No, not at all. It's just the combination of a very busy few days and the amount of information to process.
I wholeheartedly agree that the combined inputs of various disciplines would help build this model. To get everybody together in one room sounds exciting - maybe one day at a SPAH convention...
As for Bernoulli/Venturi effect, I'm sure air entrainment is only one of the facets of this model that would need to be broken down. There is so much going on, it seems to me that to create a theoretical model of what's really happening to a harmonica reed, we would need to create a series of models, each one representing one aspect and then put them together. I'm sure things get even more interesting when you factor in a second reed in the system along with playing bent notes!
We play such a modest instrument...
As far as moments of laminar flow versus moments of turbulent flow, it's just a gut feeling.
I know that reeds of various materials have a different sound and feel when played. For example, old Hohner brass (with high lead content), new Hohner brass and Stainless reeds all have dramatically different timbre. They can all play the same pitch and respond the same to air flow, but the sound they make will be different. My suspicion is that the difference has something to do with the "rate of rate of change" (not a typo) of the movement of the reed tip.
If the velocity of the reed in motion can match the velocity of air for a portion of the cycle, let's say that creates a period of laminar flow. So you are cycling between laminar and turbulent flow. Different materials could change the rate of rate of change which would mean the reed would spend more or less time of the cycle in laminar flow.
I imagine stiffer stainless steel to snap back (or accelerate) faster than a reed of the same pitch made of brass. If that means there is a smaller ratio of laminar-to-turbulent flow, this might explain why reeds of different materials each have a distinct timbre.
Michelle i do the same meathod as you and it works great. But it seems to me that putting this offset in the reed is probably not good as it effects the shape. And the manji With the welded reeds dont really seem to need it as they sit lower to the plate.
I'm just putting my thought in here to see if yall can make things clearer. I'm not saying one thing IS or ISNT. I'm a "Noob" at all this. So im saying what i think is right, in hopes that you will correct me where I'm wrong.
Andrew .... Like the new Signature Emblem. BTW .. Idk if you remember, but i emailed you about my order not comin in yet. WELL ...... Somebody at my house had misplaced it. So it was here all along. So. ...lol .... i found it. The Gray Comb is sharp lookin. I love your combs they sound fantastic and airtight factor is wonderful. F Tool works like a charm too.
If u get a chance could you read over my question above about the french tuner. It's probably a dumb question, but i would still like to know for sure. ---------- ......." Where Does He Get Those Wonderful Toys?" .......
Last Edited by Killa_Hertz on Jan 18, 2016 10:08 AM
A modest instrument indeed! It never ceases to amaze me the many facets of the little jewel. So many ways to become as deeply immersed as you want. Or maybe even deeper than you want!
I like the idea of a SPAH seminar or even a mini-conference within a conference.
Air entrainment? I'd never heard of it, but Wikipedia says it has something to do with air bubbles in concrete. Please explain what you mean.
Whether the air passing through the reed/reed plate “orifice” undergoes laminar or turbulent flow depends on the Reynold's number of the system. Reynold's number relates to the physical properties of air (density and viscosity), how fast it is moving, and the physical size and shape of the orifice. These elements are either readily available or fairly straightforward to calculate. I intend to take a stab at it when I get a couple hours to devote to it. When I do I'll document my sources and calculations. Should be a fun exercise and the results should be interesting.
I totally agree about the “feel” to the player in terms of responsiveness and ease of bending of harmonicas with different reed materials, even brass reed models from the same manufacturer. But, I've a bit of a different take on the reason why.
I think air “swishes” past the reeds at a significantly higher velocity than the reeds themselves. If you recall Antaki's high-speed “wind tunnel” video, that air is really blowing by that reed into the chamber. I believe that the different timbres are due to the physical properties of the different alloys the reeds are made of. I'm no materials engineer but I have taken classes in it. Different metals, in fact all different materials, have different natural frequencies of vibration. Due to forces between the atoms making it up, each material reacts differently to mechanical forces applied to it. Each material has different vibration damping characteristics that result in different harmonic frequencies of vibration. That's why rubber absorbs vibration where metals and other like materials transmit it. So if we were able to measure the frequency spectrum of the vibrations absorbed or transmitted by the different alloys, we'd see significant differences that manifest as the different timbres we're talking about. At least that's the way I see it.
Good ideas as usual, Andrew. Thanks!
Michelle ---------- SilverWing Leather - Custom leather creations for musicians and other eccentrics.
Last Edited by mlefree on Jan 18, 2016 11:55 PM
Killa, you're gonna have to show me pictures of how Suzuki reeds "sit lower to the plate" than other manufacturer's. Most likely, if the bottom surface of a reed isn't flush with the top surface of the reed plate to which it is attached, either it won't sound at all or it'll whistle like a tea pot.
Can you expand on what you mean by "putting this offset in the reed is probably not good as it effects the shape."
Frankly, if Richard Sleigh teaches dipping the reed into the slot close to its root, that's good enough for me. The harps I've set up that way play as well as any I've ever played. I'll admit that I've never owned a custom but I've played some. (I learned to tweak reeds before you could but a custom unless you were a dignitary and now I can't afford 'em.)
Michelle
---------- SilverWing Leather - Custom leather creations for musicians and other eccentrics.
Last Edited by mlefree on Jan 19, 2016 6:36 AM
Michelle i will try to take pictures to show you. Manji reeds rarely need any work at the root. In my experience so far.
I agree that if R.Sleigh teaches it is probably the best advice to date, but even he has changed his opinions and techniques over the years.
What i mean is: sometimes the offset required is pretty heavy. And in either event the reed is no longer straight as it now has an offset. Instead of being flat from rivet to tip, it now has apretty heavy deviation from that origional shape. It just seems like that must have some negative effect. I'm not sure what it is. Or if it is, but i thought ide bring it up and see what yall thought about it.
Idk, like i said, I'm just thinking out loud. Im new at all this so I'm just trying to get a better handle on how i can make what I'm doing better. ---------- "Trust Those Who Seek The Truth. Doubt Those Who Say They Have Found It."
"Does it matter if you tune both blow and draw plates with it while blowing. What i mean is....if i tune the draw reed as if it were a blow reed, would it have any negative effects? Because it seems easier to just keep using it. Especially to get the octaves beat free. "
They key is that your embouchure can affect the pitch. When tuning, it's probably best to use an embouchure that's as natural as possible. Using the FT on the draw plate wouldn't allow for that. Anyway, the draw reeds are on the outside so they are easy to tune with the reed plates assembled onto the comb.
Michelle: "Air entrainment? I'd never heard of it, but Wikipedia says it has something to do with air bubbles in concrete. Please explain what you mean. "
Back when I was a Respiratory Therapist, we used "Venturi Masks" to deliver a precise concentration of oxyygen to patients. These masks would use the Venturi (or Bernoulli) effect to entrain room air (21 per cent oxygent) at a precise ratio to end up with the desired concentration. For example, we would put a 35 per cent connector on the tip of an oxygen line (100 per cent O2) and run it at 8 liters per minute. The resulting flow to the patient would be about 45 liters per minute and 35 per cent oxygen.
As the reed swings back and forth, I believe air is entrained in different ways during the reed's journey. I'm sure the magnitude and direction of of these flow currents change dynamically.
Also back in the 90s, the state-of-the-art neonatal ventilator was made by Sechrist and use a Fluidic valve. A puff of gas would direct the flow of gas to either the patient or a relief valve. The timing of the puffs of air was set to the patient inspiration:expiration ratio and breath rate.
I digress, but it's amazing to me that two channels are wide open but the gas only flows down one of them because of the laws of fluidics. And you can flip between one or the other by directing a puff of gas perpendicularly to the stream of flow. Not sure about the application to harmonicas but when we bend notes, there are instances where one reed stands still and the air flow out the opposite slot. I'm sure the biggest influence is resonance but maybe the laws of fluidics "help out".
Andrew what i have been doing is flipping the draw plate around and over so that it sits in there like a blow plate accept the short reed to the left and longer to the right. The thing is, the harp is already apart to do the blow plate. And with it being by itself i know im not getting any bending energy what so ever from the blow reed set. So i blow into the FT to tune the draw reeds. Do u know what i mean? Maybe a dumb idea, but seems to work ok.
I also find it easier to have a relaxed embouchure ---------- "Trust Those Who Seek The Truth. Doubt Those Who Say They Have Found It."
There sure a a lot of folks principles in this little instrument, Hooke,Euler, Bernoulli, Newton, Reynolds, Helmholtz, and probably a lot of others I have left out.
I'm still waiting for someone to use two reeds riveted into the same hole to lower the pitch. I guess I'm going to have to go to Harbor Freight and get a tool to try it myself. I have this crazy theory that two thinner reeds would worry less than one thicker reed, but I've only tested the pitch altering aspects with a pluck test on some brass strips I had lying around.
Nate, your idea is similar to a leaf spring in a car. Multiple leaves make it more complaint than one thick leaf. You also get a lot of damping as the leaves slide past each other. You want this damping in an auto spring, but not in a harmonica reed.
If you double two thin beams the stiffness of the system doubles. If you double the thickness of a solid beam, the stiffness goes up 2^3 or 8 times.
I'm about a million miles from really knowing what I'm talking about, I've only been playing a year, so I'll just say what I've noticed in my own meagre experience.
Arcing on the marine band series is a relatively quick job and I get good results most times.
Arcing on suzuki is a little more of a fiddle and results vary.
Arcing on my sole 1847 classic is seemingly some kind of secret voodoo magic which I cannot figure out at all! Some reeds play well, some don't (2 blow is a nightmare), despite similar profiles across the board (and similar profiles to my other harps) .
I think learning how to play the harp very well is the most important place for a player to focus their attention. All else is just.....stuff... have a good day. Mark ---------- I'm out of the Biz for a while till I get over my burnout. You can try HarveyHarp or arzajac, or just look the page nacoran put together under Forum Search. .
Yes. But having a harp that plays well makes it that much easier for you to do so. I don't know why anyone would not want to have the instruments/equipment they spend so much time using in peak performing condition. ---------- "Trust Those Who Seek The Truth. Doubt Those Who Say They Have Found It."
Might make sense to buy some reedwork from me if you're interested in how it's done here. I have several very reasonable options available on my service menu.
I'm applying somewhere beyond 150,000 reeds worth of empirical testing and results, and was sighting slots ten years ago. Even so I'm very hesitant to publicly say "this is how it's done" because I'm finding it more elegantly complicated as I go.
I think some people on here need to back off with the expert attitude. As well as those who attribute some sort of master status to others who are frankly pretty low on the learning curve. On one hand it's disrespectful, and embarrassing on the other. I do enjoy reading the discussions and they make me think deeper. And I'm not picking on anyone. I'm just saying that whenever I think I about have it all figured out, something else reveals itself to me. It's all very fascinating and my work is constantly being rethought and refined. Like Dick Sjoberg said once, "every customizer has his own truths." ---------- www.spiersharmonicas.com
Joe, I would have you work on all of my harps if you were a bit closer. Unfortunately for me I'm in the UK and the postage back and forth would probably make it way out of my budget. However, I have promised myself that I'm going to get one of your harps one day.
Surely would be a learning experience to crack into one of your harps. Ive certainly thought about buying one and reverse engineering it. Lol. But they are a bit out of my range right now. It will happen at some point. Definitely on my wish list
Joe i agree with your other comments as well. And I'll leave it at that.
---------- "Trust Those Who Seek The Truth. Doubt Those Who Say They Have Found It."
I have the greatest respect for technicians. It is a skill that is not unlike musicianship. Some folks think there are trade secrets and shortcuts, and there may be, but without the hours on end of experience, the "secret" is useless.
I am interested in understanding the harp a bit better analytically. I have found that beam equations or Finite Element Analysis (FEA) do a very good job of modeling the fundamental frequency a reed will vibrate at and predicting where it will break, but this only begins to hint at the complexities of the harp involving air flow and the interaction with the other read in the chamber. There is an analysis method called computational fluid dynamics (CFD), which is kind of like FEA for airflow, which could help to understand how the air flows through the harp. From Andrew's description of fluidics, it seems like the relationship between fluidics and CFD is similar to the relationship of the beam equations and FEA.
You would need a CFD program that could interact with and FEA program as the air pressure moved the reed and the reed shape impacts the airflow. CFD is commonly used with thermal FEA to model air flow over a circuit board and how it impacts heat buildup. Coupling CFD with structural FEA is not a common but not unheard of. I don not have any experience with CFD.
All analytical tools require a good grounding in empirical methods to validate the model. Small wrong assumptions can lead to big errors, so you need to have some way of making real world measurements on the system you have modeled if you are to have any hope of the model being accurate. I have learned things building models this way that I could not have learned by taking measurements.
I think Everything has its trade secrets. I'm an industrial electrician. I can explain to somebody how to do nearly anything in the field provided they are good with thier hands and somewhat smart.
Conversly You could teach someone for years and if they just arent good with that kinda thing, they aren't gonna get it as well.
So i don't think it takes more than a short time to get a good grasp on the concept. It just takes the trial and error time of years to figure out, without someone who has been thru it to teach you their findings and save you all the time they spent figuring it out the hard way.
I didn't mean any disrespect To anyone. Just everyone was new at one time.
Some people treat apprentices like shit and some take them under their wing. Is just the way it is.
Which kind are you? (Retorical not directed at anyone) ---------- "Trust Those Who Seek The Truth. Doubt Those Who Say They Have Found It."
I have a job on the bench at the moment, It's a service/repair job including a sp 20 that was hard to play. Needed a good clean up, some corrosion in a few slots and some burrs, and looked like a sticky drink had got among the reed side of one of the plates. While I was cleaning up the slots with a shim I noticed the root of the reeds were set pretty high, compared to where I normally put them, and where I've seen most custom harps have them. I've seen Kinya Pollard advocate for .002" but I've not found any other custom harps set up that high. That's about where these were though. Having cleaned the slots and fixed s couple alignment things I set the gaps at the free end and reassembled to test all working. To my surprise the harp played very well. Bb harp, both 10 blow bends easily obtained tongue blocked, in addition to all other bends. This is without any special attention to reed shape beyond standard gapping...I expected I was gonna reset the so called 'zero point' before looking more closely at reed shape, but harp plays so well as is, I'll assess it again tomorrow before I decide. Sometimes a sleep in between testing can make a difference to my perception but at the moment seems like ain't broke don't fix. Anyway, I just thought it was interesting. I've been setting those reeds at less than .001" for so long I thought it was the way things had to be, but at the moment I'm very impressed with the performance of the high end on this with the higher setting.
Last Edited by SuperBee on Jan 21, 2016 4:48 AM
I am low on the empirical pole and have only vague and distant memories of the theoretical pole. I can still calculate how long it would take me to hit the ground from the top of either one (in a vacuum, of course).
With that in mind, I've read of different approaches which deal with the gap that SB and others have mentioned in this thread. I've been looking forward to the splain for this with no satisfaction for some time.
So I made one up. A Suzuki reed and plate are a spot-welded assembly of dissimilar materials. Pressure is applied, heat is generated and the reed tends to somewhat 'melt' or slide downward into the slot.
On the other hand, Hohner applies pressure, without the bonding heat, just at the point where the reed pad is weakest (ie the rivet hole to edge distance). There is less distortion of the plate and the reed tends to form a 'V' shape away from the slot.
@Superbee, I stopped playing customer's harps before I cleaned them quite some time ago, and as a result, sometimes they are fixed before I get a chance to do the work LOL
Winslow Yerxa recommends disassembling and reassembling the harp when you first get it. I would suggest that this process, combined with a superficial cleaning, would solve most problems.
Reed arcing, not so much.
My experience with the gap at the rivet pad is that, as long as it's fairly tight, there is some latitude. Of course, I'm not Joe Spiers! But the goal is surely to have the reed free to vibrate, and the reed and reed slot as airtight as possible, but with an opening near the tip so that air can cause the reed to vibrate.
Last Edited by Gnarly on Jan 21, 2016 8:11 AM
Killa I'm certainly the mentoring type. Just about any serious tech will confirm that. Some of the ideas discussed on here and elsewhere originally came from me caring and taking the time to help others understand. But when the conversation dies and people move on, the context gets buried. ---------- www.spiersharmonicas.com
"You would need a CFD program that could interact with and FEA program as the air pressure moved the reed and the reed shape impacts the airflow. CFD is commonly used with thermal FEA to model air flow over a circuit board and how it impacts heat buildup. Coupling CFD with structural FEA is not a common but not unheard of. I don not have any experience with CFD. "
It sounds like you are saying that although there are many dynamic process happening at the same time, the number of things which need to be considered in this model are finite. It sounds encouraging!
In addition to modeling the properties of the reed and the properties of air flow, I think resonance would be a third point of interest in making this model. Empirically, resonance can affect just about every note we play.
In one of Adam's early videos aimed at the beginner, he focuses on getting a good sound from the 2 draw. Proper embouchure is the difference between sounding like a quacking duck or making a fat sound. I think as we adjust the embouchure, we are adjusting the resonance to match the note, in this case, the tonic of the blues scale, the 2 draw.
But to encompass resonance, the model would have to take into account a lot more stuff, like the shape of the covers and the tissues of the vocal tract! That's getting further away from looking at a single reed swinging through a slot...
" And with it being by itself i know im not getting any bending energy what so ever from the blow reed set. So i blow into the FT to tune the draw reeds. Do u know what i mean?"
You certainly can apply bending energy to a single reed!
And in the example where you blow into a French Tuner on the draw plate, your embouchure is completely different than when you play a draw note. On blow notes, your cheeks puff out and on draw notes, your cheeks suck in.
Some folks always tend to bend the 2 draw down, no matter how they are playing. So they prefer to tune their 2 draw a little sharp. I think you would have trouble dialing in where you want your 2 draw unless you were using your natural embouchure (as a draw note).
Sure, you can get the reed to make a sound but I can't promise it will be at the pitch you want it to be when all is said and done.
This is an amazingly esoteric thread getting into detailed analysis of harp building, modification, and optimization. It is cool that this kind of discussion is available here. I am going to review this thread from time to time as I work on my harps. I enjoyed Richard's workshops at Harmonica Collective addressing some of these issues.
To those who are in the early stages and just beginning to play, I would suggest that you work on your playing more than working on your harps. Just my opinion...
When you are able to play well enough to approach the limits of your instrument and you have the technique and breath control, then you should learn how to modify your harps to this extent to extend your playing. In the meantime, learning how to set gaps on your reeds should be sufficient.
Rather than jumping into modifications I would suggest that you buy a customized/optimized harp from someone who knows what they are doing, and see what it is all about. For many beginners, a harp modified to this extent would hinder learning how to play. ----------
Andrew ... i know you can put bending energy on the single reed, but i was refering to the blow reed in the same hole slightly effecting the tuner reading.
I check it again when i get it on the harp. This is just to be quick and get in the ball park. Then the next day i take it apart and do both plates again because it's surely changed.
Then put it back together and fine tune the beats out. I always tune my 2 draw high, because it tends to drop as volume increases. All the lower holes 123 for that matter, but 2 most of all. When using the french tuner my cheeks don't puff as i try to just breathe, not blow, with a natural relaxed mouth, jaw, throat feel. I know what your saying about embouchure effecting it, but i think it's minimal and i fine tune it afterwards and after switching back to draw there doesnt seem to be any changes. Other that the drop at higher volume. ---------- "Trust Those Who Seek The Truth. Doubt Those Who Say They Have Found It."
I was told by a model airplane guy that air doesn't behave the same way, or it might have been follow all the same rules, with miniature parts. Or something like that. Any comment about that?
A problem with trying to mathematically solve how to optimize reed shaping is the variables involved. Embossed or not? What angle? How much overhang? Resulting affect on the flow window? And air speed etc? If not embossed then how much side tolerance? Material hardness tolerances, and resulting on-the-fly adjustments by the reed maker (art in itself) to achieve target pitch? As well as the spring rate and balance that sticks you with? Reeds aren't all exactly the same, even of the same slotsize-pitch-model-alloy. Precision of reed indexing relative to the slot? Deflecting of plates on assembly due to non-flatness of the frame (each plate, plus comb)?When you flatten a draw plate, what about the reed side and the arc and/or unevenness that's still there? These are all areas that I try to manage with every harp I build. Maybe I take it all too seriously, while the answer is as simple as a magic comb and good gapping. I firmly believe there's a master code so to speak, to make a reed do everything well, but it can't be boiled down to a single holy grail parameter. It's a general recipe that depends on the ability to manage a lot of ingredients with tools and techniques. Richard's process puts you in the ballpark, but all the variables is why it may need to be tweaked from there. That's a boatload more information than players had 5 years ago, and more than enough to get your harps playing very well. Maybe even as good as it gets, with time and patience. Trade secrets beyond that more or less just facilitate being able to consistently knock it out of the ballpark in less time, leaving more time for tuning, all so it can work as a way to make a living. ---------- www.spiersharmonicas.com
@harpwrench, what the model airplane guy was talking about was probably similitude. If you just took a full size plane and scaled it down to say, 1/10 scale, it will probably not fly well. If you understand similitude, you can make calculations to make adjustments to the size of the control surfaces so that the model will behave more similarly to the full size plane.
If you go even smaller, say to insect size, forces that were previously insignificant, like static attraction, come in to play and can no longer be ignored. A good example of this is the classic ball drop experiment. If you drop a bowling ball and a baseball off a tower at the same time, the will hit the ground at the same time. If you use a baseball and a ping pong ball you will get a different result because the air resistance that was insignificant with the larger balls is critical to the ping pong ball.
You description of the many pitfalls of creating a mathematical model of something as complex as a harmonica is spot on. One of the challenging things about making a good mathematical model is determining which of the variables are important and which can be ignored with little effect on the results. Then there are the critical variables that haven't even been thought of yet!
Last Edited by STME58 on Jan 21, 2016 11:49 AM
Andrew, you are correct about resonance being important, but resonance is not a separate issue. FEA can easily find mechanical resonance. Here is an analysis I did a while ago of a reed I took out of a harp and measured. Here are the first few resonant modes and frequencies that the FEA found Most of the time only the first mode is important. I believe that when you have a squealing reed, you are probably exciting one of the other modes. You could verify this by measuring the frequency of the squeal and comparing it to the frequency of the mode. IN this case, mode 3 at 10935 Hz, would only be heard by young folks with good high range hearing. Mode 2 at 6715Hz would be quite annoying to most of us.
I have not worked with it, but I assume that CFD would find Helmholtz resonance just as easily as FEA finds mechanical resonances. That would mean modeling the oral cavity though.
Last Edited by STME58 on Jan 21, 2016 11:48 AM
Hi Gnarly, I agree. Quite often I clean them and then have to ask the client what it was they wanted me to do. When I first took work in And encountered this, it confused me. I thought I was supposed to know what was wrong and spent lots of time trying to improve harps that were already quite good. Now I just ask.
These harps are a bit like that. Client gave me 26 harps and wants me to service 6 specific harps and return. He couldn't tell me what was wrong with them. It's been wrong too long.
After cleaning, I found a Manji that seemed to have a 6 draw reed touching the slot, and a 2 blow reed in a sp20 which was doing similar. Apart from that the only obvious problems I can find are gaps and tuning. Looking closer, I find some small alignment issues and some less than fully clean slots. Not everything will clean off with water and a brush. Manji was unusual. Alignment problem with a welded reed? That didn't seem likely to have been a situation that developed with use. Investigation revealed Non-reed side of slot appeared to have had something dragged along one edge, like a half-hearted abandoned embossing attempt. (Not sure why one would attempt to emboss a Manji. They're pretty tight to begin with.) The end of the reed was just tickling the resultant burr. Anyway, I get a kick out of making things work, or work better. So that's a win for me. Doesn't take much...
“Back when I was a Respiratory Therapist, we used "Venturi Masks" to deliver a precise concentration of oxyygen to patients... As the reed swings back and forth, I believe air is entrained in different ways during the reed's journey. I'm sure the magnitude and direction of of these flow currents change dynamically.”
I'd never heard of air entrainment. Learn something every day if you keep your eyes, ears and mind open. Thanks, Andrew.
When I took Physical Acoustics in grad school, we spoke in terms of the compaction and rarification of air molecules. Sound waves are rhythmic regions of alternating compaction and rarification of air molecules traveling through space. In other words, waves of varying air pressure. So, that's how I view the dynamics of air traveling through a reed vibrating inside a reed slot. The chopping effect of the reed alternately stops and then permits air flow, creating alternating waves of air pressure that travel out the cover plate-comb aperture.
Steve, your list of scientific dignitaries number among my biggest heroes, Especially Euler and Newton. Years ago PBS had a series called,”The Ascent of Man,” all about the great scientists and mathematicians. It's on Youtube now. You really should check it out!
“I think some people on here need to back off with the expert attitude. As well as those who attribute some sort of master status to others who are frankly pretty low on the learning curve. On one hand it's disrespectful, and embarrassing on the other. I do enjoy reading the discussions and they make me think deeper. And I'm not picking on anyone. I'm just saying that whenever I think I about have it all figured out, something else reveals itself to me. It's all very fascinating and my work is constantly being rethought and refined. Like Dick Sjoberg said once, 'every customizer has his own truths.'"
Joe, I take your point. But there are few people on earth who have tweaked 150,000 reeds. The rest of us who want to understand how harmonicas work, lacking that level of experience, have to rely on their own meager reed tweaking experience and also bring to bear other aspect of their life's experience. I personally want to better understand two things. First, how harmonicas work from a scientific and engineering perspective, because that is who I am. I've spent my life trying to figure stuff out and educated myself to be better able to do that. The other is to be able to improve the performance of my own harmonicas.
I started my own quest to be able to work on m own harmonicas out of necessity 15 years ago. There wasn't an internet or a Joe Spiers out there available to provide custom harmonicas non-dignitary workingman-level players. I accumulated every resource I could lay my hands on to do this. I'm proud of my ability to greatly improve and maintain my own harmonicas. I make no claim to be at the level of a Joe Spiers or Brendan Power but I am able to keep my harps in fine enough playing condition to satisfy my needs.
Would I prefer to have a full set of Filisko or Spiers customs? You bet! But I am retired, living on fixed income and that just isn't a possibility. I am a person who seeks to have a better technical understanding but isn't able to afford your customs. So I strive to satisfy my scientific curiosity over the tantalizing problem of the physics of harmonicas at the same time as trying to elevate my own comparatively meager abilities to improve my own instruments. Some of us need to climb that mountain ourselves.
If you find that embarrassing or disrespectful, I am both sorry and baffled.
SuperBee, I have high respect for Kinya Pollard. Do you happen to remember the source when he advocates .002 clearance at the root?
Andrew, since the wavelength of sound produce by a harmonica is measured in feet, I don't think there's enough room inside the harp even for ¼, 1/8, 1/16 wave resonance. But I concur completely about the need to consider the player's head, mouth, throat and lung resonance.
“I was told by a model airplane guy that air doesn't behave the same way, or it might have been follow all the same rules, with miniature parts. Or something like that. Any comment about that?”
Here's my take. The effective area of the reed/reed slot gap is so small that it has a profound effect on the velocities of he air flowing through it. As a result, the Reynolds Number of the system is much higher than were it to be on a larger scale. High Reynolds numbers mean turbulent rather than laminar flow and those two flow conditions behave very differently.
As to the complexities of trying to optimize reed shape mathematically, we are in agreement. However, as Steve and I have outlined above, it is common engineering practice to use computer modeling to get in the ballpark and then to take over empirically from there. That saves loads of time and money and might avoid having to tweak 150,000 reeds to arrive at a good understanding of the solution to the problem. And Steve, with his access to FEA software and that high-speed camera has the capacity to conduct such empirical experiments.
And I couldn't agree more that we are arguing 2nd or 3rd order effects here. The old 90/10 rule. If a player follows your gapping series on Youtube, they're 90% of the way there with 90% of the work yet to go in achieving the other 10%.
Steve, those images are very exciting. Love 'em!
But I think you and Andrew are talking two different kinds of resonance. I think, and Andrew, correct me if I'm wrong, that he's talking about acoustic resonance not the vibrational modes of the reed itself.
This has turned into a terrific thread owing to the varied perspectives of all the active participants. It's great to hear scientific and engineering mixed in with comments from technicians with a wide range of experience from beginner to world-class.
I'm indebted to all of you and want to express my genuine appreciation for past and future contributions.
Thanks!
Michelle
---------- SilverWing Leather - Custom leather creations for musicians and other eccentrics.
Gnarly and SuperBee, cleaning can also create tuning issues. If someone re-tuned corroded reeds, removing the gunk will sharpen them. If they were close before, they'll be off after a good cleaning.
I use Barkeeper's Friend with warm water and a toothbrush as recommended some years ago by Harpwench hisse'f.
I wonder what y'all's current reed plate cleaning wisdom is?
Thanks,
Michelle
---------- SilverWing Leather - Custom leather creations for musicians and other eccentrics.
"But I think you and Andrew are talking two different kinds of resonance. I think, and Andrew, correct me if I'm wrong, that he's talking about acoustic resonance not the vibrational modes of the reed itself."
I was talking about both types of resonance. I just don't have easy access to a CFD program to show the modes of air resonance in the system, of which I suspect the most important is the Helmholtz resonance of the oral cavity reed chamber system.
I can't prove it, but I suspect that when you match the Helmholtz resonance with the reeds mechanical resonance, you will get a large shift in tone and volume. Allowing the harp to be louder with low breath force.
Last Edited by STME58 on Jan 21, 2016 1:59 PM
Hi Michelle. I believe Kinya says that in one of his tech videos on Dave Barrett's Bluesharmonica dot com site. He has a series of videos in which he sets up a harmonica, discussing quite methodically the issues, tools and techniques. Of course, it's only one approach but I think it's good to see a range of approaches. I appreciate what Joe said about workshop practices which sometimes relate more to efficiency than the end result as such. That is, you can get there either way, but 'this way' is quicker. Kinya demonstrated a method for 'setting the zero point' in one of those videos, using a vice to do the entire plate in one go. I haven't tried it. I spent a little time with KP in his workshop one Sunday morning, thanks to his generosity and the miracle of modern communication technology. It was valuable I think. Re tuning, yes I agree. I'll have to tune all these harps anyway, so may as well start out clean-ish. I've heard of bar keepers friend, but it's not a product I've seen here. But Google is a friend so I'll ask
Joe I agree that there probably will never be a boiled down formula. You just have to do it. However, as you said, with knowledge comes ability to not only know what direction to go to fix an issue your having, but also the ability to get it dialed in faster. I'll take all the help i can get.
STME .... those FEA images are very interesting.
Add for the rest of it .... All i can hear is Charlie Browns Teacher ..... WOMP WOMP WOMP WOMP ..... WOMP.
But Hope yall really figure somethin out with all that College Talk. Lol. Good Luck. ---------- "Trust Those Who Seek The Truth. Doubt Those Who Say They Have Found It."
Michelle if you go to my site and select "service menu." For relatively little money invested you can have 20 reeds to examine and roll your own from the pattern. I don't obfuscate anything and there's no black magic. I'm not trying to sell you a set of harps or even one harp, in fact I'm not trying to sell you the service just letting you know it's available. As far as respect. If what I'm talking about needs further explanation then I give up, I'm not going to waste energy on it. It's not that big of a problem just annoying. Good chance I'm just turning into the old man that hollers at kids to get the hell off his lawn. ---------- www.spiersharmonicas.com
I know what your saying Joe. Dont worry. Also Im much younger than you and Ive BEEN the guy yelling at the kids to get off the lawn. Lil' Bastards.
F#*@ 'Em If They Can't Take A Joke. ---------- "Trust Those Who Seek The Truth. Doubt Those Who Say They Have Found It."
Last Edited by Killa_Hertz on Jan 21, 2016 4:37 PM
---------- "Yes. But having a harp that plays well makes it that much easier for you to do so."
Killa Hertz, Hmmm, well, of course, buuuuut a new Hohner is just fine. If someone tells you otherwise they have an ulterior motive. Customs are for cats like Boris Plotnikov or other high level pros.
According to Kim Fields, 'the average thickness of a harmonica reed is 1 200th of an inch.'
I did not know this bit of 'stuff' when I learned Little Walters 'Roller Coaster' It did not help me then and doesn't help me now. I was 16 when I learned it and am 59 now. I still play the livin' hell out of it on most any old harp.
I am fair at setting up a harp. I'm not a customizer and never claimed to be. I'm a fixer if it's broken.
I've had no complaints from my fixes as the harps always play better after they are returned. Besides... Almost all the best music in the world was played on stock harps. I tweak all my harps but hell, an MBD or Crossover or a GM or SP/20 out of the box is cool w/ me. This kind of thing is great for techs but I've seen too many cats waste time and money trying to fix perfectly fine harps. One guy lost a couple of grand when Michalek died. He went back to playing sax. Another cat went back to playing slide and dobro after trying to learn how to be a customizer. It goes on and on etc. etc. Go figure.
If i see money about to be thrown away on information and gear i say, "Hey! Wait a minute! The idea is to play the thing. And get off the lawn! It's embarressing me. :-) See yah..MP PS. Get ready. Some fine harps are coming out soon from a very trusted source. ---------- I'm out of the Biz for a while till I get over my burnout. You can try HarveyHarp or arzajac, or just look the page nacoran put together under Forum Search. .
Last Edited by MP on Jan 21, 2016 8:17 PM
MP your full of it. Half the hohnerz i get barely play. I'm not talking about buying customs. I'm taking about doing it yourself. And people like you, who claim to play great harp without as much as opening the covers, drive new players who don't know any better crazy as they are trying techniques that a OOTB marine band just won't do.
I had the hardest time with 3 hole bends until i learned how to set the reeds up right.
Your right to say not to waste all of your time customizing, as there is no time left for playing. But if you want to play harp well you better be atleast mediocre at seeing up a harp. Taking anything to the extreme is no good, but that's not what we re taking about here is it?
The only time i even hinted at buying a harp was to reverse engineer it and learn how one does it on that level. ---------- "Trust Those Who Seek The Truth. Doubt Those Who Say They Have Found It."
Last Edited by Killa_Hertz on Jan 21, 2016 9:18 PM
KH, MP is anything but FOS. I have no doubt he can play great harp without opening the covers. He's being doing it longer than you've been alive. And he knows more about the insides than most people.
I will second that MP knows what he is talking about. I have many harps that I have not opened the covers on. I find that as my playing gets better I can do much more with the box stock harps than I could when I first got them.Some harps are harder to get overblows on but I am getting to the point where I can get them on most harps. I will admit that it is easier on a well set up one, but I have progressed enough that it is easy for me to believe that a for very proficient player, there are no "techniques that a OOTB marine band just won't do. " I am not saying that equipment doesn't matter. Even though a very good player can get amazing sounds out of stock equipment, many will prefer top notch equipment because it is just easier and more fun to play.
I am reminded of the time I went to a slalom race in Long Beach and the promoters had invited the top 5 SCCA drivers to perform an exhibition in stock Toyotas. They turned in faster times than most of the drivers using expensive and well prepared Porsches and Ferraris.
Last Edited by STME58 on Jan 21, 2016 9:23 PM
I got a new marine band in C sittin on my counter right now. If you can make the 2draw or 3 draw reeds even sound ill bow Down to you. Its a bad one. All im sayin is its not all that hard to teach people the bare min. To get them goin in the right direction without scaring them into Thinkin its impossible to tweak a harp without being an engineer.
Yall r crazy.
Have a meeting about it. Imma go do it.
Peace. ---------- "Trust Those Who Seek The Truth. Doubt Those Who Say They Have Found It."
I have no doubt that setups vary from harp to harp OOTB. They are more consistent now they they were a few years ago, but they still vary quite a bit even on the better harps. Learning to set gaps on reeds is something that most harp players should probably know. I still contend that a very skilled player can get good sounds out of a poorly set up harp. Of course if the harp has the reed jammed against the slot or if the reed is missing, no one is going to get that to sound!
STME ... I can see it from the back side. The 2n3 draw reeds are about 1/8" up off the plate.
MP. I over reacted a bit bro. . My bad
I'm just tired off all the sagely advice that's sooo contextual. I think what u ment was that BUYING a custom harp is unecessary. But people get the wrong idea and think that the people they hear all have stock harps. Which just isn't true. Everyone does SOMETHING to their harp. OOTB harps do play, but not how you want them to.
I just think light setup should be taught as something easy that you just do. Because it is. Instead i find most new players to be mystified by how someone can do simple reed work. That's my level of"customizing" anyways. I'm not taking about the pro level. Just gapping and light arching or reed shaping. And not everyone is as hands on, but i believe everyone is capable of these things to some extent.
Or on the flip side. New players trying things like embossing because it's unclear what he SHOULD do. Learn the to play the 2 hole draw. I'm not picking on anyone. Just making a point
I'm not saying any of these clarity issues are anyone's fault in perticular, but we should be doing our best to make it clear (for anyone who is serious about harp) how to make a harp play well. If only in its simplest form. Because this would only progress the instrument, as people may not give up as easy because they are frustrated. I mean all you need to make a harp acceptable to play is a piece of paper and a toothpick.
Anyways my rant is over. I know this thread was on a more pro level discussion, but ..... o well.
---------- "Trust Those Who Seek The Truth. Doubt Those Who Say They Have Found It."
Last Edited by Killa_Hertz on Jan 22, 2016 4:26 AM
Addressing the OP i.e. what is reed arcing and can some theory help tell us. I don't think modelling is going to shed much light, at least not without a lot of work. I've worked in mathematical modelling - and I don't mean typing parameters into an off-the-shelf FE/CFD package but doing the physics and numerical solvers from the ground up. On the whole you don't make a maths model of the system and expect it to bring understanding and predictions just like that. More typically you are looking to understand particular observed features, or to explore what tweaks to a system might do.
If the experience of the customisers said that one reed-profile did this, and another one did that, you might use that to build and verify a model. If you can reproduce those results, you might start to believe your model.
As discussed there are many possible physical parameters and effects that may be at play - you can't model them all, and you probably don't have data for many of them. If you were lucky, you might uncover some dominant factor and do something with that.
And really, trying to understand how the reed vibrates using common sense and applying this or that physics effect - you might get lucky but it's probably wrong. Those physics effects are typically simplifications that apply in specific circumstances - and the expertise is in working out what regime applies. One of the aims of simple physics experiments is to put you squarely in the right regime: ignore friction, assume quasi-equilibrium, all that stuff.
What I'd be looking for to start with is some strong consensus from the experienced customisers about the dominant effects. But instead what I'm reading is that there are many small effects that are all important..
And oh yes, your model has to explain odd effects like being able to overblow using a straw, held at some distance from the hole. Explain that with your Helmholtz resonance :) Got to go, some kids on the lawn.
Last Edited by MindTheGap on Jan 22, 2016 5:26 AM
@MindTheGap, I think we are in agreement about the likelihood of finding anything significant and accurate from the results of a model without putting a tremendous amount of work into the model. When you ask a computer an overly broad question, you usually get an answer like 42, with an admonition that you have not asked the right question!
Much of the work required to get a reasonable model would be in verifying the model with actual measurements, without this a model is just not trustworthy. I think this is the point you were making. I have found it to be the case frequently that just going through the process of setting up a model, determining what you know, defining the constraints, detailing exactly what it is you are looking for, etc. will get you to an acceptable solution before you even set up and run the model. Sometimes the insights you get from working on one model are helpful on an unrelated model. Even if I make no progress on understanding how a harmonica works, what I learn may be useful to another problem.
This discussion reminds me of many I had years ago on the topic of building spoked bicycle wheels. There were many different ideas on how to do it best, thin spokes thick, spokes, grease the threads, Loctite the threads etc. Jobst Brant did a lot of research and math on the subject and published “The Bicycle Wheel” . This book really helped my understanding of the topic. Some of the concepts I learned in the book helped me in building a model of a belt driven scan carriage and understanding how it was susceptible to vibration and how to make it less susceptible. Especially controversial, and helpful to me, was Mr. Brandt’s “push a rope” description, in which he claimed that a spoked wheel is best understood as standing on the lower spokes rather than hanging from the upper ones as the stress in the spokes changes most significantly as they move to the bottom of the wheel. This directly related to the section of belt that has the most impact on the control of a scan carriage. The model I built in this case was as you described, built up from the basic principles of physics. The tool I used to code it was Matlab Simulink.
I have been using FEA sporadically for 30 years. I am no expert but I have seen a lot of changes in the user interface and in the connection with CAD models. 30 years ago you entered tables of coordinates of node points into NASTRAN. Now, the NASTRAN code is still there but there are interfaces that allow you to select constraints and loads on a CAD model and it does the meshing and generates the tables of coordinates for NASTRAN. What has not changed is that if you do not select appropriate constraints, the results are still garbage. What I can do now is make some really cool graphics that may convince someone not familiar with how FEA works that there is more solid science behind the solution than is really the case. Most of the older folks around here will want to see what kind of verification I have done of a model before they trust it at all. I have not used CFD at all but from what I read, it is not as advanced as FEA and the interaction between the two has only been recently explored. Most of the interactions done between FEA and CFD seem to be thermal, not mechanical.
I have gotten some reasonable correlation between FEA and reality on the pitch a reed will sound at and where the high stress areas are as evidenced by where reeds tend to break. These are done without taking any air effects into account and are a far cry from exploring how a harmonica actually works. I have a project on the back burner to add scratches to the reed in FEA to see how it “tunes” the reed and if the amount of material removal needed to shift the pitch squares with reality.
Your point about the straw method of generating an overblow is a good one. Either there is more than one way to create an overblow, or the mechanism is not Helmholtz resonance. I have noticed that on many harps, there is more than one mouth configuration I can use that will produce an overblow. I had assumed that they were different ways of creating the same oral cavity volume. This article by Robert Johnston seems to indicate there may be Helmholtz resonance. This article by Bahnson, Antaki and Beery also indicates Helmholtz may be a factor. Both of these place an adjustable volume just ahead of the harmonica and look at the variation in pitch as the volume varies.
Last Edited by STME58 on Jan 22, 2016 4:07 PM
So at what point do you have the perfect reed shape for each reed? You will never be able to measure it accurately if there are many variables that can change.
What is the basis of the perfect reed shape? Does it change when embossing? does reed slot tolerance affect the shape? If you play hard does it effect the shape or just gap? How does it effect tone?
Is there one best reed shape to get the job done? seems I read lots of customisers can shape reeds differently and seem to be happy with their results.
Is it possible there could be multiple reed shapes equally giving close to the same results?
It's more complicated than an ideal static shape because of the different modes and relationship to the slot. I've been working on and very recently seem to have pretty much nailed down one optimal dynamic pattern for how a reed should interact with the slot. And do everything better. With the exception of overblows/overdraws which can also work perfectly with the same pattern, but it depends on the qualities of the milled profile and properties of the reed.
I'm looking at and trying to control 8 different things as the reed closes, x 2 because I check the pattern from each side of the reed.
The other variables can interfere with the ability for all the components of my pattern to be met simultaneously. If any aren't met I can feel it in the behavior of the reed. On the 2-3 holes especially. And know where to recheck my work because I missed something. By the end of the day my eyes are tired. Whether you can feel it/hear it or not depends on the player. Some can pick out anything and I mean the slightest little thing, within a minute of playing it. Others don't care as long as it makes the right note.
When I said how many reeds I've worked on it wasn't to make myself out to be superman. I'm just a mechanic not a rock star customizer. The point was that everyone has access to a boatload of empirical testing, and I just charge for my time if you have something to work with. ---------- www.spiersharmonicas.com
Most of the time only the first mode is important. I believe that when you have a squealing reed, you are probably exciting one of the other modes. You could verify this by measuring the frequency of the squeal and comparing it to the frequency of the mode. IN this case, mode 3 at 10935 Hz, would only be heard by young folks with good high range hearing. Mode 2 at 6715Hz would be quite annoying to most of us.