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Everything posted by francoisdenis

  1. David, You constantly refere to "Cremona tradition" "Cremona design" you use a lot "traditional" : "traditional geometry" "traditional features"etc We can all recognize the way of making a violin from a complet form as a cremonese tradition but beyond that and specially speaking of designs and measurements can you explain what you mean ? I understand that you are defending the idea that craftmen of the past used some ratios to define the framework of the outline. That was what old italian language called the "lineaments" , the lines (actually that was the only info collected by Baggatela from the violinmakers he was questionned "the old masters started drawing lines". Baggy drawn 72 of them in the lenght...a bit too much!). So, that ratios have been used to do this is a very reasonnable idea because that being the case in every trades, that avoid to do a special case of the violin making.. . But, to constantly speak of "traditionnal - cremona - design...." I imagine that you found something specific to Cremonese tradition. Could you explain what it is?
  2. Marty, actually your practice was not the topic and you avoided answering to a simple question ... but it remains very instructive to discover your production
  3. Who think that this equality would deserve to be related to the acoustique efficiency ?
  4. Thank you to share this reference- II defended the same kind of ideas in Augut Strad mag issue The way how perception evolved during the XVI-II° century is amazing . Direct understanding is almost inaccessible
  5. Hi Marty, yes, that Strad used few templates in an empirical way is an idea probable. I had the opportunity to defend this idea many times. But the sentence "....the used of mathematical equations" is just a no-sens except if you considered that adition and Thales are the "mathematical equations" you are speaking about. At the end, the question is to know if it's possible to draw a convincing template according to the knowed processes of the Renaissance. You seems to know the response to this question without the support of any demonstration and constantly referring to incomplet or not enougth informed researchs (at least on the historical side of the measurements) . In these conditions, I wonder if the argues which could rise a doubt in your mind exist ? Is it, an original form with violins probably made on it with could perfectly fit to simple geometry would convice you? Yes -No?
  6. I did the analysis on the external measurements of the plates David did them on the mold and both lead to known relations. This may seem surprising but it is the most general case ...and it is also the reason why it is not always easy to know if the measures apply first to the mold or to the external contour.
  7. Hum....I calculate 349,2/200,2=1,727 (not 1.654) and...... 350,8/201,6=1.74 (not 1.752) - could you explain? (may be a problem with your data Note that measurements come always with a margin of approximation - (until more or less 2mm on a violin plate-!) that's huge, increasing the scatter of the dimensions that makes sometime ratios understanding a bit tricky and furthermore other artefacts can interfere- mistake during the measurement process (for example a 50 cm plastic ruler can varie of more or less 1 mm depending of the t° ) bad paralaxis of the shot...etc That's the reason why I insist on the quality of the source. Speakping of the ratio L/W -it's better to have the info for the two plates - L ; the length , is one of the less reliable measure (shrinking, setting of a new neck....) And last, 349,2 and 350,8 are under the margin of error the average of this two ratios is 1.733 - that's root of 3 (could be the signature of a construction with a square) Could you find some better examples to support your ideas?
  8. For those curious to know how on buit a format starting from the lenght here are some ways to start with a ruler and a divider...and Thales
  9. So what? You first realized that Pollens' conclusions regarding his data are eroneous, you just realized (thanks to the Washingtonpost that the database itself was poorly built. So you argue your belief about the false conclusions of a bad data base. So here we are now with more consistent data regarding the L / W ratio. I propose you to use the most reliable data (only small differences) that I have published myself for the measures of the forms we have the ratios: and for plate measurements the ratios: To interpret its data it is necessary to agree on a margin of error the mold asymmetries make it necessary to retain in the length the +/- 0.75 mm value and for the plates +/- 2 mm . This being done , it is sufficient to see in what range the LW ratio is situated. We then observe a more coherent distribution. Two forms deviate from the averages the P / B (presumably retouched) and the SL. We could do the same work with the forms with the same kind of result, a close distribution around a small number of format easly constructed . I consider that we honestly can't retain that none format originates this distribution But my grand mother was used to say , "you can also chose to don't see the sea at the beach" I still believe , I repeat that, that Stradivari used them in a more or less empirical way ( I would be happy to change my view)
  10. Are you speaking of the measurements of the forms or the measurement of the plates?
  11. Hmm ... after studying these forms closely, my conclusions were different. On the contrary, I recognized that, as Pollens had already observed before me, the same radii of arcs were precisely used on forms of different dimensions. This suggested the idea that these radii of arcs belonged to an original model that I have called "archetype". If we geometrically reconstruct this archetype from the arcs, It happens that we refind the standard forms of the Amatis. The conclusion of all this appeared to me quite logical. Strad had used Amati-like patterns to made his own forms empirically, and I still do not know today what could be the Strad's level of knowledge in drawing. By cons that the violins made in Cremona or Brescia in the sixteenth century were built according to the habits of the time is an obviousness that I find strange to challenge.
  12. Of course we study the documents available but we must be aware of bias and relativize our conclusions. I just drew attention to the fact that a photo can be fairly faithful or not and that if you want to draw conclusions from a photo you need to be well informed about its quality. I have many examples I already talked about the problems I had with Strad's forms before I could study the scans. Recently I studied the form PM 1062 published on this site by this dear Addy. This form interested me so I asked Addy where she came from. He replied that he had copied it from a publication (a habit since this dear Addy has bothered to copy all my scans to publish on this site while the originals are freely available on my site). My experience is that it's risky to draw conclusions from a photo, I needed more guarantees and I went to Cremona. Indeed the deformations of the photo were significant and I have had to change my conclusions. Always the quality of the conclusion will depend on the quality and number of sources. We can't change that.
  13. Yes , that's seems logical but that says nothing about how the original templates were made...
  14. Ok, so your conviction comes from that unique source, the wooden form of Strad So we will stick to this source and study the ratio L/W following Pollens the measurements are: MB, 1.75 (form) 1.72 (top) S , 1.75 (form) 1.72 (top) P/B 1.74 (form) 1.71 (top) T 1.76 (form) 1.73 (top) Q 1.77 (form) 1.74 (top) PG 1.72 (form) 1.69 (top) SL 1.78 (form) 1.75 (top) B 1.78 (form) 1.75 (top) B 1.75 (form) 1.72 (top) S 1.73 (form) 1.71 (top) P 1.72 (form) 1.69 (top) PG 1.73 (form) 1.70 (top) Again Pollens made a weird conclusion "the predicted ratio of 9:5 (?) is not observed either in the forms or in the instrument made for them" He is clearly blinded ( ignorance of the nature of proportions ? belief ?) Anyway It's clear that Pollens never heard about the harmonic section because he would have notice a perfect match between numbers and proportional relations. ratio 9:16 0,563 1,78 4:7 0,571 1,75 harmonic approximation square or compass 0,577 1,73 root of 3 use of the 1x2 square 7:12 0,583 1,72 harmonic approximation square or compass 0,586 1,71 harmonic section Again, like the previous drawing, you quote a perfect counter-example of your belief. You trust Pollens only because that consolidates your conviction but you don't take 10 mn to check if it is correct! And unfortunately he is not and i just give right now, a mathematic proof of his mistake.
  15. Ok, probably the simple way, I will do that and return the result
  16. I guess that the pictures comes from the Pollens'book. Actually the repro of this book shows some significant distortions in some parts which can lead to some wrong interpretations. For a long time it has been the only source available for me. When, after 3 years of talks with the italians (hours of talks, letters, travels..) I finally get the authorisation to make the scans I have been surprise to came across such differences. Theses new data lead me to deeply change my opinion with the feeling to have lost a lot of time working on the Pollens data. You should know that most of the strad forms are strongly warped almost 6-7 mm for some of them . We are waiting the ctscans possibilities to improve the data and may be make other conclusions. A more accurate data lead always to a better conclusion. Pictures can be good enough or completely wrong so we have to be cautious with that and avoid them as much we can (specially if you want to publish something...).
  17. Dear Marty, I don't know who you are but I could have the feeling to lose my time if I was not convince that other people share your point of view . I ask you "where are your data? " please share honestly your info or gave up, and not only data, also which are your sources? Do that come from? Pictures, Ctscan, Strad posters, museums....etc . We don't care of your intuition in that case, it's time to be accurate. Notice that moreover you chose a perfect counter-example of your argue!!! The surface of the square 1_2_root of 3 one of the most commun surface ever used. You sadly made the proof that you even not have spent five seconds to check your very doubtful assertions.
  18. why one either other? What a weird statement from somebody knowing almost nothing about compasses and others proportional stuff.... That's true, but why call to mind all this maths stuff!!! Thales is enough to do the job, It's even a lot to learn to use it properly. Probably, he seems to have used some Amati patterns as template- that was my conclusion but may be one day somebody will demonstrate the opposite (David?) Sorry to tell you that, but following my experience your statement is wrong. Speaking of instruments made between 1550 and 1650 (violin and viols family) what is the data which leads you to a such conclusion? You can sent it to me I'm curious and not afraid to change my views
  19. Dear Joaquin, of what I can understand of your process, you use a square to define the centers of your spirals so the placement of the spirals is the crucial issue of the process (spirals which, furthermore, must be tangency) I don't see that the nature of the measure has any importance in the meaning of the process so right now... I rather class your proposition beside other like Adolphe Beck (1923) , Carl Schulze (1901), Greysalmer(1924) (Sacconi (1972) the category "centers first"
  20. you are right, It's just a feeling...You know hum...there is something there, may be.. the pass remaining unexplored
  21. Interesting, so the approximative formula would be Surface ~ (width x height) x .75
  22. I have often thought that the measurement of the blocks was not something trivial. Already for the reason that the historical texts all call "table" the distance between the blocks and then also because I found that the measurement of the blocks is still the basis of the construction of lutes in the east (at least in the region of magrheb) - it is also a reference for Zwolle (which probably quotes an earlier oriental source) I have some ideas (a possible analogy with the monochord) but it will always be very hypothetical given the scarcity of sources....
  23. I'm looking for a formula to calculate the surface of violin back and table. Does somebody know a solution?