Rotary valves: Open Port Vs. Closed Port

[Backbone]

What exactly does open or closed port mean? Why are there these two types?

[Neo Bri]

I'd like a better explanation, too. I know the idea is a drilled hole in the valve wall designed to eliminate the 'pop' when going between sides. Or maybe that's 'venting.'

[tbonesullivan]

Where did you see this referenced? Can you link to a website?

There's several different things it can mean.

Generally it's used to refer to certain trombone models with F-attachments that use Rotary Valves. A certain maker (BACH) has for years used rotary valves that many feel are undersized in general, and have oval ports that just aren't big enough to do the job. So, one of the standard modifications that many repair shops offer is opening up the rotor ports.

Most other makers have moved to larger rotary valve designs, or improved rotor designs, which don't have these limitations. Even the Conn 88H, MADE AT THE SAME FACTORY, has nicely designed rotors. Yet Bach, like Harley Davidson and Gibson guitars, refuses to change things, so you want to upgrade to a more expensive model.

[harrisonreed]

Open ports means that the bore isn't constricted through the rotor interior paths. Techs can "open ports" up on a rotor so that there isn't a step down through the rotor, and then a massive step up to the larger F tubing on the other side. The other thing they might do is adjust the tubing entry angle so that the rotor entry and exit isn't extremely oval shaped.

Over sized rotors allow you to have larger pathways through the rotor, but there are other benefits/aspects. For one, a large rotor adds weight and might have a heavy valve cap. Another thing it's that you can have crazy pathways like the Minnick rotor or CL2000 rotor, both of which have very open pathways.

[Bonearzt]

This sounds more like a mashup of two different thoughts.
"Open" and "closed" USUALLY refer to the configuration of the valve wrap. Closed meaning the compact wrap with several 180 deg. crooks, and open meaning the longer, less "coiled" configuration.
This also relates to the configuration of the knuckles on the rotor casing. "open" being the one that has the 180 deg. return knuckle coming from the valve section going back into the neck pipe, and "closed" having the 2 90 degree knuckles going into and out of the valve tubing.

As to "ports", that is in reference to the passageway in the rotor, and the rotor core itself can sometimes be ground out to increase the bore and allow more air to flow.

<<I know the idea is a drilled hole in the valve wall designed to eliminate the 'pop' when going between sides. Or maybe that's 'venting.'>> Correct Brian, "venting" is the elimination of the "pop" that you sometimes get when actuating the trigger, and drilling passages in various places allows this to occur.


Eric

[GabrielRice]

What exactly does open or closed port mean? Why are there these two types?

Can you point to where you see these terms?

I am not an instrument designer, but I used to do sales for the Shires company. The Shires standard rotary valve may be one that you refer to as "open port." The ports in the valve are not completed by the rotor piece itself, but by the casing. This provides a little bit of venting, and it allows for a valve that is a little smaller (and therefore lighter) than it would be if the ports were contained entirely inside the rotors.

[Backbone]

What exactly does open or closed port mean? Why are there these two types?

Can you point to where you see these terms?

I am not an instrument designer, but I used to do sales for the Shires company. The Shires standard rotary valve may be one that you refer to as "open port." The ports in the valve are not completed by the rotor piece itself, but by the casing. This provides a little bit of venting, and it allows for a valve that is a little smaller (and therefore lighter) than it would be if the ports were contained entirely inside the rotors.

https://www.instrumentinnovations.com/products

Click on the rotary valve link and read the descriptions. Seems Bonearzt has the answer.

[GabrielRice]

Huh. That's a weird way to label them. Instrument Innovations calls a valve with two 90 degree ports "closed port" and one 90 and one 180 degree ports "open port."

Steve Shires has long thought that 90/90 ports play more open than one 90 and one 180 degree turn, which is why you see that configuration on all Shires rotary valves. That makes it essentially impossible to get the valve tuning slide long enough for an E pull, however. With one 180 degree port, you get more straight tubing in the valve section, so an E pull is easy to design for.

[tbonesullivan]

I guess it comes down to how you were introduced to the valves. In general the "open" wraps use the 90/180 configuration, which is how they are on Bach, Conn, Yamaha, and Kanstul (now defunct). Also Willson and others make them that way.

Generally if you're looking to replace valves, you're not going to replace ones on a high end custom horn like an Edwards, Greehnoe, Shires, Rath, etc.

This reminds me of items that are for the right hand, but worn on the left side. Do you advertise it as left? right?

[Schlitz]

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[Tooloud]

In favour of Bach / Conn and respective "derivatives": A smaller port produces a bit of resistance, that is needed to produce a substantial tone, or at least makes it easier for the player to make a sound, that can carry even in large halls.
Very open valves force the player to produce the resistance in his own embouchure in order to to make a sound, that is neither 'woofy' nor tubby'. For this reason the double valve Thayer grow out of fashion with trombonists, who don't want to sound like bad (french...) horns or euphoniums. ("Tuba on a stick"...)
No offense - but that is, what I watch in my surroundings. Maybe a bit euro-centric, maybe it is not the case in the US..

[tbonesullivan]

I have a Bach 42T, an I would definitely agree that it is open, and in some days getting the trigger register to speak is more difficult than on my other trombones, which all have some type of rotary valve. It's one of the aluminum core examples, so eventually it will need to be replaced, and I'm torn on whether to have a new design axial installed, or to go to a standard rotary.

[Matt K]

I have a Bach 42T, an I would definitely agree that it is open, and in some days getting the trigger register to speak is more difficult than on my other trombones, which all have some type of rotary valve. It's one of the aluminum core examples, so eventually it will need to be replaced, and I'm torn on whether to have a new design axial installed, or to go to a standard rotary.

I'd probably swap it out for an infinity; worst case scenario, you can probably sell that valve section and use the funds to replace with a rotary. If you go rotary right away, you won't be able to use most of that tubing anyway, including the neckpipe because of the different dimensions of the Thayer vs. whatever rotary you'd use... and you're likely to find a new thayer that is sealed well goes a long way. (Just replacing the thayer is going to be a lot cheaper and possibly sufficient.)

[brassmedic]

It's one of the aluminum core examples, so eventually it will need to be replaced

I am puzzled by this statement. What does having an aluminum core have to do with whether or not it needs to be replaced?

[BGuttman]

It's one of the aluminum core examples, so eventually it will need to be replaced

I am puzzled by this statement. What does having an aluminum core have to do with whether or not it needs to be replaced?

I think it might be because some of the early aluminum cores were not treated and would corrode. I know Shires played with anodizing aluminum cores when they experimented with making their own Axial. That would slow down the degradation, but I think they ran into some sizing problems.

I wonder if a soft metal like aluminum changes the sound you get. I've never played an axial of any sort so I can't comment on that.

[tbonesullivan]

It's one of the aluminum core examples, so eventually it will need to be replaced

I am puzzled by this statement. What does having an aluminum core have to do with whether or not it needs to be replaced?

I have Bach 42T with valve serial 0064, with an Orla Ed Thayer marked valve. The core is grayish, and I believe teflon coated. The core coating has abraded in several areas, which has resulted in oxidation, and I have been told it will spread. I've been told it would probably be better when that happens to just replace the whole valve.

Also, the the back plate for the aluminum valves has no replaceable spindle bearing, like an Edwards or Shires valve does. So, once that wears, there's really no choice.

[tbonesullivan]

I think it might be because some of the early aluminum cores were not treated and would corrode. I know Shires played with anodizing aluminum cores when they experimented with making their own Axial. That would slow down the degradation, but I think they ran into some sizing problems.

I wonder if a soft metal like aluminum changes the sound you get. I've never played an axial of any sort so I can't comment on that.

Yes, it corrodes. The early version of the Aluminum cores were at least partly cast, and then coated with some type of teflon. The surface is somewhat matte. These were later replaced with fully machined and anodized cores, which should be far more resilient to wear and corrosion.

The valve core material is going to make a difference, regardless of what it is. I have always liked the sound of the instrument, even when it had excessive end play, because when Bach originally made it, they did not know how to properly fit the thayer valves. Which is why I've had to have it worked on. Twice.

[Roberto28]

I’m really loving this discussion. It’s very enlightening. One thing that is not clear to me though is the difference between open vs closed wrap. Not talking about the ports, now. Just the tubing configurations.

Why would one be preferred over the other. In my blissful ignorance, I thought that open wraps were just the updated more modern version of the closed wrap. Kinda like a “wrap 2.0” but I might be wrong about this.

[brassmedic]

I am puzzled by this statement. What does having an aluminum core have to do with whether or not it needs to be replaced?

I have Bach 42T with valve serial 0064, with an Orla Ed Thayer marked valve. The core is grayish, and I believe teflon coated. The core coating has abraded in several areas, which has resulted in oxidation, and I have been told it will spread. I've been told it would probably be better when that happens to just replace the whole valve.

Also, the the back plate for the aluminum valves has no replaceable spindle bearing, like an Edwards or Shires valve does. So, once that wears, there's really no choice.

I never played a teflon coated Thayer, so I can't comment on that. But the anodized ones are actually pretty resilient
as long as they aren't abused. That's why I was puzzled by what you wrote, because it sounded like you were saying all aluminum Thayer valves need to be replaced eventually. Now I see that's not really what you were saying.

[brassmedic]

I think it might be because some of the early aluminum cores were not treated and would corrode. I know Shires played with anodizing aluminum cores when they experimented with making their own Axial. That would slow down the degradation, but I think they ran into some sizing problems.

I wonder if a soft metal like aluminum changes the sound you get. I've never played an axial of any sort so I can't comment on that.

Yes, it corrodes. The early version of the Aluminum cores were at least partly cast, and then coated with some type of teflon. The surface is somewhat matte. These were later replaced with fully machined and anodized cores, which should be far more resilient to wear and corrosion.

The valve core material is going to make a difference, regardless of what it is. I have always liked the sound of the instrument, even when it had excessive end play, because when Bach originally made it, they did not know how to properly fit the thayer valves. Which is why I've had to have it worked on. Twice.

I was always bugged by the poor Bach installation of those valves. The stock OE Thayer neckpipe doesn't really fit on a Bach trombone, and instead of fixing the neckpipe design, they just put it together at a strange angle and left a gap between the receiver and the bottom of the valve. Some of them played really well in spite of that, though.

[tbonesullivan]

I never played a teflon coated Thayer, so I can't comment on that. But the anodized ones are actually pretty resilient
as long as they aren't abused. That's why I was puzzled by what you wrote, because it sounded like you were saying all aluminum Thayer valves need to be replaced eventually. Now I see that's not really what you were saying.

It looks like this. You can see where the coating is coming off around the ports. Anodized coatings don't wear like that, and given that anodized aluminum is quite a bit harder than brass, it shouldn't wear like that. I have a friend who had a 1st gen Bach 42T, and she let it sit for years. When she opened up the casing it was full of aluminum oxide. I've been using mostly Hetman Oils on the valve, which has pretty much stopped progression of the oxidation.

You can see the kinda strange neckpipe that is on my horn, which was used on all of the early versions. It does however play VERY nicely, especially after Bann Hansson refit the valve, and modified the receiver to more properly mate with the bottom of the valve.

Core


Valve casing:

[Kevbach33]

I’m really loving this discussion. It’s very enlightening. One thing that is not clear to me though is the difference between open vs closed wrap. Not talking about the ports, now. Just the tubing configurations.

Why would one be preferred over the other. In my blissful ignorance, I thought that open wraps were just the updated more modern version of the closed wrap. Kinda like a “wrap 2.0” but I might be wrong about this.

I view open wraps as being in three camps: standard or wide (90/180 for the rotor, like Bach, Conn and Yamaha, among others), Minnick-style or compact (90/90, like Getzen and the custom makers), and those that complement the other valve styles (axial, Hagmann, etc.) seen only in trombones for the most part. The idea is that with fewer bends in the tubing, there would be less resistance (however, read on...). These wraps generally extend beyond the main tuning slide and are in vogue.

There are two general camps of closed wraps as well, and I'll just call them American (90/90) and Yamaha (90/180) style. These are just generalizations. Both are usually contained before the tuning slide, nice for those pit gigs with tight spacing. Before the open wrap, you either had a valve or you didn't, to put it bluntly.

In practice, wrap doesn't matter as much as a well designed and assembled valve. For instance, a traditional (closed) wrap modern Conn may be more open than its open wrap counterpart, and vice versa. The difference may be less exacerbated between two Yamaha tenors. Of course, ymmv. Me? I like the compactness of traditional and Minnick-style wraps since they don't stick out as far as the normal open wrap.

Bonearzt said it first though. I'm just expanding on the thought and question.

[tbonesullivan]

Well, there's also the total amount of bends and how gradual they are. The "traditional" wrap replaced the "pancake" wrap, which had a lot of sharp bends, and didn't allow for an E-pull. The traditional wrap changed that, and now the E-pull was possible.

However while the traditional wrap has the 90 90 valve configuration, there are also two very tight 180 bends, almost as tight as a valve itself. The "Open" wrap used by Bach, Conn, Yamaha, etc. has much wider radius 90 degree bends, but ends with one very sharp 180 bend, which feeds into the goose neck.

Which is better? Depends on the player. One definitely does allow for more room to make an E-pull though, so for a single valve bass that may need an E-pull, traditional is the only way to go. Many open wraps can't make the pull to E anyway.

Yamaha also calls their wrap a "semi-open" wrap, as it's pretty much an open wrap with an additional turn around to keep the valve tubing within the main tuning slide. The Pro-level horns with this wrap also have two tuning slides on the semi-open wrap, so that they can empty out condensation that collects. this second tuning slide is also what allows the Doug Yeo model bass trombone YBL-822 to have a valve that can be relatively easily removed and replaced, without having an excessively long linkage.