I know this is going back a bit, but I have one of these Barnes & Mullins ZB's with the patent mute. I've never had it to pioeces but I know how they are supposed to work.  It's a kind of cone arrangement which when the mute is selected brings into play a sort of cone thing which clamps on the vellum if I remember correctly.   Sorry it's taken me so long to mention this.  This particular B&M of mine is a lovely instrument and plays beautifully with a lovely action.

Best Wishes,

Jake.

Jake Glanville said:

Dear Carrie,

Hello again.

I was most interested in your picture of the patented mute on a Barnes & Mullins ZB.  I have seen four or five B&M ZB's, some of them claiming to have a patent mute, and had always assumed this to be a modification of the standard ZB wooden pot as all of them had nothing extra fitted.  Now I know different and I'm most grateful.  Very many thanks. No need to comment or reply, I know you are a busy person.

All the Best,

BJ.   

Interesting. There's also a cammeyer vibrante on on eBay, but I don't have the money to drop on it because I just bought a new car.

They seem to be popping up everywhere because even on reverb there's one but I think it's overpriced.