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First mute I bought was a beautifully carved and polished piece of mahogany. I just had to have it as a beautiful thing.
Doesn't mute much, just changes the tonality.
Then I bought a couple of different rubber mutes and sort of came to the conclusion that the heavier the mute, the more it muted.
Then I bought one of those solid metal ones and also an Artino (metal core, rubber on outside). I hated the solid metal one - there seemed too much risk it would harm the bridge or the fiddle or both. However, that Sihon wire slide doesn't look very bridge-friendly, but if it comes off, it won't hurt the violin at least.
So I use the Artino (the fiddlershop price is half what I paid!), but I saw a FS demo video, where the solid one was preferred.
Is it only about weight?
I wonder if you could have a solid heavy-metal one that just has a rubber "lining" where it sits on the bridge, so that it doesn't harm it, and the friction makes it sit more securely?
But if it's not just about weight, the physics of it might mean that the rubber lining would give the bridge just that little bit more freedom to vibrate.
@Fiddlerman, can I ask, please, those nuts and bolts on the Artino, are they really only decorative, or can you pull the thing apart and adjust it? If so, how do you do it?
(it's incredibly tight initially, so you want to adjust it - I attacked it with a screwdriver and deformed the rubber a little. Eventually I got it on, but luckily it was strong enough to survive the abuse)