I saw Brendan's video with the Turbo Slide harmonica and that got me wondering how it works.. and I watched Dr. Antaki's video that said the magnetic force "softened the springiness of the reed." That explanation didn't really click in my head, so I pulled this strong magnet off the refrigerator, took a Seydel with some steel reeds and did some experimenting to see what's going on. My findings:
The magnetic force applied to the reed has the same effect as adding weight to the reed. If you apply magnetic force to the free end, it drops in pitch. If you apply to the rivet end, the reed RAISES in pitch. I noticed that on Antaki's videos the bends sounded a little sharp, from my experiments I could never get the reed to go down a full half step. In my experiments it approached around 25 cents sharp of a half step down,!the reeds choked and there was nothing I could do about it, they just flat choked - if you were using a magnet a little more appropriately chosen than one you just pulled off the fridge, I would assume you could get a little flatter - but to me, it is obvious there is a bending floor. I think if you centered the magnetic force onthe very center of the reed, the theoretical point where adding material would make it neither sharp or flat, I think it could lower pitch by slowing down the reed. Now what is really interesting to me- if you apply a weaker magnetic force at a specific point - the only way I could vary the strength of the magnetic field was by varying distance, something weird happens. Before the field becomes strong enough to change the pitch- right at the point where it happens, there is a significant change in tone. It's as significant as when you close a side vent, there's a loss of treble. This could only be because of a change in air flow and I find it very interesting.
This change in tone happens during the bend, it just starts -and is significant when it starts - before the reed changes measurably in pitch. I noticed this tonal phenomenon with the magnetic force applied at the rivet end, actually away from the reedslot, about where the rivet is.
So, if you added a second slide button you could not only bend a half step down, but also up AND, if you added a second magnetic slide near the rivet end, you could raise the pitch nearly a half step and there would be clearance to do so. This would be extremely useful.
Im not perfect and I can be wrong at times, but Ive never bullshitted anybody before on anything like this. If I say it dropped 75 cents, it dropped 75 cents. yes I'm a little offended, but I'll get over it and I still get a chuckle out of your perpetual bluntness, even if it is directed at me ;) Do I really have to go to the trouble of making a video about this? ---------- David Elk River Harmonicas
yes i wanna see a magnet stick to a stainless steel reed and a cheapie magnet like whats in a shower curtain or a chinese fridge magnet my sis has a stainless steel fridge devoid of childrens art because magnets wont stick to stainless steel. i did an expewriment once with a stainless steel wire and a lead clipped to both ends plugged into an amp and held a strong speaker magnet to it. i didnt get anything from the stainless i did get sound from a copper wire and rusty steel wire. im not saying the magnet has no effect at all on stainless but a cheapie fridge permanent mag? yeah i wanna see it. if a mag does stick to a seydel reed then its the cheapest stainless ever and youre getting robbed by them.
Billy, there are different grades of stainless. Some grades are magnetic. It depends on the mix of the alloy. It's not necessarily about cheap, it's about selecting the right grade for your application- the right flexibility, resistance to corrosion, etc.
Elk, I wouldn't think balancing the magnetic force would slow the reed. I think it would work kind of like throwing a ball in the air. When you throw the ball it decelerates until it's speed reaches zero, then it accelerates back down, and if you take out the effect of friction it's going just as fast when it lands as when it started off. Since reeds cycle so fast I don't think you'd get much net result. Of course magnetic fields created by small magnets drop off much more quickly than the Earth's gravity. You might get the reed to swing farther on one part of it's trip, below or above the reed plate, but I think the cycle time would remain the same. Still, the net energy has to balance out because of the good old law of conservation of energy.
The video on the Turbo site actually mentions that they have plans for a slide that will help you bend notes both ways. Electromagnets built into a circuit might give you even more control. You could vary the field to vary the bends. Was it Brendan's video or the one on their site that said they were going to make a version with weighted brass reeds? I wonder if they are just using something ferrous at the end of the reed or if maybe they are adding magnets to the reed tips to get a more powerful reaction.
I've wondered also if there would be a way to adjust the magnets slightly with a secondary knob or something. If you designed it right, it might be possible to change the key of your harmonica with the turn of a knob.
Electromagnets with regular magnets on the tips would give you some interesting possibilities if you had a circuit that gave you fine control. Sure, your harp would have to be plugged in, but if you could cycle the pulses of the electromagnet you might be able to get some neat effects- a volume knob comes to mind. You might also be able to work something up in the way of an internal microphone. (I think Turbo has an internally miked harp, but I think it works differently.)
I have no idea if it would be useful, but as best I can tell there are six ways something can interact magnetically: North, South, universally attractive (like iron to either a north or south end of a magnet), not react at all, react by becoming magnetic but only in the presence of a magnetic field (paramagnetic) or to be universally repellent to magnetic fields (diamagnetic).
(There are some neat experiments that use diamagnetic substances to make something levitate. It's much easier to use a diamagnetic substance like bismuth than just a magnet because it doesn't flip over and suddenly become attractive... hmm, just like a date after a hard night of drinking? I have no idea how to make any of that particularly useful to your experiments, but I thought I'd share anyway. For some reason they didn't cover that in any of the science classes I took. It wasn't until my friend and I wanted to make a rail gun that I learned it all. :)
Magnet picking up stainless steel from Wenger and Victorinox knives and Seydel reeds. This was the same magnet used on the reed test. The reeds that did not get picked up were brass reeds. I put the Victorinox and Wenger steel on there, because those are two great steels. Victorinox is like 69 on the Rockwell scale. Watch it, Im not lying about this... This is my last post here.
As for a harmonica synthesizer that can be washed in the dishwasher... there are apps for smartphones that turn them into very basic harmonicas, and there are waterproof phones. :)
Another crazy idea would be to put piezoelectric strips on the reeds. You could make electricity while you were playing! Again, I have no idea why you'd want to do that, but it would be cool.
piezoelectric shoes to charge a cellphone is a possibility. but yeah eddy current is amazing. and ive yet to have anyone explain to exactly how magnets stick to iron its unexplainable a truly magic thing we take for granted. but if you drop a magnet through brass or aluminum it wont do that only copper works.
