Yamaha YEB-321 Conversion from top-action Eb
to front-action Eb with additional 5th valve
This was an 'interesting' project. My customer requested me to make a front-action Eb tuba out of a top-action tuba. The logic was that he liked the open bugle of the YEB-321 but didn't like the top-action valves. Makes sense to me since I have no use for a top-action horn in my stable at all.
I started with a perfectly good Yamaha YEB-321. The first operation was to remove the valve section from the horn and take apart the bugle. Once that was done, the bugle had to be 'reversed' into a front-action bugle.... meaning that the leadpipe needed to be mounted to the opposite side of the bell.
The next step is to 'harvest' a 2nd piston from a donor valve section to add to a 3V section to create the 4V valve section. This is done by cutting the cross-ports in and out of the 2nd valve leaving as much length on the port as possible. This means that the #1 and #2 casings are now going to the scrap heap. That's OK with me. I keep the spare #1 and #3 pistons. They are the ones most likely to get damaged on a 3V horn, anyway. It's good to have spares around. I like to use the King .688" valves sections. The bore is a good choice for many applications and there are plenty of them out there.
The old 3rd casing is connected to the new 4th valve by making a contoured sleeve. The contour is necessary to get as much solder-seal area between the casings as possible... for strength... and to prevent leaks. In the left-hand picture, I'm using a caliper to transfer the contour of the casing to the sleeve. I like to use silver-bearing solder instead of regular soft solder to make this assembly as it's may times stronger. In the right image, I've yet to add the 'nubs' to the top and bottom 'nubs' on the casings.
The above images show the build-up of the 1st, 2nd, and 3rd tuning circuits. This valve section will have slides at the bottom for tuning and slides on the top for making adjustments 'on the fly'. I won't build the 4th valve circuit until the valve sections is mounted on the bugle. Note that all of the tuning circuits had to be cut from BBb to Eb. Some of the parts in the valve section are a mix of King, Olds, and Reynolds components. Some of you may have already noticed that the ferrules are Reynolds.
Above you can see the build-up of the fifth rotor and the right hand picture shows the valve section now mounted on the horn. The rotor came from a no-name European Eb tuba with a .684" bore.... very close to the bore through the rest of the valve section. The 5th valve is tuned to a flat whole step.
Above is a picture of the start of the configuration of the 4th valve. I saved this for after the cluster was mounted on the horn since it is the longest tuning circuit and would eventually have to be braced to the bugle.
Below are several images of the finished product. The thumb-ring is adjustable. The horn plays great and has the biggest bottom end of any Eb I've had my hands on.
And.... the backside looks as good as the frontside!
Page created on October 22, 2009
Last edited on October 22, 2009