Venting rotary valves

[Bob Kolada]

Should #3 be interpreted as "vent only the slides that you commonly push/pull?"

[Wyvern]

My only experience of venting is the 2nd valve on my rotary Neptune because that slide is fitted with a trigger. I personally do not like it vented. When I came to play Mahler 6, I could not get satisfactory trills as air was escaping out of the vent. I have also experienced 'gurgling' sounds coming from the vent after oiling. So for Mahler 6 I covered the hole with insulating tape which has remained in place ever since.

I have specified for my new handmade Neptune to NOT have the 2nd valve vented (and no trigger, as I rarely use)

[tbn.al]

My 184 first valve is vented just above center and at a slight angle. It doesn't leak or otherwise cause any trouble. It drove me crazy before I had it done. Every attack after a pull would be subject to a clam. It was much improved after venting.

[Dan Schultz]

I won't vent my current rotary horn simply because it doesn't need it. It's a Marzan and has the main tuning slide on top so there's no need to pull individual slides... even if I COULD get to them! Frankly... I'm quite surprised that tuba makers don't wake up and deal with the problem of the main slides not being accessible.

[imperialbari]

Pros?
Cons?

Discuss.

It definitely should be done by pros rather than conmen.

K

[windshieldbug]

I won't vent my current rotary horn simply because it doesn't need it. It's a Marzan and has the main tuning slide on top so there's no need to pull individual slides... even if I COULD get to them! Frankly... I'm quite surprised that tuba makers don't wake up and deal with the problem of the main slides not being accessible.

What he said. Only one slide to push/pull, and a GAPING hole for it!

[imperialbari]

I see the point of a pull-/pushable main tuning slide. Only the consequence will be a larger portion of the main bugle going cylindrical.

Klaus

[Dan Schultz]

I see the point of a pull-/pushable main tuning slide. Only the consequence will be a larger portion of the main bugle going cylindrical. Klaus

I don't understand your comment. ALL of the rotary horns I've seen have main tuning slides that are 4" or so in length. It's just a matter of putting this slide where it's accessible.

[jeopardymaster]

I've mentioned this before and I'll mention it again. Venting has another advantage even if you don't pull slides a lot. If your horn is subjected to significant temp variability, since warm air expands and cold air contracts the air pressure within the valve tubing will fluctuate, and without venting you may get a slight bump (really a tiny pressure drop or increase) when you engage the valve. Ruffling the valves before you play equalizes the pressure for a while, but in my experience, especially on a particularly big rotary horn, every once in a while you can still get that little bump while you're playing, even if you have ruffled first. I hate that, and have been thinking seriously about getting my Neptune's valves vented. But yeah, it has to be done right.

[jeopardymaster]

It almost never happens on my piston Gnagey or Besson, but happens lots of the time on my rotary Neptune. I dunno. Go figger.

[Wyvern]

happens lots of the time on my rotary Neptune. I dunno. Go figger.

Strange, I have never noticed this problem on my Neptune

[Art Hovey]

If I had to use a rotary tuba I think I would put a little water key on any valve slide that needed manipulating, instead of drilling into the valve casing. But that would not work so well on a second valve slide. Maybe the kicker mechanism could simultaneously open the water key when the slide is moved?
-Or maybe I'll just stick with pistons.

[iiipopes]

If and when a director notices the "thump" of the pressure/temperature release, and comments to me about it, then I'll vent the valve. Until then, unless an expert does it, there is way too much potential for screwing things up, and added water keys can interfere with nodes & anti-nodes and affect (although probably no more noticably than the "thump") intonation.

[J.c. Sherman]

Should #3 be interpreted as "vent only the slides that you commonly push/pull?"

Yep... I would...

J.c.S.