Recorders and Supercorder: Some Tips and Principles:
Some Recorder design notes for aspiring makers, general and Supercorder specific

by Craig Carmichael
November 2015

Hi Mark,

I always like to pass on my findings/knowledge/experience to those who'd like to improve things. In answering you, it occurs to me I should put this rather poorly known general info up on the Supercorder page for posterity, and at the same time, I've put in more info than I would otherwise would just writing to one person, feeling it's probably more than you were asking for.

Best,
Craig

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I am considering making some innovations on me and my friends recorders, and wanted to ask where you got information about, well everything?

Thanks-
Mark

Well, here and there. It's too long ago to remember specific web sites. You'll have to search and read up on various topics yourself: voicing, tuning, general principles, and so on. But here's a few pointers, info that may be harder to come by...

My shortened beaks with the tuning hole covered by the lower lip still (AFAIK) make them the only duct flute you can tune by ear as you play, hardly thinking about it, making it fit in in "any old" ensemble where they won't understand if you can't, eg, do a fade ending or play pianissimo in tune. I don't think hardly anybody appreciates what a real difference that makes.

One might (?) lengthen the beaks and windway, and then make the lip tuning hole larger diameter. I haven't tried it. But in order for the lip to cover the hole nicely, the shape against the lips needs to be something like I made it, not the traditional/familiar arc -- that really has no particular musical/playing purpose.

My wider windway (16-18mm or so) that follows the inner bore with no undercutting makes for more volume especially in the lower register, where the strong tone is really like no other instrument. This is also helped by the large diameter surround "shading" the sides of the labium in a sense. In the second octave the sound becomes more typically 'recorder'. In the third octave it gets somewhat hissy unless you suck the moisture out just before blowing the note. Since the exact sonic character depends somewhat on the "waves" of the moisture lining the windway, different windway materials with different textures and maybe porosity can provide different characteristic sounds especially in upper registers. (Eg: With plastic recorders the upper notes often hardly sound at all the first time, then sound great on the second try once the moisture has been blown out. Frustrating!)

A narrower windway/labium might improve the upper octaves, but would probably reduce the power of the lower one, which needs the most power to be heard in an ensemble. (Worth experimenting with?)

The longer bore with a tone hole in the right place for each semitone and keys where needed gives more power and resonance and more even volume on all the notes including the low ones. (Most altos are made acoustically too short for the lower notes in order that the bottom finger holes are reachable.)

I originally followed the bore of the Paetzold/Mollenahuer "Modern Alto" which has very nice lowest notes. But since I didn't undercut the windway, that modified the bore profile... and all for the better, it seems to me. The note holes all had to be changed, moved down the shaft a bit. But my thumbhole is (IIRC) in the same place, so it's farther up from the index finger hole. Some highest note fingerings changed, but then it has keys too, so it's a bit of relearning anyway.

The holes must be both in the right place and the right size to be in tune in both octaves. In the lower octave the tuning is most affected by the distance/position down from the labium, and in the upper it's more affected by the size of the hole. And this all depends firstly on the inner bore profile, and the hole size depends also on the thickness of the wall between the bore and the outside, the "chimney height".

There's more on metalworking for doing keys in a jewelery making book than a metalworking book. "Nickel-silver" AKA "German silver" AKA "nickel-brass" (Cu:Zn:Ni eg 65:18:17%) is the metal you want for keys. Web search to find sources. (The one I used most was metaliferous.com) Brass is okay too but a bit softer and best lacquered or plated. Pure actual silver (Ag) or sterling silver is much too soft. Piano wire, eg .030", is good for inner shafts. I made my cups from sheet metal and the levers from 5/32" nickel-brass rod. The rod I flattened and bent as required (I eventually made a jig to clamp them and got a jeweler's rolling mill to flatten them evenly, and for the cups I made punches and dies from carriage bolts and drilled-out nuts. In forming the wire it may be necessary to anneal it to keep it workable, either before or during bending/flattening. A hammer & anvil also works okay for flattening if you don't want to bother finding a rolling mill.

The B/B-flat key was an original idea that inspired me to make the supercorders in the first place: lightly cover the open tone hole for B, and press it down to cover both tone holes for B-flat and notes below. The low A-flat hole and key gives strong sound on both low A-flat and A, and as long as it needed a key mechanism, I made the longer bore and low E key as well to extend the range a bit. (It also replaces functions of a "bell key" that might have been added.) The E-flat and D-flat keys were inpired by clarinet E-flat/(B-flat in upper register), but I put two rings on the middle two right hand fingers to activate them instead of just a triple one on any of three fingers.

The porcelain beaks are very nice but owing to the difficulties with dimensions as the clay dries and then is fired, and the hardness of fired porcelain, I expect ceramic (bisque fired clay) would be much easier to work with. It took me a long time to get good voicings, in fact I didn't really accomplish it until well after I had quit making them, and the hardness of the porcelain was a definite contributing factor. The one I play now sounds fabulous... after 3 or 4 years, once I had "tweaked" the windway a couple of times and sharpened the labium. Ceramic would be easier to sand and grind smooth and flat. You won't get good voicing without hiss unless the windway is even with good bevels and aimed correctly lined up with the labium, the edge of which should be quite sharp.

But I figured all along that if I had met someone who had some experience voicing recorders who would help, the problems would have been quickly solved, instead of dragging on for years and after everything else was history. These days, the first place to check would probably be youtube.

Denser, heavier woods give more resonance - not a myth or just, um, 'snobbery'(?). Some woods "fur up" gradually or quickly with breath moisture, and maple expands unevenly, becoming an oval that doesn't play well. My favorites are pau ferro (Brazil) and African Blackwood. Other smooth, hard rosewoods are probably great too. Indian rosewood I used was rather coarse grained. (I only made a couple of dozen instruments altogether.) With the porcelain mouthpiece, allergy to rosewood may be less of an issue. An ebony recorder I made kept cracking and was nothing by trouble. Great for violins that stay dry, but I'd never use ebony again for a wind instrument.

Hope that helps,
Craig