Cerveny 686 Fourth Slide Lengthening Advice

[daktx2]

I have a 90s Cerveny 686 C tuba (Sanders is the stencil name) that is a great player, but unfortunately has a pitifully short fourth slide, equivalent to 1+3 with the first slide pushed almost all the way in. It needs about 4 inches more total of length to be in tune, so something like 2 inches more pull on each side of the slides. If this were wrapped like a B and S, this would be a pretty simple modification, but these are wrapped in a way that make this operation not straightforward.

There's not enough clearance to simply add more length at the end, there might be between half an inch and 1 inch or so that can be added there before problems start to happen. I don't see any other place in the routing to add more straight tubing either. I'm trying to avoid having entirely new fourth valve tubing fabricated, but I don't see a way around this. Have any of you gone through this with a Cerveny/similarly wrapped horn before? What's the simplest way to lengthen the valve by this much? A picture is below for reference:

[arpthark]

See if you can find another two of those slides from someone's spare parts and have someone use the crooks to make an extension. It looks like there's enough clearance in the back, but I don't think it would have to be completely square if the fourth valve tubing is in the way.

I'm thinking of something like this (crude Paint drawing alert):



If you can't find used tubing (I see this but I think the 681 bore is smaller), Buckeye Brass is the importer for Cerveny now. They might be able to import parts to make an extension or even a completely assembled longer slide for you. I ordered a new Piggy leadpipe a few years ago and it took a while to come in but was a good fit.

[the elephant]

This is a common fix for Miraphone 186 BBb tubas. (It is not an issue on the CC 186 at all.)

Usually, the slide crook is replaced with two 2nd crooks, which are installed with lengths of inner slide tubing going down to the old crook, the slide "folded" over to keep it short enough to remove, but a good bit longer. You do not gain any pull, but you gain the length needed. The "folded" slide can then be removed, disassembled, and trimmed if it is too long.

Alternatively, and much better, but very expensive, and you gain pull: rebuild the 4th slide circuit to match the CC version of the model, which is an excellent slide circuit. The one you have seems to have been set up that way to keep it from being damaged if the horn falls over, but I have never had my CC 4th slide damaged from anything, ever, so maybe this is not the case.

If you want to pay a LOT of money on parts and labor, I can share with you the photos of when I did this BBb 4th to CC 4th slide conversion. The folded slide thing is fairly common and can be done OFF of the tuba, no disassembly required. The conversion will be like major surgery. That horn looks nice and will not if you do the conversion. I would advise you to go with the "folded slide" route.

You will need two second slide crooks and about five or six inches of inner slide tubing and about two inches of outer slide tubing for ferrules.

[LeMark]

swap the 3rd and 4th valve slides. Might help. if not, you're going to have to do the folding slide method.

[daktx2]

Thanks to all for your advice! The third slide is the same length as the fourth, so switching doesn't help. I'll be going with the folded slide.

[Sousaswag]

Fold it that way (like the HB2’s 5th), or fold it like a pretzel ala Rudy Meinl.

Either way, that shouldn’t be too big of a job!

[dp]

Times like this I regret not making a permanent habit to snap pictures of every "double-take" build feature I've seen, and only partly because searching for photos on the internet is such a cr4ap shoot now (the "i" for intelligence is a joke)

some of us have seen the OLD Mirafone 4th slides that weren't folded, rather, instead of a loop they were shaped like a "w"....
a picture of that might provide an option to the old fold-a-roney. I couldn't find said picture, someone else have one?

[TheBerlinerTuba]

Hello daktx2,

I modified a customer' horn with this issue a couple years ago.

I removed all of the original tubing and copied the layout of a B&S PT3/PT6 etc.

It was more work, but the end result was remarkable. The tuba had a significantly more open low range and the 4th slide could be used on the fly for adjustments.

Cheers,
Berliner Tuba

[Matt Walters]

I've done this many times and call it the "Megules Mod", after Carl Megules. That bottom crook where you've put on a water key needs to come off. Flip it around and cut just enough off the then now longer side that it touches the tube coming out of the bottom poet of the 4th rotor and the 4th slide outer tube all lines up. Make an extra-long ferrule to replace the short ferrule fill the gap of the now short side of the original crook and do a good job putting a sleeve inside the extra-long ferrule so there are no gaps. Solder everything together and if you do it right you will have a tack solder joint where the two lower 4th valve loop pieces now touch. You will make the 4th loop longer and can still pull the 4th slide out. If you do it well, it will fool others into thinking it was originally that way and just re-lacquered after some de-denting, etc.
You'll need a piece of inner and outer slide tubing to do it this clean, neat and actually easier way.