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Hi All! I am a tubist/band director. I have 8 Conn 20K sousas at my school. I have trouble with them playing flat with the tuning slide pushed in especially on the third partial F, which is weird. We are using the standard neck and two bits. Has anyone else come across this? Any solutions?

Jason Harrell

The Conn 20J/K tubas and sousas were designed with a flat 3rd partial F. This compromise allows for everything else to be pretty well in tune. It was a conscious choice by the Conn development lab. That F is meant to be played 1&3.

Thank you for that info. I just learned something new!

If the 20K sousaphones are all playing flat thoughout the range of the instrument, then I'd suspect leaks. The last 20K I worked on had bad intonation, and I traced it to the receiver for the upper mouthpipe, which is soldered to the lower mouthpipe. That joint was not properly soldered at the factory, and simply pulling it off (not that much was holding it on!), and sizing and soldering it properly brought everything into focus. I'd also mention that the valves with oval ports must be well-aligned, as only a little variation can make it VERY MUCH OFF.
Having played Conn 20K's for decades now, I'd also suggest that I find them easiest to play in tune with 1) undented bits, 2) 1st slide pushed almost all the way in, 3) main tuning slide in to where you're riding 3-5 cents sharp, and 4) play with your "ears on." I've never had trouble getting the F in tune this way, and 1st slide in helps a lot with the C in the staff.