Valve Making Popping Noise

jbtb · by **jbtb** » 2023-05-04 11:32 p.m.

Just got back my Bach 42BO from a clean/repair service. Playing through the valve feels and sounds great, but now it's making a popping sound whenever the trigger is pushed.

It's like a quick puff of air that can be heard coming from the bell opening. It will only occur the first time if I repeatedly press the trigger very quickly. Waiting 2-3 seconds before pressing again results in another pop.

Any ideas? I already made sure it was well oiled, but no idea what else to troubleshoot.

Burgerbob · by **Burgerbob** » 2023-05-05 12:23 a.m.

Sounds like it's sealing.

brassmedic · by **brassmedic** » 2023-05-05 4:35 a.m.

Don't repeatedly press the trigger very quickly?

Sweaty · by **Sweaty** » 2023-05-05 7:20 a.m.

I have found that venting valves helps to make slurs smoother. A good technician can do this.

Blabberbucket · by **Blabberbucket** » 2023-05-05 7:26 a.m.

Check in with the folks that serviced your horn. More often than not they'll be able to offer more help and a better diagnosis than you'll get on here.

jbtb · by **jbtb** » 2023-05-05 9:13 a.m.

Thanks everyone. I'll email my tech and get his thoughts. Figured I'd check here first on the longshot it was user error or there was an easy fix.

Burgerbob · by **Burgerbob** » 2023-05-05 10:08 a.m.

Again... This is not a problem. It means the valve is well lubed and doesn't leak.

jbtb · by **jbtb** » 2023-05-05 10:49 a.m.

[quote="Burgerbob"]Again... This is not a problem. It means the valve is well lubed and doesn't leak.[/quote]

Well, from a playing perspective it is causing a bit of a new problem for me. Trying to slur with the valve is nearly impossible. The pop comes across like a harsh articulation or a hiccup between the notes.

If this is normal for a valve, is it possible there's just too much oil in it that is suddenly causing the pop to be much more noticable?

Burgerbob · by **Burgerbob** » 2023-05-05 10:50 a.m.

[quote="jbtb"]<QUOTE author="Burgerbob" post_id="209190" time="1683295716" user_id="3131">
Again... This is not a problem. It means the valve is well lubed and doesn't leak.[/quote]

Well, from a playing perspective it is causing a bit of a new problem for me. Trying to slur with the valve is nearly impossible. The pop comes across like a harsh articulation or a hiccup between the notes.

If this is normal for a valve, is it possible there's just too much oil in it that is suddenly causing the pop to be much more noticable?
</QUOTE>

With a rotor with tight clearances and a good seal, this is inevitable without porting it.

Elow · by **Elow** » 2023-05-05 10:54 a.m.

Even with a perfect rotor, nothing will slur perfectly like a thayer.

jbtb · by **jbtb** » 2023-05-05 11:06 a.m.

[quote="Burgerbob"]With a rotor with tight clearances and a good seal, this is inevitable without porting it.[/quote]

[quote="Elow"]Even with a perfect rotor, nothing will slur perfectly like a thayer.[/quote]

Thanks. It's quite possible that my valve was not functioning/sealing 100% properly before the service. That could explain why it plays much better now and how I never really noticed a popping before.

trombonedemon · by **trombonedemon** » 2023-05-05 3:40 p.m.

It's something your chops have to adjust to.

BigBadandBass · by **BigBadandBass** » 2023-05-05 4:57 p.m.

This is part of the reason thayers are so popular, the pop is much less noticeable.

Crazy4Tbone86 · by **Crazy4Tbone86** » 2023-05-05 8:39 p.m.

It sounds like your technician adjusted the bearing plate and made it so that the rotor has no lateral play. In other words, your valve was probably not sealing correctly prior to the service. When I do this service, most players feel like the sound centers better and has more core, when the valve is both engaged and disengaged.

Chances are that you will adjust to this and the good will outweigh the bad. My recommendation is to play it for several weeks and see how you feel about it after that.

jbtb · by **jbtb** » 2023-05-06 10:40 a.m.

[quote="Crazy4Tbone86"]It sounds like your technician adjusted the bearing plate and made it so that the rotor has no lateral play. In other words, your valve was probably not sealing correctly prior to the service. When I do this service, most players feel like the sound centers better and has more core, when the valve is both engaged and disengaged.

Chances are that you will adjust to this and the good will outweigh the bad. My recommendation is to play it for several weeks and see how you feel about it after that.[/quote]

I noticed the bolded part as soon as I got my horn back from the shop. I thought it was from having the bracing changed, but maybe it was fixing the valve as you mentioned.

Fwiw - the loud popping is no longer as prevalent after a few days. It still happens every once in a while, but slurring notes with the valve sounds much better now. :idk:

Crazy4Tbone86 · by **Crazy4Tbone86** » 2023-05-06 1:27 p.m.

Yes, it’s a little adjustment that not many trombone players know about. As a rotor is used repeatedly for many years, the metal tends to wear at the bearing on the bearing plate side. When this happens the rotor itself can shift slightly from spindle end to spindle end. It only takes a small amount of shift for the horn to loose focus and eventually air compression.

I see it on about 50-60% of the horns (with rotors) that come through the shop. A good technician should know how to address this on any rotary valve. Not a difficult or time-consuming job, but it does take some know-how and experience. I have seen some inexperienced techs take too much metal off the bearing plate and that results in a new set of problems.

Of course, this is just an assumption that your tech made the adjustment on your bearing plate. There is the possibility that your bearing plate was simply loose and was tapped the full way in when reassembled. This brings up another tech topic: Trombone players…….if your bearing plate is loose, don’t tap it in with a metal hammer! Take it to your tech! I have seen several bearing plates that were marred and severely damaged by do-it-yourselfers who used improper tools.

Model34 · by **Model34** » 2025-07-18 12:22 p.m.

[quote="Burgerbob"]<QUOTE author="jbtb" post_id="209197" time="1683298155" user_id="16552">

Well, from a playing perspective it is causing a bit of a new problem for me. Trying to slur with the valve is nearly impossible. The pop comes across like a harsh articulation or a hiccup between the notes.

If this is normal for a valve, is it possible there's just too much oil in it that is suddenly causing the pop to be much more noticable?[/quote]

With a rotor with tight clearances and a good seal, this is inevitable without porting it.
</QUOTE>

AIDAN, I just noticed this slight pop when trying to use the valve. IF porting a valve fixes this unwanted noise why aren’t all valves ported? I’m still new to trigger horns even though I been playing for a very long time. What does porting do?

Burgerbob · by **Burgerbob** » 2025-07-18 12:35 p.m.

Porting is relatively new in valve land. And not everyone likes it.

Model34 · by **Model34** » 2025-07-22 11:31 a.m.

Burgerbob: In a full reveal of my ignorance: exactly what is porting? What does it do? Why would some people like it and others not like it? Is there some other way to get around this slight click “noise“? what exactly is causing this click “noise“?

BGuttman · by **BGuttman** » 2025-07-22 1:19 p.m.

Valve popping is caused by the air in the valve section being at a different temperature than the air in the main instrument. When the valve is opened this difference tries to equalize with a little pop. If the room temperature is warm enough there is no pressure difference and hence no pop. This isn't always the case.

Porting the valve involves making a way for the pressure in the attachment to match room air so there is no pressure difference. Sometimes this is a modification to the rotor itself. I did a crude sort of valve porting by drilling a small (1/8" or 3 mm) hole in the valve casing between the legs of the valve loop. It cured a bad popping in an old Sansone tuba.

ghmerrill · by **ghmerrill** » 2025-07-22 4:17 p.m.

[quote="Burgerbob"]Porting is relatively new in valve land. And not everyone likes it.[/quote]
It's been commonplace in tubaland roughly forever (sometimes called "venting"). With a classic German/Czech style rotary tuba, it's common to port the first valve so that you can easily use the valve slide to adjust intonation on the fly. With a piston tuba, there seems to be more propensity to get the "popping" effect when slurring (I don't recall it happening noticeably with my rotary horns) and so it's reasonably common to port each of the valves. I encountered that problem with my little Buescher Eb and ported the valves.

On a piston valve, this is a fairly straightforward DIY operation if you have some basic skills and understand what you're doing. On a rotary valve it's trickier (you have to port it through the casing). I've never tried that myself. :roll:

Possibly this is relatively new in tromboneland because you have only one or two valves and they don't interact as much as in multiply valved instruments -- where of course you're doing valve slurs all the time.

Burgerbob · by **Burgerbob** » 2025-07-22 4:51 p.m.

It's not always popular in tubaland either!

hornbuilder · by **hornbuilder** » 2025-07-22 6:02 p.m.

Venting and porting are not the same thing.

Venting is as described by Bruce. It doesn't have a place on a trombone, ever. IMO. It is useful on tubas for pulling slides for intonation, without pulling against a vacuum, and eliminates a loud pop when activating the valve after pulling the slide.

Porting is shaping the valve face in such a way that there are air channels around the rotor that allow the pressure to equalize during the activation of the valve between the open horn and the valve loop. It does not involve drilling a hole in the valve casing.

ghmerrill · by **ghmerrill** » 2025-07-22 6:04 p.m.

On a tuba at least, doing it as a matter of course (rather than using it to address a particular problem or goal) is a bit nutty. One thing you lose is the ability to use certain very simple tests for air leaks -- since the venting in effect introduces air leaks that prevent you from testing compression. On my old Buescher (which was hardly air tight when I got it), I did it on the 2nd and 3rd valves because ... (1) I put a kicker lever on the 3rd valve so I could dynamically affect pitch by moving it (and you can't do that if pulling the slide induces a resistant vacuum), and (2) I did it on the second slide so that I could quickly pull the slide to dump it without also having to hold down the piston to avoid the vacuum. If you don't have a specific problem in mind that venting will solve, there's no reason to do it.

ghmerrill · by **ghmerrill** » 2025-07-22 6:06 p.m.

[quote="hornbuilder"]Porting is shaping the valve face in such a way that there are air channels around the rotor that allow the pressure to equalize during the activation of the valve between the open horn and the valve loop. It does not involve drilling a hole in the valve casing.[/quote]
A significant distinction.

Conflation of the two seems to appear in this somewhat older thread: <LINK_TEXT text="viewtopic.php?t=24332">https://trombonechat.com/viewtopic.php?t=24332</LINK_TEXT>

tbonesullivan · by **tbonesullivan** » 2025-07-23 4:21 p.m.

Which of the currently available valves for trombone are "ported" or internally vented? Hasn't it been relatively common since the Greenhoe valve was released? The CR valve from Kanstul, the "Balance Response" Rotor from Yamaha, the Open FLow valve by Meinlschmidt?

hornbuilder · by **hornbuilder** » 2025-07-23 7:30 p.m.

Some of those brands you mention, the term "vented" is doing some heavy lifting. The Kanstul valve is not, IMO. The 2 little holes in the intermediate web are not anywhere near adequate, and would actually add to the unwanted "noise" in transition. I'm not going to comment specifically on any valve still in production (I hope the reason for that is clear)

Model34 · by **Model34** » 2025-07-24 2:34 p.m.

Thank you guys! I really appreciate your thoughtful exclamations!

Sesquitone · 2025-07-25 1:51 p.m.

[quote="Model34"]Thank you guys! I really appreciate your thoughtful exclamations![/quote]

“Venting” is a more general term referring to relieving unwanted pressure differences—for example, when extending the third valve on a trumpet. In that case, the extension causes a decrease in pressure (a “partial vacuum”) resulting in a loud “pop” when the valve is actuated. “Venting” in that case consists of drilling a small hole in the stem of the piston so that atmospheric pressure exists inside the external tubing at all times. [See Jon Talks Trumpet “Vented Valves—A trumpet Player’s Guide” for an informative video on that.] On tubas, venting of valves with sliding tubes consists of (very carefully) drilling one or more (tiny) holes through the casing—exactly half-way between the edges of two adjacent ports. Which means that that point in the sound-path is open to the atmosphere. [Why this does not produce wolf tones for some pitches must be purely a matter of luck as to where the pressure nodes/antinodes fall.]

On a trombone rotary valve, “venting” consists of modifying (or designing from scratch) the rotor geometry (well away from the “sound-path” through the channels or ducts) in order to provide a “flow-path” for air flowing through the valve as the rotor transitions from one active orientation to the other. For intact ducts through an otherwise solid cylinder, for example, the “flow-path” is effectively blocked off at the half-way point between active orientations—causing a pressure build-up. This is suddenly relieved when the final orientation is reached: causing a loud “pop”! That occurs no matter which way the valve is moving. It is exacerbated if the hand-slide happens to be moving inwards at the same time (causing greater volumetric air-flow through the instrument). [The original Rotax valves were like this. Playing was accompanied by what sounded like someone randomly popping bubble-wrap! The rotor was soon changed to a more conventional sculpted-butterfly design, approximating a constant-area sound-path.]

Venting (in the design of) rotary valves sometimes consists of drilling holes (or milling other “cut-out” shapes) that the flow-path “sees” in the intermediate orientation—resulting in (almost) pop-free performance. If the shapes of these “cut-outs” are carefully designed, this can result in a “lipped-tube” (Greenhoe, ULTRA, CAIDEX) or “lipped-channel” (Meinlschmidt Open Flow) geometry. The more “open” the intermediate flow-path, the more “quiet” the valve action. On a well-designed rotary valve, there should not even be the slightest “catch” (felt by the player) when using valve legato articulation.

.

Posaunus · 2025-07-25 2:01 p.m.

Interesting explanation.

hornbuilder · by **hornbuilder** » 2025-07-25 5:25 p.m.

They aren't "vent holes" in the "sculpted butterfly", nor the Meinlschmidt, nor the Kanstul, nor the Bosc pictured above. The only way they could be, is if the valve rotation is backwards, and that in and of itself is going to create more noise in transition than any vent holes could make up for.

Sesquitone · 2025-07-26 12:47 p.m.

[quote="hornbuilder"]They aren't "vent holes" in the "sculpted butterfly", nor the Meinlschmidt, nor the Kanstul, nor the Bosc pictured above.[/quote]

Yes, you’re right—my mistake! Those little holes in the butterfly and Bosc, and the cut-outs in the Kanstul don’t seem to provide a direct flow-path (from hand-slide to bell) in the half-valve orientation. Perhaps they have some other function. The scavenging in the Meinlschmidt may help reduce rotational inertia a bit. However, the lipped-tube geometry of the ULTRA, Greenhoe and CAIDEX provides a very “open” flow path—around the outside of the intact ducts themselves. You can see that “external” flow path by visualizing the ULTRA valve turned 45º (I’m sorry I don’t have a picture of that).

Here’s a simple “test” to see if a valve is adequately “pop” or “catch” free. With the instrument in playing position, keep your lips closed (i.e. sealing the mouthpiece end) while quickly moving the slide over several positions (in either direction) and simultaneously operating the valve (in either direction)—i.e. four combinations. What do you hear out of the bell? “Swish”, “pop”, “click”, or silence? [We’re not talking about mechanical noise due to backlash in the linkage.] Repeat all of the above while blowing air (without buzzing) through the instrument. This may amplify air blockage-and-relief sounds, especially with inward slide motion.

A well-designed valve (and properly adjusted linkage) should be completely silent—both aerodynamically and mechanically—providing “catch-free” legato articulation using the valve.

Sesquitone · 2025-07-27 1:28 p.m.

First, I need to apologize to the designer and manufacturer of the Kanstul CR valve. It is indeed properly vented, thereby minimizing (and most likely eliminating) any “catch” due to blocking-and-relief during transition. [The previous picture I posted showed only the “barbell”-shaped cutout, not the two additional holes 90º away in the wall of the barrel. Actually, on review, they are (just) visible!]

Below, I have attached a couple of pictures modified from one posted on TromboneChat by elmsandr on January 20th, 2019, in response to a query by BflatBass about what the rotor of the CR valve looks like (same as the one shown earlier by Hornbuilder). That picture shows clear views of the pair of holes in addition to the “barbell”-shaped cutout. Evidently, these are repeated 180º apart—although, for venting, you only need the ones shown. [These others don’t participate in the venting. They may help in balancing mass distribution (and they reduce non-functioning mass a bit further, thereby reducing rotational inertia—which seems to be the main object of the multiple holes in the two webs).]

The first picture shows a rough sketch of the air-flow directions into (from the hand-slide) and out of (along to the bell) the inside of the barrel—around the outside of the sound-path tubing—when the rotor is in the half-valve orientation.

The second picture indicates how the existing holes/cutout configuration approximates a truly “lipped-tube” design.

.

Sesquitone · 2025-07-27 3:43 p.m.

Here's a slightly more detailed rough sketch of what a "lipped-tube" CR valve might look like—where I've tried to indicate the exterior of one of the two sound-path ducts as it turns 90º inside the barrel. The incoming air flows over and around that duct and then exits between the two ducts after a 90º turn.

Of course, this is all very quick as the valve transitions (either way), but this open vent path is certainly enough to equalise pressures so that there is no build-up-and-relief causing a "catch"—even with the actual two-holes-plus-barbell cutouts.

.

hornbuilder · by **hornbuilder** » 2025-07-27 4:43 p.m.

WGWTR180 · by **WGWTR180** » 2025-07-27 11:03 p.m.

Ahh I loved the internet. Some much accurate information being passed around. <EMOJI seq="1f923" tseq="1f923">🤣</EMOJI><EMOJI seq="1f923" tseq="1f923">🤣</EMOJI><EMOJI seq="1f923" tseq="1f923">🤣</EMOJI><EMOJI seq="1f923" tseq="1f923">🤣</EMOJI>

hornbuilder · by **hornbuilder** » 2025-07-27 11:41 p.m.

tbonesullivan · by **tbonesullivan** » 2025-07-28 10:49 a.m.

[quote="Sesquitone"]Yes, you’re right—my mistake! Those little holes in the butterfly and Bosc, and the cut-outs in the Kanstul don’t seem to provide a direct flow-path (from hand-slide to bell) in the half-valve orientation. Perhaps they have some other function. The scavenging in the Meinlschmidt may help reduce rotational inertia a bit. However, the lipped-tube geometry of the ULTRA, Greenhoe and CAIDEX provides a very “open” flow path—around the outside of the intact ducts themselves. You can see that “external” flow path by visualizing the ULTRA valve turned 45º (I’m sorry I don’t have a picture of that).[/quote] Is the "butterfly" valve a Yamaha? I remember seeing some pictures when they first premiered the "Balanced response" valve, but they do not seem to have used the design much further than that. Looking at the pictures, it seems to me the entire purpose of the additional holes would be to provide pressure equalization.

If they aren't there for that reason, why exactly are they there? With the "Sculpted butterfly" I can see no purpose they would be there for machining support. The entire purpose seems to be to create an air passage from one side of the valve to the other. During counterclockwise rotation this would connect the air space inside the attachment tubing via the forward port to the airspace in the gooseneck port, prior to the main air passages in the valve reaching those positions.

For the Kanstul CR, it's a hollow core valve, and has significant space between the ports on the casing. There are times when none of the air passages are aligned to the ports, however the "vent holes" would be aligned with those ports, connecting the air space between all four ports through the hollow center. I'm fairly certain that the holes on the outside of the CR valve are not just there for show.

tbonesullivan · by **tbonesullivan** » 2025-07-28 10:59 a.m.

Are some claiming that the Greenhoe valve and other similar designs are not meant to be internally vented to equalize pressure? Because that is directly contradicted by the abstract from the Greenhoe patent itself.

ABSTRACT

A rotary valve for a musical instrument includes a cylindrical casing having a sidewall closed at opposite ends thereof, and a rotor mounted within the casing for rotation between unoperated position, in which the main tubing is connected to a further tubing portion, and an operated position, in which a length of extension tubing is connected into the air passageway through the instrument, the rotor including a hollow shell member and rotor primary and secondary airway tubes mounted within the rotor shell member for selectively communicating input and output ports of the valve as the rotor is rotated between its unoperated and operated positions, and a plurality of vent openings in the cylindrical sidewall of the rotor shell for providing pressure relief areas for air directed into the rotor during rotation of the rotor between its unoperated and operated positions.

US Patent 5686678.

Inventor: Gary H. Greenhoe.

hornbuilder · by **hornbuilder** » 2025-07-28 2:12 p.m.

If you're referring to my comment, please re-read it.

In regards the "sculpted butterfly" in the picture. The hole is in the wrong place (and too small) for it to provide any sort of effective "venting". Similarly the Kanstul valve.

It seems many makers have started cutting bits off their rotors, all so they can proclaim their valve to be "vented", when in fact it does nothing of any use much at all. It isn't sufficient to simple remove bits of random metal. Consideration has to be made for where the air flows, how much needs to flow, and when.

IMO

tbonesullivan · by **tbonesullivan** » 2025-07-28 2:23 p.m.

[quote="hornbuilder"]If you're referring to my comment, please re-read it.

In regards the "sculpted butterfly" in the picture. The hole is in the wrong place (and too small) for it to provide any sort of effective "venting". Similarly the Kanstul valve.

It seems many makers have started cutting bits off their rotors, all so they can proclaim their valve to be "vented", when in fact it does nothing of any use much at all. It isn't sufficient to simple remove bits of random metal. Consideration has to be made for where the air flows, how much needs to flow, and when.

IMO[/quote] Well, you can certainly ask Sesquitone about that, as he is the engineer who developed both the ULTRA and CAIDEX valves.

hornbuilder · by **hornbuilder** » 2025-07-28 2:26 p.m.

Yeah, no. I'm good.

Sesquitone · by **Sesquitone** » 2025-07-28 4:08 p.m.

[quote="hornbuilder"]

In regards the "sculpted butterfly" in the picture. The hole is in the wrong place (and too small) for it to provide any sort of effective "venting". Similarly the Kanstul valve.
[/quote]

That's correct regarding the small hole in the sculpted butterfly. However, the Kanstul CR valve is correctly vented—not unlike the original Greenhoe in the 1997 patent (see below).

Figures 9, 10, and 11 from the ULTRA patent of 2000 show the un-activated, half-valve, and activated air-flow paths, respectively. Figure 16 shows the concept for a lipped-tube ULTRA rotor. This was sketched by the patent artist using a prototype (of what subsequently became the idea for the CAIDEX rotor) that I had fashioned from one of the original intact-duct Rotax rotors of the mid-1990s—by hand-scavenging material with small rat-tail file. The lips widths on that prototype were very narrow but, with precise alignment, it worked perfectly—and was absolutely "silent" in transition.

.

hornbuilder · by **hornbuilder** » 2025-07-28 4:18 p.m.

I've said this before. Some of us live in the theoretical world. And some of us live in the practical world.

Just drilling some holes in the face of a rotor does not mean it is "correctly vented".

It's funny you post that diagram of the GH valve. The actual prototype valve made from that design didn't look anything like that, so the drawing is misleading in regards this discussion.

Rotation direction makes a difference. Did you ever wonder why Steve Shires wanted to change the geometry of your "ultra" rotor??

You can keep posting as much as you want, but I'm done bashing my head against a brick wall.

Sesquitone · by **Sesquitone** » 2025-07-29 2:11 p.m.

Here's another attempt to show some streamlines for the (correctly vented) CR valve in the half-valve orientation. [All the air-flow is sealed within the casing/ports.] Inflow from the hand-slide on the left, outflow to the bell on the right. Mostly through the holes/slot, into and out of the interior of the barrel and around the outside of the sound-path duct that's visible. There's a small (very transient) flow through the end of the duct itself between the overlap regions. As you can see, without the cutouts, no matter which way the rotor is turning, in transition there would be major blockage of the air-flow causing a pressure build-up, which is then suddenly relieved as the sound-path duct aligns with its new active position—causing the dreaded "pop".

.

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