pros and cons of reverse tuning slide

[DouglasJB]

What are some of the pros and cons of a reverse tuning slide, and why do we not see it on more horns?

[Tabor]

It is really quite simple. A reversed slide puts the small gap in the tubing caused by the slide-tubing variant being pulled out farther down the bugle than on the traditional slide, surmounted by a malleable logarithmic alloy casing. When not cryogenically treated, of course, this creates a dramatic shift on the axis of the the phrenologicoustical nodule curve placement which allows for an up to 12.62% increase in the vociferous-ness of the sub-tones, as measured by turboencabulator.

[PaulMaybery]

To quote Tabor: "phrenologicoustical nodule" That's it!!! That man is a genius. Who would have ever thought of it being a phrenological issue?
Me thinks that is sort of the case with 'psychoaccoustics' and other maladies claimed by 'hypotubiacs." Sometimes we are just not serious enough to delve into what makes a tuba tick... But perhaps a slide reversal may contribute to an identity crisis, requiring hours of vinotherapy. Wow!!!

[windshieldbug]

hours of vinotherapy

Bibereotherapy works just as well for many tubophites...

[NCSUSousa]

Trumpet players debate whether there is an advantage to having it done on the main slide. All the reversed slide does is change where the airstream bump occurs. Based on the relative size of the tubing bump that occurs, I'm sure that they would notice it much more readily than those of us playing a larger bore instrument where the main slide is significantly further from the player.

Until trumpet players can agree that it actually does something to change where that bump occurs, I'm content to leave my tuba as-is, with bracing to the outer slides and removable inner slides.

I've also seen it done on the MTS of Horns and Trombones. Again, not sure that there's anything to it other than psychology and placebo effects.

[imperialbari]

The most obvious effect is that the airstream isn’t met with a sudden restrection of the bore, but by a sudden expanse of the bore. The sudden bore restriction is bound to create some turbulences sensed as resistance and heard as noise in the sound. The sudden expanse in bore may also create turbulences, but likely of a less resistant nature.

The sick low Bb of rotary tubas by more than one writer has been associated to the situation in the first branch of the combined main tuning slide assembly. One writer tells that filling the gap before the pulled tuning slide with a piece of tubing similar to that of the the first male branch, improves the low Bb radically.

Another writer reports that a German made F tuba worked well when tested at A=443Hz at the factory. When he came home to his own A=440Hz country, the low Bb started having severe problems. His remedy was having the factory making a longer main tuning slide, so that much less pulling was necessary.

These reports suggest that a gap with its associated sudden narrowing a this spot in a rotary F tuba is problematic.

If the main tuning slide had been reversed that would change 2 elements:

The gap would occur 2, 3, or 4 inches later.

The sudden restriction of the bore after a gap would be eleminated.

No guarantee from here that this would solve the problem of the low Bb, but wouldn’t testing this attempt of a solution be quite worthwhile?

Klaus

[Three Valves]

It is really quite simple. A reversed slide puts the small gap in the tubing caused by the slide-tubing variant being pulled out farther down the bugle than on the traditional slide, surmounted by a malleable logarithmic alloy casing. When not cryogenically treated, of course, this creates a dramatic shift on the axis of the the phrenologicoustical nodule curve placement which allows for an up to 12.62% increase in the vociferous-ness of the sub-tones, as measured by turboencabulator.

You write copy for Laabs/Schiller, don't you??

[roweenie]

Ok, I'll take the bait.

I have been told by more than one highly respected (ie. at the top of their respective professions) technicians/players/designers that the place where the small end of the MTS meets the valve nest is a critical spot where a bore gap exacerbate problems, at least as far as piston valves are concerned (I have zero experience regarding rotary valves). Postponing a bore gap there can have positive effects, according to them.

YMMV

[roweenie]

I'm not the most sensitive player out there, and one thing may not do very much by itself, but I'm a believer that little things in tandem can add up to a lot.

The stock Model T engine is rated at 20 HP. The last one I rebuilt, I put several different "enhancements" in (larger valves, high-lift camshaft, high-compression cylinder head, polished ports, etc.), each one increasing the HP by small (1 or 2 HP) increments.

When I was done, I had a motor that could reach 30 HP - I know that doesn't sound like much, but an increase of 33% is significant.

[roweenie]

I'm going to guess that this procedure will have varying effects on different makes and keys of instruments (some negligible, some a little). Unfortunately, oftentimes you won't know in your particular case until it's done....

[bort]

Wasn't there some post long ago about some kind of "hack" (<--hate this use of the word!) to use spacers on a Cerveny F tuba MTS to basically achieve the same thing?

The MTS on the Neptune is reversed, which I thought was cool. Why stop there, though? Let's reverse all the slides!

[roweenie]

Not to be a math nerd but...You increased the stock 20 HP by 50% (10 extra HP). A 50% power increase is huge in anyone's book.

Thanks for the correction - I always sucked at math in school....

[Lectron]

Not to be a math nerd but...You increased the stock 20 HP by 50% (10 extra HP). A 50% power increase is huge in anyone's book.

Thanks for the correction - I always sucked at math in school....

Going back would only give a 33% decrease though......

[roweenie]

That's ok, I know my limitations, anyway...

Yeah, now I can go 50 mph in it (and with two-wheel mechanical brakes and hickory spoked wheels with 3 1/2" tires, it's a hair-raising experience, I can assure you.....)

[MaryAnn]

I was wondering how the rest of the Model T reacted to the extra HP, since the rest of it wasn't designed for that level of power. Like, if you punch the accelerator (does it have an "accelerator?") does it leave parts in the road, just like the old British motorcycles used to do? (They got faster over time because of all the parts that vibrated off.)

[windshieldbug]

So if I reverse my MTS, swedge, scoop, vent, and rotate my valves all the same direction, what is the percentage of practice reduction can I expect and still achieve the same results as if I just left the horn as is and just practiced as normal?

Not only will practice time be reduced to zero, but the horn may end up owing you practice time at the end of a gig...

[roweenie]

Mary Ann, the throttle is controlled by a lever on the right side of the steering column:



Simply put, the car doesn't, does not, like going that fast, but it's nice to know it's there if you need it....

[pjv]

Getting back to the OP's question, it was also partially discussed here.

viewtopic.php?f=2&t=6213" target="_blank

[Tabor]

All kidding aside, it does change where the bump in the airstream will occur. I could see it potentially helping or hindering, depending on what or if the bump does when it is in the different places. Cool stuff on the model T. I had no idea about the reverse pedal.

[PaulMaybery]

I'll stick my neck out here, and perhaps I'm missing the point (and bordering on being just plain 'dense') of the "bump" or "gap". But isn't the reasoning behind the reverse MTS, that of doing away with a bump or gap - by having the tubing continually expand into larger telescoping diameters? To clarify, the exit from the last valve (with the normal MTS) is met with a gap, the length of which is determined by how long the slide is drawn. The tubing decreases then in size as it goes from the gap back into the crook.

At least on the one tuba that I have with a reversed MTS, that expansion of diameter is never reduced back to what it was, but at the other end of the slide actually goes into a larger tube. (which allows for a continuation of the taper.

My take is that the reversed MTS is to smooth out the taper at that point and totally do away with a bump or gap. This should make some difference, but whether good, bad or inconsequential, is well in the mind of the beholder.

Turbulance within the air column is pretty much a given. It is what gives the horn its certain feel and characteristics. Reduce or increase that and the overall characteristic of the instrument is changed, albeit perhaps rather minuscule.

In most cases, is that really discernible?

As a side bar: I have a former student who is an instrument builder and produced a trumpet about a decade ago in which he incorporated 3 modifications that had been designed to "improve" a standard Bach trumpet. A MTS crook, a bell and a modified lead pipe. Individually each of those elements had what could be contrued as a positive change to the instrument with regard to the beauty of the sound, intonation and flexibility, etc. Each element, had as one of its purposes that of creating a more freely blowing instrument. When all three were combined, the result was dissaster as the trumpet now had very little turbulance or resistance and it basically had a very dull sound and required way to much wind. Another recognized colleague at the testing commented, that brass instrument design is "all about turbulence" and how it is treated.

So, is that little gap at the juncture of the last valve and the MTS a good or bad thing? I believe generally thinking, it has been pretty much figured into the make up of the horn and is expected to be there. Change it, well, then there is a chain reaction, however small. I happen to like the tuba that I have (Wessex Berg) which features a reversed MTS. But then it is a remarkable tuba and since I don't have one identical to it with a normal MTS, there is no way to make an A to B comparison.

Since I am an adult pro and do not abuse the tuba, I'm not worried in the least that a reversed MTS has less bracing. The ferule going from the last valve into the MTS is actually (and thoughtfully) a bit longer than the others and offers a bit more support. So it need not be an ultra-fragile situation.

There, I've already typed too much.