Advocatus Diaboli

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About Advocatus Diaboli

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    Up some canyon

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  1. Advocatus Diaboli

    CT Scans - Costs, Crowdfunding, etc

    If you can get access to an instrument you want scanned, I can probably help arrange the scan itself.
  2. Advocatus Diaboli

    Stradivari's secret was a concept?

    I'd argue that there's plenty of evidence of it's being an artifact from a gradating system, although I don't believe that it was made by a compass point, or that it was a result of working from the inside out. It's also worth mentioning that quite often, especially on Amatis, the pin hole wasn't filled with anything. Also........ Steiner used not one, but FIVE pin holes in his instruments. Via CT scans, the Steiner pins in any given instrument seem to match each other in taper. The pins I see in Del Gesus also match each other from one instrument to the next, and Amatis the same. This implies, to me at least, that it was an artifact from a tool with a set taper. My interpretation of the whole thing is that the pin location started out as part of a fixture that centered the C bout rib structure while marking the outline. (Neil Ertz pointed out once or twice that although the pin location on del gesus varies quite a bit, the width of the ribs at the pin is always the same!) Once the arch was more or less completed, a drill with a conical point on the bit was used to drill through onto a hard/flat surface. Assuming the depth of the point at the end is just slightly longer than the final desired thickness of the center of the back, graduating is extremely fast with only minimal measuring required. This is how I graduate the backs on almost all my instruments. It cuts the graduating time down by about half!
  3. Advocatus Diaboli

    Craig Tucker Memorial Instrument

    Joined and (approximately) flattened back is on its way to Jackson in tomorrow's mail.
  4. Advocatus Diaboli

    A.D.'s new bench

    Very crude homemade saltpeter with a very tiny amount of natural dye added.
  5. Advocatus Diaboli

    A.D.'s new bench

  6. Advocatus Diaboli

    Stradivari's secret was a concept?

    Tons of makers use potash in their ground color, for making pigments, etc.. Maybe the secret is to not use potash, but pot ash.
  7. Advocatus Diaboli

    A.D.'s new bench

    The ground color under two different light sources.
  8. Advocatus Diaboli

    Stradivari's secret was a concept?

    I remember the first post with these steps, I'm more interested in how you go about applying it, and what results you're seeing, other than 'different'.
  9. Advocatus Diaboli

    Stradivari's secret was a concept?

    You've mentioned alchemically treated wood over and over, but you haven't given much of anything close to a process yet.
  10. Advocatus Diaboli

    Craig Tucker Memorial Instrument

    Happy to donate any materials needed (purfling, spruce, willow for blocks and linings, maple, ebony, varnish, etc.). The only thing I'm running low on are fittings, but it looks like there are already some offered.
  11. Last year at the Oberlin Acoustics workshop we focused almost exclusively on the function of the bridge. I took the topic from the start to mean Curtin and Sam Z gave a great deal of thought to the driving system. I also came out of it with a fairly decent understanding of the bridge's function, and am going to have to disagree with you about how the modes are stimulated.
  12. Advocatus Diaboli

    Stradivari's secret was a concept?

    Agreed.
  13. Advocatus Diaboli

    Stradivari's secret was a concept?

    I find this statement a bit odd... As far as I know there isn't any direct evidence the channel was completed after the box was closed other than theorizing about possible methods, mostly by Sacconi and Hargrave. I'd go as far as to say that there's a decent amount of evidence towards the contrary, especially in Bergonzi. For example, Bergonzi's pins are often well inside the purfling, but on occasion are close enough to overlap. Unlike on Strad or others, the pin pushes the purfling aside instead of the purfling cutting through the pin. Looking at these pins under magnification it seems obvious, at least to me, that the crushed purfling came from the metal nail used to pin the instruments together and not the piece of wood used to fill the hole. Assuming the purpose of the pins is functional in aligning the rib structure and plate, and not purely decorative (hi-res CT scans show original pin material going through the plate and into the blocks on several Bergonzi instruments), my conclusion is that the purfling was completed before the plate was attached. To reverse engineer a step further, the glue ghosts present on some Bergonzis around the channel couldn't possibly have occurred from glue soaking through the material as I think was suggested in a previous thread, but looks like it was wiped across the surface in some way. The only possible step I can think of that this could occur during is in gluing purfling. (I've had the same sort of ghosts on some of my instruments.) If both of these are true, the channel must have been mostly completed before the purfling was inlayed and/or glued in, which must have happened before the plate was attached.
  14. Advocatus Diaboli

    Blind test in which Strads and del Gesus came out on top

    Changing the internal volume of the violin will change the frequency, not the volume of the A0. The output is changed quite a bit by the overall flexibility of the violin and as far as I can tell the internal shape.
  15. Advocatus Diaboli

    A.D.'s new bench

    I know I have a bench thread buried somewhere out there, but I couldn't figure out how to find it without scrolling through a year or two of threads, so I figured I should just start a new one... I thought I'd start with a picture of my favorite piece of art in my shop at the moment (early 20th century French), and end with a couple primer and varnish shots, since that's what seems to be the craze at the moment. Cheers!