Yes, in a way the metaphone is like the sordine for the violin, a device to alter the timbre but not to add expression.
In this example it even diminishes a bit the expression.
On some instruments the change in timbre might have been too big to make a progressive version of the device.
On the other hand..
I compared the sound of my Schiedmayer to a Mustel of the same period. Just as you have stated in the past,
the sound of some registers are quite a bit sharper than Mustel. The biggest difference are the harpes eoliennes. If I use them on my
instrument with metaphones, they sound much like the ones on Mustel WITHOUT metaphone.
although the effect of the metaphone is huge in my case, I did some test on my instrument playing with one hand and controlling the
metaphone-slider gradually with the other, ..the results are fantastic...
Not every register changes as much as another by the metaphones, I think it's incredible beautiful to make a crescendo and
to hear some dynamic timbral balance change in the sound while doing so. Just like the horns who turn to "cuivré" in an orchestral context
![Smile](https://2img.net/i/fa/i/smiles/icon_smile.gif)
of course this is already present in some degree, but still..
![Smile](https://2img.net/i/fa/i/smiles/icon_smile.gif)
I wonder how it would have worked if I could have controlled the metaphones with the knee levers...