Jump to content

Dana Johnson

  • Content Count

  • Joined

  • Last visited

About Dana Johnson

  • Rank
    Heavyweight Boxer

Profile Information

  • Gender
  • Interests
    Playing ITM and making concertinas
  • Location
    Kensington Maryland. USA

Recent Profile Visitors

933 profile views
  1. Here is a link to a coromandel chest that has that that sapwood heartwood combination in the same coloration. I think the grain structure is more reminiscent of woods like zebra a dense wood with long large pores. All of the Brazilian rosewood I’ve seen has a finer structure than that end. That said, I’m sure there is overlap in the range of appearance, I wouldn’t discount the coromandel reference though. https://eronjohnsonantiques.com/products/c0894-dutch-jacobean-style-coromandel-wood-chest-on-stand
  2. Hey Johan, I love the Parable of the Lice 😄. I have only had to do brass reed setting on Organ reeds, but on my steel concertina reeds I am in the straight reed camp. This was after giving the reed tips a slight swoop upward so the tip entered the window later than it would if the reed was straight. I think I did this because it was easy to have the tip bent slightly downward so it appears the set height is good when actually it grows a little behind the reed tip. After getting in the habit of looking at the reed under the microscope on edge, I could see that happening. After many many reeds, I find that having the reed basically flat from root to tip. So the reed closes off pretty much at the same time as it swings. I use thin slips of shim steel to lift the reeds and adjust the set. They are a few inches long and tapered from about 7/16 inch in width at the wide end to 1/4 inch at the narrow that has been ground to a thin knife edge. I use the heel of the lifter placed at the root of the reed and rock it forward to lower the set from the root and slip it under the reed from the tip toward the root and lift slightly to raise the set. This keeps the reed straight. Concertina reeds need to be as responsive as possible. The interesting reed bending variants that are used to affect the tone in other reed instruments tend not to be optimal in that regard. None of that matters in an organ that tends to operate at a more or less constant pressure level, but concertinas can’t afford it. I think of reed as a little like pre-loading the spring that splits the difference of being high enough to ensure it doesn’t die in the window, but low enough to require little air flow to close it and start the oscillation. It does need to be high enough so that the reed can produce enough volume, but that is a trade off between volume and response. I find stiffer reeds can operate at a lower set than thin or weak reeds. Dana
  3. Talas makes a water reversible Pva/Eva bookbinding adhesive that works very well for bellows making. It is acid free and suitable for archival work. It works well with all the materials involved. As far as hide glues, I think Alex’s suggestion of rabbit skin glue is a good bet. It doesn’t have a really fast grab which is helpful for positioning. here’s the Talas link. https://www.talasonline.com/Jade-R
  4. Hurray! Socket head screws on your reeds. Why not on the end bolts too, or do you make those yourself? Sorry everyone, I am not a fan of slotted head screws. Perhaps they have a place, but it isn’t on things that are designed and destined to be taken apart. BTW. Fine looking instrument. Bet it sounds even better! Dana
  5. My blower is for six inch ducts and is relatively quiet at the speeds I run it at, certainly not close to the volume of the reed. I have a larger one that can reach a much higher pressure, but it is really overkill. The squirrel cage type blowers freewheel at too low a pressure unless they are quite a bit larger than the centrifugal one here. They are designed to move high volumes at low pressure. On mine, I attached it vacuum side up beneath a hole in the table that I clamp my tuning jigs over. These blowers are quite commonly used in long runs if ductwork, and should be available from places that stock equipment for plumbing and heating companies. I got mine from MSC more than 20 years ago. ( mscdirect.com). I set a date check tuning pressure with a digital manometer, though the magnahelix gage did well for me for years. Since keeping the pressure relatively constant is the important thing, a gage of some sort is more important than the air source since like Alex, you can use ordinary bellows or other manual things as long as you can see the results of what you are doing. I tune so many reeds that just leaving the blower on and flipping the lever operated flap valve if I need to temporarily shut off air flow, make for a lot less effort over a day of tuning. Dana
  6. I never considered the output from the speed control. Since AC is going in, I thought it might just be a switching type speed control, like a lot of dimmers that simply vary the time the power is going to the filament. Regardless, I just looked in a catalog for in line duct fans and picked a speed controller in the right power range. Sounds like you have a monster blower, more like a vacuum cleaner to work at those pressures. All I know is that my blower motor bears no resemblance to my 2 hp you may be able to force more air through the reed though physically that becomes increasingly difficult past a certain point. At some point the reed simply stops oscillating (what I call choking). The less stiff s given reed is relative to its pitch and length, the sooner this happens. It seems possible though that the greater the reed amplitude, the less time it spends in the power zone. That is an interesting concept. I know it all gets turned into heat, but is that in the air cooled reed or in the muscles / blower that does the driving? It is funny to realize since our experience is all about the exercise we get and the resulting sound out. On the other hand, since sound pressure can sympathetically drive a reed I wonder if the natural feedback mechanisms don’t increase the reed’s physical amplitude.
  7. Buying valves will be cheaper than buying valve leather, if there is any real agreement on what that is. When I started looking into it 30 years ago, “cabretta” ( a variety of hair sheep )was what people mentioned. But finding that in the various thicknesses was not easy. I have since settled on Columbia Organ Leathers Chrome Pneumatic Leather (cpl). They also sell cabretta in various thicknesses, but I prefer the cpl after comparing them. Even so that is generally too soft as sold so I wet it and let it dry flat on glass which restores some stiffness. Then when you cut valves you need to orient the length in the direction of least stretch which is where you get the best spring back. Valves cut the other way will be much floppier. The leather is not tapered in thickness, but usually is wider at the base than the tip which improves the lifting characteristics of the valve.. Generally thick or stiff valves dull the sound while thin brighten up to the point of no valve. Too limp and the valves, especially longer ones, will not close as rapidly when the pressure is released which will increase valve “slap” as the valves are sucked closed on the bellows reversal. The difficulty with buying precut valves is that you don’t really know how or where on the skin they were cut. Hopefully the sellers are experienced and grade their valves accordingly.
  8. Just how do you do that? Do you use a ball mill cutter? I can't see that you're cutting the sides with some kind of file or scraper, so maybe I really don't understand what you mean by a "belled" relief angle. I use specially made scrapers in three sizes and curved cutting edges. I scrape from the bottom of course and the tips of the scrapers touch the steel jig before the bell is cut too deep and wrecks the top side of the reed window. The Jeffries was belled with a file. The scraper works quite quickly, and I mostly just do the long sides of the window and leave the regular draft at the tip. I do have some issues with the blower ( axial duct fan ) speed pitches, but I don’t find the kind of interference with reed vibration that the tube resonances have. It is also easy just to change the speed slightly to move it away from the reed pitch. I agree. Would you agree that the effect is a little like that of a thinner shoe (plate)? I would agree it is a little like having a thinner reed plate, but unlike a thinner reed plate, the reed efficiency increases noticeably on the oscilloscope amplitude up to a point of no further improvement, so even as the reed enters ever wider sections as the pressure goes up, some effect on the sound creation requires some degree of containment. I don’t really know what creates the actual sound amplitude. If it were just pressure of the bellows, then physical reed amplitude would make little difference. Perhaps it is pressure at a certain air flow. In electricity, that would be watts which is a power term. ( pardon my daughter’s 8th grade physics class ) so that sounds reasonable, but increasing the pressure past the point where the reed no longer swings farther doesn’t make it louder. Maybe that is because the reeds start to choke up and you can’t really force more sir through. This surprises me because the major amount of energy addition to the vibration is during the downward movement of the tongue through the slot. With high draft angle, there's a lot more air flow between the edges of the tongue and the walls of the vent, lowering the pressure driving the motion. I think we might need to distinguish between reed amplitude and sound amplitude. The reed is after all primarily a mechanical valve perhaps it is a bit like the base in a transistor (or grid in a vacuum tube ) that controls the gain , ( dating myself ) between the emitter and collector operating at some larger voltage. I don’t know... probably just more bad analogies . Best Wishes, Dana
  9. Jeff is a good guy and excellent craftsman. As a maker, I am always interested in the innards as well as the playability, and he clearly can be proud of his work. He used to work with a metal flute maker I believe and is used to doing careful accurate work. If he is up to #38 now, he has likely improved from an already excellent beginning. From my experience with them, he is up there with the best. You would have to make your choices by tone preference, not quality. The one I played was fast and responsive. Unfortunately it was in a very noisy space that made it hard to hear over the incredible din in the auditorium where he had a table set up.
  10. The draft angle varies with depth so the cross section shortwise across the reed shoe looks mildly shaped like a musical instrument bell. All this means is that the reed sees side clearance increase faster than a single angle draft. I found the amplitude increase over straight draft held over most of the note range from about b3 on up though I didn’t graph the values. When concertina reeds have too low a draft angle, they require more pressure to get to max volume. Whatever happens in a belled vent, it happens sooner in the cycle than in a straight one. I originally tried it because the reeds on my old Bb/F Jeffries had all the reeds carefully belled by hand. It was a lovely. clear sounding instrument. I did vary the amount of belling with shoe size. What I found as far as the sound goes is that the belled reeds go from quiet to loud more quickly with increasing pressure. If you are looking for a more honky sound, that helped. As far as mechanisms go, I can’t see a curved draft is really any different than a straight one except that whatever is happening at the side clearances sees a gap that increases at a accelerated rate. that may have been the case, but I seem to remember that it affected more than one reed. ( of course things can gave multiple resonances.) I am quite aware of the issue though. My current tuning setup has a resonance around G4, which I get around by opening a second chamber. It extends about halfway to G# but heavily influences the affected reeds. An earlier setup I used with a more powerful blower that could easily get to 4” and above, had a exit pipe of 4 inch pvc about 6 feet long. Had to ditch it because of the resonance problem. Even room resonances can cause problems. I am coming at this from the wrong direction for any kind of mathematical analysis. As a player and maker, I pay attention to the things that get musical results which have to include the complete unisolated package. I am stuck poking around things until they seem to give the best subjective result, with modest experimentation to home in on the desired result. Not practically being able to separate out very much and still tell anything has been frustrating. It is relatively easy to make general statements about chamber depth and size, the general effect wood species has on both tone and damping, But I have pretty much given up on trying to understand the mechanisms by which it all happens. Trial and error can be an effective way of coping with complex interactions without really understanding them. When I was younger and more ignorant of my lack of critical thinking powers. I was invested in “understanding” how it all worked. The more I learned the less I knew. Now, I get my enjoyment from the craft of making concertinas and getting lost playing them. I’ll leave the ciphering to cleverer folk. Best Wishes, Dana
  11. You can change the low f to f#, but I find the low notes better for support notes and chords. They are often s bit slow for rolls and triplets. Given the C row has the press E’s , where the G row doesn’t have an E until E5. It is s long way from E3 and I prefer the nice E3 B3, E4 press mostly Eminor chord. If the F#3 were on the draw, it would go with all the f#’s in the G row, I currently have a D3 in that position on my concertina, but have been wondering about changing to the F# just to see what possibilities it gives. If you play in C, F, or Bb, not uncommon keys even in ITM, it might be good to find good uses there for the low F natural. Since changing reeds generally requires tuning the new reed, I think doing it on a whim for some possible utility might be more trouble than it is worth. If you make your own concertinas, experimenting is little trouble. Still I haven’t got round to trying the F#3 yet. Perhaps a case of shoemakers children... Dana
  12. Regards trying to figure out reeds in isolation, I am not sure how easy it is to get to a place where you can afford to discount the reed’s environment. The pitch change with bellows extension is one example, but once I thought once I’d be clever and build a foot powered tuning bellows ( or really a dropping weight one ) using a smallish accordion bellows about twice the area of my concertina bellows that could be used both with or without the blower. I was surprised that my reeds would not sound with that big a bellows. Given the requirement to have the positive side of the reed isolated from the negative. Just how do you look at the acoustics of the system ? I know you can’t look at wind instruments without considering the upwind side, be it vocal tract or mouthpiece cavity design. I know others have had tuning bellows with larger areas, but I could not use the same setup I use with the blower / concertina bellows mount just transplanted to that accordion bellows. I do have separate chambers on the plenum I use with reeds being rough tuned, not in the reed pan. I have three chamber sizes in the plenum, each works best with a certain pitch range. Reeds stop sounding when the chamber gets too big . I could probably do better with 4 sizes, but having the chamber on the backside makes a huge difference to whether the reed operates or not. When getting too close to the reed too small for the chamber pitch, the reeds get muted and lose their harmonic richness. I cover the unused slots with flaps of silicone rubber, and when I get to some notes, especially at the transition zone. I find that as the notes dull, partially opening the adjacent port will allow the reed to sound clear again. I know chambers etc complicated things, but I am not sure how possible it is to ignore the kind of spaces reeds need to work. I know people have brought up different thoughts about resonance, mostly discounted because the sizes involved don’t really fit the wavelengths involved, and are far from critical dimensions, but some property of the spaces involved has a very large influence on reed function. well, have fun with it all. Best wishes, Dana
  13. Concertinas radiate most of their sound from the ends, away from your ears. You sound much louder to people on either side. If you want to hear yourself in a session, sit in a corner, like harpists sit with a wall behind them to hear the sound as it bounces back to you. Most decent concertinas are plenty loud enough for sessions. Mine certainly are without having to exert much effort. Both violins and flutes are right next to your ear when playing and are much easier for the player to hear. I tune my reeds in the reed pans with a plate with one pad hole over the chambers. It sits about the same distance from me as normal playing position. I think it is quite close to what the concertina produces fully assembled, especially since I often will hold the concertina end up facing me if I am listening for any reed or valve issues. That's surprising. Do you see higher or lower pitch with extended bellows? I’m trying to visualize the readout, but only see the numbers. I often have to recheck the readings because I forget to write down the sign. I am thinking that the pitch is dropping though. Now I think about it, I don’t think the deviation is that large. Again I am fooled by the readout which is in tenths of cents. It does vary by a couple cents though. Thinner refers to the tongues. I do find that thin sets tend not to be able to reach the same volume as thicker sets, which does connect to the pressure required to drive the reed through the thickness of the vent. Concertinas with thin reeds trade responsiveness for maximum volume. The vent angle change is a way to get the most out of a reed. I once did an experiment measuring the output of a reed ad the vent angle changed and how belling the vent instead of using a straight taper. I measured the voltage out of the mic and thought I’d really found something when the amplitude doubled in the belled reed shoe. Then I remembered that in audio, one db increase is x10 . The belled set was noticeably louder, but just. It did change the volume / pressure curve, jumping to high volume more quickly. Good for some music, bit makes dynamic control more fifficult. I did arrive at my current draft angles by testing to find the point where increasing draft started to reduce power. Re: accordion reeds, they generally have little or no draft angle because it eats more air than an accordion with multiple reed banks sounding at once can afford. This is from an accordion maker. Dana
  14. Sorry, I haven’t mastered responding to quoted sections. I’ll just mash it all together. i still get caught making incorrect analogies between the slugs of air in woodwind finger holes and the flow through the ports, though with reeds vibrating hundreds of times per second, sound waves kinda have to result somewhere in the process. I use a digital manometer to set my tuning pressure. 1” provides a reasonable volume, sufficient to avoid too much pitch change in the normal dynamic range of playing. 4” is quite loud for my concertinas. I do measure it directly through a port in my tuning bellows, though I just use the bellows for mounting my reed pans and use a coaxial blower to generate the vacuum. My reeds generally don’t vary by more than 2-3 cents over the normal playing range. I do find that under too much pressure they can go quite flat, but this requires quite a lot of pressure, and is only a bending effect I use purposely requiring extra effort. Oddly the higher 6th octave reeds can actually go sharp instead of flat. Go figure!. I do find a lot of variation in pitch with the degree the bellows is extended, Maybe as much as 5-6 cents, even at constant playing pressure. I have to be very careful creating my tuning charts to take this into account. Re f#5, yes you have the right pitch. I cut my ports with a .125” end mill, leaving an arc at the ends. For a couple reeds, the arc encroaches on the corners of the swinging reed. I have to square off the ends because the reeds will hit in the mid part of the dynamic range or higher. I can’t be sure how high this can happen since the progressively smaller reeds get more clearance in the ports. I don’t find having the higher reed ports closely match the reed widths makes much difference, so I avoid an extra tool change. I do increase the window draft angle from 5 degrees per side at C3 to 20 degrees per side at G6. For my reeds I find this increasing draft angle is required to get a similar volume at a similar pressure over the entire note range. I hypothesize that thinner reed sets may need less draft angle because they deflect more at a given pressure than heavier reed sets. But they do max out in volume before the heavier sets.what my reeds need and max volume / pressure levels are empirical findings. I have not experimented with light reed sets, though I have worked on instruments with overly thin reeds that both were kind of on or off as far as volume is concerned, and quite pitch unstable. Reminding me that part of my choice for my reed stiffness/ pitch curve is my requirement that the reed be pitch stable even at higher volumes. I don’t really know why varying the draft angle has the effect I find, just that it answered my question about keeping the high reeds volume comparable to the low at the same playing pressures. The shoe thickness is the same from C3 to G6 even though the reed length goes from about 1.5” to .5” .
  15. Hi Tom, I find this circumstance at least up to f# 5 at a medium to high volume still within the normal playing range. Most of my reed shoes are .063” thick, though I go to .093” for the long reeds below C3 in my low pitch instruments. f#5 reed is .846” long x.090” wide. I don’t know how far below the reed shoe bottom the reed travel is, and it is possible some reeds above that pitch can travel below the shoe. I only know this because the ports in the reed shoe for the f#5 reed are just barely longer than the reed window and the reed can begin to hit the wood at moderate volume, giving a wonky pitch change. You can press down on the reed tip and feel it stop against the wood. The stock thickness of the old Wheatstone reeds I have from an old duet are .080” thick, but I don’t think that is enough to cover reed travel in that same range. Their brass is considerably softer than the brass I use, and I go up in thickness because long reed shoes are subject to bowing with my reed mounting method. Also, I find that reeds in overly thin shoes can lack power, and the long reeds benefit from the added time the reed spend in the confines of the shoe vent. What happens once the reed enters the port in the reed pan I don’t really have a good idea of since the gap at the reed tip becomes quite large in comparison to being within the shoe window. Nor do I have any idea about the small slug of air in the port that goes from tight confines immediately to complete openness. I wonder what might be reflected at this change in impedance. I tune my reeds at around 1” of water column, though bellows playing pressure can certainly go as high as 4”. My target for starting to sound is .2” of water. In open air. When in properly sized chambers they will start at half that. Travel at those pressures is really minimal, just requiring the reed tip to enter the window. hope this information is useful. Sorry I don’t have info on amplitude vs. bellows pressure. Measuring audio amplitude is easy (ish, since reeds radiate sound differently depending on pitch and one mic position may not be ideal for all frequencies ). Measuring mechanical amplitude is much harder since the reeds are in a confined space when playing, either in a chamber or in the bellows. If they were in the open you could use a strobe and make a feeler jig to gage the physical travel, but absent the chamber interaction, it would hardly be representative of real world data. Best Wishes, Dana
  • Create New...