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robedney

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  1. I realize that this is an old thread -- and I haven't been on Maestronet in a long while now -- but we've had an inquiry about carbon fiber sound posts specifically referencing this thread. I thought I'd answer here and share what we've found: We make carbon fiber violins, so you might assume that we'd fit carbon fiber posts. As a general rule, we don't. The reason -- as suggested in some of the replies above -- is entirely pragmatic. Luthiers are well equipped and experienced in fitting/adjusting spruce posts, not so much carbon fiber. As sound post adjustment is a key component in any good setup, it makes no sense to put an obstacle in anyone's way. It's basically the same reason we use ebony nuts and maple bridges. When it comes to the real difference between spruce and CF, in my experience there isn't any -- not that I can hear or measure. Here's my pet theory: The use of the sound post in violins may very well have had to do with simply keeping the top plate intact -- maintaining the arch and avoiding cracks under the treble foot of the bridge. This is an evolutionary thing. It turns out that the sound post -- when well fitted and placed -- also has a significant desirable impact on sound, so the adaptation persisted. In my own experience (and testing) the primary (other than structural) impact of the sound post is to mechanically link the top and bottom plates. Any effect of the sound post itself transmitting sound is drowned out by the activity of the plates. So, so long as you make the thing out of something structurally suitable the material doesn't much matter, although the diameter does have some impact. The fitting does matter however -- and quite a lot. We do -- upon request -- fit CF posts, just as we will pressure permeate an already cut and fitted bridge with epoxy resin. The reason here is to create an instrument that can tolerate really adverse conditions, like ridiculously high humidity, extreme temperatures/variations, or even the possibility of full immersion. As a side not, if someone wants to mess around with CF posts on a wooden instrument I do suggest veneer on the sound post area of the top plate, which in my book is good standard practice anyway -- regardless of the material there is still significant point loading in that area. Cheers!
  2. I can do that (measuring and adjusting the resistance in the area of the bass bar) -- good thought. I've had the same thought (as you, above) about adding damping. My latest prototype is somewhat thicker with more mass. I was looking for a more focused sound, and I thought it worked. The pros I've had play the two I'm working with at the moment like the thinner, lighter instrument better, in fact asking me to make something as thin and light as possible to try on the next round. They felt I was pretty darned close with the lighter instrument. I'm listening to them. So, I'm back to where I was at one point -- building as light as I can while still producing a highly durable instrument -- and adding damping if and where needed. I'm moving my shop right now to gain space. As soon as I'm done with that I'm going to work on the next one. I'm going to take some time while doing that to develop some version of an adjustable post, and perhaps a CF bridge. I'm a little reluctant to take on the bridge right now because it is such a critical component and there is so much territory to explore. We'll see. John, I will definitely send you the next one to have a look at (once I've gotten some feedback from the aforementioned pros).
  3. A perfectly fair statement. Part of the inventiveness involved in creating any sort of "upgrade" is taking what you're talking about into consideration. I've learned to monitor myself when it comes to becoming too attached to an idea, and I actually sort of enjoy scrapping something that's not proving out. That takes me one step closer to something that works. Also, I should clarify: I wasn't saying that anyone's views here were wrong. Someone who is very skilled at setting and adjusting wooden posts would appropriately have little interest in such gizmo.
  4. And that's where I think I have something of an advantage. Anyone looking at a CF violin is already demonstrating an open mind. What we've seen here is that many respectable folks have a negative reaction even before any sort of design is finalized. It is not at all a complex gizmo, but the tendency is to decide that it is. In truth it's a rather simple and sensible gizmo. We've also seen that those who have experience successfully installing traditional posts don't see what the big deal is. And, I assume that there is some resistance to making what is traditionally the task of a luthier less complex and daunting. On the other hand -- how many of us would be able to avoid tweaking the sound post tension if we could do so with an allen wrench from the back of the instrument? We're a lot of tweakers on this forum And how much more likely might we be to vary the position of the top of the post if it were easy and safe (safe from knocking the post over) to do so? Much of this same sort of discussion happened when people starting bolting guitar necks on. It was a simple, sensible solution that stirred many to the defense of tradition. It's also now a common place practice for many reputable makers.
  5. OK, after pondering overnight and reading the additions above, I'm thinking that step one (working experimentally) is to significantly lower the profile of the existing bar in a prototype. Thanks for the floor joist example John, that helped me with the mass vs. stiffness issue. I have one prototype with a zip off top (it's glued on with black high temp silicone). It also happens to be the variation with the thinnest plates. So, I can record some open strings and spectral analysis before, then again after re-profiling the bar. That ought to demonstrate something. One thing that's occurred to me is that it's easy to put mass back if needed, so I'll judge the new profile based on my sense of how the plate handles loading on the bass side and take it down as far as I'm comfortable with.
  6. I'm quite certain that John's response to you was in good humor.
  7. A _careful_ reading of the gizmo discussed on this thread will reveal that it allows for a great deal of adjustment, very likely with the same results as a wooden post. Part of the design parameters as discussed make it easier to install and adjust -- not just for amateurs but also pros. One thing you can't do with a traditional post is adjust the tension easily. One gizmo version (above) makes that very simple. It's not for everyone, anymore than Peghead tuners or composite tail pieces, but it's far from running in leg irons.
  8. Interesting. Do you remember where? I'm more or less convince that a spring loaded post on its own isn't going to do the trick -- the spring will introduce way too much damping in the linkage. What seems to work is a more or less rigid connection (just how rigid being open to debate). John seemed to suggest the possibility of a spring to hold the thing in place when the string tension is removed, but solid contact when under tension. That might work. And please everyone, don't take offense. We're just throwing ideas around here. Sometimes good stuff comes out of that.
  9. I wouldn't worry about the luthier business -- carbon fiber is unlikely to replace wood in large numbers. Moreover, it I start to sell these things -- instead of just investing in them -- I'll have more expendable income, and the most likely expenditures will be on wooden instruments from contemporary American makers I'd like to own (and Manfio, of course). Edit: I think I need to include the Aussies in that too -- and maybe the Brits. You can see where this is going...
  10. Hah! So right you are (about the speculation). I think maybe you've got a point. The bass bar may prove to be redundant, but I do agree that if you eliminate the sound post you both stray too far from the violin sound (been there, done that) and you remove an important adjustment point. I've found that if you go sans sound post you lose much of the focus of the mids and highs (although you get a richer low end). I'm guessing that this is because the top and bottom plates are no longer mechanically linked, and the bridge behaves very differently without the post in its vicinity. So, I'll do that (just try it) and report back. If that proves confusing, I'll maybe take John up on his very kind offer with Abacus, although I'm not sure I'm up for the learning curve. I started this whole project from a theoretical/analytical perspective and ultimately concluded that the empirical approach is not only more direct but -- for me at least -- faster. I seem capable of learning new tricks (in regards to the analytical approach) but lack the sort of background that, for example, John and Don have to fit it all into and make sense of it.
  11. Actually, I'm thinking that it might amplify movement. If the bass bar does indeed rock, beyond some measure of initial resistance it might rock more with more weight on the ends of the beam. This is pure speculation -- and very possibly wrong.
  12. Hey J, only the foot of the post is fixed in position (in one imaginary version, at least). The top of the post can be tapped around to your heart's content. The nice thing is that you could de-tension it just enough to make said tapping easy, than re-tension to whatever degree you wanted.
  13. I hear what you're saying, and I might even agree. In part the question is "simpler for whom?" Such a post would certainly be simpler for the end user -- the player, much in the same way that a modern, well engineered car is simpler to own and more economical to drive than something from the sixties, even though is far more complex to initially make. It's simple for an experienced set-up person to adjust a post, but far from simple for anyone else. I understand any reservations regarding having players messing around with things, but some would be skilled enough to make adjustments and perhaps improve sound for themselves or their students. And who knows? Would a post that was very easy to re-tension/position improve sound at times? Clearly this is a niche sort of thing -- not everyone would want one. The question is are there not advantages for those who would?
  14. And John, I think your idea for a patented adjustable post may have real potential. Despite the way we tend to think here, most of the violins in the world are student level instruments and many of them in schools. Such a patented post could be installed and adjusted in a matter of a few minutes with even minimal practice. Any adjusting tool could be cheap and included with the post. A video on YouTube could demonstrate the process and the results. Many string teachers would be adept enough to do it on their own. Not to put an luthiers out of business, but the schools need all the help they can get these days -- particularly strings programs (in other words, instruments that don't normally appear on a football field). Not to mention the fact that I'd be happy to buy such a thing from you and skip the development process on my own
  15. Continuing to think here -- and based on ideas John put forward -- why not: Envision a sound post of carbon fiber with a pivoting shoe where it contacts the top plate. The bottom of the post has a ball threaded on to it, with a hex socket in the end of the post. The ball sits in a keyed shoe/half socket affixed the to bottom plate. A hole through the bottom plate allows access to the hex socket, allowing for tensioning or loosening the fit of the post. The two ended pivot arrangement and adjustable height allow the top of the post to be placed within the normal range of sound post adjustment points. In other words, the post tension is fully adjustable from the exterior (as John suggested) which might prove to be a real advantage in lots of ways -- just one being set-up for optimal sound. Re-positioning the post in relationship to the bridge would be very easy because the post could be de-tensioned during the process. Being able to simply de-tension a post might also have ramifications in conservation, shipping, etc. The downside -- of course -- is the necessity of a hole through the bottom plate -- something that bothers me not in the least but is probably a non-starter as a retrofit post in wooden instruments. However, John's idea of a turnbuckle might work very well because it could be fully internal, but easily adjusted (perhaps just like the clamps on a chin rest with a similar tool designed to work through the f hole). Such a thing would requite threads with some level of interference to insure a snug fit and things staying put. I'm starting to find this idea fascinating from a CF perspective because (1) I can get away with it and (2) I can tension the post well beyond the limits of wood and -- therefore -- potentially create small and incremental changes in the actual arching of the plates -- and who knows what that would do?????
  16. There are many on this forum who have a much greater understanding of the movement of the plates than I do. I'm wondering what you think of this perhaps screwball notion: Because I'm working in carbon fiber I have the opportunity to try some things that would be difficult in wood. For example, I can mess with the bass bar within larger parameters because I'm less dependent on it for structural support. I've been thinking that an interesting experiment would be to start with a smaller profile than a traditional bar, and then add mass at the ends of the bar. Think a carbon fiber bar with -- perhaps -- a small ball of lead fitted at each end. I'm assuming (perhaps incorrectly) that given the fact that the two ends of the bar are attached to plate areas of differing resistance (due to differing surface area of the lungs vs. the belly) that some rocking probably occurs in the bar, and that more mass out at the ends may serve to amplify this rocking. And, that experimentally moving these little hunks of lead fore and aft along the bar might be a means of tuning it in some way. I should add that of the instruments I've made so far that bass bar is thinner than traditional wood but more or less traditional in profile. People like these instruments. However, one very accomplished player suggested that he heard "more in the instrument than was getting out". He then suggested that -- in his experience -- that was often related to the bass bar, and that perhaps in a CF violin the bass bar needed to be cut down in profile. I'd really appreciate any thoughts here -- including wild speculation
  17. I'm not the best one to answer you because I'm already out of the box (CF violins), but I think you're on to something. Based on my own testing, the sound post is a mechanical link between the top and the bottom plates. Within certain parameters, what it's made of doesn't matter much. It must be stiff enough to provide efficient linkage without excessive damping. Equally, the need for a spot-on chalked perfect fit may be overrated (OMG, is that sacrilege or what!). I agree that the contact location on the bottom plate is far less critical than the top plate -- this having to do with the bridge. I also agree that the arrangement you've described -- if I'm understanding it correctly -- would be acoustically indistinguishable from the traditional fitting method. Moreover, why not take it a step further? If you fitted both ends of the post with a pivoting shoe I suspect that would work equally well. That would allow for a very good fit top and bottom with minimal or no carving. Adjusting the height -- thereby tension -- of the post would be as simple as sharpening a pencil (then rounding over the end). The bottom shoe could be fixed on the bottom plate, while the top shoe could be fixed to the post with something like a small amount of silicone to allow pivoting. Once in place and under tension it would behave -- structurally -- just like a standard post. It would also be equally adjustable. My thought experiment suggests to me that it would -- again -- be acoustically indistinguishable from a standard, well fitted post -- but that remains to be tested. I may very well go ahead and try this in my current CF violin. Based on what I've learned (hands and ears on) the critical parameters for a post are: Tension, positioning at the top plate in relationship to the bridge and efficiency as a linkage between the plates. It seems to me that the perimeter of the contact area of the post/shoe may influence things, which could be controlled by the size and shape of the shoe(s). In fact, varying the shape and area of the shoes might add a new feather in the set-up person's quiver. Yes, some makers/players are very resistant to innovation. This is not always without good reason. However, some are very open to it, and even receptive. I'd say just go ahead and do it, you may find less resistance than you think.
  18. Watch Craig's List. The police don't have time to do this, but a remarkable amount of stolen property shows up on CL. The thieves likely have no idea what they have, so pay attention to generic "violin" for sale ads. Pay particularly attention to ads with no pics. If you see anything suspicious, just send an email and ask them if they can tell you who made the fiddle. Generally speaking, people who commit this kind of theft are bowing with no rosin. I you think you've found it on CL, don't do anything silly -- hand the info over to the police and harangue them until they quickly follow-up. Just realized that you indicated that it has no label. That makes is pretty tricky. I'd watch CL anyway, and request pictures if there aren't any.
  19. Well done This thread really does need to die. I'll just have to agree to agree with you, mostly...
  20. I love her shoulders! Very ladylike but not at all weak.
  21. There is no argument about what's generally understood. I'm not sure, actually, that there's really an argument at all. There are questions, however -- the primary question being the ability of a violin to withstand high normal humidity -- all other things being equal. Because some instruments distort does not necessarily mean that a fine instrument cannot be built that won't distort (at least as quickly as the one in the example that started this thread). It also does not mean that all distortion is related to humidity. That's where the questions are. Another question that's come up here has to do with the idea of mitigating the impact of consistent high humidity by introducing the instrument to it in a gradual, controlled fashion. The idea has been proposed that doing so will make the instrument more resistant to the long term effects of high humidity. I don't know the answer to that. One has to -- I think -- carefully interpret what the general field of wood technology has to offer to violin makers. Much of the research done -- and the conclusions reached -- is/are based on wood as an engineering material in applications very different that the thin, light tensioned structure of a violin. I would never undertake the restoration of a decent violin with body distortion. I don't know enough. However, I do know enough to at least question what may or may not have caused that distortion -- remembering that none of us have seen the instrument that started all of this.
  22. Obviously I have a lot of experience with epoxy -- and it's the best vapor barrier I know of for wood. The downside is that you have to build to a sufficient film thickness to maximize that. As I've said before, that might introduce too much damping for a wooden instrument. I am curious about what Don Noon is doing, because something I've read about the process he's using indicates that it reduces vapor absorption rather significantly.
  23. We're gradually descending into the mucky minutia . My point is simply that wood maintains a reasonable amount of its strength along the grain (the direction we're talking about) at the highest moisture content it will hold once stabilized, and that that strength ought to be enough for a violin to maintain shape. I once did an extensive series of tests with everything from aircraft grade spruce to Brazilian Rosewood with strips (in thickness) from 1/16" up to 1/4" in increments with a fixed longitudinal load and slowly increasing humidity. That was the baseline. The test was repeated with various finishes to see what level of protection each offered. The purpose of the test was to evaluate finishes, but it also yielded data as to deformation -- data that is long buried now. What I learned is that going from what we environmentally refer to as low humidity to high humidity had relatively little impact on deformation in the uncoated wood, and next to none at all with wood finished with even the least protective product. That's my own baseline for looking at this. Extrapolating from that -- and my work with the violin form -- I find it hard to believe that consistent environmental humidity would result in accelerated deformation of the corpus should the humidity be higher than the midpoint in what we might call an average light instrument of good make. Clearly there is no substitute for experience, and you have lots more than I do with restoration/repair. Odd things happen in the real world. However, I can't help but think that violins that fold up in high humidity have some other mitigating issue. On the other hand, I'm now working in carbon fiber, which means that I should probably take the position that wooden violins are vulnerable to high humidity, and that the only solution (for, say, the Eastern Seaboard and south of the Mason-Dixon Line) is an alternative material
  24. This is slowly turning into a non-argument So, as they say, the creep of these materials is several times that determined for solid wood, which creeps a lot less. I just don't call it creep. Creep -- to me -- represent movement between two separate object, like me and the floor when I creep along it -- or two sections of wood at a glue line. What's happening with a plank of wood is that the bounds of elasticity are being exceeded and the wood is taking a set -- fibers are stretching on one side and crushing on the other. One can argue that there is cellular "creep"going on for that to happen, but that's "stretching" it in my view. At any rate, there are plenty of places in this country where humidity is very high for prolonged periods and plenty of violins living in those areas that hold their shape. I'm just saying...
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