Mack Brass euphonium: valve compression

[davewerden]

It dawned on me that I can't report on my own horn because the valves are vented!!

One gauge would be the clarity in fast slurred passages. Compensating horns generally have better note clarity, although I'm not sure why. On a horn with bad compression, the notes will blur together more. But on a horn with normal compression you hear each note in the slurred scale clearly. Also, a horn with poor compression will feel stuffier.

Counterintuitively, as the valves get broken in properly they seem to seal better. It is not nearly as noticeable on horns with stainless steel pistons, but back in the days when Besson used monel valves it was a huge factor. I got a new Sovereign 967 to test out. I liked the sound, but I literally could not get the lower notes in the 4th-valve register (just above pedal Bb) to come out of the horn! It took several tries to get a tone out. However, after playing the horn for a week and then a month, it got better and better. I was not sure if perhaps I had just gotten used to the Sovereign compared to my New Standard. But I was not sure I liked the horn in some other ways so I asked for a new one to be sent out. When the new one arrived I had the exact same trouble in the 4th-valve register. That would indicate it was not just getting used to the Sovereign. As I played the 2nd horn it also improved. That was the one I kept.

So I'm not sure if a valid compression test can be made on a showroom floor. It might be possible, given the general improvements in valves today. It may also be a factor involving the seal of the slide tubes - maybe they need to seat in a bit as well, although that would be the smaller factor I would think.

In any case, and this is why I really jumped in again today, we of course recognize that the seal will never be total. If it were, then the valve action would probably be poor. I'm not sure what the best balance is, or even the best way to test it. I KNOW that my 120-year-old tenor horn leaks badly, and that absolutely affects its playing characteristics. And I know my Adams does not leak in any way that creates a playing issue. Same for my Besson baritone and tuba. But what I don't know is how many seconds a 3rd-valve pop should be available, and whether it matters if it is 3 or 5 seconds.

[RandyL]

The devil is in the details here, Ernst. We might get a general idea from a good number of responses, but determining the "leak" time could get tricky. Do you go by what you hear? Or do you go by how long it takes before you don't get much pop when pressing the valve? How much is "not much"? And the telescoping portion of some third valve slides is much longer than others. So you might need to specify, say, three inches, to equalize this factor across horns.

If anyone is inclined to pursue this idea, I'd suggest going by ear rather than trying to define "not much pop." A reasonably tight valve is going to retain at least a bit of pressure for quite some time, if not indefinitely. A valve that's leaky enough to cause a problem would let its compression off fast enough to be audible, I'd think, so the duration of the leaking sound would seem to me the best simple measure. Perhaps someone more knowledgeable would overrule me on that point.

I have a Yamaha 321S at hand that is in good condition, with just a couple of years' use. None of its 4 valves allows an audible loss of compression with several inches of slide movement--except that of course the second valve allows only half an inch or so. An 842 that I tested back at the time of my original post on this thread seemed to hold its compression quite some time, with no audible leaking. I never tried to determine just how long it would hold. Seems that I recall waiting 30 seconds or so. My Mack Brass horn is not at hand, but as I recall, the duration of audible compression loss ranged from about 2 to 4 seconds. Also available is a Besson Prestige 2052. It's not convenient to check right now, but as I recall from a former test, it did not hold compression as well as the Yamahas, but better than the Mack.

[ernstlanzer]

Thanks again guys. I think "not much pop" was a misleading phrase. It really is no pop to speak of. And there is three seconds or so of very audible hissing noise, which clearly indicates escaping air. This is just from pushing in the long 3rd valve slide, without pressing the valve down at all.

I'd love to be able to say that I can tell the difference just by how it plays, but I'm only recently getting back into playing after 10 years away from the horn, so I don't quite trust the consistency and accuracy of my fast, slurred passages. It seems fine to me, but I'm worried about what will happen a year down the road when I'm in better shape. I'd hate to start looking for a new horn all over again.

It certainly stands to reason that it won't be a perfect seal (although it seems Yamaha horns get pretty darn close). I'm just wondering how much compression is reasonable. I realize everyone's horn is different, but I guess I was looking either for a little reassurance that this sort of thing is normal, or for some confirmation that I might have received a flawed horn.

EDIT: this isn't just the 3rd valve, it happens on the 1st and even 2nd valve with it's short slide. You can hear the hissing best by putting your ear up to the mouthpiece receiver.

[RickF]

I too have vented valves on my M5050 so can't test this. But 3 seconds of a 'hissing sound' seems about right pulling the 3rd slide on my Yamaha 641 (when I still had it). As Dave Werden said you can't have a complete seal or the valves would be too sluggish.

My opinion for what it's worth. YMMV

[RandyL]

It dawned on me that I can't report on my own horn because the valves are vented!!

When I saw a note about vented valves a few days ago (I had not heard of that feature previously), it occurred to me that this seems relevant to our discussion. Dave seems to imply that valve compression is not possible on a horn with vented valves. The vents apparently "leak" badly enough--by design, not by accident--to prevent significant compression.

So does this mean that compression is not really a factor to concern ourselves with? Obviously a vent of a given size might leak less than a badly worn valve. But if a horn plays fine with a vent that prevents (ahem!) meaningful compression, does it follow that any amount of compression indicates that a valve is sealing well enough not to degrade the playing characteristics of the horn?

Or does it matter exactly WHERE the leakage happens? In that case, I assume that the vented valve would be located so as not to degrade the performance of the horn, while an equivalent or even lesser amount of leakage elsewhere might still be problematic.

[RandyL]

Or does it matter exactly WHERE the leakage happens? In that case, I assume that the vented valve would be located so as not to degrade the performance of the horn, while an equivalent or even lesser amount of leakage elsewhere might still be problematic.

Oh. I think I get it. A vented valve probably vents externally, to the top or bottom of the valve cylinder, whereas a leaky valve allows air to flow internally to or from other sections of the horn's tubing, thus affecting the sound. In that case, just cancel the suggestion in my previous post, that only a very badly leaking valve would really make any difference.

[davewerden]

My pistons on the new horn are exactly like the ones on the old horn, except for one small hole. The hole aligns with a valve tube when the valve is UP so any trapped air can escape. See this blog post for a photo of my 4th valve and its vent:

http://www.dwerden.com/forum/entry.p...dams-Euphonium

[RickF]

The vent hole will be different on each valve depending on where it needs to line up with an opening to the slide. On my first valve, the vent hole is pretty low to align with the bottom tube to the slide.

See this post for a picture:
http://www.dwerden.com/forum/showthr...866#post119866

[RandyL]

Dave and Rick,

Thanks for clarifying the function of the valve venting. Dave's blog post was where I encountered the idea a few days ago, but I did not read it carefully enough to get a good mental picture of how it works. I can see now why it should be irrelevant to the flow of air through the horn. Presumably if a valve were leaking badly enough to let "playing" air get to that vent, the vent shouldn't make it much if any worse.

I checked my horns more carefully just now. The Yamaha 321 has a little less than 3" of slide movement. Compressing the slides that full dimension does create an audible leak after all (not as loud as my other horns). The 3rd valve leak is audible for about 30 seconds; the first valve for about 15.

The Prestige 2052 is "worse" than I recalled. First valve is audible for about 2 seconds; 3rd valve for about 5. On every horn I've tested, the 3rd valve has better compression than the first. Wonder whether that's because the first valve gets more use and therefore exhibits more wear.

[ernstlanzer]

Thanks for checking on that, Randy. That's a big help. And thanks to everyone else who responded. It's interesting how in the first couple pages of this thread folks were thinking that a leak like this might be a significant problem, which is part of what got me worrying in the first place. But it seems like valve compression is all over the place between different manufacturers. I'm still curious to hear from others about the amount of compression they have, but at least I'm satisfied there's nothing abnormal about my horn.

[davewerden]

Of course we COULD also talk about what people have told me in the past: not pushing down the valve while pulling the slide causes extra wear.

What do you think? Shall we see if this thread can stretch out to 10 pages????

[RandyL]

I suppose the topic of valve wear could stretch out the discussion, even if it is off-topic. But what would an internet discussion be without going off-topic? I'll play the skeptic on the matter; I'd like to hear an argument about how air or oil could cause wear. Oh; maybe I see something here: someone could argue that the vacuum pulls particulate matter into the valve cylinder that would otherwise remain in the tubing, and that particulate matter could cause wear. Maybe so. . . . But would any particulate matter be abrasive enough to wear the metal surfaces? I suppose if someone regularly uses a toothpaste with an abrasive and doesn't rinse well (say, just after breakfast) and then plays the horn while some abrasive is still in the mouth (say in first-hour band at school), then some abrasive ends up in the valve cylinders. Maybe I could move from skeptic to believer after all. :-)

It is interesting to me that there's such a difference between the Besson Prestige and the Yamaha 842. Both horns are roughly the same age: the Yamaha was 2 or 2.5 years old when I tested it; the Besson is less than 5. We bought both horns used, so I don't know how much playing time each has had. We no longer have the Yamaha, but my son (a pretty decent player) played them head-to-head and felt that any difference was to the Besson's advantage except that the Besson demands more effort--but repaid the effort with a bigger, fuller sound. BUT we've only played one Prestige. How would our Prestige compare against another Prestige? We picked it up on eBay at a very good price, without knowing the owner's reason for selling.

So it would be easy to be a little paranoid and think perhaps our Prestige is not up to spec on this point. But both my son's teacher (doctorate in Trombone) and the Southeast sales manager (maybe not exactly the right title) for Buffet out of Jacksonville have played the horn and thought it played well for them. So I gather that very little, if anything, is amiss.

If you're going to keep the horn long-term, you might want to get a pretty exact timing of the duration of your leakage hiss on the various valves (say, minimum, maximum, and average of ten different timings), record these values somewhere (a spreadsheet seems most natural), and then try it again in six months or a year, and then periodically after that. It would also be interesting to try it right before oiling valves or greasing slides and then again right after; also right before and after a bath, so see whether those factors make any difference. I think I'll do this with my Mack Brass horn and see how it does over a couple of years' time.

Will I remember to report back here? We shall see. Bath-time is coming up soon, so perhaps I can remember to report at least that experiment. :-)

[RandyL]

On the wear question, perhaps someone is thinking that the extra force required to pull the slide implies more friction and therefore more wear? But I would not think that the extra force required to draw the vacuum translates into more forceful contact between hard surfaces that would be required to cause wear. Of course moving air CAN create wear (as wind blows against rocks, for example), but is it really the AIR that wears the rocks, or is it the particulate matter that the moving air carries? And this brings us back to the topic, since the leaks we're talking about do involve moving air. But I'm skeptical that the amount of air that would move with increased friction past the metal surfaces inside a euphonium when a slide is pulled without pressing the valve would, over the lifetime of the instrument, cause an amount of wear that would perceptibly degrade the playing characteristics of the horn. If the air carries particulate matter, though, then the bets are off for me. And perhaps even the air alone can do more damage than I think. Somebody should probably design a doctoral dissertation study to explore the question. :-)

[davewerden]

Ok, try this. Suppose the issue is not valve wear. Suppose the issue is that as you push or pull the side with greater force, the tubing may warp slightly, even if temporarily. When pulling out the side, might it create more wear if the structure is warped? And of course if the warping is NOT temporary, then valve wear could be affected (assuming the valve casing warps a bit under pressure).

I'm not sure that's as goofy as it sounds. When I first saw Miraphone's early compensating euphonium, Luke Spiros was with me. He picked it up and wiggled the valves. No problem. Then he squeezed the first valve tubing a little and stopped the valve in mid travel.

[RandyL]

Well, Dave, what can I say? That sounds like a pretty convincing demonstration that it's possible to deform the tubing--apparently even the valve cylinder, if I'm understanding you correctly. I assume that he squeezed the valve cylinder, not the first valve loop tubing? If the latter, did the deformation of the tubing also create a deformation of the valve cylinder that stopped the travel? Or did the slight increase in pressure in the loop tubing push the valve piston (in a position to block both ends of the loop off back against the cylinder wall? I guess maybe that seems more likely than deforming the valve cylinder itself.

Now the question becomes whether the vacuum would create an UNEVEN pressure that would deform the tubing. If the vacuum were evenly distributed, would it deform the tubing? And when we consider the slide grease, wouldn't the deformation have to be sufficient to displace most or all of the lube before you could have sufficent metal-to-metal contact to create wear?

You did get me on the main point, though: I wasn't considering deformed tubing at all.