various makes of sousaphones' bell tenon diameters...

[Dan Schultz]

Without me dragging a bunch of them down and measuring them, could someone (who has this committed to memory) remind me which maker(s) of sousaphones utilize a 6 1/2 inch diameter male bell tenon ?

thnx.

Don't know about the 6 1/2" ones. But... you can eliminate these:

Sousaphone tenons:
Conn 14K/36K - 19 1/16 circumference - 6.067" diameter
Selmer/Bundy/Signet/Buescher - 6.067" and will probably work on a Conn
King - 20" circumference - 6.366" diameter
Yamaha - 6 9/16"
Conn 'jumbo' - 9 1/4"
Conn 20K - 7 1/4"
M & M - 7.28" diameter
King 'Giant' - 7 1/8" diameter

Upright bell tenons:
King - 6 5/16"
Conn 2XJ - 7 1/4"
Marzan - 6 5/8"

[Paul Scott]

A Martin Medium sousa (the smaller, non-Mammoth Martin sousa) takes a bell with a 6.5" tenon, (very nice sousas, btw!). The detachable-bell Medium tuba takes the same tenon.

[Paul Scott]

I believe it might be for Reynolds but am not sure for Olds, (IIRC, a friend has a Reynolds recording bell tuba that takes a Martin bell). I think of the two (Reynolds and Olds) as being so similar that I would think so.

[sticky_valve]

I've tried a Reynolds brass bell on a Martin Fibreglass sousa body recently and it did not fit.