TubeNet

I see a lot of F tubas nowadays with 19-22mm bore. Is this becoming rather an industry standard and what is the effect of bore size (both large and small) on a horn, in your experience...
Ta

Seems to me that the bore size is being driven by the marketing folks who think that's what we want. The truth is that a big bore on a horn that does not have tapers designed for it is pretty useless. It's a matter of the horn being efficient. Remember the days when all makers would do is slap a bigger bell on horns?

Are mouthpiece receivers generally the same internal diameter, irrespective of the "bore" measurement at the valves? I wonder if the larger bore is actually because they want a certain taper all the way along the leadpipe, from that fixed starting point?