TubeNet

Hi-
Just curious re. JinBao over the rotor turning of their 410 model 186 CC clone. When I got a stenciled JinBao in lacquer a while back, all the rotors-#1-4--moved in the same direction. I just got a silver JinBao model 410 186 CC clone today, and now it is like the old way--rotors #1&2 move in one direction, and rotors #3&4 move in the other direction. It is not a big deal--a tax write off to have my repairman 'turn' rotors 3&4 (and some loot in his pocket besides!), but I am curious why and when JinBao changed this--anybody know?

Thanks-
mark

question what is the benefit of having all the rotors turning in the same direction is it a styling issue or is there a mechanical reason or advantage?

sousaphone68 wrote:question what is the benefit of having all the rotors turning in the same direction is it a styling issue or is there a mechanical reason or advantage?

Hi-
Think of a hallway with 4 doosr--the first two you push to open, and the next two you pull to open--you would have an 'interruption' of air--this is nothing new--the old King rotor tubas even had their rotors move the same way. It makes slurs smoother--example 1st mve't Prokofiev 5. Some people find this to be true--others don't find a difference--I am one of those that feel a difference having them all move in the same direction--nothing cosmetic, just for 'smoother' playing...

mark

bloke wrote:I feel ya' man.

My old B&S Symphonie F tuba has the horrible/unplayable contrary-motion rotor design. I finally gave up on it, stomped it flat, and threw it in my pile of brass scrap. I will not tolerate anything that destroys the playing characteristics of an instrument as much as rotors going "that-this" (as opposed to going "this-that").

that is disappointing to read I just got a Cervenyish! tuba from ebay nice and cheap it has two rotors that go one and two another had not noticed any major sound problems other than my not knowing how to play Bb

I have never understood the principal of having all valves rotating the same way. In playing you are not always putting all valves down, or up - sometime one will go up and another down - so does it really matter which way they move? They have got to move upstream either going up, or down

I have never noticed a difference either way

The difference in the 186 clones makes me wonder "are they all made in the one factory, or does Jinbao sub-contract some parts production?" I don't know!

jonesmj wrote: Think of a hallway with 4 doosr--the first two you push to open, and the next two you pull to open--you would have an 'interruption' of air--

I'm not sure I like this analogy. When rotor valves turn, they do not 'enter a doorway'. They do not expand back towards the air stream, or for that matter, away from it.

A better analogy would be to think of a hallway with four automatic sliding doors, the first two sliding left, the second two sliding right. In that case, I don't care what the doors do, so long as they open when they're supposed to...

Andrew (who's not saying that the direction doesn't make some difference, but hates sloppy analogies...)

Oh crap! You guys are right. I never thought about this, but just checked my Cerveny 781 and also the Amati oval euph (which, let's be honest, is almost certainly a stealth Cerveny). In each case, two of the rotors rotate counterclockwise and two rotate clockwise. No wonder I have trouble with some slurs. This is a very valuable discovery.

Maybe at some point JinBao realized that they hadn't correctly cloned what they intended to and changed to the inferior conflicting rotation scheme in a pathetic attempt to make the instrument seem more European (or at least, maybe, more Czech).

But maybe the opposing rotor configuration reduces turbulence effects in certain valve sequences (both externally and internally). More study is called for. (I'm still trying to get my head around the door analogy. Don't they have to be revolving doors?)

the elephant wrote:Joe,

Get a penny. Face me. I am facing you.

YOUR penny has a relief of Lincoln that faces to your right. But MY Lincoln faces to your left. I will sell you MY penny for one million dollars.

Yeah, but what about *my* penny? My penny has a relief of George W. Bush. Does that make it worth more?

Jeff "Wondering..." Benedict

Neptune wrote: The difference in the 186 clones makes me wonder "are they all made in the one factory, or does Jinbao sub-contract some parts production?" I don't know!

Hi-
I am really beginning to think the same thing. This silver186 clone seems to have better bracing and all the slides are in alignment-toe, it looks like it was put together using a jig (yeah!)- similar but different (luckily in a good way) than my old lacquer 186 clone.
Mark

P.S. Why even bother asking questions on Tubenet anymore.. it is getting to be a waste of time....

I had the rotors flipped on my old 186, thinking it would solve a problem with sluring using the 3rd valve... after the "fix" I still had a problem. What solved the problem was practice. It took throwing money at the horn to figure that one out. Some people swear by this "fix". It sure "fixed" me.

*

bloke wrote:OK...enough of all of that, and a possible guess (??) at what may have happened with your instrument.

Is this scenario plausible?

- That instrument was built at an earlier time.
- The buffing-guy had an accident with it, and it was set aside.
- They later replaced or repaired the damaged part, refinished the entire instrument, and shipped it out.

JinBao only make instruments to order, so they would not have replacement if there was an accident - more likely the order would be delayed in your scenario. Seeing my recent order is one month late from the factory, delays do happen

I'm going to charge $1,000.00 more for "same direction" rotors!

Al

ghmerrill wrote:..... Maybe at some point JinBao realized that they hadn't correctly cloned what they intended to and changed to the inferior conflicting rotation scheme in a pathetic attempt to make the instrument seem more European (or at least, maybe, more Czech).....

Oh, my! Think maybe the Germans might be making making rotor assemblies for JinBao?

I was disappointed earlier on in the thread and went off and tried different rotor combinations and did not feel any difference in the stuffiness or air flow.
In my opinion it looks to be as easy the factory to mount them all turning the same direction as it was to have them two clockwise and two anticlockwise.
So I can only assume it is done two and two for either an appearance reason or there is an ergonomic reason.
I have not studied instrument design and have for the last 30 years played only top or front action piston tubas and sousaphones.
So I was completely taken by surprise by how good rotors as a design are. Even on my questionable origin Cervenyish Bb of at least 40 years of age that has some very poor construction and light weight brass the rotors all though not stainless steel and have had a serious pitting problem repaired in the past still work smoothly quietly and even when bone dry. (recently bought on eBay)
I am that impressed that I am thinking about getting an Eb rotary valve tuba.

TubaTinker wrote: Oh, my! Think maybe the Germans might be making making rotor assemblies for JinBao?

An interesting hypothesis. But it may be even more complicated -- as in the case of a number of software development scenarios now where development of stuff in the US is outsourced to India, and the Indians turn around and "re-outsource" their work back to the US. It is -- and I know this may be shocking -- that unknown to the world, the Germans are making parts for the Germans and the Chinese are making parts for the Chinese. But this is clearly just fanciful speculation.

The Bone Ranger wrote:

jonesmj wrote: Think of a hallway with 4 doosr--the first two you push to open, and the next two you pull to open--you would have an 'interruption' of air--

I'm not sure I like this analogy. When rotor valves turn, they do not 'enter a doorway'. They do not expand back towards the air stream, or for that matter, away from it.

A better analogy would be to think of a hallway with four automatic sliding doors, the first two sliding left, the second two sliding right. In that case, I don't care what the doors do, so long as they open when they're supposed to...

Andrew (who's not saying that the direction doesn't make some difference, but hates sloppy analogies...)

Hi Mark!
Glad you're happy with your Tuba! I have to agree with the 'Ranger, though! Wether pistons or rotors, the direction of travel has no influence on sound or articulation, IMHO! Try slurring up and down, one valve at a time. Then reverse to down up. I tried for 1/2 an hour to see if I felt any difference, but could not feel any! I played on my 25-J, a St. Pete, and a Mini. It didn't feel any different starting with a piston or rotor actuated, either. I think many of us are thinking that we're pushing the sound through our instruments. Remember iiipopes' cigarette smoke post of a while back? If we're really moving the sound by pushing air through the bugle, then why does it take so long for the cigarette smoke to exit the Bell? Sound moves Through the air at Mach one. There's no way we humans can produce and/or sustain such air speed!
The function of air in brass playing is to initiate a vibration, much as a drum head does when struck by a stick or mallet. We can sustain that vibration as long as our air supply holds out. A Drummer must constantly "attack" a drum head to maintain the same level of intensity/volume. Our air stream peters out as soon as it exits the bowl of our mouthpeice, and the "disturbance" we created is sent on it's way until all the "energy" we initially gave it is dispersed...
The diameter, shape ( conical and/or cylindrical ), and length affect only the wavelength of the vibrating air. The bugle amplifies the sound of our instrument because the vibating "disturbance" we set in motion is protected from dispersal into the unaffected air over the length of our instrument! This also helps one to understand why a French Horn and an F Tuba, Two instruments of identical bugle length, sound so different, and play so well in different areas of their potential range. The "protective" bugle also limits the developement of wave length(s) on their way through the instrument! The higher a given pitch, the shorter it's wave length, and the energy needed for us to "hear" a pitch decreases as pitch rises! When we add/subtract tubing via rotors or pistons we momentarily cut off the "disturbance". Do you notice any "gap" in your sound during a slur? Not when the sound's traveling at Mach one inches from your ears!
Now go enjoy your new Tuba!

Al

Al-
Thanks--but I know what works.
mark

Mark,
That's what REALLY counts!
Al

TubaTinker wrote:

ghmerrill wrote:..... Maybe at some point JinBao realized that they hadn't correctly cloned what they intended to and changed to the inferior conflicting rotation scheme in a pathetic attempt to make the instrument seem more European (or at least, maybe, more Czech).....

Oh, my! Think maybe the Germans might be making making rotor assemblies for JinBao?

In Frankfurt?