Why are brass reeds more variable in pitch than steel?

[Big Squeezy Accordions]

I tune accordions and melodicas, and I had thought that the melodica's greater variability in pitch based on air pressure had something to do with the fact that you are blowing into a melodica with lungs rather than a bellows. I came up with a method for tuning melodicas using a CPAP machine to maintain a consistent air pressure. However, since coming into possession of a couple of Borel Claviettas and working on a Borel Accordina for a client, both of which have stainless steel reeds, I find that the pitch is quite even and more accordion-like. It's quite hard to bend notes at all on one of these the way you could with a melodica or even on a lower accordion note by half depressing a key. So the variability in pitch must be due to the reed metal, which is brass in melodicas. Does anyone have a technical explanation for this? Is it somehow due to brass being softer than steel?

 

[debra]

The pitch bending is mostly due to opening the pallet part-way, close to the reed. On a harmonica this is done by partly blocking the hole (through which the air flows), again close to the reed. On an accordina you need to remove the decorative (or solid) sides and then you can also partly block the airflow through the reed (the reed sits on the inside on the reed plate): when you put your finger on the reed plate, near where the rivet is you can parly block the airflow without touching the reed itself and this will bend the pitch.
When the airflow is partly blocked you have to increase the air pressure to keep producing enough sound, and you then achieve that the air flows faster through the smaller hole.
So tone bending is not easy on the accordina (with everything in place) because you cannot restrict the space through which the air flows, close to the reed. If you partly block the air going through the mouthpiece it doesn't work because that's still too far from the reed, so by the time the air gets to the reed it has normal pressure.
The ability of tone bending thus mostly depends on how the air flows, and not on whether the reed is brass, steel or stainless steel.

 

[Gonk]

Stainless steel is between the normal spring steel and brass in terms of hardness.

 

[Alan Sharkis]

Just a guess, and having nothing to do with pitch bending but with pitch stability, consider the following:

1. Brass is much more flexible than stainless steel.
2. Brass and stainless steel have different coefficients of expansion.
3. Brass will oxidize and the oxide coating will affect the mass of the metal. There’s a reason why stainless steel has its name.

 

[Big Squeezy Accordions]

The pitch bending is mostly due to opening the pallet part-way, close to the reed. On a harmonica this is done by partly blocking the hole (through which the air flows), again close to the reed. On an accordina you need to remove the decorative (or solid) sides and then you can also partly block the airflow through the reed (the reed sits on the inside on the reed plate): when you put your finger on the reed plate, near where the rivet is you can parly block the airflow without touching the reed itself and this will bend the pitch.
When the airflow is partly blocked you have to increase the air pressure to keep producing enough sound, and you then achieve that the air flows faster through the smaller hole.
So tone bending is not easy on the accordina (with everything in place) because you cannot restrict the space through which the air flows, close to the reed. If you partly block the air going through the mouthpiece it doesn't work because that's still too far from the reed, so by the time the air gets to the reed it has normal pressure.
The ability of tone bending thus mostly depends on how the air flows, and not on whether the reed is brass, steel or stainless steel.

Okay, but I'm talking about tone bending using the keyboard, not my mouth. Why then is tone bending easier on a brass reed melodica than on either a clavietta or an accordion, the clavietta being essentially just a melodica with steel reeds instead of brass? I can bend notes quite a bit on my Hohner melodica by pushing the key down half way, and almost not at all on the clavietta using the exact same technique.

 

[Ffingers]

As Alan Sharkis wrote, the very nature of the reeds' materials come into play here; consider the difference on a guitar between steel strings, nylon and original gut - all three are at variance.
Or an organ with an assortment of soft iron, steel, brass and even wood pipes.
Each has its own responses.

 

[debra]

Okay, but I'm talking about tone bending using the keyboard, not my mouth. Why then is tone bending easier on a brass reed melodica than on either a clavietta or an accordion, the clavietta being essentially just a melodica with steel reeds instead of brass? I can bend notes quite a bit on my Hohner melodica by pushing the key down half way, and almost not at all on the clavietta using the exact same technique.

It is strange indeed. But the same applies to accordions. I have made an arrangement of "Milonga del Angel" (Piazzolla) in which you need to play a one measure long A3 (the note that's 220Hz) and then bend down to G#3 and hold for a whole measure and then repeat 3 more times.
I played this in a small ensemble for a few years, on a Bugari 505/ARS without much trouble. I later sold this accordion and currently have 4 other ones. I cannot do the bending of the A3 down to G#3 as well as on that Bugari on any of the 4 accordions. (And I cannot do it on my accordina either.) It is very dependent on the specific instrument and on the note as well. In another piece a player needs to bend D3 down to C#3 and then up to D3 again. It happens to go well on his old Pigini Sirius bayan, but doesn't go well with other notes.
How well tone bending works is thus very dependent on unknown specific characteristics. The keyboard and pallets on instruments like a melodica, clavietta, accordina or even "vibrandoneon" make it harder to do tone bending with the half-press of a key.
I believe that tone bending is easier with brass reeds because they tend to bend down more under higher pressure (when you play louder), just like for some reason low notes on an accordion go down as you play louder, and go down more under push than under pull.
But... for the (rich) accordina players there is now the "mellowtone" accordina which has a built-in tone-bending mechanism that "toys" with the internal air pressure to do tone bending without the need to do anything like a half-press.

 

[Big Squeezy Accordions]

It is strange indeed. But the same applies to accordions. I have made an arrangement of "Milonga del Angel" (Piazzolla) in which you need to play a one measure long A3 (the note that's 220Hz) and then bend down to G#3 and hold for a whole measure and then repeat 3 more times.
I played this in a small ensemble for a few years, on a Bugari 505/ARS without much trouble. I later sold this accordion and currently have 4 other ones. I cannot do the bending of the A3 down to G#3 as well as on that Bugari on any of the 4 accordions. (And I cannot do it on my accordina either.) It is very dependent on the specific instrument and on the note as well. In another piece a player needs to bend D3 down to C#3 and then up to D3 again. It happens to go well on his old Pigini Sirius bayan, but doesn't go well with other notes.
How well tone bending works is thus very dependent on unknown specific characteristics. The keyboard and pallets on instruments like a melodica, clavietta, accordina or even "vibrandoneon" make it harder to do tone bending with the half-press of a key.
I believe that tone bending is easier with brass reeds because they tend to bend down more under higher pressure (when you play louder), just like for some reason low notes on an accordion go down as you play louder, and go down more under push than under pull.
But... for the (rich) accordina players there is now the "mellowtone" accordina which has a built-in tone-bending mechanism that "toys" with the internal air pressure to do tone bending without the need to do anything like a half-press.

Interesting. I hadn't heard of the "mellowtone" accordina, but it reminds me of the "Blues Box" pitch bending accordion that was invented some years ago. I wonder what ever happened with that. It sounded like a major innovation at the time, but I've not heard anything about it since.

 

[godgi]

Recently I bought a diatonic harmonica and couldnt get to grips with note bending. Then I bought a chromatic harmonica and the issue became less important. While reading up about note bending on the diatonic harmonica many interesting observations noted. I think note bending on an accordion unisonic is a different concept. I am not sure what the reference to a melodica means in above discussion. Any melodica I have come across in an earlier life were of a budget type mabey with even plastic reeds so I am out of my depth on this one. By the way what amazed me about the diatonic harmonica draw bend is that the reed which was not in use(and a different pitch) for the draw but was in the chamber opposite the played reed - had a major impact. They could prove this when it was blocked/sealed the note draw bend was effected. Strange! It appeaers they are still learning about the capabilities of the diatonic harmonica and its capabilities it has are not fully understood. With an accordion I think its the reduction of air through the reed chamber that creates the down bend. By the was chromatic harmonic a great instrument to add to an accordionist arsenal in performance ideas.

 

[saundersbp]

I found the Suzuki M-37C melodica a good one for pitch bending. Tried it on my accordion too but it was a bit hit and miss and by the time I'd messed around with it I couldn't remember why I wanted to do such a thing in the first place! I think even the cheapest Melodicas have steel reed plates.

 

[Jim2010]

Interesting. I hadn't heard of the "mellowtone" accordina, but it reminds me of the "Blues Box" pitch bending accordion that was invented some years ago. I wonder what ever happened with that. It sounded like a major innovation at the time, but I've not heard anything about it since.

Here is a link to the Melowtone website.
In French

https://melowtone.com/

In English

https://melowtone.com/en/melowtone-en/

Marcel Dreux can build accordinas that have what he calls the "Bend" effect. Here is a link to one that comes with this as a standard feature.
In French

Signature Ludovic Beier | accordinas

Le modèle construit avec Ludovic Beier est un « 2000 » avec un habillage en laiton laqué noir mat. Le clavier est noir et blanc. Il est équipé d’axes qui lui permettent de faire l’effet « Bend ». Le clavier a été légèrement durci grâce à des ressorts plus forts. Il est accordé à 441 Hz. Cet...

www.accordinas.com

In English

Signature Ludovic Beier | accordinas

The model built with Ludovic Beier is a “2000” with a matt black lacquered brass casing. The keyboard is black and white. It is equipped with axes which allow it to produce the “Bend” effect. The keyboard has been slightly hardened thanks to stronger springs. It is tuned at 441 Hz. This...

en.accordinas.com

 

[Big Squeezy Accordions]

I found the Suzuki M-37C melodica a good one for pitch bending. Tried it on my accordion too but it was a bit hit and miss and by the time I'd messed around with it I couldn't remember why I wanted to do such a thing in the first place! I think even the cheapest Melodicas have steel reed plates.

They are brass, typically.

 

[saundersbp]

They are brass, typically.

Not my experience I'm afraid. I do have rather a lot of them......

 

[Big Squeezy Accordions]

Not my experience I'm afraid. I do have rather a lot of them......

Okay, I stand corrected then. Are you talking about Hohners, or some other brand? All the Hohners I've seen have brass reeds. At least, they look like brass.

 

[saundersbp]

Suzuki, they are main manufacturer. Melodica is big in Japanese schools and in some parts of Yorkshire too!

 

[saundersbp]

The pitch bending is mostly due to opening the pallet part-way, close to the reed

To pitch bend on a wind keyboard instrument you partially open the pallet and then at the same time increase the wind pressure. A lot of coordination is required and every note can behave differently!

 

[debra]

To pitch bend on a wind keyboard instrument you partially open the pallet and then at the same time increase the wind pressure. A lot of coordination is required and every note can behave differently!

To "increase the wind pressure" it's important that the volume of air between the "inlet" or "outlet" (depending on pull versus push is small. The accordion pallets are very close to where the reeds are, so it can work. On the accordina that should work as well, but I have less control over the button/pallet so in my case it's mostly open or closed but I can't really get the pallet to open part-way. Others may have a different experience. On a melodica the problem may be similar: rubbish pallet control through the keyboard.

 

[Big Squeezy Accordions]

Suzuki, they are main manufacturer. Melodica is big in Japanese schools and in some parts of Yorkshire too!

Understood. Of course, if we want to be pedantic, technically only Hohner makes melodicas. Suzuki makes melodions, Yamaha makes pianicas, Borel made claviettas, and so on. All essentially the same instrument, but with some differences in materials and construction. But I realize that "melodica" has become the proprietary eponym, like Jell-O or Band-Aid, for an instrument that has no generic name of its own.

 

[Ffingers]

From wikipedia (which accords with my slight knowledge of the topic):

"...The modern form of the instrument was invented by Hohner in the late 1950s,[1] though similar instruments have been known in Italy since the 19th century."

 

[Dingo40]

Are brass coloured accordion reeds necessarily brass? Could they be of brassed steel?
My foster father's late 1940s Settimio Soprani had brass coloured reeds.