Do Leadpipes Fundamentally Kill Response?

[Bonearzt]

I'm saying the wall thickness at any point along the shank is dependent on the size & shape of the backbore. Considering the standard Morse taper, the wall thickness will vary from thin with a large backbore, to thick with a small backbore.

Not to be condescending to anyone, but here is a description of a "venturi":

http://www.hendersons.co.uk/wms/venturi_principle.html

So with this in mind, the "venturi" of a leadpipe does not function in a similar manner.
The only "venturi" will be the throat or transition from the bowl/cup of the mouthpiece to the backbore. And from there it's a constant taper through the leadpipe into the upper slide tube of the hand slide, or through the trumpet leadpipe into the legs of the tuning slide assembly.
In my 30+ years of repairing and building brass instruments, I have never experienced a leadpipe of ANY kind that actually restricts the airflow past the end of the mouthpiece shank.

Eric

[elmsandr]

I'm saying the wall thickness at any point along the shank is dependent on the size & shape of the backbore. Considering the standard Morse taper, the wall thickness will vary from thin with a large backbore, to thick with a small backbore.

Not to be condescending to anyone, but here is a description of a "venturi":

http://www.hendersons.co.uk/wms/venturi_principle.html

So with this in mind, the "venturi" of a leadpipe does not function in a similar manner.
The only "venturi" will be the throat or transition from the bowl/cup of the mouthpiece to the backbore. And from there it's a constant taper through the leadpipe into the upper slide tube of the hand slide, or through the trumpet leadpipe into the legs of the tuning slide assembly.
In my 30+ years of repairing and building brass instruments, I have never experienced a leadpipe of ANY kind that actually restricts the airflow past the end of the mouthpiece shank.

Eric

Where I am talking about the wall thickness is only at the exit of the mouthpiece, also mostly irrelevant to my point, I should not have brought it up. The only point there being that with a standardized taper, the gauge line at the end of the mouthpiece is the same diameter, nominally, for every horn that accepts that mouthpiece.

Again, if there is no venturi, the minimum diameter of the interface for two large shank leadpipes would be identical (a Bach 42 and a Bach 50, for example). The exit diameter of a 6.5 is the same as a 1.5 (and a 4G, 3G, 2G, and 3 different 1.5s that I have handy). They are all the same ID going into the horn, but I can clearly feel a difference in diameter inside the pipes. Beyond a few pens, I have nothing at home to get a better measurement than that. If there was no venturi, what was George McCracken trying to fix with his deisgn of the Duo Gravis Leadpipe?

I tend to agree that we probably WANT there not to be a venturi, that a defined taper from throat to bore of horn is the most logical and consistent design, but it is not what currently exists in the most of our horns. We have a defined choke point about 1/2" into the horn from the end of the mouthpiece. It is there intentionally and repeatably.

Cheers,
Andy

[BGuttman]

I think what we really need to consider is the rate of taper of the leadpipe from the mouthpiece into the upper inner tube. I'm sure there is a difference between a faster or slower taper (or none at all in my CoolWind trombone).

[timothy42b]

Yeah, we're hung up on the word "venturi" and can't get past it. (I warned you.)

If mouthpieces were more standardized, I think the ideal shape would be a step in the leadpipe.

The shape of the leadpipe would be a contracting cone to match the taper of the mouthpiece shank, but that would end with a right angle step that the mouthpiece end hits, and an expanding cone from there. But that step has to be larger than the largest ID of the mouthpiece shank or you have a sharp edge in the path of the sound wave. And mouthpieces vary a lot.

[FOSSIL]

Okay, the story of a wasted 30mins of my life..
My two piece ex Phil Teele pipe plays amazingly...there is quite a gap between the end of the mouthpiece shank and the start of the pipe section, so tonight I got out the torch and moved the pipe in so there was only a small gap. Ruined it !!! Torch out again and restored the gap.. back to amazing.
If it works, don't mess with it.

Chris

[Doug Elliott]

Eric is right, I was going to post that myself but decided not to waste my time.

By the loose definition of "venturi", the entire bottom inner slide is a venturi, getting smaller from the end crook. And then some small bore horns have a "choke point" at the beginning of the gooseneck where it's smaller than the slide bore. So I guess you could say 4 venturis.

[harrisonreed]

This thread is crazy.

"Does a leadpipe fundamentally ruin the response?

"No. Next slide"

[Dennis]

Eric is right, I was going to post that myself but decided not to waste my time.

By the loose definition of "venturi", the entire bottom inner slide is a venturi, getting smaller from the end crook. And then some small bore horns have a "choke point" at the beginning of the gooseneck where it's smaller than the slide bore. So I guess you could say 4 venturis.

In Vincent Bach's writings on brass instrument design, he discussed the need for "choke" points in the designs. As I recall, the intent was two-fold: to provide some resistance to the player, and to bring the overtone series back into alignment.

I'm not sure if this justifies the underbore valves used in the 42B or not. I am pretty sure it is partial justification for using the same neckpipe in the 36 and 42.

[Doug Elliott]

Yes, some Bach models have that choke point... But the better ones don't.

In any case it would be a stretch to call it a venturi.

[Posaunus]

I know very little about leadpipes (all my trombone pipes are soldered in), but it's my understanding that at least some (most?) trombone leadpipes narrow a bit downstream of the mouthpiece receiver end, and then expand toward the pipe's downstream end as they widen to the inner slide bore. (This could easily be resolved by showing a cross-sectional drawing of a leadpipe.)

If my speculation is true, the narrowest point of the leadpipe would be known to most fluid mechanicians as a "venturi." As fluid (air, in this case) flows through the narrowest spot (the "venturi"), the velocity is higher and the air pressure is lower. This region will provide a slight additional resistance to flow through the tube (pipe) than if it were cylindrical or uniformly tapering wider as the flow progresses downstream.

I'm not sure what this controversy is all about, but I see no reason to not label the narrow region a "venturi."

[timothy42b]

I'm not sure what this controversy is all about, but I see no reason to not label the narrow region a "venturi."

The reason some of us don't like to label it that is because that narrow region has a mouthpiece shank in it, and the mouthpiece bore is widening in that area.

If that section is empty of a mouthpiece shank then it is narrowing and it does "look" like a venturi.

We've been arguing this point for at least 10 years that I can remember and this is probably the most polite discussion we've had, compared to some of the previous.

Chris's experiment is very interesting. I had always thought a gapless transition would be better and I think trumpet players pay extra to have that installed, but it appears this is not the case.

[FOSSIL]

I'm not sure what this controversy is all about, but I see no reason to not label the narrow region a "venturi."

The reason some of us don't like to label it that is because that narrow region has a mouthpiece shank in it, and the mouthpiece bore is widening in that area.

If that section is empty of a mouthpiece shank then it is narrowing and it does "look" like a venturi.

We've been arguing this point for at least 10 years that I can remember and this is probably the most polite discussion we've had, compared to some of the previous.

Chris's experiment is very interesting. I had always thought a gapless transition would be better and I think trumpet players pay extra to have that installed, but it appears this is not the case.

No no, as I have it from our trumpet playing brethren, a small gap is an important part of the design. I've messed about with this before and found that on two piece trombone pipes, there has to be a gap. You can fine tune that gap, but get rid of it and the pipe does not work properly. I can think of no physical reason for this but it is what it is.

Chris

[timothy42b]

https://stomvi-usa.com/learn-about-the-annulus-gap/

https://www.grmouthpieces.com/category-s/244.htm

From the trumpeters.

[Bonearzt]

No no, as I have it from our trumpet playing brethren, a small gap is an important part of the design. I've messed about with this before and found that on two piece trombone pipes, there has to be a gap. You can fine tune that gap, but get rid of it and the pipe does not work properly. I can think of no physical reason for this but it is what it is.Chris

This "gap" is another part of the lead pipe voodoo!!

[Doug Elliott]

Bach trombones (and probably others) have a huge gap in the bell receiver just under the valve.
It's really the same situation of a tapered receiver plus badly fitted parts. There's no acoustical reason for it.

The leadpipe is the same, The only reason that venturi exists is badly fitted parts - and the only reason a gap is necessary is because it's compensating for something else. The same effect can be accomplished other ways but everybody's used to it being that way, so it continues. The only necessary venturi is the throat of the mouthpiece.

Things like the MAD pipe and other one piece designs are a start in the right direction, but need to be vastly improved from what I've seen.

[elmsandr]

No no, as I have it from our trumpet playing brethren, a small gap is an important part of the design. I've messed about with this before and found that on two piece trombone pipes, there has to be a gap. You can fine tune that gap, but get rid of it and the pipe does not work properly. I can think of no physical reason for this but it is what it is.

Chris

That's pretty much all I have been trying to point out. There is something "there" on leadpipes a short distance from the end of the mouthpiece. The size of that something and the distance downstream from the mouthpiece is very important to our expected response of the leadpipe.

This is a prime example of where I think good metrology could add a lot brass instrument construction. I do not think that any manufacturer that I have seen (and I've been to a lot of them) honestly has any idea how much variation they have here. It is a lot easier to make things the same and optimise them when you know where they actually are and how much they vary.

Unfortunately between this thread and the leadpipe materials thread, I began playing with my drawer of pipes again... I remember now why I forced myself to not care about it. Too many variables for me.

Cheers,
Andy

[elmsandr]

No no, as I have it from our trumpet playing brethren, a small gap is an important part of the design. I've messed about with this before and found that on two piece trombone pipes, there has to be a gap. You can fine tune that gap, but get rid of it and the pipe does not work properly. I can think of no physical reason for this but it is what it is.

Chris

That's pretty much all I have been trying to point out. There is something "there" on leadpipes a short distance from the end of the mouthpiece. The size of that something and the distance downstream from the mouthpiece is very important to our expected response of the leadpipe.

This is a prime example of where I think good metrology could add a lot brass instrument construction. I do not think that any manufacturer that I have seen (and I've been to a lot of them) honestly has any idea how much variation they have here. It is a lot easier to make things the same and optimise them when you know where they actually are and how much they vary.

Unfortunately between this thread and the leadpipe materials thread, I began playing with my drawer of pipes again... I remember now why I forced myself to not care about it. Too many variables for me.

Cheers,
Andy

[elmsandr]

Bach trombones (and probably others) have a huge gap in the bell receiver just under the valve.
It's really the same situation of a tapered receiver plus badly fitted parts. There's no acoustical reason for it.

The leadpipe is the same, The only reason that venturi exists is badly fitted parts - and the only reason a gap is necessary is because it's compensating for something else. The same effect can be accomplished other ways but everybody's used to it being that way, so it continues. The only necessary venturi is the throat of the mouthpiece.

Things like the MAD pipe and other one piece designs are a start in the right direction, but need to be vastly improved from what I've seen.

Not to derail further... but on that handslide receiver... I happen to know that some handslide receivers were made special with that gap on that assembly on a brand that did NOT have that gap designed in because some REALLY great players wanted it there. Was a treat walking around and checking all valve sections to make sure they were properly identified and not mixed with the standard parts.

Expected response, not the acoustic necessity drove them being swapped out.

Cheers,
Andy

[FOSSIL]

Sorry Doug, I don't buy into the badly made parts need gaps idea.... when I first went down to see Mick Rath, I put the idea to him about butting all the tube together so there were no gaps....he just laughed and said it was far from that simple.... some places need gaps, others don't. Good old trial and error over long periods of time have gotten us to where we are now. That area between the slide receiver and the valve is a crucial design point... some makers leave a gap, some butt the valve tube up, some fit a restrictor.... depends on the overall concept...

Chris

[Doug Elliott]

Of course I agree it's the overall concept. But also, judging by the extreme inconsistency in both leadpipes and slide receivers, I agree with Andy's comment "I do not think that any manufacturer that I have seen (and I've been to a lot of them) honestly has any idea how much variation they have here."

There remains plenty of room for improvement in both design and manufacturing. My 42B (that I don't have anymore) had a space between the slide receiver and valve that was .630 ID and about 3/8" long. I think that was badly made parts, not a design feature. And right now I have a 36 slide receiver that has almost no inside taper - another badly made part.

The "good old trial and error over long periods of time" tells us that parts that fit better play better. When it's part of the overall design concept.

[FOSSIL]

Yes Doug, I've taken a NY Bach apart and been amazed by the shabby build quality...but it was a great horn...even if it was thrown together. There are people who build to high standards...on the large scale side Yamaha are very good with build...again, I've taken a Yammy apart and was very impressed. The shoddy Bach played better....

Chris

[Tbarh]

Yes Doug, I've taken a NY Bach apart and been amazed by the shabby build quality...but it was a great horn...even if it was thrown together. There are people who build to high standards...on the large scale side Yamaha are very good with build...again, I've taken a Yammy apart and was very impressed. The shoddy Bach played better....

Chris

I somehow doubt that the bell flare was a result of shabby build quality..

[FOSSIL]

Yes Doug, I've taken a NY Bach apart and been amazed by the shabby build quality...but it was a great horn...even if it was thrown together. There are people who build to high standards...on the large scale side Yamaha are very good with build...again, I've taken a Yammy apart and was very impressed. The shoddy Bach played better....

Chris

I somehow doubt that the bell flare was a result of shabby build quality..

Everything you could see was fine...it was tubes sawn at an angle, inconsistent gaps ,etc... Just not what you would expect from a legendary maker.

Chris

[mrdeacon]

I somehow doubt that the bell flare was a result of shabby build quality..

Everything you could see was fine...it was tubes sawn at an angle, inconsistent gaps ,etc... Just not what you would expect from a legendary maker.

Chris

If anything that really speaks to how much the effect of juju magic has on instrument production. Having magical parts can overcome shoddy construction.

I'm also sure that these old designs like the Bach 42 and Conn 88h are designed in a way to work despite shoddy construction if that makes sense.

[Bonearzt]

I somehow doubt that the bell flare was a result of shabby build quality..

Everything you could see was fine...it was tubes sawn at an angle, inconsistent gaps ,etc... Just not what you would expect from a legendary maker.

Chris

Ya gotta wonder if these "inconsistencies" are what made the horns special!

Eric

[Tbarh]

My point was that the magic of superb bell construction (and the craft of spinning) can make up for bad assembly.. When i visited the Shires shop in '98 Steve left all part of manufacturing to his crew except the bell spinning, which was almost like a sacred ceremony.. There is said to be some mojo regarding how Bach wanted the bell thickness to be along the flare..

[FOSSIL]

My point was that the magic of superb bell construction ( and the craft of spinning) can make up for bad assembly.. When i visited the Shires shop in '98 Steve left all part of manufacturing to his crew except the bell spinning, which was almost like a sacred ceremony.. There is said to be some mojo regarding how Bach wanted the bell thickness to be along the flare..

Interesting how we started at one end of the trombone and have ended up at the other ! I think Steve is a little unusual.... making bells is really hard work...in a factory situation I would think it's not the most popular specialization...though buffing is for sure the least popular.... in a design, everything is important, but if I had to say which bits had the biggest effect, I would say leadpipe, then bell....
does that bring us back on thread ?

Chris

[GabrielRice]

Steve tried training somebody else to spin bells many times over the years before he one who could do it to his satisfaction. That guy's name is Rodrigo, and he took over that job completely in the couple of years before Steve left the company.

It is hard work, but it also requires touch, especially to spin bells from thinner metal like the 2RVE and the 7YLW and 7GLW. Unless you have a good feel for it, those lighter weight bells can tear very easily.

[tombone21]

Decided to provide an update to my initial inquiry into leadpipes. I decided to take the plunge down the rabbit hole, searching and buying leadpipes for my Shires large bore. I now have several very different designs and materials at my disposal but I think I am zeroing in on a setup that works for me.

To start off, Shires has been making a series of leadpipes that pretty accurately matched my original quorum: creating a leadpipe that retains contact with the inner slide, therefore all the vibrations of the leadpipe are (theoretically at least) transferred to the slide. They're called "H" pipes, and I believe can be had in any length or venturi. They are constructed by milling a solid piece of brass, therefore keeping the venturi but making the outside shape a totally straight line. I ordered mine as a 2.5L, which was my leadpipe of choice at the time. When I received it, I immediately noticed a weight difference. When weighing all of my leadpipes, I got this data after weighing each pipe 10 times and taking the average. (I am using a crude coffee scale that only rounds to the nearest half-gram.)

Pictured from top to bottom:
2.5: 31.5g (8 & 3/4")
2.5L: 34.5g (9 & 3/4")
2SS: 36.5g (9 & 3/4")
Brasslab T-90 Hwt: 38.5g (8 & 3/16ths inches)
2.5HL: 45.75g (9 & 3/4")



As for how the Shires heavy pipe plays: the response is there. Really requires little to no effort to make the notes speak, across all registers. If you've tried a Hartman mouthpiece, it's a similar feeling (to me). I often find myself using both more air and tongue than I need to make note connections happen; backing off and relaxing really makes the horn sing with this setup. But at the end of the day, for me, I don't really like things that add weight or mass to my instrument. I play one of the lightest bells that Shires makes and 10/10 times will pair it with a lightweight mouthpiece.

Adding weight in this very specific place on the horn (inside the inner slide tube) has been incredibly fascinating, and the BrassLab pipe that I had for a while before Shires delivered this H pipe to me is great as well, but to different effect. If you squint, you can see that there is still a definite venturi in the BrassLab leadpipe. I'm not sure what makes it heavier, but it is (and is also the shortest leadpipe in the arsenal). The result there is mostly in sound, and a more subtle version of the change in response the Shires H pipe affords. Very curious to see if there are any reactions or questions, I will do my best to answer them all.