Hello

 Both instruments are built in 53cm and usually there are some sound mechanics natural to the instrument design that need to be addressed, for example, the so talked about "Bb4 problem". Turns out this is fixable after the handpan is finished, and this knowledge allowed for a chromaticism build aiming at the cleanest sound possible. The "Bb4 problem" was often addressed as an "impedance", and this is a quite vague term that very often led to the misunderstanding of what could be causing the distorted sound of some notes in a given handpan size. After all, in simple terms, what's happening is a distortion of a given note related to a given size and is clearly created by the introduction of an air chamber, as prior to the gluing of both parts of a handpan, for example a Bb4 in a 53 cm shell, these "problematic" notes sound clean. If we address the problem as an overdrive/distortion problem then as a guitar player what I would do is either switch the effect pedal off or lower the volume of the amp. So how do we lower the volume of the note ? Without lowering the volume of the overall "amp" ? By transferring energy that's exciting the specific frequency into another medium. And this is the principle of Helmholtz resonators. This is why a water bottle works better or worse, it's not about the water bottle, per say, because this works even with different materials, it is more about in what frequency the bottle is "tuned in". In other words a water bottle works as a Helmholtz resonator. Why is this important ? Number one it means we can now use many different materials other then plastics to achieve the same result, number two, sound wise we are now able to solve a distortion problem without meaningfully impacting the volume of the other notes and be precise about it.