Flat C on BB Tuba

[pittbassdaddy]

I recently acquired a small 3 valve Bb tuba. I tried to play it and it just plain didn't work. Checked a few things and it turns out that the first and second valves were swapped. Easy fix.
It played ok but didn't slot well. Sat down with a tuner and was amazed that the entire thing was about 25c flat...all slides were fully inserted...not good. 1st valve C in the staff was reading as an in tune B natural...unplayable instrument?

I took some time and penetrating oil and was able to get the slides freed up then gave it a bath ended up with lots of gunk in the water. Upon closer inspection water key pads (spit valve corks) were not looking good. Dried, lubed, and reassembled it.

Still plated flat. Time for electrical tape over the spit valve holes! Tuning is better but not up to pitch and that C is still way flat. Knowing my own limitations, it was time to see my local repair tech.

He gave it the once over and replaced the water key pads. Valves, compression, and alignment were good. Played it again and was pleasantly surprised that it now slots well and plays up to pitch...except that C which is still about 15c flat. I tried 1+3 as an alternate fingering and its about 15c sharp with 1+3 in tune for C+low F.

I thought maybe this tuba was sensitive to the type of mouthpiece being used, so I tried all that I had (from shallow bowl to deep funnel and everything in between) and the results were similar.

Any thoughts on what the issue could be?

[pittbassdaddy]

So there is nothing that would be an obvious cause for this, just a normal quirk of most Bb tubas to varying degrees?
D is good
Db/C# also good
C FLAT
B natural is 5c flat with 1+2 or 20c sharp with 123

[Tubajug]

If you can reach the first valve slide while playing, you could always just play it as 1-3 and pull the 1st slide out a bit to get back down. What kind of horn is it? I'm just curious...

[iiipopes]

My Bessophone has a shortened 1st valve circuit that the slide is usually pulled @ 5/8 inch to be in tune for the Eb, Ab, etc., and can be pushed if needed for 2nd space C, although as bloke says, "Hey! It's a tuba!" Before the bell swap, my 5th partials were flat as expected, and 1st ledger line Eb wouldn't center, as the node was on the detachable bell collar. After the bell swap, almost everything is in tune, even the 5th partials! Go figure! I will blame it on the logarithmic taper of the Besson bell providing proper resonance through the range, as well as a longer main tuning slide putting extra cylindrical tubing at the right place, which tends to expand the pitch between overtones. Sounds like you've done a great job getting your tuba playable. I would consider shortening the main slide outer tubes so A=440 at room temperature is about a 5/8 to 3/4 inch pull, and shorten the 1st slide outer tubes so you can shove as necessary for the 2nd space C.

[toobagrowl]

15c should be fairly lippable. If you find it is too much, then just cut about 1/2" off the 1st slide. That way, it should only be 5 or so cents flat, the other 1st valve notes 5-10c sharp, which are easily correctable/lippable. If you can't deal with that then I don't know what to tell you......

Conn 14K/36K sousaphones' (Elkhart production) 1st valve C is so flat that I ALWAYS use 1-3 when using mine.

How flat is yours? My Elkhart 14k plays about 10-15c flat on 1st valve C, which I find lippable. Playing 1+3 in that register sucks response-wise, and it also changes the sound slightly; I'd rather deal with lipping that note up a bit

[pittbassdaddy]

The tuba in question is an early Wessex Stumpy. It looks like improvements have since been made on the design such as changing the routing of the 3rd valve tubing.
That C is unfortunately still 10-15c flat when I lip it up as high as I can (which does not sound good at all).
Cutting the first would require significant disassembly and moving of braces.

Using 1+3 is possible and the main tuning slide is easy to reach/pull but needs to move about 2 inches to get C in tune.

Does anyone know where (as in length from mouthpiece) where the nodes would be for this note? Just curious to see if there is a joint/brace there that would be causing an issue.

[toobagrowl]

So I played my Selmer Signet sousaphone recently and tested the pitch (I didn't feel like getting the old Conn 14k out of the case, assembling it) with my Boss tuner. The Selmer Signet is closely based off the Conn 14k/36k sousas, with very similar playing characteristics. My Signet responds, intonates and sounds very similar to my Conn 14k. To bloke's credit, using 1+3 isn't too bad on second space C; but I still prefer 1st valve, lipping it up. The open 4th partial Bb right below that C is also about 10c flat (dunno why noone mentions that note; they always focus on the C above it). 6th partial open F rides sharp, but fairly easy to 'relax' the embouchure to bring that note down to pitch. There are no "major" pitch issues with the Signet or 14k, just a handful of fairly minor pitch quibbles

That C is unfortunately still 10-15c flat when I lip it up as high as I can (which does not sound good at all).
Cutting the first would require significant disassembly and moving of braces.

Using 1+3 is possible and the main tuning slide is easy to reach/pull but needs to move about 2 inches to get C in tune.

So that second space C is still at least 10c flat even with you lipping it as much as you can?
Yeah, it's not good to lip something to the point where it affects your sound. Looks like you just need to use 1+3 on that with a slide pull. You stated that the main tuning slide is easy to reach. Get that slide nice, smooth and fast to use on that note. I'm not sure about the nodes; I think even a good repairman would have to guess where they are....or use a special acoustic-checking computer Does anyone but the large brass makers have such equipment?