all four valves vented

[jsswadley]

Has any of you seen a tuba where all four valves are vented? What would be the reason for doing that? Replies appreciated. John

[skeath]

In the mid-70s, there was a popular theory that venting rotary valves aided in slurring. Wes Jacobs was involved with this, and worked with a manufacturer (RM?) to produce a model that had not only vent holes in each casing, but a groove cut around the rotor to match the location of the vent hole. I don't know if anybody ever proved if it helped. I had valves 1-4 on my Alexander vented at this time (but not grooved). I thought it helped, but it was probably my imagination. Eventually I taped over the vents on 2-4 (they started leaking), but kept 1 open, as I did work that slide while playing, and it helped a lot for that.

FWIW, I lapped the first slide with dental pumice, and made it work like a trombone slide.

SK

[tubeast]

I have had all valves "vented" on my Willson rotary BBb.
My intention was to be able to move slides before using valves, especially #4, which I happen to use as my "main triggering slide".
They didn´t quite do it right (drilled the valve casing only, but not the valve itself. Consequently, the inactive valve branch is still sealed off, as if there were no hole at all).
Whenever I used one of the valves, though, air would leak out of the hole during the switching process. "Phhhtt !!"
I figured I could live with advanced requirements on the timing for the triggering motion rather than putting up with that sound. For the same reason, I didn´t take the trouble to raise hell and make WILLSON complete the venting work.

So I simply sealed off the holes with tape (hardly visible at all) and filed the experience under "lesson learned".
Next time I might invest in a well working main slide trigger, instead. Should be the superior solution.

[bigbob]

Man I have seen the word "vented" several times what does it mean???? and what benefit does it do?? and is this just done on rotory horns?? thanks.................................bigbob

[tubatom91]

My new to me F tuba has 4 valves vented. They were vented by the previous previous owner, They leak a little if you don't have them pushed all the way into position. I could live with 1st and 4th vented and be quite happy. I wouldn't have troubles but the valve springs are extra tight and require a good amount of force to wrestle down, my 188's springs are about half the tension. But I look over these things because it's got the sound I want, I just have to keep figuring out the horn.

[tubashaman2]

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[skeath]

Man I have seen the word "vented" several times what does it mean???? and what benefit does it do?? and is this just done on rotory horns??

On rotary valves, a very small hole is drilled through the casing between the ports, so that when a slide is moved (and the corresponding valve is not depressed), suction/pressure will pull/push air around the valve (through the hole) and equalize the pressure inside the slide. Thus, when the valve is depressed, there is no "pop". For tuning purposes, a player might push in the 1st slide whenever he approaches a note that is flat on 1st valve (or pulls if it is flat), without getting blowback. Larger bore (and older) tubas often need this manipulation to fine-tune the tuning. Some players, of course, skip that step.

It is most commonly done on 1st valves, but some players will use 3, 4, or even 2 as a kickslide, and venting makes it much more practical. The late Ev Gilmore (Dallas Symphony, retired), had a kickslide on the main slide (he was a trombone player before he saw the light), but venting is not required in this case.

Piston valves can be vented, but that is probably better left to the factory. Some piston tubas come that way, but I have no knowledge of doing that aftermarket. Some one else on this board would know.

SK

[windshieldbug]

My 1974 Mirafone 184CC came factory vented on all 4 valves. The job was well done, and I can't think of any reason not to do it that way on a rotary valve instrument just in case one EVER desires to pull/push any valve.

As a practical matter, I RARELY need to pull any slide but first on that horn, and even that one not very often.

None-the-less, I have never been sorry it came that way, so why not?

[JHardisk]

The reason is that tubas are BIG. When cold air blows across the valve section (which much resembles a radiator in design) the air pressure changes within each valve loop "compartment". If pistons remained un-depressed for several seconds (as tuba players tend to 1/ sit without playing anything at all and/or 2/ play whole notes and whole rests without moving very many valves), those cooled air columns (once "released") will cause pops against the main air column and against the embouchure...


bloke "who doesn't care for those pressure-releasing 'pops' when I'm trying to play music"

I couldn't agree more! I have all my valves vented, and dislike this "pop" of air on my chops when I'm playing. Tremendously distracting!

Also, I do some slide pulling, and this helps greatly... especially with the 2nd valve trigger on the JBL!

My 6450 came vented from the factory, and I just had my JBL drilled out.

The Firebird I have at work was vented at the factory, as well.

[Peach]

Does the size of the hole matter?
I had the valves on my old Fafner vented and it definately improved slurring any running scalic passages but the firm who did the work drilled rather bigger holes than I was expecting. I think this caused quite a bit of air loss in practice?
Seems logical that the smallest of holes would do the job- just prone to filling with gunk and blocking up perhaps?
Also, there was no disassembly before the venting so the hole was at quite an angle which made the hole seem even bigger. The whole job was quite a stuff-up really...

[skeath]

Also, there was no disassembly before the venting so the hole was at quite an angle which made the hole seem even bigger.

Drilling the holes on an already assembled tuba requires a flexible extension on a variable speed drill. When I had this done years ago, the repairman put a point on some used clarinet reeds, wedged them between the slide tubes, and drilled through them, as the drill bit would slip against the metal otherwise. The holes created were centered, plumb, and level.

[Bass Flatulance]

At last year's Army Tuba Euphonium Conference Matt Walters mentioned venting of valves and it made sense to me. From the hand-out:
"VENTING VALVES

I believe venting the valves to be a good and inexpensive upgrade to any non-historical or non-leaky horn. This is well within the ability of a competent repair person but offers many opportunities for the “do it yourselfer” to mess something up. Venting the valves (rotor or piston) will let the slurred passages come out cleaner and minimize the need to do frantic slide pulls at the last millisecond. The newer and tighter the tolerances in the valves, the more dramatic the results will be.

Do not vent the valves on historic or older horns because of two reasons.
1) Horns with leaky valves (especially rotor valves) will end up with too much blow-by. It won’t play as well and will make annoying hissing sounds.
2) Historic horns that have been vented, won’t offer that “Pull the slide and press the valve to hear the pop”, that collectors want.

Piston valves are easy to vent.
1) I use a #2 counter sink drill bit to minimize the risk of going in too deep.
2) There are two places you can drill. If you target the ghost hole that is found on the same radial plane as the very bottom hole of the piston, you will have a vent hole that corresponds with the lower valve knuckle when the valve is in the up position. Here there is more space between the wall of the valve and the internal tubes in the valve.
3) Buff the area of the vent hole and clean before you put the valve back in the horn.


Rotor Valves are more work and venting is most economical when done in conjunction with a full clean and service as the valves have to be removed and the horn washed out to remove all brass slivers and sanding grit.
1) Here is the new secret to getting a better job. Drill the vent hole of the rotor valve above center. I suggest about ¼ the way down between the tubing loop knuckles. This gives more sealing area, plus keeps the valve sealed for a longer time in the stroke cycle. This decreases the chance of blow by and the rare but annoying subtle hiss some vented rotor tubas have when playing slurred passages.
2) Use a spring loaded center punch set on weak to mark the hole. Then use a #52 size aviation drill bit (about 16” long) to drill the hole. While operating a cordless drill with one hand, you can use the fingers in the other hand to English the longer drill bit into the exact spot you want.
3) Be sure to de-burr the inside of the valve casing. I use a Dremel style tool with a pointy fine grit tip to create a very small crater with the newly drilled hole in the center.
4) Wash out the horn before putting it back together."

Seems to have helped for me.

[Lee Stofer]

This procedure, as described by Matt Walters, is a mechanical way to clean-up technical passages. I have now done this on a number of instruments. For rotor instruments, I'll vent 1st, unless more valve-venting is requested. On piston instruments, I now tend to vent them all, as it is pretty easy and really seems to clean up technical passages.

I may use a slightly larger bit on a piston instrument, but care should be taken not to make the hole too large on a rotor. Matt's suggestion about keeping the hole off-center for better sealing is a very good one, too.

[Mike Finn]

This procedure, as described by Matt Walters, is a mechanical way to clean-up technical passages. I have now done this on a number of instruments. For rotor instruments, I'll vent 1st, unless more valve-venting is requested. On piston instruments, I now tend to vent them all, as it is pretty easy and really seems to clean up technical passages.

I may use a slightly larger bit on a piston instrument, but care should be taken not to make the hole too large on a rotor. Matt's suggestion about keeping the hole off-center for better sealing is a very good one, too.

Lee, is this an operation you would be able to perform for folks at the Army Tuba Conference, or something that you'd need to do in the shop?

[jsswadley]

Thanks for your very helpful responses. I decided to cover up the venting on valves 2,3 and 4 based on your advice. I think the (factory made) vent holes may have been slightly large. The horn definitely plays more effeciently, the lost air feeling went away. I will take a little more difficulty in the slurs in the bargain! John

[Rick Denney]

Drilling the holes on an already assembled tuba requires a flexible extension on a variable speed drill. When I had this done years ago, the repairman put a point on some used clarinet reeds, wedged them between the slide tubes, and drilled through them, as the drill bit would slip against the metal otherwise. The holes created were centered, plumb, and level.

There is a much easier way to do this safely. I mounted a drill bit in the handle of a jeweller's screwdriver. Using finger pressure alone, I was able to drill through the casing on my 186 in just a minute or two. Very controlled. Power tools can be too powerful in the hands of the inexperienced.

Bloke drills the hole off-center, above the centerline of the two valve-branch knuckles, close to the edge of the figure-8 cutout of the rotor. As long as the hole opens into the cutout, the tubes are vented when the valve is not in use. The off-center hole is less likely to leak--it will not be in the thinnest part of the rotor surface between the cutouts when the valve is IN use.

A piece of tape will not cure leaking--the valve branch can still leak across the hole when the valve is in use. The hole has to be filled and then filed smooth on the inside to prevent that. But that doesn't mean the valve isn't leaky otherwise.

As to the puff of air coming through the hole, that is only audible within a short distance of the instrument.

I have vented the first valve on my Miraphone 186--but the valves on that instrument are pretty worn now and I would want to have them restored before venting the rest of them.

All the valves on my piston instruments are vented. Matt Walters vented the valves on my York Master, and bloke vented them on the Holton. I vented the valves on my Yamaha 621. Given the difficulty in drilling a proper hole in the piston (techs use a carefully constructed jig to prevent accidents), I used the cut-off tool of a Dremel to cut a slot instead of a hole. The slot runs lengthwise on the valve and works perfectly.

As much as anything, the venting allows me to pull and dump slides without having to hold the valve down.

Rick "preferring vented valves" Denney