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Dana Johnson

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About Dana Johnson

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  1. Dana Johnson

    Strengthening Push and Pull Muscles

    Greg has really good advice re exercising. One quirk of concertina playing is that most people hold one end fixed when seated and move the other. This means that one arm is basically doing isometric exercise while the other is dynamic exercise. It is a good idea to intersperse some moving exercise for the static arm with your playing practice. Otherwise, you will develop strength but not range of motion that can cause trouble, especially in the neck and shoulder since any force you apply has to be countered by an opposite force on the other end of the muscle attachments. Playing concertina can be enjoyable enough not to want to stop. Then all of a sudden it starts to be painful and requires a long break to get back to where it is safe to play again. Dana
  2. Dana Johnson

    FREE REED PHYSICS - 3

    Hi Tom, I haven’t been following this that closely and missed the request for clarification. When I make a set of reeds, there are a number of things that are important to me as a maker. First, the reeds all need to respond at the same starting air pressure,. Second, they need to do this at as close to the same spot in their pressure-volume curve so the reeds individual dynamic ranges are in sync with each other. Given the extreme difference in reed length and area, perceived volume of the individual reeds need to be as close as practical to each other so that larger reeds don’t overwhelm smaller ones. While a reed of a given pitch can be made within a wide range of length/width aspect ratios and with a wide range of lengths, even without varying the material, by adjusting the overall flexibility of the reed tongue and how the moving mass is distributed along its length, (reed profile ) the playing requirements listed above severely limit what is actually practical. When I talk about reed stiffness, I am referring to the amount of force required to deflect it by a certain defined amount. Another term for this is spring coefficient. Since I don’t think this number is linear for flat springs like reeds, I measure it for 2 degrees of deflection on the bold assumption that such a small deflection will be in a more linear part of the curve. I have found that a stiffness curve for MY reeds that starts at about 14 gm / 2 degrees deflection for c below middle c and reaches a high of around 20 gm/2 degrees for mid range reeds about e above middle c to d an octave above that then dropping to about 8 gm/2 degrees or less at g6 on a c/g Anglo. It looks like a shallow bell curve, with each reed being close to the ones on either side. This distribution makes for reeds that all sound like one family, whose harmonic content changes similarly as playing volume increases. Other ranges are perfectly possible depending on what the maker is after. Accordion reed are matched with each other to make lighter or heavier sets for similar reasons. In making a reed, I start with a blank of a given width and length that fits the concertina, has been proven to produce the right volume for balance, and then adjust the thickness profile so that it has a finished pitch, a smooth bend, and an overall stiffness that allows it to respond properly with the rest of the reeds. No reed profile ( of mine anyway) is straight. Low reeds are thick at the tip, thinner in the middle and going back to thicker at the root. Middle reeds have a little thinning in the center and high reeds are very thin at the tip an thicker at the root, but not in a straight slope. There is a neutral place in a reed where varying the thickness balance the pitch lowering of reduced stiffness and the pitch raising of reducing the moving mass. I use this area to adjust the stiffness of the reed to fit on my curve. I am sure that a set of formulas could be created to describe the profile curve, taking into account the mod of elasticity of the material, it’s density, along with some way of scaling for volume at a given pressure, aspect ratio etc., but there is a range of possible solutions that work. When trying to make a mathematical model, choosing the simplest reed possible in order to see how the materials compare, having two reeds that have things like length width and deflection and pitch at a given pressure in common sounds like a good challenge, certainly beyond me. I know that side clearance has a strong effect on tone, but I don’t know how the traverse time of things like the reed tip effects tone if it is thicker or thinner. What I can’t figure out and hopefully you can is whether the differences in stiffness and density of the different reed materials varies how they vibrate, or simply force a different geometry in the reed that changes how it traverses the window. Best wishes, Dana
  3. Dana Johnson

    My Reed Measurement activities

    Besides the fact that I’m pretty sure GB had not gone metric when these reeds were designed, keeping the heel distance the same allows consistent use of clamp blocks since the front edge of the clamp block needs to be directly over the start of the reed window to avoid buzzing or other pitch problems. Consistent tip distance keeps the chamber as short as is practical, while still leaving room for the flap valve to completely cover the reed port on the draw reeds. Too short a tip distance puts the end of the port too close to the end wall. Too long a tip distance in higher notes especially makes the chambers longer than needed which can adversely affect quickness of response. Glad to see another person taking on the concertina making challenge. Dana
  4. Dana Johnson

    FREE REED PHYSICS - 3

    Hi Guys, re Jake’s comment, I don’t remember making a carbon fiber reed, though I may we’ll have opined on the subject at one point. I am still reluctant to consider them on a practical level. It was enough of a chore ( months of work ) to adjust my steel reed profiles to provide a smooth grading of stiffness from the lowest reeds to the highest to get a homogeneous sounding and playing instrument. I wouldn’t know where to begin with carbon fiber. ( not to mention the self destructive aspect mentioned in 1 or 2 of this series. I do remember an incident where the carbon fiber tail of an airliner self destructed when subject to the turbulence of the wing vortices left in the air from a 747 that had gone before it.) I think Tom’s exploration is at least academically interesting if it can shed some light on how different properties affect reed vibration, especially from a point of efficiency. Since this all seems to be a result of calculation rather than physical trial, i’m Not sure it is fair to blame the raw materials for the tonal differences people ascribe to brass or steel. Listening to Johan’s sound files of a steel reed vs a titanium one, I really couldn’t tell the difference. The chart does show the different strengths of the harmonics, but our ears probably aren’t designed to distinguish between sounds that are proportionally so similar, especially since both seem to have strong odd harmonics as the defining feature of the tone. I am not sure how you can control for variations in stiffness in these models so all reeds are equally stiff at the designated pitch. Since the point of physical profiling is to take a reed of practical length and tinker with its mass distribution and overall stiffness to reach the desired pitch with the desired response to bellows pressure, I don’t know how you can create mathematical reeds of these materials that differ so much in density and modulus of elasticity so that at a set pitch, stiffness and swing amplitude you can make a comparison of harmonic amplitude. I still have no idea how the musical harmonic series is created (which it certainly is ) when the reed’s natural cantilever bar mode harmonics are decidedly non linear. Tom doesn’t’ agree with Benade’s explanation and convinced me it may not be correct, but that is as far as I got. have fun guys, my brain is tired Dana
  5. Dana Johnson

    Tuning stability

    Hi Tom, late reply, just saw this. Grinding the top surface of the reed to create its overall profile creates a slight downward bend away from the ground face. Which indicates to me that the balance in tension from whatever source changed in favor of the unground surface. Straightening them moves the dislocations in the steel structure to allow the change to hold. There is nothing guaranteeing that stresses created then will go away, only that they are not high enough to move the dislocations again. However, adding the vibrational force may allow some of that stress to exceed the force needed to change the structure. I find that hours of vibration are enough to allow these changes. Blue tempered 1095 steel may be annealed in some part of its creation, (in order to roll it to thickness, ) but it is hardened after that and then reheated to around 600 deg.F to temper it and bring it down from file hard to about 55 on the Rockwell C scale. Different metals I am sure behave differently, but I find that in spring wire, too small a coil size relative to wire gage creates compression failure on the inner diameter while the outer diameter shows no damage. Not sure what that really means, since bending is not the same as pure tension or compression. Best, Dana
  6. Dana Johnson

    Tuning stability

    I find that newly made reeds often go out of tune after being played awhile. Removing material to create the reed profile changes the stresses in the steel and vibrating eventually equalizes things. I find reeds come off the grinder with a small amount of curvature, which I straighten out. They are set in this condition, but the set can change with stress relief, changing pitch. I have taken to running the reed pans on a vacuum ( my tuning rig ) for 3-5 hours either direction, after the initial tuning. After tuning again, I find they stay in tune for a long time. Lots of things can affect pitch, including set, pad or valve lift or stiffness, or even the variation of density of the reed pan with changes in humidity. I don’t know if air density has a significant effect, but day to day changes in pitch are to be expected, and without knowing why a reed you just tuned is now off, you may be chasing a moving target to the detriment of the reed. Dana
  7. Dana Johnson

    Secondary Key: Ab/Eb vs Bb/F

    I’ve made C/Gs,(lots of them ) G/ds and an A/E which is my all time favorite. Mine is every bit as fast as my C/gs, though the G/Ds are very slightly slower on the low end. You can certainly play at session speed on any of them. I love the sound of the G/D, but it is just lower than I like to play. The A/E is just right though. Richer than the C/g and without the shrillness of the high end, everything just sounds better. Bb/f is just too near C/g to make that kind of difference, though it is useful for playing transposed in certain sessions. It really isn’t difficult to learn to play in the keys a Bb/f is mostly used for on a C/g.(F has become one of my favorite keys) I use my C/g at sessions or for teaching, but when I am playing alone, I always play the A/E.
  8. Dana Johnson

    Turning End Bolts

    A lot of people do like the slotted head bolts. At least I didn’t use torx . Hmmm...🙄. Hey Alex, you are one of those I admire. It has probably been done, but i’d Like to see an engineering encyclopedia full of all the ways things like this have been done. I “ invented “ a gear version of the Chinese windlass, only to find that it was in a friend’s engineering textbook. At least it was a good idea! Dana
  9. Dana Johnson

    Turning End Bolts

    Made a steel replacement bolt for an old Wheatstone duet 30 years ago or so. The originals were NS. And some had already been replaced after breaking. Not knowing about the availability of appropriate dies, and only needing one, I cut the threads on my lathe with the gear box set for 44 or 42 tpi, the way I was taught in high school. Can’t remember which but found whatever I used was a very good match. Very sharp, very centered threading tool and very light cuts worked well. But I’ve seen too many broken brass and NS screws, so I bailed on them for non traditional stainless steel socket head bolts ( sick of people scratching things up with slipping screwdrivers, or buggering up the slot with a bad fitting screwdriver.). After 80 plus instruments, I love these things. I may have lost sales for being too modern, but I have never had a shortage of customers. I provide a tool kit of the 4 driver sizes I use, so people don’t have to hunt them down. I admire great craftsmanship, and also the ingenuity of the older generations. I just have a soft spot for screws that don’t break.
  10. Dana Johnson

    Reed tuning query - more or less ?

    The belly of the reed, (generally the central portion of the reed ) is where changes in thickness effects are balanced by changes in weight. Metal removal there will affect the pitch little or not at all, while lowering the overall stiffness and power of the reed. If you are making your own reeds, you file the belly to bring the reed in line with the stiffness of its neighbors so they will respond at similar pressures. For an existing instrument, assume that has already been done, and the bellies are where they should be. I tend to restrict my tuning to the first and last quarter of the reed length. Weight changes nearest the tip and thickness changes near the root are most effective , meaning the least metal removal. When initially filing a reed, you need to blend toward the belly to have a reed that curves evenly. I agree with Alex that 40 cents is weighting range for the low to midrange. Mind you at some point you will add a bit of solder and file nearly all of it away again. Still, you haven’t weakened the reed. I use Kester low temp. Silver containing lead free solder with a synthetic rosin core. Other solders that require an external flux generate a very corrosive condition unless very well cleaned and chemically neutralized. The Kester solder wets the steel very well, and I wipe off the flux with a piece of tissue paper as soon as the solder freezes. Generally, I slide a piece of silicone rubber sheet under the reed tip. It lets the reed tip heat fast and the flux doesn’t stick. It also takes the temperature of the melted solder. One nice thing about solder is that it is both fast and reversible. Especially for lower reeds, a loss of strength by filing to lower pitch makes them more prone to flattening in pitch under increasing pressure. I have seen otherwise nice instruments that had reeds so weakened that they were very pitch unstable.
  11. Dana Johnson

    Irish Trad in D Major

    There are plenty of times where playing on the g row is the place to be in D or A, but don’t focus on it as the best way, right way. ITM has a solid rhythmic core. This is something you create by choosing what notes you play in the same bellows direction, or choose a note to separate by a change of bellows direction. Some rhythmic effects require two notes to be in the same direction. Certain chord combinations are only easily available in one direction. Lots of d tunes go lower than the compass of the g row, so you need to go to the c and or the outside accidental row anyway. In the beginning, it helps to establish your primary notes you will use most of the time, whether along the rows or cross row. I personally think that you want to consider that there are lots of tunes in keys besides g and d, so thinking of the instrument as a whole, not revolving around a particular row is a good plan. Whatever plan you use, keep phrasing as your goal. Most difficult fingering can be overcome with practice, so that is of less concern to me than phrasing, or dynamic effects. Good players use all the buttons, making choices to make the music better. Dana
  12. Dana Johnson

    Bellows Card Depth

    On prototypes, I have used 1.25 inch cards and .875 inch cards with opening angles of 90 degrees. I currently use 1.125 inch cards. The short pitch of the shallow cards reduced the open volume. The deep cards were much less stable, and any increase in volume from extra extension seemed eliminated by the loss of volume as the valleys excluded air that would have been inside the bellows with shallower cards. 1.125 inches seems a happy place with decent volume and good stability. For people who use a lot of air, I think adding folds makes the most sense. I play primarily ITM, and only really use all of a six fold bellows for some airs. Other types of music may need more air with heavy use of chords, but bellows stability is the most important factor, since it affects how well the bellows reacts to changes in direction. This is most important for anglos where note changes on the push and pull need to be quick and accurate. English’s or Duets, don’t usually take advantage of that, and can handle less stable bellows. Dana
  13. Dana Johnson

    Accordion Reed v Concertina Reed

    Accordion reeds that live in a box that really works with them can easily be better than a poorly made set of concertina reeds with way too much clearance. (Many, but not nearly all Lachenals). Construction details can make a huge difference in the final sound. I have heard hybrid instruments with wonderful low end sound as well as other hybrids that were mediocre at best. More or less “traditional” concertinas have a long history compared to hybrids. Their construction details were stabilized around what worked best with their reeds. The much more recent hybrid makers are having to find out what works with accordion reeds over the range in a concertina format. The end result won’t be the same, but can still be well worth the money.
  14. Dana Johnson

    Accordion Reed v Concertina Reed

    Feel free to check my website for a pretty detailed explanation of that and other useful bits of information. http://www.kensingtonconcertinas.com/kensington-reeds.html Lots of threads here dealing with it over the years. It is an often asked question.
  15. Dana Johnson

    Concertina Bow Arm

    In Noel’s style of play, one end of the concertina is held in a way that eliminates most movement. The other hand then is under complete control of bellows variation / reversals. By giving the air button hand the job of bellows control, all the air jobs are in one hand. The job of backstop to the bellows to the left hand, simplifies the work your brain has to do. Brains being what they are, they will accommodate just about any circumstance, but I have had students who push or pull the bellows with whatever finger is pressing a button at the time. (Anglo’s only). They never develop the bellows control of the ones who choose a fixed side. Noel has taught a generation of concertina players, and is not a stupid person. My much more limited teaching experience has taught me that bellows control is very important and habits that don’t support that limits what you can get out of this amazing instrument.
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