TubeNet

Everyone wants their horn to play to the best of its ability; sometimes minor tweaking is done, and other times major tweaking is considered. My Miraphone 1295 (which replaced the 1290) is considered by some to be somewhat stuffy, and quite possibly so. I believe this was one of the reasons it was replaced by the 1291.
I saw a picture of a 1290 on here for sale and noticed how open the 4th valve wrap was. My 1295 has 3 sharp 90 degree bends in the 4th valve wrap.
My questions to the smart guys are:
1. Am I correct that an "open wrap" is one that eliminates sharp bends in its path?
2. If the 4th valve wrap were re-done to eliminate the 3 sharp bends, what are the odds this would make a major improvement in the sound?
3. Would this be a minor or major modification?

The 1295 also has a different leadpipe than the 1290; nickle silver vs. brass. I do not know if any of the dimensions are different.

Avoid tight turns on the bottom. They tend to gurgle with only a little water.

Is it beneficial to keep tubes round in cross-section through bends? If so, why--if not, wy not?

Just curious.

Open wraps were made to open up the sound by removing sharp bends in the wrap. This is referred to in the trombone world as resistance. You are right on the mark in this aspect. The comparison suggested in the Bach model bass trombones is a good starting point.

Where the tuba is going to have a setback is the valves. Since tuba manufacturers have not utilized the axial flow valves, you will find that there are 6 sharp bends in most valve/wrap units. (the four wrap bends and two in the valve)

[No, I do not advocate developing axial flow valves for tubas.]

What is not being highly publicised is that some (not all) people like a little resistance so that the ability to get pedal and real low notes is helped a little.

There are other places where resistance can be eliminated without having to cut the horn. The size of the throat/bore inside the shank of the mouthpiece is the most common area.


Tom Mason

I have never seen a study which shows that an open wrap offers less "resistance" than a closed wrap, empirical evidence notwithstanding.

I admit its popularity but I would still like to see a study.

The closest thing to a formal (or informal) study is the Miraphone 1291/2 with their asymetrical tubing. By their account, the asymetry eliminates an acoustic reflection.

I've often wondered if the 180 degree, 2nd valve turn, created acoustic problems in a tuba but I haven't seen any research. Old Cerveny's used to have an "eyedropper" shaped 2nd valve slide but they eventually abandoned it.

Anybody got research on the resistance of the open wrap?

I will admit that I have not seen written research as well, but my experience came from playing a Holton TR 181 at the time that Bach started buildong the open wrap 50B3.

I was in graduate school working on a bass trombone degree and playing a TR181. For those not familiar with the TR181, it has a closed F trigger, and an open Gb/G second trigger setup. For my playing, I noticed that my 1st position low F and C were a little stuffy, as well as having some tuning tendancies to be a little flat. I started playing the low F/C in second with the second trigger and pulling in a little to get better pitch and a more open sounding note. (from my perspective)

I sold the 181 and got a 50 B3OLG, and noticed more consistency in sound from 1st and 2nd trigger notes. This held true no matter the mouthpiece.

From that time on, I have not noticed as much difference between valves, except for the speed in which the transition from no valves to a valved section note happens. Some of this is due to the reduction of area that the valve has to rotate to get from one port to the other, and the elimination of some of the angle of deflection of air in the valve.

Yes, much of my statement is from personal experience and not from imperical data. There it is though, for what its worth.

Tom Mason

I appreciate the difference between your trombones but comparing two different makes is like comparing apples and bananas.

I can't even imagine a scientific test to make the determination but if you used a Bach 50 with a detachable valve section and had 1) a closed wrap valve section 2) an open wrap and 3) Thayer valves to interchange; then you could try to measure "resistance." What a challange that would be.

I wonder if any of the major orchestra bass trombonists have done something like this?

I compared two different wrap setups on the same horn. I did not make the observation based on comparing the 181 to the 50B3. The comparison was made on the two different wraps on the 181.

I will concede that there are some trombone players who will tell you that there is not a significant difference between the two wraps, as well as different valves.

Tom Mason

Hey, Tom -- I appreciate your reference as to whether or not there is a "significant" difference, rather than what most people would oversimply say as no difference. Because even in the expression of it, there is a difference.

Sorry for what looks like doublespeak. I just finished a long post on the difference in the two concepts in another thread.

I can believe that a trombone player can tell the difference between an open wrap and one that's wound up tight as a pretzel--after all, a trombone (without the valves) has a wrap that's about as open as one can get. About the only way to improve on it would be to eliminate the bell crook and have the bell fire backwards.

Tuba players clearly don't care a fig about the "open wrap" thing or we'd all be playing sousaphones or pit tubas. We'd be scorful of the narrow-body rotary-valved German tubas like the Miraphone 186.

And we'd cherish the tall horns like the Besson New Standard, which managed to avoid a full loop of the main bugle.

The squat Yorks with their very tight wrap would be anathema.

I believe that the closest things we have to modern open wraps are the Jupiter 582 and the Thein tubas that cost an arm and a leg. Not having any experience with the Thein horns, I have to speak from the Jupiter experience that I do possess.

The experience that I have suggests that there is still more that tuba player can accomplish from experimenting with throat size. Being able to play on a horn with a graduated bore size through the valve set may be a better way to get a more open feeling and sound.

I have played some horns that feel more open than my 582, and some that feel less. Both extremes come from differing sizes of horns in both the dimemsion of instrument and bore.

Tom Mason

On some of the tubas that I've built I used a rather tight, 2nd valve style, crook for the 5th valve slide. On others I've used a wider crook. It's impossible to tell any difference between the playing characteristics of the two versions. In the bore sizes of tubas it's hard to believe that the openess of the wrap really effects the resistance to the air flow. In fact the amount of air that actually flows through the instrument is pretty small compared to to size of tubing. My findings indicated "resistance" mostly comes from the instrument vibrating unsympathetically to the pitch that the player is trying to produce. This becomes a study in bracing and damping unwanted "ringing" in the horn.
FWIW