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Is there a precise definition of the "size" of a tuba, 3/4, 4/4, 5/4, 6/4? And what are the defining characteristics that determine the size? Bugle shape (bore along the entire air route)? Bell size? How open the wrap is? Bore at valve set?

Apologies if this is obvious to everyone else. Seems like some instruments are called 4/4 by some and 5/4 by others.

Size is "big". Really, they're all pretty big. Be happy! But no, you're right, the terminology is vague. The categories aren't sharply defined, and its usefulness doesn't provide much motivation for an improved size classification.

That said, it certainly isn't about how wide the small end is, valve bore, etc. Tubas belong to the conical brass category. Nor is it the wrap, of course. Some say it may be precisely measured as how much beer the tuba can contain, but if anyone has ever actually made this measurement, they haven't publicized it that I know of.

donn wrote: ↑Wed Feb 19, 2025 2:06 am Some say it may be precisely measured as how much beer the tuba can contain.

That's a useful metric!

There’s nothing scientific or officially defined by the tuba sizing committee. Heh, heh... These generally accepted groupings are something we’ve adopted for ease of looking at, and talking about, other people’s stuff.

Mostly driven by complete and purposeful nebulousness. “X/4” size descriptors are applied at the whim of the seller depending upon the target buyer.

In all aspects of like... some people measure differently to make themselves seem bigger than they are.

Whenever anyone takes a picture of me with one of my tubas, I hold that tuba way out in front of me, particularly if it's not a particularly large tuba. That's just the way I roll.

All tubas are HUGE. Some are more huge than others.

Are there any tubas that could have been fairly described as 7/4 in size?

Compared to some others, maybe what RM calls a 6/4?

Is it mostly about the "bugle" (bigger inner diameter before it gets to the bell section)?

tubatodd wrote: ↑Wed Feb 19, 2025 5:32 pm Are there any tubas that could have been fairly described as 7/4 in size?

Sam Gnagey had a really nice monster Frankentuba at MWRTEC last year.. 5 valve front action built from a Conn 2XJ that he called a 7/4. I only spent a few minutes with it... but it blew a hell of a lot better than it had any right to.

cskatz wrote: ↑Wed Feb 19, 2025 8:48 pm Is it mostly about the "bugle" (bigger inner diameter before it gets to the bell section)?

Bell stack and throat play a roll, but, in general, yes.

Historically makers made tubas in medium, full size, and large with different trade names like monster, mammoth, giant, medium which were other words for 3/4, 4/4, and 5/4, however when hirsbrunner made a size larger than their kaiser tuba in their line they referred to it as a 6/4 size if i remember correctly. That's how 6/4 came into the lexicon of referring to historically 5/4 size tubas. As other said, it depends on what the manufacturer refers to it as and no scientific measuring device. The bell throat is the best way I read on the ild forum to find where your tuba stands in comparison to other lines. Anything over 18 inch circumference above the tenon brace in the throat I think is considered a 5/4 or 6/4.