Header Graphic
Dirty-South Blues Harp forum: wail on! > How far can you tune a reed
How far can you tune a reed
Login  |  Register
Page: 1

HarveyHarp
403 posts
Nov 28, 2012
8:02 AM
There has been discussion for years about how far you can tune a reed, up or down, and how to go about doing it. Well, last night, I tried an experiment.

I have replaced all my Low Tuned Big Rivers with Low Tuned Marine Bands, Optimized, of course, and I decided to make a Low C Big River out of a Low D Big River. I actually like the Low Big Rivers, because the reeds do not hit the cover plates, as the do in the Marine Bands, so you do not have to alter them.

Now, as you probably know, the two ways to do this are to add weight to the free end, such as Blue Tak or solder, or to remove brass from the rivet end. I chose to remove brass, which has the additional benefit of more responsive reeds. The amount of tuning necessary is Two Semitones, which is very achievable.

However, I had a fractured 10 draw, and I did not have a donor reed to put in it. So, I took a reed from a G and transplanted it to see if I could lower the pitch by the rivet end method by the necessary 7 semitones. Generally speaking the thought is that it would not work, but I tried it. Accidently, however, I transplanted the 10 Blow, instead, which would have to be lowered by 10 Semitones. No way, but, I tried it just for kicks.

I did it, and it works good. The Big Rivers I had were some of the mid 90s ones, with very thick, stiff reeds, and the big rivet heads, so I has a lot of brass to work with, and and the tool I used was a very soft, but aggressive bit that I put into my Dremel. I learned this Technique from Smoky Joe Leone, so you will have to ask him about what it is, since I never give away anyone else secrets.

The harp had been customized by me and it is now way more responsive than before, and I can actually bend all the notes that you can normally bend, including the 10 blow bend. The 10 draw is very thin, so I do not know if it eventually will cause me trouble, but if it does, then I will put in the reed I meant to put in originally, which will only have to be lowered by 7 semitones.

I plan on changing out the plastic, stock comb, with a Brass Reynolds Comb that I have had for years, it should be great.

----------
Photobucket

HarveyHarp
STME58
302 posts
Nov 28, 2012
8:24 AM
Thanks for sharing the results from your experimenting. I am interested in math and physics but it is important to make sure the theoretical matches what is seen in the real world.


Mathematicaly, the frequency of anything that has mass and a spring is

f=square root(k/m)

where k is the spring rate and m is the mass. A harmonica reed is both the spring and the mass. Any part of the reed that moves contributes to the mass. Any part of the reed that bends contributes to the spring rate.The part near the rivet works mostly as a spring. The part at the end works mostly as mass. Removing material from the tip mainly reduces the mass and the formula predicts the frequency will go up. Removing material from the root mainly lowers the spring rate and the formula predicts the frequency will go down.

You mentioned that reeds are more responsive if you remove material at the root than if you add mass to achieve the desired frequncy. This makes sense to me, as the lower mass reed will take less energy to get moving. Of course if you go too thin at the root, the reed gets weak. Some interesting mechanics of materials com into play here. As you make the reed thiner is can bend further without failing, however the thin reed takes less force to make it fail. There is an optimization to be had here that can be discovered from some combination of analytical and emperical work. I assume this kind of work is being done by the big name manuracturers R&D departments. I know a lot of good emperical work is done by customizers and optimizers. Do any of you customizer/optimizers here use an analytical component to your work?

I am not asking for secrets, just wondering if anyone uses mathematics to try to answer the question posed in HarvyHarp's post.

Last Edited by on Nov 28, 2012 8:26 AM
laurent2015
554 posts
Nov 28, 2012
8:42 AM
Just for kicks as well, I tried that kind of transplant, but with a reed that needed to be cut at the good lenght, and whose width had to be slightly reduced.
I picked up that reed from a C harp Hohner to replace a sharp A of a A Hering harp, and once in place, the (new) reed produced a kind of Ab.
OK, now this is a half step, and I can't understand why you speak about 7 or 10 semi-tones?
HarveyHarp
406 posts
Nov 28, 2012
9:12 AM
@STME58. I certainly do not use mathematics and physics when I work on harps, though I do have knowledge of such thing from my Engineering and Mechanical backgroud. I think that understanding mechanical principals are very important in Optimizing Harps.

Shoot, In my High School Physics classes I thought I was pretty good, but the female instructor gave me a B because she said that I did not ask enough questions. The next semester, she gave me a B because I asked too many questions. Go figure.
----------
Photobucket

HarveyHarp
Zadozica
229 posts
Nov 29, 2012
5:18 AM
Would it be possible to tune a reed from an A to a C or visa a versa?
HarveyHarp
411 posts
Nov 29, 2012
6:29 AM
C to an A is definitely possible, but a lot of work. As I said earlier, you would either have to add weight to the tip, or file the reed near the rivet. It would be 3 semitones, and that is quite a bit, but possible, if the reed os thick enough to begin with.

A to C is different. You have no choice but to file at the free end of the reed. Again it is 3 semitones, and on the high end of the harp, the reeds get pretty thin, and you could lose a lot of tone, if you have any tone at all.
----------
Photobucket

HarveyHarp
HarveyHarp
412 posts
Nov 29, 2012
6:35 AM
@ STME58. Now I understand why, when I go out and play music all night and have a few drinks too many that I have trouble walking. My mind forgets Physics. LOL.


----------
Photobucket

HarveyHarp
rogonzab
161 posts
Nov 29, 2012
6:27 AM
HarveyHarp,

A friend of mine needs a harp in B, but in Chile no one sales harmonicas in that Key.

Can I tune up a Bb to a B, or that is a tone killer as the A to C that you describe?
HarveyHarp
414 posts
Nov 29, 2012
6:46 AM
That should be no problem at all. It would also be a good time to figure out what tuning scheme that you want. For exasmple, if you wish to make a natural minor, which I absolutely love, then you would only have to file 15 reeds, instead of 20. Or if you want to chage a equal tuned harp to some form of Just Intonations, this would be a good time.

Watch out though, changing tuning on a harp is addictive once you figure out that it is not hard, and you might wind up being a harp tech.
----------
Photobucket

HarveyHarp
HarpNinja
2934 posts
Nov 29, 2012
8:12 AM
I would tune a C down to B rather than Bb to B.
----------
Mike
OOTB Harmonica Price List
VHT Special 6 Mods
Note Layout Comparisons
Quicksilver Custom Harmonicas (Updated 10/25/12)
HarpNinja
2935 posts
Nov 29, 2012
8:18 AM
STM58, please shoot me an email at harpninja67 AT gmail DOT com. Thanks!
----------
Mike
OOTB Harmonica Price List
VHT Special 6 Mods
Note Layout Comparisons
Quicksilver Custom Harmonicas (Updated 10/25/12)
rogonzab
163 posts
Nov 29, 2012
8:42 AM
HarpNinja,

But tuning down (removing material close to the rivet) dos ahve an impact on the life of the reed?

It is the area where the reeds tend to brake the one that you are making thiner.
HarveyHarp
418 posts
Nov 29, 2012
9:01 AM
it will actually make that situation better, because it removes those milling lines which act as breaking points
----------
Photobucket

HarveyHarp
Zadozica
230 posts
Nov 29, 2012
9:41 AM
So can you change a standard 10 hole diatonic on the draw reeds to the following notes:

D F A B D F A B D F

Some like the 1 draw don't change but others are a two note change. My goal is to have a 10 hole solo tuned harp.
STME58
309 posts
Nov 29, 2012
9:47 AM
"it will actually make that situation better, because it removes those milling lines which act as breaking points"

This is true if you do not replace the milling lines with file scratches or grinding marks. If you use the right tools and leave the surface smoother than it was you will have less "stress risers" and stronger part.

Thining the reed will also reduce the stress in the reed for a given deflection. I do not know what happens to the distance the reed deflects during playing with these modifications.
HarveyHarp
421 posts
Nov 30, 2012
8:48 AM
I am really loving that Low C Big River. I can overdraw all of the top 4 holes easily, and I am not a great overblower. It feels like that 10 draw is going to hold up. I have been beating on it, and it isn't breaking. I played it at a gig last night through my Super Sonny, and my Greg Huemann Ultimate 57 and wireless set up from across the room, and it sounded awesome. Even my band commented on it.

I don't think I could have done it with a newer MS, because of the thinner reeds, though I have not tried it. I wish I had more of them. HINT HINT
----------
Photobucket

HarveyHarp
HarveyHarp
422 posts
Nov 30, 2012
8:53 AM
@ Zadozica I imagine that it could be done, but it would be a lot of work. If you paid someone to do it, it would cost a lot more than buying one already set up that way, I would think. You might want to contact Greg Jones at 16:23 Custom Harmonicas. He is real good at doing things like that. He has enough reed inventory that he can do it by swapping reeds rather than retuning, I think.
----------
Photobucket

HarveyHarp
nacoran
6236 posts
Nov 30, 2012
1:23 PM
Zadozica, why not just buy a 12 hole solo tuned? You'll keep three full octaves that way.

Uh oh. Another crazy idea just popped into my head. If I had have the motivation compared to inspiration harmonicas would look like pianos by now. It all comes back to toothpicks...

----------
Nate
Facebook
Thread Organizer (A list of all sorts of useful threads)
Zadozica
231 posts
Nov 30, 2012
2:24 PM
Nat, that is my intention however this thread got me thinking of what I could do with an extra C harp I have laying around.
nacoran
6237 posts
Nov 30, 2012
5:46 PM
I've got 10 or so harps in various stages of disassembly on my computer desk in front of me. I should have figured that was the reason!

That reminds me, I need to order some blue tack. :)

----------
Nate
Facebook
Thread Organizer (A list of all sorts of useful threads)
laurent2015
555 posts
Dec 02, 2012
11:03 AM
Am I crazy, or someone could agree with me?

If you want to replace a reed (X) by whatever (Y) reed, possibly longer and wider than the replaced one, and if the replacing reed is perfectly adjusted to the reedplate slot, the pitch you'll get will never be far from the original one.
Sure that the replacing reed loses its original pitch.
That's why I don't understand Harvey's statement:"I transplanted the 10 Blow, instead, which would have to be lowered by 10 Semitones".
But...yes, it's not very important.
nacoran
6241 posts
Dec 02, 2012
12:15 PM
Laurent, that's a good point. It wouldn't have to be the case, since rigidity of the reed plays a factor (that's how the Turboslide changes pitch- the magnets change the rigidity of the reed), but I'd assume that in a mass produced harp if the reed fits well it's going to be close. Of course, there are long slot harps and short slot harps, and even the tiny Puck reeds still play in the normal C and G ranges.

You can change the pitch of a reed the same way you would a guitar too. After watching SBWII seeming to stick his fingers in the back of his harp I played with tooth picks in the back of my harp. By sliding the tooth pick down the length of the reed you can change the pitch. I understand the reason putting more or less weight on the end of a reed slows/speeds it. It has to to make inertia formulas work, but my physics is weaker when it comes to why removing brass from the rivet end works, and I wonder if it's not just because you made it thinner it bends easier. Anyway, the tooth picks (which are probably terrible for the reeds) let you shorten the length. I've never seen the inside of a Banson harp, but I wonder if it does something like this. It seems if you VERY carefully drilled holes through your cover you could put thin rods through that would essentially act like a finger on a fret board. I guess that off topic, but thinking about exactly what it is about reeds that makes them vibrate at a certain rate got me thinking about that.

----------
Nate
Facebook
Thread Organizer (A list of all sorts of useful threads)
HarveyHarp
425 posts
Dec 02, 2012
12:59 PM
@ Laurent. Take for example, a 10 blow on a G Marine Band. It is, of course tuned to G. It is appx 8.5 mm long, and 1.9mm wide. Now take a 10 Blow on a C Marine Band. The 10 blow is tuned to C, of course, but it is still 8.5mm long and 1.9mm wide. The reed profile is different between the two reeds, which is why they are tuned to different notes.

If you transplant the 10 blow tuned to C into the G harmonica, it will fit just fine, but you will have to lower the pitch 5 semitones to get it to be a G. If you reversed the operation and install the 10 Blow G into the C harps, then you would have to raise that G to C, which is also 5 semitones. A difference of 5 semitones is not ever close.


----------
Photobucket

HarveyHarp
laurent2015
556 posts
Dec 02, 2012
5:58 PM
Yes, that's obvious!

I never compared reedplates between a C harp and a G harp, but can I deduce from your explanation that they might be the same,(as for slots) and then, that the combs are the same as well?
After your successful transplant, did you really get a G pitch on your C harp?
And, if the profile of a reed makes the pitch (I thought it was the length, width and thickness) why not
change the reed's profile, instead of working on the material?

@ Nate: I know the future name of your new harp, using that new technology: hedgehog!
No, it's a joooooke, but what you describe generates other questions, I think.
arzajac
905 posts
Dec 02, 2012
6:20 PM
Laurent - On Hohner harps, Dd and higher harps use shorter slots and their combs have shorter chambers. (Most aftermarket combs only come in the long size.)

Just as an example of the different slot lengths, the 4 blow on a D Marine Band is the exact same reed as a 6 blow on a G...

As for profile: there is profile and there is profile. Reeds are not smooth on both sides. The underside is smooth and the top side has some material cut away - you see mill marks because of this. More material is cut away from the last third near the rivet end. If you look at the typical reed from the side, some metal is scooped out. Where the scoop is at it's deepest is where the reed is thinnest and that's where it usually fractures. So looking at the reed from the side and pushing the reed flat against a surface, you can see its physical profile.

But "profile" can also mean the shape the reed has because it's been bend. When "profiling" a reed as in changing it's arc, you are bending the metal and taking into account the shape of the underside (flat) as well as the top (scooped) to get your desired effect. So you have to take into account the reed's physical profile (appearance from the side) when changing it's shape profile (curve or arc).

And changing a reed's curve or even gap can affect tuning, but only by a few cents. Just enough to make tuning it perfectly a pain.

I hope this helps ahd I didn't make things more confusing.
----------


laurent2015
557 posts
Dec 02, 2012
6:32 PM
It just means that a diatonic harmonica is very far from a toy, let's say: even rather complex.
Do you think that, adding weight on a reed changes the tune BECAUSE you change the profile or because you add material?
arzajac
906 posts
Dec 02, 2012
6:47 PM
Adding material to the tip doesn't change the profile ( in both senses of the word - either the physical shape or the bend in the metal). Adding material to the tip will cause it to swing slower and lower the frequency. Removing material from the base will cause it to swing more rapidly and raise the pitch.

----------


Last Edited by on Dec 02, 2012 6:48 PM
STME58
311 posts
Dec 02, 2012
10:11 PM
@arzajac, your stament about removing and adding material reminds me of the gag "heads I win, tails you loose". I don't think you typed what you intended to. ;-)
HarveyHarp
426 posts
Dec 02, 2012
10:42 PM
@Arzajac. Not true. Both adding weight to the tip, and removing metal from the base, both lower the pitch.
----------
Photobucket

HarveyHarp
arzajac
907 posts
Dec 03, 2012
3:03 AM
Ha! Ha! Just checking to see if you were paying attention...

Here I go again:

Adding material to the tip will cause it to swing slower and lower the frequency as will removing material from the base. Removing material from the tip will cause it to swing more rapidly and raise the pitch. You cannot add material to the base to make it swing more rapidly and raise the pitch.

It's a good thing these laws of physics never change... Otherwise I'd have a hard time keeping track....
----------


laurent2015
558 posts
Dec 03, 2012
9:14 AM
Thanks for the precisions, Arzajac.


Post a Message



(8192 Characters Left)


Modern Blues Harmonica supports

§The Jazz Foundation of America

and

§The Innocence Project

 

 

 

ADAM GUSSOW is an official endorser for HOHNER HARMONICAS