5th valve in leadpipe or after valve cluster.

[Tom Mason]

After looking at The Elephant's reconstruction of his BAT, I noticed in his initial posting that he comments on taking the 5th valve out of the leadpipe (before the valve cluster), and placing it after the valve cluster.

I would like real tech people to answer the question:

Is after the valves the best way to add a 5th valve as far as playability and not restricting the air flow from leadpipe to valves as it appears to be?

I am considering a 5th valve as an add on to my older King 2341, after I take the curl out of the 3rd valve. As I am looking at it, I see a better mating of a larger rotor after the valves as opposed to a smaller rotor before the valves.

I am not interested in your opinion as to the need of a 5th valve on a BBb horn. Just pursuing knowledge on a possible addition.

Thanks.

[Dan Schultz]

I prefer a strictly conical approach to the valve cluster. That being said... the appropriate location for a 5th valve on a piston horn such as a King would be right after the cluster and before the main tuning slide.

On a rotary horn where the leadpipe is quite long and has only a slight taper... I think the appropriate location for a 5th valve is before the cluster.

I see no reason to make a 5th valve dependent as Kiltie suggested. I know some of the Tibener (sp?) euphs did that.

[NCSUSousa]

Is after the valves the best way to add a 5th valve as far as playability and not restricting the air flow from leadpipe to valves as it appears to be?
I am considering a 5th valve as an add on to my older King 2341, after I take the curl out of the 3rd valve. As I am looking at it, I see a better mating of a larger rotor after the valves as opposed to a smaller rotor before the valves.

If you're looking for some examples of HOW to do this, take a look at Sam Gnagey's handiwork on new/old horns. He uses a King valve block as his starting point and adds a 5th valve. They come up for sale here every so often.
Here's one currently for sale (see pics):viewtopic.php?f=4&t=59304
Here are a few that recently sold for additional pictures:
viewtopic.php?f=4&t=52461&hilit=Gnagey#p474228
viewtopic.php?f=4&t=58593&p=494248&hilit=Gnagey#p492612
viewtopic.php?f=4&t=48902&hilit=gnagey#p423926

[Mitch]

I am not a tech person, but can tell you I think it depends more on the individual horn than any general guideline.

I once owned a very special HB-2P. It was an early one, supposedly one of the first in the country. At the time, I was told it was the horn that was sent all around to "the big guys" (i.e., Jacobs, Perantoni, etc.) to introduce the model to the US market. In fact, it was purchased from Custom at MidWest, December, 1985.

It had the 5th rotor in the leadpipe. Within only a year or two, they moved the rotor to after the pistons.

That horn had a few special things about it, so I don't think it was necessarily only the rotor position, but I can tell you that everyone who ever played it who owned an HP-2P with the rotor after the pistons said, "Wanna trade?"

[Mitch]

I am not a tech person, but can tell you I think it depends more on the individual horn than any general guideline.

I once owned a very special HB-2P. It was an early one, supposedly one of the first in the country. At the time, I was told it was the horn that was sent all around to "the big guys" (i.e., Jacobs, Perantoni, etc.) to introduce the model to the US market. In fact, it was purchased from Custom at MidWest, December, 1985.

It had the 5th rotor in the leadpipe. Within only a year or two, they moved the rotor to after the pistons.

That horn had a few special things about it, so I don't think it was necessarily only the rotor position, but I can tell you that everyone who ever played it who owned an HP-2P with the rotor after the pistons said, "Wanna trade?"

[tofu]

I recall Lee Stofer telling me of a 5th valve he added to a 2341 for a customer and that it turned out pretty well. I believe it was after the valve cluster. You might want to contact him for his insights.

[Lee Stofer]

I have added a 5th rotor to two different King 2341's, and both were a success. The bore size of the King right after the main tuning slide is just right to insert a .770" rotor (I used a Mirafone unit on each), and with the rotor in that vicinicty, it was relatively easy to construct a linkage and lever system for the 5th valve that was quick and responsive.

In general, the smaller the bore, and the closer to your mouthpiece, the more critical the dimensions are in a brass instrument. For instance, on the instrument I'm building from the G-50 parts, I'm eliminating the rotor from the leadpipe area, for I think that it plays better without a 4" long interruption in a short leadpipe, where the bore at best is cylindrical. I've replaced that set-up with a straight-in, consistently-tapered leadpipe that seems to make the instrument a lot more consistent in all registers. I am convinced that, the larger the bore, the less sensitivity, as I added a 5th rotor to a Conn 2J two years ago, and the .750" rotor after the main tuning slide resulted in a horn with a better low range than I could have imagined. The .770" rotor at the large end of the King main tuning slide assembly is so easy that I would not seriously consider doing that any other way, particularly since it works so well. It is possible and reasonable to add a rotor right after the 4th, and I've done that, but I think that it still does not play as freely as when the valve is after the main slide.

One note on the early Hirsbrunners vs later ones - the older they are, the more hand-crafted they were, and that will most likely make as much difference as the configuration.

[MartyNeilan]

I have kicked my small bass tuba project into high gear within the past week. I think I understand why Richard Barth prefers the 5th spliced into the 4th valve loop. The leadpipe is very short and there is no way I would have room for a small bore rotor before the .656 valve cluster unless I put a pigtail in the leadpipe. The tuning slide bow has a very slight taper but the horn begins to taper immediately after leaving the tuning slide. There is just no place to put a rotor without seriously disrupting the bugle or having one side of the tuning slide way too short.
On my BART project the Kaiser bore 5th valve is immediately before the main tuning slide and after a tapered dogleg coming out of the 4th valve. The tuning slide expands so large I doubt they make a rotor large enough to put after it. The leadpipe is a short straight-in shot to the piston cluster, it would be hard to fit a rotor in without really disrupting things.

[Lectron]

'making room' for it might be an argument on an Eb and especially an F, but not on a CC and BBb.
I do however support the 'disturbance' in the air flow factor