Page 1 of 2

Double stack Reed plates

Posted: Sat Jul 27, 2019 4:56 pm
by dodtsair
I wanted to see if it was mechanically possible to move the bottom reed plate on top of the top Reed plate and close off the comb on the bottom. I want to know if two reeds are stacked like this and activating in different directions will the harmonica still work. Will it still bend, will the bending be more responsive since the reeds are near each other and may be more likely to resonate like a sound board

I do not have the tools or the skill to experiment with this

Re: Double stack Reed plates

Posted: Sun Jul 28, 2019 8:41 pm
by EdvinW
It is certainly possible, but I don't know if it has any advantages over the normal configuration.

I've tried this but only in passing and never very seriously, just to verify that I get a sound. I have heard a rattling which I suspect is caused by bad alignment, but It could be due to the reeds actually touching. It takes some work to get one plate to lie flat against the other, at least when reeds are riveted. You would probably need to file or sand the rivet bumps flat if you were to try this seriously.

I would also be very interested to hear from anyone with more experience with this than me!

If this works it could be a hack to build an x-reed harp from normal diatonic parts :o :geek:

Re: Double stack Reed plates

Posted: Tue Jul 30, 2019 12:41 pm
by Brendan
It couldn't work with standard reedplates. Besides, the reeds won't "work in different directions".

When you move the draw reedplate to the top of the comb, the reeds become blow reeds. That's because they are now under the reedplate instead of being on the outside, as they were when the drawplate was on the bottom surface of the comb. Some models with long comb slots (eg. Suzuki Harpmaster, Kongsheng Amazing 20) will allow you to use the draw reedplate on top of the comb and act as a blow plate, because the entire reed fits inside the slot.

However, with all harps, if you leave the standard blow reedplate in place and stack the draw plate on top of it, you will have massive air loss, because the reed pads of the draw reedplate will lift it up by about 0.4mm along its length. That's with welded reeds. Riveted reeds will give you a huge gap between the plates of over 1mm.

The only way to eliminate this gap would be to have a specially shaped spacer plate between them. But even then, and even if you can get the reed alignment right, you'll have two blow reeds in each slot. I doubt they would work well, and would wonder what the point of going to all this trouble would be.

Re: Double stack Reed plates

Posted: Tue Jul 30, 2019 5:03 pm
by triona
Brendan wrote:
Tue Jul 30, 2019 12:41 pm
I doubt they would work well, and would wonder what the point of going to all this trouble would be.

Me too, especially the latter.

dear greetings

Re: Double stack Reed plates

Posted: Fri Aug 02, 2019 2:15 pm
by EdvinW
@dodtsair: THIS IS SUPER COOL! :D :D Thank you for suggesting this!

I've experimented further and to answer your questions: Will the reeds will still play? Yes. Will they respond differently than in the normal configuration? YES!! (though a little different than normal)

Before going into details, let's just make sure we're on the same page.

@Brendand and @Triona : I think you both misunderstood the question, or at least you don't interpret it as I do.

On the top reed plate the reeds are facing downwards. Adding another plate with downwards-facing reeds is, like you both pointed out, not only practically very difficult to put together, but would not obviously produce any more sound than a single blow reed. (IF one could get the two reeds to operate in the same slot, there might be some draw notes hiding somewhere, but I have no way of testing this and your intuitions might well be right.)

What I think dodtsair talks about is letting the second reed to operate on the outside of the slot. With the harmonicas I've seen this is not possible with traditionally set-up reed plates, simply because how the slots are located. However: if one removes all the reeds from the draw reed plate and re-attach them on the other side and THEN put it on top of the blow reed plate, each slot would look something like this:
doublereed2.png (2.67 KiB) Viewed 4334 times
Or possibly like this:
doublereed1.png (2.75 KiB) Viewed 4334 times
One simple way to test this is by simply holding the plate in place so that the bottom slots align. I've tried this and both reeds DO play. It's not 100% air tight, so the draw reed doesn't sound as strong as the blow reed, but this is surely fixable. The opposite reeds directions (ORD) seems to work better if the plates are somewhat shifted; I think this is because it allows for better air flow, see picture.
doublereed3.png (7.6 KiB) Viewed 4334 times
Both reed directions seem to work to some extent. The ORD should be easier to build and I think it bends better. The bending observations could be due to less leakage with the ORD, but also the physics intuitively should behave more like a normal single reed.

The point is not the HOW though, but that it ACTUALLY SEEMS TO WORK! Closing off the bottom of the chamber I can play both notes, blow and draw, of the top two reed plates.

The really exciting news though is this:
Both the blow reed and the draw reed will bend!

No matter which of the blow or the draw reed is the highest, I can produce interactive bends on the highest note, but also a bend similar to a valved bend on the lower note. With the reeds tuned in unison, both reeds bend. The interactive bends only seem to work with ORD, but I have not investigated reeds pointing in the same direction enough to completely rule them out.

If this would be realised in a whole instrument and be made to work, this would constitute a new class of harmonica along with the half-valved ones and the x-reeds! :D

I say "if", because there might of course be some issue that shows up on the way from single-hole prototype that sort-of works to a complete instrument.

The fun has only just begun though!

With a top-mounted draw reed lower than the blow reed TOGETHER with an ordinary draw reed down where it's normally located, any drawing by the player seems to mainly activate the lower draw reed. Blowing, on the other hand, activates the blow reed which may interact with the top draw reed and thus bend downwards. The result is a new kind of x-reed harp!

There are more ideas here, but the post is already long enough.

Once again: Great question dodtsair! :D

Re: Double stack Reed plates

Posted: Fri Aug 02, 2019 7:51 pm
by triona
Fine drawings, btw. I think I have understood quite well what was meant. Your post at least is showing that the idea is not as useless as thougt at first sight. But the problems for realization can be seen easily at your drawings.

Maybe we can discuss it in Norrköping? Would spare a lot of typing, drawing, scanning etc at least. 8-)

greez tri

Re: Double stack Reed plates

Posted: Fri Aug 02, 2019 8:52 pm
by dodtsair
@Edvin yeah, you have grasped the depth of my question. I agree, with the mechanical problems of trying to do this. I had already taken apart my diatonic and positioned the bottom reed plate on top of the top reed plate and noted how I had flipped the direction of the bottom reeds and defeated my goal. I had not realized the issue with the welds/pads/rivets causing air loss.

I was originally thinking of same reed directions( (SRD) as with ORD the amplitude of the reads vibration would be limited before it started striking the base of the companion reed. Hypothetically with SRD both reeds would vibrate in the same frequency and period allowing them both to have a large amplitude.

But with the ORD design, looking at your diagrams if you erased the horizontal middle line you effective combine the two plates into one, with reeds mounted on either side.

Bending in both directions? I had not expected that.

Overall the goal was to reduce the amount of space consumed by reeds. So that you could have a similar sized harp that could accomplish more. Normally a diatonic harmonica has 10 holes, 20 reeds. If you go and start saying things like, wouldn't it be great if I could bend all the notes, you start getting into at least 30 - 40 reeds. Then you ask yourself if you could bring in a chromatic harmonica's slide and be able to play all notes of the chromatic scale, which would be amazing, but then you would be putting something like 80 reeds in your mouth and look like a metal porcupine. I didn't want to be carrying around a full size piano.

So the key part of the question, could they be stacked to reduce space and allow for more reeds in the same sized instrument.

I have other related questions too, I thought I would start those on new threads in due time
1) Can you cnc reeds and reed plates together
2) To facilitate bending does the sympathetic reed need to be a free reed or can it be a beating reed(not sure these are the proper scientific names)?

Re: Double stack Reed plates

Posted: Fri Aug 02, 2019 10:33 pm
by dodtsair
One further thought, with the double reeds, they are sitting in the same air channel. If you put a comb on the outside separating the blow exit streams you could then value that stream. This would enable you to have a sympathetic blow reed that would not sound on draw.

Code: Select all

                                                                           │                            │
                                                                           │                        top reed
          │            │            │                                      │                         cover
          │            │            │                                 blow valve                        │
          │            │            │                                      │                            ▼
     blow valve   blow valve   blow valve                                  │
┌─────────┼────────────┼────────────┼──────────────────────────────────┐   │┌───────────────────────────────┐
│     ┌───┼───┐    ┌───┼───┐    ┌───┼───┐   ┌───────┐    ┌───────┐     │   ▼└Λ────────────────────────────┬─┤
│     │   │   │    │   │   │    │   │   │   │       │    │       │     │    ╱ ╲                           │ │
│     │   ▼   │    │   ▼   │    │   ▼   │   │       │    │       │  ◀──┼── ▕   ▏sympathetic blow reed   * │ │
│     │       │    │       │    │       │   │       │    │       │     │    ╲ ╱                     ***** │ │
│     │       │    │       │    │       │   │       │    │       │     │     V                 ******     │ │
│     └───────┘    └───────┘    └───────┘   └───────┘    └───────┘     │    ┌───****************──────────┴┬┴────┐                           ┌────────────────────────────────────────────────────────────────────┐
│                                                                      │    │                              │     │                           │                                                                    │
│                                                                      │    ├──┬******************─────────┤     │                           │                                                                    │
│                                                                      │    │  │                 *****     │     │                           │                                                                    │
│                                                                      │    │  │ active blow reed     ***  └─────┘                           │    ┌───────┐    ┌───────┐    ┌───────┐   ┌───────┐    ┌───────┐    │
│                                                                      │    │  │                         *                                   │    │       │    │       │    │       │   │       │    │       │    │
│                                                                      │    │  │                                  ◀─────comb face───        │    │       │    │       │    │       │   │       │    │       │    │
│                                                                      │    │  │                                                             │    │       │    │       │    │       │   │       │    │       │    │
│                                                                      │    │  │                         *                                   │    │       │    │       │    │       │   │       │    │       │    │
│                                                                      │    │  │sympathetic draw reed***** ┌─────┐                           │    └───────┘    └───────┘    └───────┘   └───────┘    └───────┘    │
│                                                                      │    │  │                ******     │     │                           │                                                                    │
│                                                                      │    ├──┴─****************──────────┤     │                           │                                                                    │
│                                                                      │    │                              │     │                           │                                                                    │
│     ┌───────┐    ┌───────┐    ┌───────┐   ┌───────┐    ┌───────┐     │    └──Λ─******************────────┴┬─┬──┘                           │                                                                    │
│     │       │    │       │    │       │   │       │    │       │     │      ╱ ╲                 *****     │ │                              └────────────────────────────────────────────────────────────────────┘
│     │       │    │       │    │       │   │       │    │       │     │     ▕   ─────▶                ***  │ │
│     │   ▲   │    │   ▲   │    │   ▲   │   │       │    │       │     │      ╲ ╱                         * │ │
│     │   │   │    │   │   │    │   │   │   │       │    │       │     │     ▲ V    active draw reed        │ │
│     └───┼───┘    └───┼───┘    └───┼───┘   └───────┘    └───────┘     │     │┌─────                ────────┴─┤
└─────────┼────────────┼────────────┼──────────────────────────────────┘     │└───────────────────────────────┘
     draw valve   draw valve   draw valve                                    │
          │            │            │                                        │                             ▲
          │            │            │                                   draw valve                         │
                                                                             │                          bottom
                                                                             │                        reed cover
                                                                             │                             │

                                                                                                                                                                             front face
                              rear face                                                Cross section

Apologies, the forum does not seem to use a monospace font for code. You can see it with monospace here: ... 1da37e6c56

Would need something like this: ... B07FKJXZ78

Same concept, but it would need to be in different packaging. Air resistance would become an issue, how much effort does it take to open the one way valve?

Re: Double stack Reed plates

Posted: Fri Aug 02, 2019 11:05 pm
by EdvinW
I thought along similar lines! With standard blow and draw reed plates and an extra sympathetic draw reed plate outside the blow reed, you could use a standard harmonica valve on the lone reed plate to get nice interactive bends for both blow notes and draw notes.

I also had the idea of using double reed plates on both sides of the harp to create a new kind of chromatic, much more compact and hopefully more air tight. With the new kind of bending I described added in you really have all you could wish for, and it shouldn't be that complicated to build either :D As for selecting which of the two pairs to activate, I was thinking more along the lines of this: , Brendan Power's Overblow Booster! You wouldn't have to separate the reeds, but sealing the cover plates and somehow selectively blocking one of them could work.

I need to leave for bed now, but I'll write some more in the morning.

btw: Is this an old idea of yours or a new one?

Re: Double stack Reed plates

Posted: Fri Aug 02, 2019 11:40 pm
by triona
dodtsair wrote:
Fri Aug 02, 2019 10:33 pm
Would need something like this: ... B07FKJXZ78

Same concept, but it would need to be in different packaging. Air resistance would become an issue, how much effort does it take to open the one way valve?
Talking about valves you might have a look here, if you did not yet:

about ball valves (among many other themes):

and about Brendan's new gasket valves:

dear greetings