Dunno who can answer this, but here goes:
Some of the early Brassy Polly whistles exhibit an odd kind of “hollow” sound in the lower end of the second octave - almost like an echo. It’s not a “bad” sound, just a bit odd, and you usually can’t even hear it when playing in a group or along with a CD, say, but it’s a little disconcerting when playing alone in a silent location.
My surmise is that the blade angle on these whistles is too shallow. What I think is that the turbulence of the high-velocity airstream on top isn’t going fast enough to avoid some of it being entrained by the vacuum created by the bottom of the blade, creating a secondary turbulence in the tube that produces this (kind of) “echo”.
Does that seem reasonable? Anybody heard this before, or shed light on the phenomenon?
TIA,
serpent
I’m inclined to think it’s not the low blade angle that’s doing it. My tweaked Shaws have an extremely shallow blade angle, and they don’t have that echo.
Sometimes when a whistle seems to be mixing octaves (high component in the lowest notes or low components in the high notes), putting a little bevel on the end of the fipple plug at the window end of the windway cleans it up, in my experience.
If I remember the photos correctly, you’ve got an Alba style soundblade, which I’ve no experience with. The dynamics may be different than what I’m familiar with.
The blade is similar to Stacey’s older ones other than the SE, but the profile is flat rather than slightly concave. Paul Busman also uses a similar blade, but his is roughed in with a milling cutter, I think, and finished by hand. I’ve been trimming the flash off, and leaving the blade edge pretty much alone unless it’s obviously bad, in which case it just gets re-cut a few thou. I already do bevel the plug a bit. Maybe I’ll make that a little more pronounced.
Hmmmm, though. The mill does leave an extremely sharp, very smooth edge. I’ll try dulling it a bit, too, and see what effect that has.
Thanks for the idea, Jerry!
serp
(edit) Stacey suggested bevelling the plug on my older whistles, and I do that on all of 'em now. Some it helps, some it doesn’t. Different problems, I guess. (/edit)
Nope-- I haven’t worked out how to do the milling in my drill press yet short of an x/y table which is tough to find for a drill as small as mine. I do the blades entirely by hand starting with a one sided triangular file ( other two sides smooth), finishing up with fine grit diamond files and 400 wet/dry sandpaper glued to a small wooden blade.
Paul, give me a call. I can help with milling the blade.
The problem has been solved via a combination of ingredients:
Changed blade angle from 25 deg to 35 deg
Chamfered the fipple plug ever so slightly, to 45 deg.
There is still a teensy bit of the “echo” left, which IMO enhances the character of the voice (which became almost too “pure” with the blade angle change).
Cheers,
serpent
Over the night, I’ve been puzzling with a similar problem (“echo,” buzz or mixed registers in some of the notes) with a prototype tweaked Generation I’m working on.
So far, all my production tweaked whistles play best with a knife sharp soundblade, so I’ve been assuming that’s always better.
However, this prototype tweaked Generation hasn’t responded well to having a very sharp blade, so I’ve been forced back to the drawing board.
I’ve been exchanging messages with Bryan Poe, who recently sent me a prototype low D of his (excellent whistle, BTW). Among other minor adjustments, I suggested he try a sharper blade, and he replied that he already had, and it made the notes unstable.
Remembering what Bryan said, I went ahead and rounded the edge of the soundblade with 350 and then 600 paper. (This would be subtle to most people; however, since I do a lot of sharpening of tools to razor sharp, it doesn’t seem subtle to me.)
Eureka! I now have my first prototype PRODUCTION near perfect tweaked Generation. Now I have to make five or ten more to prove the tweaking system. If it proves consistent, I’m off and running with something I’ve struggled to accomplish for almost a year.
Serpent…(and Paul, too, I guess) I know that this ain’t whistles, but, after all, the whistle is only an end blown fipple flute. There is an outstanding source of information available, and I DO mean OUTSTANDING, in two books by Lew Paxton Price. ‘The Secret of the Flute:’ and ‘More Secrets of the Flute:’. More mathmatical formulas than you can shake a stick at…real nitty-gritty flute stuff. Everything from theoretical sounbd chamber length to tapered bores. This book is authored by a NA flute maker, so most of it is aimed precisly at end blown fipple flutes. It is available at:
They are $15 each. I ordered ‘The secret of the Flute’, but they sent me ‘More secrets of the Flute’ instead. I think both books are needed to fully understand what goes on when you blow that first breath through an end-blown fipple flute.
Anyhoo, if Serpent or Paul tries these books and finds them useful, my finders fee can be in the form of credits to a new whistle
Eric, there are actually quite a few books by Price. I have four:
Secrets of the flute: The physics, math, and design of non-mechanical folk flutes
Creating and using the Native American love flute
Creating and using Grandfather’s flute
Creating and using smaller Native American flutes
These are softcover books, about 5x8" and roughly 50 pages. If anyone has questions about them, let me know.
