Leadpipe design/profile

[Daniel C. Oberloh]

Some pipes taper all the way to the 1st valve, others may be cylindrical to one degree or another. Parabolic pipes exist as well. Really, there are a lot of combinations, some work well while others not at all. I have removed a couple 45SLP pipes in the past having found it to really not be working that well on a particular 2165. Same with a 2155. Thats not to say it would not work on other examples. In those cases what I made to replace what had been substituted previously, got the horn playing very respectably but was not even remotely similar to the 45SLP but probably equally different then what was originally on it when new. Go figure.


Daniel C. Oberloh
http://www.oberloh.com" target="_blank

[MikeW]

According to legend, John Fletcher had the mouthpipe from a cavalry tuba fitted to his Imperial Eb, to bring the mouthpiece down to a convenient height (also fixing the tuning). This was a shorter mouthpipe, so it had to flare/expand more rapidly than the original. This turned out to be perfect for the horn, giving it a much wider dynamic range. When the Sovereign was launched (effectively a re-badged Imperial with stainless-steel pistons), it came in two models: the 981 with the rapid-expansion Fletcher mouthpipe, and the 982 with the original Imperial mouthpipe (longer than the Fletcher model, with an even taper along its full length).

A later revision of the 981 adjusted the bell-flare, and moved the mouthpiece back up to its original height. This required a longer mouthpipe, so B&H/Besson made a compromise mouthpipe that had the magic rapid-expansion taper at the mouthpiece end, with a cylindrical extension at the valve-block end. Some say they didn't get it quite right, and the late-model 981 lost some of its mojo.

The mouthpipe from the late model 981 could be installed on a 982 (or on an Imperial), but the ferrules were different: the Imperial and the Fletcher-model 981 had tapered ferrules to match the taper of the mouthpipe, and the late-model 981 had a cylindrical ferrule; The two types of ferrule were not interchangeable. However, it has been mentioned on TN that at some point the mouthpipes on the 981 and the 982 became identical, with the same part-number (and presumably the same ferrule). I don't know what the situation is with German-built Sovereigns.

It has been suggested on TN that the mouthpipe on the Chinese 981/982 clones may be cylindrical, with no taper.

Thus variants of the same basic horn exist whose mouthpipes are (or may be):

• Evenly conical along their length
• Conical at the mouthpiece end, then cylindrical at the valve-block end
• Cylindrical along their full length

[iiipopes]

And then there are the tubas, both "ancient and modern," that have a loop or return in the leadpipe with or without a tuning slide and with or without a water key, just to complicate matters.

[windshieldbug]

And then there are the tubas, both "ancient and modern," that have a loop or return in the leadpipe with or without a tuning slide and with or without a water key, just to complicate matters.

Which also make the effective bore at the valves much smaller (later in the bugle)...

[iiipopes]

And then there are the tubas, both "ancient and modern," that have a loop or return in the leadpipe with or without a tuning slide and with or without a water key, just to complicate matters.

Which also make the effective bore at the valves much smaller (later in the bugle)...

Indeed.

[toobagrowl]

I will just say that in my experience messing with my tubas' leadpipes and mpc receivers makes a BIG difference in how the tuba plays/responds. I have trimmed and 'floated' the leadpipe on my rotary M-W CC (a couple times now), and the tuba plays noticeably different now -- it's more responsive. The sound is a little more vibrant now; perhaps slightly 'brighter' than it used to be -- I can 'bark' out stuff easier than before. I may try a different mpc receiver on it someday, but am happy with it so far.
I've also swapped out the mpc receiver for a different one on my Eb and adjusted it slightly on the bell, and it responds slightly easier for some mid-upper notes.

I am a full believer that adjusting/altering/swapping out mpc receivers and leadpipes makes a BIG difference in how your tuba plays. I liken it to switching mouthpieces, but more 'permanent' since the mpc receiver and leadpipe are attached to your tuba.

And then there are the tubas, both "ancient and modern," that have a loop or return in the leadpipe with or without a tuning slide and with or without a water key, just to complicate matters.

Which also make the effective bore at the valves much smaller (later in the bugle)...

Maybe I am misunderstanding you...but don't you mean the opposite? Since most rotary tubas tend to have larger bores than comparable piston tubas (longer leadpipe -> valve cluster further down the bugle-? bigger bore)

[iiipopes]

Maybe I am misunderstanding you...but don't you mean the opposite? Since most rotary tubas tend to have larger bores than comparable piston tubas (longer leadpipe -> valve cluster further down the bugle-? bigger bore)

The key word is "effective." And you are right to a degree. The comment above relates to two tubas with the same valve block with different length leadpipes. Take, for example, two upright valve tubas, one with a "straight in" leadpipe, like a Besson, and the other with a loop in the leadpipe, like many older American upright valve tubas. The valve block in the tuba with the loop in the leadpipe is effectively smaller, although it is the same bore valve block, because it is retaining its bore diameter farther downstream where you would otherwise expect the conical profile of the bugle to be larger in diameter.

Now, take two disparate examples, say, a front action Besson 993 with a .730 bore and a Miraphone 186 with a .770 bore. The leadpipe to the Miraphone, taking the circuitous route along the bugle, puts the valve block farther downstream than the relatively direct-in Besson. So the bore of the valves in the Miraphone is enlarged accordingly to match the conical profile of that point in the bugle.

[Donn]

I think I like tooba's version better. If two tubas have the same valve block, they don't have different bores, "effective" or otherwise.

For sure, it brings up a serious problem with this notion of bore size as a fundamental measure of a conical horn, but "effective bore" isn't really enough to correct that measure, is it? Because even if bore size were measured at the same distance from the end, two tubas could have the same measurement but be very different sizes in total volume, and different playing characteristics, due to different rates of taper. So ... while bore diameter does convey something about the tuba, it isn't and can't be a rigorous measure, it just is what it is -- measured at the valve section, the only place where a tuba has a bore.

[MikeW]

My aged Couesnon Eb has a loop in the mouthpipe, which acts as a condenser to keep water out of the main body of the instrument, and is also the main tuning slide. This length of tubing is conical between the receiver and the tuning slide and through the bows, and again between the slide and the first valve, with the second branch of the tuning slide having a bigger bore than the first; the whole length between the receiver and the first valve is thus approximately conical, so it does not restrict the bore size through the valves.