Projects: Cerveny 5v Eb conversion and Mira-Bach 184

[Casca Grossa]

I am going to use the two short-length 90 degree bend legs from the original first valve circuit and the donor fifth valve circuit to route the fifth valve circuit. For the slide, I will use the longest inner/outer tubes from the donor set (from the 4th valve circuit) and the crook will be a donor from a Miraphone 183 2nd valve slide.

After that, it's just a matter of cleaning up, de-denting the leadpipe, installing a larger receiver (AGR), cutting and installing the leadpipe to accommodate the new added fifth valve, and putting a new set of linkage on. Easier said than done!

I gotta say, the horn plays great. No weird low range issues, tuning is very good. This will be very nice once the fifth is added and everything's squared away.

This makes me so happy. Thanks for taking this project on @arpthark.

[York-aholic]

Oh my! I have been struggling to turn a knuckle on a valve casing for a fifth on my BBb 186. Smooshing the first valve tubing over is a great idea. Then I can use a stock casing. Why didn't I think of this!

So on that new first valve tubing, what you lose in the length of the crook, you gain back in the longer 90 degree elbow tubing?

Thank you, thank you, thank you!!!

Darn it. The same tack won't work on a 186, as the stanchion that holds up that end of the paddle assembly comes out and would be in the way.

Back to the drawing board...

[arpthark]

Here's a very rough idea of how I am going to route the fifth slide:



Rethinking it, it makes more sense to route it with a doubled-over layout. This length pictured is way too long, those L-shaped legs will need to be trimmed, etc,, but that's going to be the general plan. The outer/inner legs will also be attached to the larger crooks and those L-shaped tubes instead of the smaller 2nd slide crook, so it will be adjustable by the left hand while playing.

[arpthark]

Rough layout dry-fit just to get an idea of what the Mira-Bach frankenhorn will look like. Obviously, the bottom bow and leadpipe still have some dent work to do.

[arpthark]

I'm tabling the Miraphone thing, put all the parts in a box, and am picking back up on @Casca Grossa's Cerveny/Amati/Lignatone Eb project in earnest.

Just to recap, Brian gave me two complete Eb tubas, one an Amati/Cerveny (nicer) and one a Lignatone (plainer) but both Czech and approximately the same age, with interchangeable parts. The Amati was less beat-up, so that's going to be the main horn. I'm adding a fifth valve, swapping out the small bass trombone receiver, and doing some other quality of life improvements to the horn. I'm pulling a valve and all other spare parts from the Lignatone.

I redesigned the fifth valve circuit I mentioned earlier when it became clear geometry would get in the way to accommodate a M3 length. This means I get to return the 1st valve slide to a normal width, which should help with slide pulling.

Here's what I've done so far:

- designed the fifth valve tubing route -- this came off of the Lignatone. I took the third valve circuit and flipped it upside down, cut the wide bow (the bottom of the original circuit) and turned it into a tuning slide using the existing slide legs, which I pulled off of the 3rd valve slide and outer slides. The bottom of the circuit (the former top of the original circuit, where the tuning slide would normally be), I doubled up with a donor 1st and 3rd slide crook, and installed inner and outer slide legs from the donor 2nd valve slide, which lengthened it to a major 3rd length and also gives the circuit two pullable slides.



- removed keel



- installed new receiver, trimmed large end of leadpipe to fit the added fifth





^no clean-up at all, just dry-fit. The original receiver was bass trombone shank sized, and these German style receivers are really just sleeves over a small reverse taper. I was able to remove the sleeve and trim it at the point of the venturi, where I was able to install a receiver that will accommodate normal American shank. I spent a good deal of time yesterday picking out the dents from this thing. I used the Lignatone leadpipe because I wanted to have the Amati on hand in case I really screwed up, but it worked out well. At the end of the day, with trimming and adding the receiver, the horn plays about 10-15 cents sharp with the main slide all the way in, which I think is ideal.

Converting the linkage from the clocksprings will be tricky with the parts I have on hand, so I actually reached out to Cerveny to see about a replacement set. Barring that, we are going to experiment with coins on the paddles for added leverage, and will remove the thumb ring. These are actually some of the nicest clockspring linkages I've encountered, and quiet, too, so if we can keep them original or have original Cerveny parts, that would be ideal.

[Tubajug]

Great progress!

[arpthark]

Great progress!

It feels like I’ve done a lot more than shown because so much of it is just staring at a tuba and thinking a lot, and then playing tuba Legos for several hours trying to find viable solutions for circuitry with existing parts. Once the fifth circuit is soldered and attached, everything will go so much faster. I guess there’s still the puzzle of the fifth linkage but that shouldn’t be too hard. I have plenty of brass rod, springs and miniballs, it’s just a matter of getting them all working together!