Posted: Tue Oct 12, 2004 10:09 pm
The bore on the Conn 22J and 21J's that I owned was about 0.770". I have heard some people call them 5/4 sized, but if they're not 6/4 I don't know what is. There is no standard for the x/4 designations, so they generally are only useful as a relative scale within a manufacturer's line. For example, Rudolph Meinl makes 3/4, 4/4, 5/4, and 6/4 sized horns that increase in size, but their 3/4 is larger than what some people might consider a 4/4. The number of valves makes no difference in this designation. My perspective on this is that as the bell and bows get larger, the size gets larger.