nacoran
5566 posts
Apr 19, 2012
10:44 AM
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Harponica, you can play with dynamics without blowing out your harp. The quieter you start the more headroom you have to get louder. The more fine control you have over your volume the more dynamics range you can get.
That said, there is a certain sound that a harp that's being pushed to the limit makes that quieter playing doesn't always achieve. That's not so much dynamics I think as maybe, well, let's call it natural distortion. It can be semi-controlled, like lightning fast hard switches between blows and draws or it can be out of control, bends taken down to the floor hard. If that's the sound you are looking for you can either figure out how to do it with effects, or you can brake a few harmonicas. Metal fatigue is just a fact of life. It's what happens to metal. Seydel is switching to stainless steel, which has some advantages, like a small range it can swing without worry. Titanium has that too. Both titanium and steel are much more expensive to work with. They chew up the machines that make them faster. Titanium is so tough that the best way to work it is laser cutting, which is expensive to start with, but even tougher with titanium. Titanium's melting point and burning point are close enough that to safely cut titanium with a laser you have to put it in a non-flammable atmosphere. That gets expensive!
I've wondered if the same lithography techniques that are used to make computer chips could be used to make reeds. Since it costs about a billion dollars (actual price, not just some big number I'm throwing out there) to equip a chip fab plant, it's not likely that we'll be seeing that in the near future, although a reedless harmonica that's all sensors might be practical at some point. They already have apps that turn your smart phone into a harmonica, but the sensors will have to get much better and cheaper before it would be practical for a small market (compared to phones) like harmonicas.
I've blown out 2 reeds in 4 years. Both times I was trying to play along at a band practice without a mic with musicians who were using amps.
It would be cool to see neat new materials for reeds. I'd love to see titanium tried (there is a woodwind reed guy who builds woodwind reeds out of titanium). I'd love to see titanium memory metals. Liquid metals might also be neat to try. They use them on golf club heads. They store and return much more energy than traditional metals (bearings made out of it act like rubber bouncy balls.) Carbon fiber, maybe even composite fiberglass. I have no idea if ceramic metals are bendable, but they can be clear. How cool would it be to have an all clear harmonica? Slow superfreezing and slow warming of metals is supposed to make them stronger. Buddha said he tried this with good results, but he was able to piggyback it because he had access through a friend or family member to the facility and he was dealing with very low volume. The thing is, most of these are very expensive to do, even just as an R&D project, let alone retooling for mass production.
All this, and you make a harmonica that is to expensive for first time buyers to contemplate and lasts to long to get repeat sales (past a full set of harps) from hard core players. Oh well. :)
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Nate
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STME58
154 posts
Apr 19, 2012
1:24 PM
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I think the idea of a short lived product drivung up sales is bogus. Kind of like the recording industry thinking that radio would destroy record sales.
If I have something that lasts a long time, I may not buy another, but I sure will recommend it to all my friends. When a something wears out quickly I do replace it, but with another brand.
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ElkRiverHarmonicas
883 posts
Apr 19, 2012
8:22 PM
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Harmonica, you're buying the harps, do what you want with them.
I don't think building a longer lasting harp will hurt sales. People will still buy harmonicas, the pie is huge and can get bigger if we go back to marketing like we were in the 1930s, marketing to the general public to take it up. Nobody at HH believed that a longer lasting harp would hurt sales over time. Even a lengthwise milled reed will blow out eventually anyway even if it's a few years.
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David
Elk River Harmonicas
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"It's difficult to think anything but pleasant thoughts while eating a homegrown tomato." - Lewis Grizzard
"Also, drinking homemade beer." - David Payne
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nacoran
5572 posts
Apr 19, 2012
9:49 PM
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STME58, I just to comment on math literacy. I wholeheartedly agree in principle; it's the practice that always gets me. Math is sort of one of those use it or lose it skills. I can understand the underlying concepts of metal fatigue and all, and I can work my way through the equations, but not in a way where I'm really understanding how the equation is working, which means at the end of it my understanding of it is really right back where I started, conceptual mathematically sound, but falling a bit short in the details.
I've been watching the Numberphile on YouTube trying to see if I can't get my brain working a bit better again. I was never really good at remembering formulas, but I could reverse engineer them if I understood why they worked.
It was actually kind of the same way I approached language. I was an English Major, but I can't tell you most of the parts of speech. It just sort of works in my head. When I tried to learn a foreign language I was terrible because they taught it in terms of verbs and nouns. Math was the same way.
Come to think of it, that's how my band teacher taught too, and he drove me out of music for a couple years. We really don't do a good job of paying the good teachers enough and firing the bad ones. In physics class (which I failed) I was always the one who set up the experiments, and I could tell if the other students had screwed up their math, because I had a good idea of orders of magnitude, but I always struggled with the actual execution of formulas.
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Nate
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STME58
158 posts
Apr 19, 2012
9:55 PM
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Nate,
Your comment reminds me a a memorable remark my differential equations teacher made to the class. He said that everyone can do differential equations. Every time you take a step you have to solve a set of differential equations in order to determine when and where to put your foot down, if you get it wrong, you fall on your face. Most of us get this solution right most of the time!
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STME58
176 posts
May 19, 2012
10:40 PM
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I manage to sucessfully replace a flat number 7 blow reed on a low D Seydel Session Steel. In the process the old reed broke the rest of the way making it clear where it had failed. It did not fail at the root as I expected but a bit further out. WHen I looked closely at the reed profile I saw that it did not step down at the root but had a gradual taper. I measured the reed and built a model in CAD. A modal analysis showed the high stress point right where it failed. The analysis also hit the frequency within a couple of hertz.
Is this were most reeds break? Do reed that have a sharp step at the root break at the root?
Last Edited by on May 19, 2012 10:44 PM
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ElkRiverHarmonicas
1012 posts
May 20, 2012
9:55 AM
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That illustration is awesome. Do you mind if I use it on my Web site with appropriate credit? It shows very clearly what I so often try to explain. I like how it shows there's virtually no stress at the tip - that's something else that people find hard to believe sometimes.
The answer is... yes. That's where stock harmonicas break. The ones I think you are referring to that have a sharp drop off would still break there. My main familiarity is with Seydel reeds 1880 to present. Those I've paid attention to that were like that stepped down still had that same basic profile and still would fail at the same place. However, I can remember some that have broken at the root and I can't remember who made them or what they look like. Perhaps Harpwrench's vast experience would be vital on that question.
A special Awesome Thread Hall of Fame should be made to put this thread in it. It's been a great one.
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David
Elk River Harmonicas
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"It's difficult to think anything but pleasant thoughts while eating a homegrown tomato." - Lewis Grizzard
"Also, drinking homemade beer." - David Payne
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STME58
177 posts
May 20, 2012
9:28 PM
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Here is an image I did a while ago with a sharp step at the root. It shows the high stress at the root. Of course a trully sharp step is impossible. For the experience David related of where reeds break, there must be enough of a radius that the stress is not concentrated at the step.
I could not imbed the moving image.
http://dl.dropbox.com/u/52636345/Mode1.avi
David You are welcome to use these images. They were created by me using the Finite Element module of CREO Elements direct modeling.
Last Edited by on May 20, 2012 10:27 PM
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SergZZZ
37 posts
May 21, 2012
12:14 AM
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This image is very clearly! If to take into account voltage, due to the "parasitical" vibrations reed, you specify the cross-section will be even more dangerous.
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www.ermonica.com
Last Edited by on May 21, 2012 12:16 AM
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STME58
183 posts
May 21, 2012
10:00 AM
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@SergZZZ,
Your comment is intrigueing if not comprehensible. It got me thinking.
I have created eddy currents in steel strong enough to heat parts for shrink fitting with a high frequency (100kHz) magnetic field. Vibrating a steel reed in a magnetic field would create an eddy current.
Has anyone noticed the reeds getting hot in one of the magnetic steel reed chromatic harps?
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BeePee
56 posts
Mar 14, 2018
9:43 PM
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Just found this very interesting old thread. I have a related question for the engineers here:
What's the lowest psi required to cause a reed to sound? Assuming the harp is airtight and reeds are gapped normally. I guess it would vary according to pitch, but just looking for an average figure. Anyone got that info?
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indigo
481 posts
Mar 14, 2018
10:24 PM
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Sorry Beepee but i think all the engineers have long departed the forum.
Well most of them anyway?
Really interesting thread though ,I remember it ,hope you get some responses.
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nacoran
9766 posts
Mar 14, 2018
11:54 PM
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I'd think, on average, that a longer reed would have more torque on the reed tip so it would swing easier with less continuous application of force than a short slot reed of the same pitch. And thicker/stiffer reeds would take more psi too.
It's an interesting question. I've had a couple L.O.'s that would sound if you held them up in a light wind and they are the only harps that I've had that would do that where you could really hear them. (Which of course, is the opposite of what I'd expect based on reed length...)
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Nate
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First Post- May 8, 2009
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STME58
2052 posts
Mar 16, 2018
7:13 PM
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I was surprised to see this old thread revived. I see that the link to my page full of equations is broken. here it is again. reed equations
I suspect that the lowest pressure to sound a reed would be near that required to open the reed enough to get significant air flow. The equation labeled "Deflection along beam" will give you the reed shape for a given pressure. Set x=l in this equation and find the pressure that gives y(x) equal to the reed plate thickness and I think you might be close.
Last Edited by STME58 on Mar 16, 2018 7:18 PM
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BeePee
57 posts
Mar 16, 2018
8:25 PM
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Sounds plausible, in theory. Would you be kind enough to do the calculation for us?
There must be some actual test data for such a basic piece of information, but I can't find any relating to harmonicas. What apparatus would be needed to do it yourself?
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STME58
2053 posts
Mar 16, 2018
10:52 PM
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For the 16x3x0.2065mm reed I am getting about 4psi to deflect it a millimeter. This seems high to me. I have video that shows the reeds deflect much more the a mm, but 4 psi is higher that my impression of breath pressure is. Omega makes a nice compact pressure gauge that could be adapted into a comb, but it only reads up ti 1 PSI. In reviewing the video, I see the reed does not need to pass all the way through the reed plate to start vibrating, It might be possible to estimate the deflection where the reed first starts to vibrate and use that to estimate the air pressure required to deflect it.
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nacoran
9770 posts
Mar 17, 2018
1:03 PM
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I just 'tested' on my G harp. It's a L.O. and blowing literally as gently as I controllably can I can get the reed to sound. I've got an appointment coming up in a couple weeks with my asthma doctor. I wonder if they have a way to tell how many PSI that is... I can ask. If they don't maybe they'd at least know someone who does.
It has to involve being focused into a tiny hole a bit. If you put your lips back from the harp an inch and don't pucker and exhale as hard as you can you get a lot less volume than if you blow through the hole.
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Nate
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