TubeNet

hey guys/gals,

this is something that i've always wondered and just appeared to me while reading up on the new MW kodiak. what are they and is this feature only available on rotary tubas? what is the benefit/effects of this feature? in the article it said that the valves were vented and made slurring easier. is this true? thanks!

ps. Roger Lewis, if you're reading this, the site looks great and i'll hopefully see you at TMEA.

When the valves are in their 'closed' position (not being used), the valve tubing is sealed off from the outside air. When you pull or push this tubing in preparation for a note, when they are opened, you get a 'pop' of air. Venting puts a hole in the normally unused part of the casing to prevent this.

If you pull out a tube slide with the valves open, and the valves are in decent shape, you will hear a 'pop!'.

It is easiest to do on rotary valves, since you know where the vent should be. Piston valves can be done, but it's a little more complex. IN EITHER TYPE OF VALVE, DO NOT TRY THIS AT HOME, because if you're not used to correctly performing a vent, it can be VERY injurious to your valves.

Venting ONLY makes sense if you are used to manipulating your valve-slides as you play. If you do, and the valves are not vented, then when you open the valve, you will have a resulting 'pop' in (or out) as you play.

I just recently did a masterclass with Alan Baer and his new Kodiak tuba. I got a chance to play it, and I have to say...the venting on all the valves DOES make the slurs easier. It takes away the pop and the back pressure every time you have a bad valve combination. Since that course i've actually gotten the venting done to both my horns on all the valves. I really see no dis-advantages to doing it. Blow a few notes on the kodiak and you will see. -Joe

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Tubaguyjoe wrote:...venting on all the valves DOES make the slurs easier...

I agree venting makes slurs smoother & easier. I'm a home machinist and vented my own piston valves, with the right tools and skills it doesn't take long. Play testing before and after (about an hour apart) proved to me slurring was smoother and easier. It is hard to notice but unvented valves do have a slight pressure pop that happens when slurring, this has nothing to do with slide pulling.

Someone mentioned trills are more difficult with vented valves. Anyone have an opinion on trills? I didn't do a trill test before and after...

Bob

Bob Mosso wrote:

Tubaguyjoe wrote:...venting on all the valves DOES make the slurs easier...

I agree venting makes slurs smoother & easier. I'm a home machinist and vented my own piston valves, with the right tools and skills it doesn't take long. Play testing before and after (about an hour apart) proved to me slurring was smoother and easier. It is hard to notice but unvented valves do have a slight pressure pop that happens when slurring, this has nothing to do with slide pulling.

Someone mentioned trills are more difficult with vented valves. Anyone have an opinion on trills? I didn't do a trill test before and after...Bob

I might add for those without the skills or daring of Bob above that having your valves done by a professional repair person is very inexpensive. I had a couple of valves done by Lee Stofer and was both very pleased with the outcome and the cost.

Alan Baer posted a good 'how to' about doing pistons about 2 years ago. Here's a direct link:

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[Although I don't usually pull slides on my euph, I do sometimes hear some popping during slurred passages. I've considered having this done to my euph... but since it's compensating, I wonder if each piston would have to have 2 vents drilled?]

My 1974 vintage Mirafone 184 came with the valves vented. Nice feature, but I don't think they do that anymore, do they? In any event, the 2d valve on my Neptune is vented also, to complement the "kicker" mechanism it came with.

Here's one aspect that hasn't been discussed yet in this thread. A tuba, particularly a bigger bore horn, is subject to pressure changes within the valve tubing as you play - also as you sit and count rests. The first time you depress the valve a significant time after the horn has been dormant - maybe as short as couple of minutes, depending on ambient air temperature - enough pressure inequality in the tubes will have built up to bump your airflow as it equalizes. A vent would prevent that. Or, riffling the valves right before you play would minimize the bump, if you'd rather not drill a hole in your valve case.

jeopardymaster wrote:Here's one aspect that hasn't been discussed yet in this thread. A tuba, particularly a bigger bore horn, is subject to pressure changes within the valve tubing as you play - also as you sit and count rests. The first time you depress the valve a significant time after the horn has been dormant - maybe as short as couple of minutes, depending on ambient air temperature - enough pressure inequality in the tubes will have built up to bump your airflow as it equalizes. A vent would prevent that. Or, riffling the valves right before you play would minimize the bump, if you'd rather not drill a hole in your valve case.

This is one of the big factors which led me to have both of my tubas vented. (Rudy 5/4 CC and MW45S F) Both are large horns, and this has helped tremendously. It also helps as has been mentioned before to smooth out slurs and take away the pressurized "pop" the valves tend to accumulate.

I am a big advocate of rotar valve venting! It makes a definite improvement to instruments when done correctly.

BAT boy wrote:There are some disadvantages to performing this to all the valves or casings. As your valves become more and more worn out your horn may be more prone to leaking air, especially if you have an extra hole in all of your casings/pistons. It may seem negligable, but I have played quite a few horns that leak too much as it is. Valve jobs are expensive. I dont want to need one sooner is what i spose im trying to say.

That is more of a risk with rotary valves than with piston valves. The vent hole on a rotary valve is necessarily close to the port openings, but that's not the case with piston casings. If the valve leaks into the port where the vent hole is, then it will be a problem vent hole or no.

Rick "who thinks proper oiling prevents the problem in the long term" Denney

Bob Mosso wrote:Someone mentioned trills are more difficult with vented valves. Anyone have an opinion on trills? I didn't do a trill test before and after...

The Neptune has a vented 2nd valve as mentioned. I found when I played Mahler Symphony No.6 that trilling using the 2nd valve was not good with hissing from the valve. I got a little brown electrical tape and covered over the venting hole and the trill was now fine proving the venting was the problem. That tape has stayed over the hole ever since.

Jonathan "who would rather have unvented valves"

Jonathan, if you have not done so already, you might want to check or have a technician check your valve alignment. Several years ago my 184 developed a nasty hiss at valves 1 and 2. Dreading bad news, and not trusting my own mechanical talent (so little there to trust) I took it to a guy who really knows his stuff. As it turned out, nothing serious - they were out of true. Fifteen minutes of work, and no issues since. Said horn turns 33 this year.

That said, chacon arson gout, or whatever. I haven't taped up the #2 hole on my Neptune, but I haven't had the other valves vented either. I just riffle them a lot.