I've been experimenting for some time with the Blue-Tac method for adjusting the pitch of reeds down from their natural pitch.
This is great for experimenting with modified tunings. You can temporarily convert a country or Paddy Richter tuned harp back to Richter using blue-tac, and you can turn a Richter tuned harp into a Natural or Harmonic Minor or even a low octave harmonica.
Essentially, if the reeds need to go down, you've got room to go, perhaps as much as a whole octave!
The physics of the matter are essentially identical to soldering the tips of reeds to weight them, only instead of solder (which is mostly a permanent treatment), the blue-tac is more malleable, reversible, and experimental. But that said, blue-tac can hang in there for a very, very long time. You may even forget it's there. (I know I have on occasion!)
I'm fascinated that not only will adding and removing material change the pitch of the reed, but so will shifting that material forward and backward along the length of the harmonica. It's just like sliding that weight up and down on a mechanical metronome to adjust the speed of its oscillations. We're just dealing with hertz rather than beats per minute, and the moves are much, much smaller.
So, tonight on my live stream, I decided I should try to tune a harmonica down as low as I could possibly go using only blue tac. I started strong... I got several hole tones down and started running into trouble with impossibly tall blobs of blue-tac towering so much taller than could ever last... And yet, it was working!
I got the C5 reed on a standard C harp down to Bb3... So I thought, why not try for lower.
Jumping over to the C4 reed (1-Blow), I stacked an impossibly tall blob, now more of a dinosaur fin, onto the C4 reed and got WAY down to something like G2. Ridiculous!
What the heck is that?!?
But at this point, I realized that for quite a while, there was NO WAY that the reed was actually passing all they at through the slot. Apparently, it doesn't have to! Just one half... The other side doesn't matter?
So I did the only reasonable thing I could think of doing...
... That's a reedplate screw...
So... I got the tuner to detect a C2. Two octaves down. I made it sound even lower at one point, but the iPad wouldn't detect the pitch to identify it.
Clearly, such a monstrosity would never fit under a cover plate, or inside a comb, but it was an entertaining exercise, nonetheless.