30K TO 20K swap????

[Bandmaster]

A while back I picked up a 1926 Conn 30K Helicon that is a fixer-upper. I was going wait until after Christmas to decide if I was going to fully restore it or just make it playable and keep it "rustic" looking. Then I had a thought when I saw a 20K body for sale. Maybe it would be easier, cheaper, and kind of cool to swap the main wrap with the bell from the 30K on to the 20K body? The 20K seems to be in pretty good shape, few dents and no missing parts, unlike the helicon. The larger tapper doesn't seem to start until the final wrap on the 20K and the bore appears to be the same. The only thing that is confusing is that the tuning slide on the 30K is much longer. (See photos below)

My question for you repair / techie types is why would the tuning slide be so much longer? Is the bell section shorter requiring the extra length to be made up in the tuning slide? If so, would this swap be doomed to a poor (tuning) outcome? I thought a helicon with short stoke valves might be interesting... if it would work. It would definately be cheaper than retoring the horn or trying to fix the original valves. What do you think?

The 30K's valve section:


The 20K body:


The full view of the 30K:

[Matt G]

Do it.

[Bandmaster]

...and I didn't stare at your helicon picture very long, but if that helicon is the "sister" to the 14K/32K sousaphone (rather than the 20K/38K sousaphone) you will run into tremendous (read: virtually insurmountable) problems swapping that helicon bell for the 20K elbow-and-bell.

I took measurements and up to the ferrule where the first brace from the valve set is (about where your left hand would hold the horn) it seems to be the same. I had it sitting right next to my Conn 38K to do the comparisons. The tapper in the main wrap and bell changes from this ferrule to the end of the bell, but the rest mearsure almost exactly the same. But even my 38K has a shorter tuning slide and it does not have the short stroke valves. So what are these "virtually insurmountable" problems? I am just trying to see if it is worth my while to buy the 20K body.

[Bandmaster]

If I already owned the 20K and the helicon, I wouldn't do any body-switching...fwiw

bloke "I don' need no short-actions"

Even if the 20k was missing the top brace and had no bell? The 20K I have my eye on is for sale without a bell... and is only going for a little over $100 right now.

[imperialbari]

Projects of the type which you plan have been carried out by another contributor to this thread. Twice.

First a York body and bell ending up in the pitch of Eb.

Next a Buescher body and bell ending up in the pitch of CC.

For me the striking fact is, that in both cases the bells were taken from tubas, not from helicons.

What my sense of dimensions cum proportions tells me, is this:

You will have to un-mount the body knee from the 20K body.

If you will make the bell from the helicon fit into that ferrule, then you will have to cut it so close to the flare expansion, that the combined tubing will be too short for keeping the pitch down into BBb. If it will end up in plain BB natural or a bit more flat or a bit sharper is impossible for me to tell from the photos.

If you want a helicon based on the 20K body, then you will need a bell from a fairly large tuba to get the combined tubing sufficiently long for a proper BBb pitch

And then the master craftsman on this matter has pointed towards an inherent problem in the project as laid out by me: the resulting instrument will be too front heavy for a comfortable carrying situation.

I wouldn’t mind owning a full size BBb helicon. I have a German one in Eb, which rather is a circular valved bass trombone. And no, it was never intended as a cimbasso. It comes out of a German tradition for marching fanfare bands.

Sousaphones in my eyes and ears are generally underrated, at least the better ones. My Conn 40K is a marvellous tuba. And yes, it is very unwieldy to transport and impossible to march due to its massive weight. But then it was made for the pre-PA dance bands from before 1930.

And then it has a problem, which really scared me the first time I experienced it. The 40K was placed in its Wenger chair. I stood in front of the bell and talked to somebody standing behind the 40K. When I opened my mouth, I sounded like somebody talking in a huge and empty cathedral.

With all due respect towards your project: I think it is a stillborn idea.

Klaus

The projects mentioned above here may be seen documented here:

You will have to join this gallery group of mine to get access to the following 2 links:

http://launch.groups.yahoo.com/group/Yo ... cPhotos20/

Thumbnails of a custom York helicon with detachable bell made out of a York Eb sousaphone and a York Eb tuba bell by Joseph Sellmansberger in 2001:

http://photos.groups.yahoo.com/group/yo ... hable+bell

A .pdf document, where Joseph Sellmansberger tells the story of the above instrument (132K) can be found here:

http://groups.yahoo.com/group/YorkMaste ... s20/files/


You will have to join these two of my gallery groups before getting access to the following links:

http://launch.groups.yahoo.com/group/Yo ... cPhotos51/

http://launch.groups.yahoo.com/group/Yo ... cPhotos54/

Thumbnails of a Buescher custom CC helicon 4P+1R made by Joseph Sellmansberger of Memphis - Tennessee out of a BBb helicon body and an Eb tuba bell with Buescher waterkeys and guard strips:

http://photos.groups.yahoo.com/group/yo ... n+4P%2b1RV

The bell engraving of the above instrument masked before sandblasting:

http://photos.groups.yahoo.com/group/yo ... asking.jpg

Links to discussions on the above project:

http://launch.groups.yahoo.com/group/Yo ... s51/links/

Joe owns the copyright of all photos’ material linked to. He has allowed me to make use of it.