Pan American Eb 4V Conversion
GADZOOKS! Look at all of them parts!
The project here was to take an old Conn Pan American Eb 'monster' and get rid of the old top-loader three pistons (which were shot!) and build a new four-piston front-action valveset. The donor horns for the new valveset were two Conn 14K sousas. First, the old valveset was removed. Then, the #2 piston was harvested from one of the 14K valvesets... cutting the #2 piston free from the other two and leaving as much of the bugle tube as possible. After trimming the exit of the #3 casing and the entry of the new casing, a sleeve was made to connect the two. It's important to get the mating parts to fit perfectly. Otherwise, there could be problems with the transition between the old #3 and the new #4.
We'll be using the Conn sousa main tuning slide so a transition needs to be made to mate up to it, too! The picture on the right below shows the cluster and main tuning slide assembled. It nice to have a large assortment of ready-made used parts available. If I had to make all this stuff, it would take weeks. Besides, having lots of parts gives me the chance to choose from a wide variety of pieces. If I dig around long enough, it seems that I can always come up with something that will work.
Once the cluster is assembled, it's time to see how it will mate up with the rest of the horn. By-the-way... I've already taken lots of measurements of the lengths of the old parts and compared them to the length of the parts I plan to use. By luck, what I am taking out is almost exactly the same as what I'm adding back in... so the horn will remain an Eb. One thing, though.... the three valve circuits are from a BBb sousa, so they will have to be cut down accordingly. The picture below shows how cleanly the match-up was to the new valveset. Things has to be juggled around a bit, but the exit of the old sousa main tuning slide is the same bore as the entry point of the old part of the Eb tuba. This is the result of a good bit of planning, and as I mentioned before, having a wide assortment of usable parts. Note how nicely the main tuning slide lays in with the bottom bow.
Next on the agenda is to fabricate a new leadpipe and fit the valve section to the tuba. The new leadpipe is a standard off-the-shelf variety that come filled with pitch so it can be bent without kinking. A little trial and error and it's ready to melt the pitch out and mount it to the horn. The valve section is supported during this operation with a couple of temporary braces. I will mount the leadpipe so it is supported by only a brace at the receiver. It won't be soldered to the bell.
The next move is to alter the valveset for Eb intonation and build the 4th valve wrap. The 4th valve will be tuned to emulate valves 1 and 3. Note that all tuning slides, crooks, and tubing are from the donor Conn sousa valveset. In the picture below you can see the 4th valve wrap. Notice that there is a tuning slide at the top AND the bottom of the 4th valve circuit. This was just a matter of convenience since I had plenty of parts, anyway. Also, I have most of the bracing in place now. Remember that the valveset was only supported by the main tuning slide and the leadpipe up until now. Braces were cut to length and added so as to not apply any pressure that might distort the tubing or valve casings.
Below are a couple of shots of the finished product. I had been cautioned about generating some serious intonation problem by using the larger bore (.737") sousa valveset. The old bore was .697"... not really that much smaller. The key to the whole thing working was the fact that there was a good match between the new main tuning slide and the old horn. Note that all the valve tuning slides are on top! This took a little extra work, but I think the owner will be pleased. I don't know if he's a slide-puller or not, but it sure makes things convenient for making those minor tuning differences.
And finally!... here's a pictue of the Eb 4v Conn alongside of my BBb Marzan. The Marzan is on the right.
Oh yeah... you might be curious about what a conversion like this might cost. Well... you need the Eb tuba to start with... (maybe $1,000) Then, you have to find two good 14K or 36K sousa valvesets... (maybe another $1,000) After that, you might be looking at $200 or so for misc. parts including the new leadpipe, springs, corks, felts, etc. Once you accumulate all the stuff (which could take quite a bit of time)... (and maybe $2,400)... throw in another 30 or so hours for labor. You do the math... perhaps $3,500-$4,000 so might cover it. IF you don't have to make any trips to the emergency room for burns, etc.!!
Email me if you have questions:
This page created on October 4, 2007
Back to home page