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I'm currently working on a 1960s conn sousaphone. While I have it all apart for cleaning and repair, I'm lightly considering adding a fourth valve. I dont need a 4th, but I like having fingering options. So, looking at the valve cluster, adding a piston valve would be extremely difficult. But, there's lots of space to graft in a rotary valve and devise a suitable lever..... it would look silly, but..... and nows the time, while I have it all apart..... anybody else consider this...

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I had one of Art Hovey's tuba that started out life as a 3v Conn that he grafted a fourth rotary valve to. It can definitely be done.


http://www.galvanizedjazz.com/tuba/HensToothCC.htm

Since the false tones are going to be outstanding, just convert the first slide to one that has an easily-sliding upper slide, so that you can pull it out to tune 1-3 and 1-2-3.

Also check the tuning for 2-3, and maybe shorten the #3 circuit. I made the mistake of building a four-valve sousaphone, when all I needed was a nice long #1 slide that could be pushed in far enough to get second space C sharp enough and 1-3 and 1-2-3 flat enough.

If a tuba or sousaphone has really outstanding false tones, the four valve non-compensating system really doesn't offer many advantages, but most people don't agree with what I just said.

My Holton Sousas have such easy to play false tones, I've never considered the added weight of a 4th valve worth it, especially as I get older. Even the 3 valve Eb gets heavy towards the end of a 3+ hour gig.

On the BBb I typically tune to play C in the staff as 1+3. Sometimes 1+2 for D if I am going to be playing playing for a long time and might not be able to lip it up into tune. Other than that I just avoid 123 at all costs, by playing low E and B natural up the octave on the rare occasions when they come up. Same idea for the Eb horn. Luckily I am almost usually playing tunes in sensible keys with plenty of flats and never with those nasty tic-tac-toe notes in the key signature.

Good enough for a hack like me, a real tuba player might feel differently.

Your right about weight being the biggest issue. That will probably trump a 4th valve. I havent played it yet as it had a catastrophic accident to the, dogleg is it? That's the main repair I'm doing, and new bracing.

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bloke wrote: ↑Mon Feb 05, 2024 7:23 pm Since the false tones are going to be outstanding, just convert the first slide to one that has an easily-sliding upper slide, so that you can pull it out to tune 1-3 and 1-2-3.

Also check the tuning for 2-3, and maybe shorten the #3 circuit. I made the mistake of building a four-valve sousaphone, when all I needed was a nice long #1 slide that could be pushed in far enough to get second space C sharp enough and 1-3 and 1-2-3 flat enough.

If a tuba or sousaphone has really outstanding false tones, the four valve non-compensating system really doesn't offer many advantages, but most people don't agree with what I just said.

Bloke beat me to it. I have done this with every souzy I have owned or had access to over the past thirty years. This includes a 38K, which had the outstanding false tones all the way down to true pedal BBb, a Pan-Am with a Cavalier bell and the .687 bore (King style bore, but Conn wrap), and the 36K Lee Stofer is putting together for me. Along the way was a King, a Reynolds, an Olds, a Bundy/Selmer Signet, and maybe another or two that were forgettable. I absolutely agree with bloke that with the 1st valve circuit thus converted to "ride throttle," there is no need for a 4th valve. All it does is add unnecessary weight to the player's shoulder with no advantages.

bloke wrote: ↑Mon Feb 05, 2024 7:23 pm Also check the tuning for 2-3, and maybe shorten the #3 circuit.

I had to do this to my Conn 38K from the 20s. There was just no way to play an F# that wasn't horribly flat. Chopped a little off the 3rd valve circuit and couldn't be happier.

Kirley wrote: ↑Thu Feb 08, 2024 12:16 pm

bloke wrote: ↑Mon Feb 05, 2024 7:23 pm Also check the tuning for 2-3, and maybe shorten the #3 circuit.

I had to do this to my Conn 38K from the 20s. There was just no way to play an F# that wasn't horribly flat. Chopped a little off the 3rd valve circuit and couldn't be happier.

You guys are lucky. All the souzys I have played needed 3 to be pulled a little bit to get 2+3 in tune. Of course, the reason for it being long is to get 1+3 in tune, which you don't need if you do the 1st valve circuit mod that bloke and I do.

So before I try to hack into the first valve, describe the process.

As in after I remove the bend on the top side, is the inside diameter the same as it is on the bottom end meaning the inner slide tubes will slide right in? I would like specifics from those who have done it to ponder before I try it.

Remember that I'm self learning how to do these things. Also, silver solder is awesome! I used some to close up a cracked seem. Worked way better than 50/50.

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Grumpikins wrote: ↑Thu Feb 08, 2024 6:25 pm
Remember that I'm self learning how to do these things. Also, silver solder is awesome! I used some to close up a cracked seem. Worked way better than 50/50.

Did you use true sliver solder (MP 750C or so) or a higher melting point Lead tin solder like 70/30. I am asking because I've heard repair guys use all kinds of inconsistent language for various soldiers and brazes. I'm not a welder but I teach a class sometimes on brazing and welding engineering, basically the metallurgy of making things stick together, so it's kind of s professional curiosity.

Some people use plumbing solder to fill cracks. To me, that's b.s.

It's not lead, but it's also not brazing wire.

I dont know the exact composition of the wire I used. I got it from my employer. It wasn't a spool, it was a loose coil in an approximately gallon sized package. He said its silver solder, uses it to solder carbide pads to steel "v" blocks for machining operations. I'm sure it's high grade stuff because of what he's using it for. Had to use a really hot torch. Worked great.

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If they were using it to "braze" carbide to steel it was proper silver solder (silver, copper, and zinc alloy).

I use braze in quotes because it is actually soldering not brazing, but machinists universally use the wrong term. Brazing requires that the braze alloy diffuses into both pieces being stuck together making a continuous metal piece betweeen the two. Soldering is like metal glue that can be cleaned off an leave the base metal nominally the same.

Thanks for clarifying, like I said I have heard so many different uses of the word silver solder, it is good to know what people actually mean.