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[Art Hovey]

I think it's a rotary-valve helicon. I have seen similar ones on Ebay, made in Russia.

[imperialbari]

Yes, the floor decoration is a helicon. Rather of the German/Bohemian type with more flare than the curled Russian stovepipes.

For a German ensemble this quartet displays quite a bit of humour in their making fun of the TQ format. This video reveals 3 F tubas and one BBb:

http://www.youtube.com/watch?v=kvQOdCBLNbE

Klaus