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Emilg

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Posts posted by Emilg

  1. 23 minutes ago, martin swan said:

    Barbé ...

    But I didn't see it in the flesh and it's kind of a guess. Just observing that the head is very close to Voirin but it ain't Voirin, the frog isn't stylized enough for Thomassin and the thumb projection and throat aren't skeletal enough for Husson. To be honest I haven't seen anything exactly like this bow but Barbé is the closest for me.

    A wisp of original lapping don't impress me much - various seedy dealers have such things tucked away to apply to otherwise compromised bows in order to make them look sexy in auction. Also I would say it's a fool's game to buy any bow without hair on it - lifts in the head are easy to conceal, lateral weaknesses in the stick can't be detected etc. Most hairless bows at auction are without hair for a reason - most commonly that they have the strength of an overcooked rice noodle.

    I see you have a Barbé in your shop right now.. i can understand the 5500 pounds now if it actually turns out to be a real Barbé. Anyway, someone (or two) will probably have been to the viewing...

  2. Hi, i was keeping an eye on some silver mounted violin bows at the Amati Affordable auction, which ended today.

    To my surprise this one got to 5500 pounds / 6450 euro / 7600 dollar

    https://app.amati.com/en/auction/1080-amati-affordable-28th-july/238-a-silver-mounted-violin-bow-unstamped

     

    I would not call this so affordable :o so it may be something more special, any ideas what it could be?

    It says unstamped but there seems to be a worn off stamp, quite unreadable.

     

     

  3. 53 minutes ago, Don Noon said:

    The correlation is not that great, and...

    true, i think you also tried the formula/spreadsheet on platetuning.org for predicting B1's and found it did not work very well. However, somehow B1- is affected bij the top and B1+ by the back wasn't it? (or v.v., i always forget)

    53 minutes ago, Don Noon said:

    Has there ever been a study showing player preference for any particular B mode frequency?  I am not aware of any... there just seems to be a tendency to latch onto a value that is held as a goal, perhaps a result of Hutchins' teachings.

    I think (like you also mentioned) they should be around the "right places" and perhaps not too weak or strong. My idea is that A0, CBR, B1- and B-1 just support the lower register and preferably not causing wolfyness. I think you mentioned every mode spreads around 5 semitones?

  4. 2 hours ago, Delabo said:

    As a supplementary question it would be interesting to know when this idea of tuning plates developed ?

    The tuning fork was not invented until 1711 so how would Amati \ Stradivari etc have tuned their plates ?

    Could they have been born with the ability to hear perfect pitch and just tapped until what they heard sounded good ?

     

    I think it is not about some absolute pitch, but rather a design parameter where the plate has reached a certain stiffness to weight ratio. When the plates are glued the M5-mode (taptone) will be gone anyway, but there seems to be a relation/correlation between M5 and B1-modes, which are more important.

  5. 43 minutes ago, David Burgess said:

    From what I've observed, this is mostly done with rosin varnishes to reduce the high acidity of the rosin. In my own experiments, a rosin-linseed varnish seemed to degrade pretty quickly if high acidity remained.

    I have wondered how resins and oils can be acidic, as acidity is defined by H+ ions in aqueous solution. I suppose it's because wood, resins, oils and even air always contain a few % moisture to allow acidic behaviour.

  6. 8 hours ago, Don Noon said:

    They worked "well enough" because the goal was to hack out instruments as fast and cheaply as possible... with acoustics being very low on the priority list.  If you have seen a few of them, you'd know that there was no standard whatsoever., and usually the plates were left very thick so that the bass bar was of less importance.

     

    I have seen a few also. One was from a 3/4 with 5 mm thick top and some sort of ridge left in the wood that had to resemble a bass bar. It did not sound like a 3/4 Del Gesu funny enough, could have been the bass bar :rolleyes:

  7. 12 hours ago, FiddleDoug said:

    Stiffness and speed of sound would be two different things .A 30" piece of 2x4 is going to be a whole lot stiffer than a 30" bow, but since the 2x4 is pine, the speed of sound would be a lot lower.

     

    Hi Doug, it's more about relative stiffness, so the stiffness with equal dimensions. Higher speed should also give higher stiffness.

    Would damping play a role in bows? Damping will decrease with age.

  8. 28 minutes ago, sospiri said:

    Hmm, the fungi treatment has been debunked though hasn't it?

     

    I missed that part ;)

    Searching the archives i found a remark by Bruce Tai:

    Quote

    By no means do I promote the idea of artificial aging by baking, boiling, UV, acids, bases, and fungi. I think these treatments are damaging and will degrade the wood in a very different way from natural aging.

    that might be the problem for many of the treatments after short term success...

  9. 1 hour ago, ctanzio said:

    Sound speeds and the elastic moduli of a material are related by the physics of how materials deform. Since an elastic modulus is a measure of how much a material deforms when stressed, it is a measure of "stiffness".

    I put stiffness in quotes because there are factors other than the elastic moduli. The geometry of the bow greatly affects the "stiffness". For example, suppose a bow maker was aiming for some target "stiffness". By selecting a wood with a high sound speed, it implies the wood has a high elastic modulus. Therefore, the bow can be made thinner than with a wood that has a lower sound speed, but still achieve equal stiffness between the bows. So the high sound speed bow could be made lighter than the low sound speed one.

    Perhaps lightness is a desirable characteristic in a bow. I don't know since every bow I have ever tried feels like a feather in my hands (flexes massive biceps). Certain bow techniques, like spiccato and sautille, are affected by both the weight of the bow and its stiffness.

    Typically, the elastic moduli of wood, and most other basic structural properties, change little over time unless there is some fundamental breakdown in the wood structure. This is a difficult area to study because of the wide variation of material properties among trees, even if they are from the same wood species.  But wooden structures that are protected from severe environmental aging affects can last for many centuries and still stand as strong as the day they were completed. Someone like Don Noon, who can artificially age wood samples and measure the mechanical properties of a single sample over time-of-aging might be able to speak to this.

    Sound speed may change over time because it is also a function of the density of the wood. Normal wood aging causes a release of "extractives", like oils. Hemicellulose content also  shows a significant decrease over time. As the density of the wood decreases, its sound speed will increase, even if its elastic moduli remain mostly unchanged.

    Aged wood also shows a marked decrease in sound dampening, mostly due to the reduction in hemicellulose. I suspect this accounts for the loudness and high pitched ringing of old instruments. Perhaps Strad's secret was to build violins that could survive for a couple of centuries.

     

    Thanks ctanzio, so the wood properties would not have changed that much in 100 years.

    I understand that a fungi treatment can speed up the hemicelluloses breakdown. Some years ago a violin from treated wood beat a Strad in a blind test. I don't know if makers here have experimented with that, but that one is on my todo list :)

     

  10. 12 hours ago, martin swan said:

    Not stiffness, speed of sound transmission ...

    Basically since the invention of the Lucchi meter everyone goes for as high a Lucchi rating as possible.

    Before people had Lucchi readings this wasn't an important factor in bow design :lol:

    Isn't speed of sound also a measure for stiffness? From wiki on speed of sound:

    Quote

    Thus the speed of sound increases with the stiffness ..

    I also thought wood gets more stiff when aging, so a Lucchi reading was probably not the same 100 years ago.

  11. 30 minutes ago, Wood Butcher said:

    So instruments can be made to sound better by polishing the varnish because polished varnish has reduced stiffness? :unsure:

    i suspect he means sanding some varnish away ..

    a weak d string has been discussed before, here's one with some more ideas:

     

  12. 2 hours ago, Davide Sora said:

     

    The willow that is used for blocks and linings and that supposedly was used most frequently by Stradivari is the White Willow (Salix Alba). The reddish wood that distinguishes it makes it often confused with the Red Willow, which instead is a shrub that is not good for making blocks.

     

    I checked and it seems to be Osier Willow (Salix viminalis) what ive been using. I took some 12-15 cm wide logs, wide enough for neck and tail blocks. havent measured the density yet but i think it's close to spruce at .40-.45. And blimey, there are indeed loads of willow species...the things you need to know as a violin maker :o

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