couldn't take a better picture of the bass bar as I didn't want to take out the end pin just yet. Wondering if these type of designs had any thought behind them or were just selling tactics.
  5. Hi I'm after some advice, I have a lovely looking German cello probably from around 1890's-1920s, but the D string sounds bad, like it's muted, hard to explain. all other strings sound great. there are a few other minor issues that I will mention just incase it could be the cause. the finger board projection is a little low so the bridge is not very tall 10mm shorter that usual. I think the front and back have been married together to the sides because the purling runs off at the top like the front and back were from another larger cello. I'm not to bothered about cosmetics more interested in good sound. also the neck is slightly short by 10mm could of been a 7/8 cello originally. i've moved the soundpost about but unsure what directions could fix this? I'm limited to how east/west I can go because of the soundpost height, I'm pretty sure the ends of the soundpost are well fitted. after length of strings from bridge to top to tail is 12mm, total string length from nut to bridge is 68mm it has a set of Larson standard strings on it, they seem to work ok on most cello's I've tried, the bridge is French despiau 2 trees and feet look well fitted. 2.5mm-3mm thick at the top where the strings meet, plastic winter tail with fine tuners, gut is steel with a plastic coating thanks for any advice I'm abit stuck
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  7. That mark makes no sense. If you follow it in a straight line to the corner block it will be below where the top is glued to the corner. If it went from the corner block to the lower neck block then it should be at the glue line and not visible.
  8. Cello setup should maximize the cello potential in terms of playability and sound. Endpin has an effect, you just have to try different endpins and play the instrument to feel the differences, and you can hear also the differences. Under the bow the difference between CF and steel is real and reproductible. I agree that compared to many other things in setup (such as strings quality or soundest fitting) it can be considered small but not small enough so that it can be completely overlooked after the basics step up has been done. Beyond the basic function of endpins (stability) there seems to be a room for further tweaking and if the rest of the set up is correct, why not exploring this path ?
  9. Didn't someone invent a guitar which was a whole body bracing frame with a type of bladder inside that could be inflated to make a membrane, to amplify and radiate the vibrations of the bars? This is why I want to build a plate with the bars on the outside. The wood for these bars should be chosen from the strongest and lightest tonewood offerings since they are the real business end of such a system. Balsa plus carbon fibre rp bracing is similarly intractable for reworking as those nomex boards are. It takes an angle grinder to make subtle modifications. Spruce is still a fantastic material for bars since it is workable and has a good shear strength wrt the axis normal to the bending moment. IE it doesn't split as readily under load as cedar or redwood braces so it can be made narrower and a little higher to reduce weight and increase stiffness.
  10. Certainly! At least in my opinion. It's a highly competitive arena, and there are many good players...
  11. Don't get me wrong, Fiemme wood is really beautiful, low density, slow growth etc... but yes, there has been hype linked to "stories" ( fables?), partly because of the tonewood trade since people actually started selling instrument wood from there, for which I haven't found any evidence before the 1960s. Also the whole tourism that has been generated in the area by all this... I would be happy to hear any evidence to the contrary, and also would be interested to know when the "Foresta dei Violini" in Panaveggio was baptized as such. Again I cannot find any reference to this before the 1960s. As I said, If am wrong, please put me right! What Andrea said about "whole trees" being acquired by Stradivari is possible, although I suspect we are talking more about billets, or sections of trees. One "good tree" may yield infinitely more soundboards than the 25 from the same tree already identified for a specific period of Stradivari's production. There are also several instances of a same tree association between the wood used by Stradivari and that used in other workshops in Cremona and, importantly, also in other towns. For instance, the wood on the Messiah ( I may regret mentioning the unmentionable...) is found on several other Stradivari, but also instruments made in another workshop in Cremona, Brescia, and Ferrara. Whether Stradivari bought the entire logs, processed them into wedges and sold some to others is also possible. I suspect, however that smaller billets, naturally far easier to transport, were circulating and sold by the dealer or dealers. ( I suspect one main dealer only) who may have travelled to different towns.
  12. I used a vacuum bag for doing my wood veneer laminations. It is important to minimize the amount of glue you use because that adds weight. I didn't experiment with light weight Nomex honeycomb cores sandwich constructions but my understanding is that they have better stiffness/weight ratios than any solid spruce wood plates which will increase sound output as guitar makers claim. But I have never seen their stiffness/weight comparisons with balsa wood or the paulownia wood (0.28g/cc) which I had used for about three dozen instruments. However a solid wood plate is an inefficient use of material (low radius of gyration which is the square root of the cross section's ratio of moment of interia/area) so I've started using a ribbed bracing construction like guitars and wooden building floors use. One of the advantages of a ribbed construction is that you can vary the bracing pattern and heights to adjust the various mode shapes and frequencies to change the instrument's frequency response curve to what ever you want. With a sandwitch construction like with a thin wood veneer and honeycomb core you are stuck with it after you make it. You can't thin it anywhere to change its vibration behavior. So you end up putting braces on it anyway.
  13. So at this point, and reading the replies, no one really knows an answer to my original question. I think maybe a better way, did Stradivari have the luxury of choosing which woods he selected? In other words, was the selection of various stiffness in density really available for him to do something like that? I don't imagine it was like going to your favorite wood shop and browsing through all the different varieties of spruce. Maybe I'm wrong, but it seems to me that would be a very labor intensive and expensive occupation to cut down a bunch of trees to find just the right one., no matter who was tasked with that job.
  14. I do the tapping on the back side with the goal to put the back under tension to balance the string tension , even if I know Stradivari was doing the tapping on the top side. here are the pics of the Reynier Stradivari 1727 showing the mark left visible.
  15. Thanks Andreas. I think it depends also how old is the instrument. The oldest seems to have lower neck angles.
  16. That’s interesting. Got the wrong information then. So what’s the hype about this wood from Fiemme?
  17. 365nM LEDs might be better for drying and tanning cabinet lights judging by this review. https://www.waveformlighting.com/tech/what-is-the-difference-between-365-nm-and-395-nm-uv-led-lights
  18. Andreas, there is absolutely no evidence (dendrochronologically or otherwise) that the wood actually came from Fiemme. Having now measured well over 300 Stradivari instruments of all periods, I can safely say that, on the whole, this is incorrect. There are, however, variations in the density proportions between early and late-wood depending on the periods. There is however, a much higher degree of variability of these parameters on larger instruments such as cellos, and forget about basses...
  19. As they say you win't get a tan from it and they are talking about compact fluorescent tubes which I haven't measured yet only standard straight fluoro tubes. I'll see if I still have any CF bulbs and measure as many other light types as I can. The sensitivity is surprisingly good but I am developing a more complex circuit. That was the quick and dirty version. I need to calibrate these off-the-shelf leds I'm using as detectors and to do that I'll need to tweak an old spectrophotometer I have --- surplus, came free with a centrifuge! Those values jotted down in that pic, ranging from approx 0.25 to 1 volt are from medium sunlight here at 35' S ,summer, RH about 50%. The 30W UVA led measured from a distance of 50mm had 2 or 3 volt values for some of those wavelengths. A white 30W led worklight had zero on all of them. Experimental Characterization of Single-Color Power LEDs Used as Photodetectors https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7570861/
  20. I don't know what your detection threshold is. There are lots of articles and studies on this. Here's one of the less technical ones: https://www.npr.org/sections/health-shots/2012/08/08/158426970/energy-efficient-lightbulbs-have-a-dark-side-when-it-comes-to-health
  21. I like to do accelerated light-fastness tests by putting a varnish sample on wood; cutting the sample in half; putting one half in a dark place like inside a drawer, and taping the other half to the inside of a windshield on a car which stays out in direct daylight, and comparing them later. I'm shooting for much longer than ten years of stability, given the amount of time that better violins seem to remain in use.
  22. This is also a psychoacoustic phenomenon, «hearing the missing fundamental». It is used in loudspeaker design. I have learnt at VSA Oberlin workshop that a similar effect is true for violins. I guess «carrying power» is a mixture of loudness, a suitable timbre of the violin, low background noise, a suiteable room acoustics and a reasonably humid room. In addition the player can form the timbre by playing closer to the bridge or louder. In my former post I write about psycaoacoustic phenomena, and not the sound transfer in a room, although that influences the perception. The sound becomes weaker at distance, it contain slightly less high frequency content. The «seat dip effect» may weaken some of the very lower frequencies of a violins. I think both the player and the instrument play a role. With an instrument with weak highs or funemantals it is difficult to compensate. For a soloist both needs to be good.
  23. If there is a correlation between ring spacing and density in maple, it can't be very strong, according to the wood that I have. I measured 3 of my lightest sets (.51 - .56 density) and 4 of my heaviest sets (.675 - .71 density), and found fractionally wider ring spacing on the heavy group. All Euro, from 5 different sources. Then there's the piece of Bigleaf with finger-width grain spacing at .77 density.
  24. I don't remember the name and details but there was a high-tech resaw owner who offered the service to guitar makers of slicing their soundboard blanks into veneers to be used in making composite soundboards with a nomex core and spruce skins. Some of those makers were using these boards for unbraced soundboards, unbraced aside from the bridge.
  25. A big problem in making duplicates of violins you like is that wood has such widely variable properties (density, and the various elastic moduli in the three different directions). Various strategies have been used to compensate for these variable properties. You have a chunk of wood in front of you and you need some goal or target for shaping the plates (thickness, arch height, weight, tap tone frequencies, stiffness, impedances etc.) and makers have often argued what strategy is the most successful for adjusting to these wood variations. But a different approach is to carefully pick uniform pieces of wood to miminize these property variations to begin with. Another method is to use laminations of several glued layers of veneer wood glued together which averages out much of the indidiual differences. Plates made from laminated wood problably show much less plate to plate variation than solid wood plates.
  26. Going by photos and scans it seems to me that early makers like Stradivari commonly used spruce with thick and dark, fairly widely spaced growth rings. And I think those are features associated with fast growth in younger trees in areas with warm summers and very cold winters which are common in European alpine areas. And those strong, thick rings are very dense and strong while the wood between them is the opposite. Spruce with very fine, closely spaced rings is structurally quite different.
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