The Pbone sound?

[whitbey]

I have a couple PBones. The white one that bounces around in the back of my truck. A pink one that hangs from the ceiling above my horns. Pink is my wife's color. And an orange one that the 5 year old grandson plays...with.

I am real estate broker and I actually use the white one at open houses to practice while no one in present. It gives me something to do and is a conversation point. And I do not need to worry about some kid or adult grabbing my good horn. ( And that is the explanation for the epoxy puddy on the neckpipe.)

I notice when playing the PBone I hear different things. Some good and some bad. Funny, I think I have learned some things to improve my playing. But I would like to understand more about the difference.

My question is that being plastic, what is the difference one would expect to hear different? Is it simply that less sound is in front of the horn and more is behind so I can hear it?

[Burgerbob]

Just like with different metal alloys (red brass, yellow brass, etc), much of the difference we hear with those is feedback related, rather than the actual sound out front.

Pbone sounds like trombone out front. Not exactly like a brass one, but not far off. Behind the bell it sounds pretty massively different due to that feedback difference.

[timothy42b]

The air column is the primary source of sound in the room. That's how a wind instrument works. The material doesn't add anything to the sound.

But the air column makes the bell vibrate, and though that vibration is very small it is next to your ear.

Your ear can probably hear the difference between plastic vibrating and brass.

Why not? When I hit an A, AND my wife's guitar is in tune, I can hear that vibration across the room.

[robcat2075]

In a physics class, it's the shape and length of the air column that mold the sound fed into a wind instrument.

In the real world, many people insist the material that contains the column is a significant factor.

However, blind listening and playing tests comparing the effects of different materials have a long history of producing little to support the assertion.



Is the Pbone intended to copy interior bore of any particular conventional trombone?

When I hit an A, AND my wife's guitar is in tune, I can hear that vibration across the room.

One day I sneezed so hard I could hear my cello across the room ringing.

[Doug Elliott]

I think you can see the differences in a spectrum analysis, even if you think you can't hear differences, due to different materials.

[robcat2075]

I shall certainly bring my spectrum analyzer to the next symphony concert to be sure I'm hearing all the brass I paid for.

[timothy42b]

I shall certainly bring my spectrum analyzer to the next symphony concert to be sure I'm hearing all the brass I paid for.

Test it on a jhorn first.

[whitbey]

Just like with different metal alloys (red brass, yellow brass, etc), much of the difference we hear with those is feedback related, rather than the actual sound out front.

Pbone sounds like trombone out front. Not exactly like a brass one, but not far off. Behind the bell it sounds pretty massively different due to that feedback difference.

Good to hear someone else also hears behind the bell as I do.
Thanks!

[boneagain]

The air column is the primary source of sound in the room. That's how a wind instrument works. The material doesn't add anything to the sound.

But the air column makes the bell vibrate, and though that vibration is very small it is next to your ear.

Your ear can probably hear the difference between plastic vibrating and brass.

Why not? When I hit an A, AND my wife's guitar is in tune, I can hear that vibration across the room.

So, question: where does the energy to vibrate the bell come from?

Reason for the question: even if the vibration is very small, most of the "finer" harmonic details that make up the sound of a particular instrument are not in the high amplitude fundamentals of the note, but in the far weaker overtones. A spectrum analyzer, as Doug suggests, can show just how weak some of those overtones are.
Seems to me that any energy consumed vibrating the instrument itself will no longer be available in the air column.

BTW: Audacity has a pretty neat spectrum analyzer feature. You can export the results into a CSV file, then import a couple spectra into a spreadsheet and overlay them in one chart. It IS interesting to record, say, a few measures of Bordogni on a couple instruments, normalize the volume level, then chart the spectra.

[timothy42b]

So, question: where does the energy to vibrate the bell come from?
Seems to me that any energy consumed vibrating the instrument itself will no longer be available in the air column.

Yes, precisely. The driven vibrations of the instrument structure can never add to the air sound, but only subtract.

(although there's probably plenty of energy available!)

And that leads to another observation. The maximum subtraction of energy from the air column system occurs at the resonances in the (brass or plastic) structure system.

Engineers use this principle to cancel out an annoying or destructive vibration in a machine. They attach something called a vibration absorber, usually a single degree of freedom spring mass damper, tuned to vibrate at the frequency we want to get rid of. Sometimes you see these overhead on a high voltage line, keeping it from a resonance.

If you want to know what the resonances in your structure are, just tap the bell and let it vibrate freely, put your spectrum analyzer on that.

There's another implication that follows. If the very small effect of the bell on the wind column occurs only at specific frequencies, why would we think the brass alloy would affect the tone of all notes, rather than those few? Hee, hee.

[boneagain]

So, question: where does the energy to vibrate the bell come from?
Seems to me that any energy consumed vibrating the instrument itself will no longer be available in the air column.

Yes, precisely. The driven vibrations of the instrument structure can never add to the air sound, but only subtract.

(although there's probably plenty of energy available!)

And that leads to another observation. The maximum subtraction of energy from the air column system occurs at the resonances in the (brass or plastic) structure system.

Engineers use this principle to cancel out an annoying or destructive vibration in a machine. They attach something called a vibration absorber, usually a single degree of freedom spring mass damper, tuned to vibrate at the frequency we want to get rid of. Sometimes you see these overhead on a high voltage line, keeping it from a resonance.

If you want to know what the resonances in your structure are, just tap the bell and let it vibrate freely, put your spectrum analyzer on that.

There's another implication that follows. If the very small effect of the bell on the wind column occurs only at specific frequencies, why would we think the brass alloy would affect the tone of all notes, rather than those few? Hee, hee.

RE: vibration absorber... a search on "A. H. Benade" and "tacet horn" should be amusing. Benade created a woodwind that could not produce a sound, pretty much because of the nodal effects you mention.

RE: changes at frequencies other than the one the bell rings at... bell ringing on a horn is, as you say, just ONE resonant frequency. Thing is, we can feel the bell (and other parts) vibrating at other frequencies, just nowhere nearly as strongly.

SOMEwhere in all the richness that is trumpet lore is an article about Schilke make bells out of a couple extreme materials. IIRC those extremes sounded like crap.

Resonant regimes... what a world

[timothy42b]

RE: changes at frequencies other than the one the bell rings at... bell ringing on a horn is, as you say, just ONE resonant frequency. Thing is, we can feel the bell (and other parts) vibrating at other frequencies, just nowhere nearly as strongly.

SOMEwhere in all the richness that is trumpet lore is an article about Schilke make bells out of a couple extreme materials. IIRC those extremes sounded like crap.

Resonant regimes... what a world

Bell ringing from an impulse will be at the set of resonant frequencies that exist in the bell (eigenvector from the stiff matrix/mass matrix)

But vibration from a driving frequency or set of frequencies is always at the driving frequency. Drive a bell at 60Hz, it vibrates at 60 Hz. If it's resonance is close to that it vibrates a lot, if not then a little.

I have read those Schilke accounts and they don't make any sense to me. I have concluded they were thought experiments rather than actual, his best guesses at what should happen.

[hornbuilder]

"Every" piece of the instrument has a resonant frequency, not "just" the bell.

No, the material the horn is made of does not "need" to be driven, to make a sound, but it is "being" driven by the energy put in by the player. This is why material and thickness makes a difference. Change a parameter of a material (weight/thickness/composition) and that material will absorb/conduct energy differently, resulting in a change to the way the horn plays.

[boneagain]

+1 Matt's points.
The trombone bell and mouthpiece intentionally do NOT favor a single resonant frequency. The exact taper of the bell and cup are what make it possible to derive 7 "standard overtones" from a closed-ended pipe that SHOULD only produce every other one, AND to do so for the different pitches at different slide lengths.

The resulting standing waves ARE going to vibrate the "container" around the air column. They do not have to resonate a particular component to vibrate it.

Richard Smith did an interesting study about vibrations along the length of a brass instrument. He demonstrated that not only do the walls get excited by the energy inside them radiating out, but also by sound traveling along those walls.

I'm pretty sure no one really has all the answers on this stuff. Not enough answers, at least, to specify what a plastic wall should sound like vs. a metal one.

The best I've seen so far is good, solid demonstration that WAY over 90% of what makes a trombone sound like a trombone is in the shape of the instrument.

I'm just glad people like Matt can hear the difference and are willing to experiment to get the most out of that other 10%, because it's a 10% MOST folks can hear pretty clearly.

[robcat2075]

We believe the plastic trombone to have a characteristic sound due to its plastic construction and yet... the sound it produces is well within the window of what the various brass trombones produce already.

The sound is not an outlier, obviously separate from real trombones. If someone hearing one didn't know it was a plastic trombone, they would just identify the sound as "trombone".

[lauriet]

I did have a screen shot of the waveform of a pbone and a brass instrument.
(I seem to have deleted it from my computer)
There are plenty of osilloscope/spectrum analyser amps around so you can't try it yourself.
There was a difference in the waveform so the spectrum would have to different.
It seems to me the plastic is dead and the brass rings to add some zing to the sound....at least for the player behind the bell.

[robcat2075]

I did have a screen shot of the waveform of a pbone and a brass instrument...

And the trombones were identical in every other way?

You would have to have that for a meaningful comparison.

[mwpfoot]

I enjoyed mellow practicing on my first one in a lively room, and thought it had potential. Then I took it at a marching band rehearsal and couldn't tell what was happening. Basically zero player feedback in a loud group. I am sure it sounded trombone enough in that rowdy setting to others, but it was an unpleasant experience for me.

My characterization a-la the original post is that it is ALL sound in front of the bell and NONE behind it. If you have good reflections, it's fine. Otherwise good luck.

My clearance price replacement plays terribly. I keep it around in case I ever need to play in the pool, or throw a trombone at someone.

[timothy42b]

My characterization a-la the original post is that it is ALL sound in front of the bell and NONE behind it. If you have good reflections, it's fine. Otherwise good luck.

Yes. I was playing one in a community band rehearsal just before covid, one where I'm the only trombone and there are 4 to 5 trumpets. I can't remember if it was the tenor or the alto pBone, probably the alto because I screwed up a run. I brought it because my wrist was killing me that day. (wrist is better now, but the shoulder hurts!)

Anyway, I hit some bad notes on a march and the director looked over, and she said she hadn't realized I was on a plastic trombone until she looked.

[Matt K]

One thing that I've been wanting to try for a few years but never had the spare cash to burn was to get a PBone and a YSL354 or something and glue the PBone bell to the neckpipe. I suspect a lot of the problems with the pbone are due to it being a $150 instrument, not the plastic per se. Especially the (lack of?) leadpipe, glued inners/stockings, and god only knows how much tension throughout the build.

[BGuttman]

I have the Cool Winds bone (the one with the F attachment). Mine came with a screw-in brass leadpipe. I think any 0.547" pipe will fit (don't know what the threading is). My big beef with it was that it sounded like it had a leak. And the slide had no stockings. I put a layer of packing tape (the clear plastic stuff that's around 0.002" thick) on the end of the slide. I put two 3" wide bands. Made a big difference.

Also, ditching the plastic mouthpiece was a must. I found an old King 29 lying around and it made a HUGE difference.

If I ever get the time I might look at some other leadpipes, but I'll be ****** if I have to pay $200 for one -- that's about what I paid for the horn.

[timothy42b]

If I ever get the time I might look at some other leadpipes, but I'll be ****** if I have to pay $200 for one -- that's about what I paid for the horn.

I'm playing one with one of Doug's mouthpieces. That's almost 3 times what the horn cost. Hee, hee.

Worth it though, the partials line up now.

[lauriet]

>>> And the trombones were identical in every other way?
>>>You would have to have that for a meaningful comparison.

Both were 0.5 bore and 8" bell

[timothy42b]

>>> And the trombones were identical in every other way?
>>>You would have to have that for a meaningful comparison.

Both were 0.5 bore and 8" bell

Are any two Bach 42B's identical? hee, hee.

But the point that was being made is that a pBone sounds like a trombone. It may not be a very good trombone, but then again there are lots of brass trombones in that boat too.

[ArbanRubank]

As far as I am concerned, THE only two things a p-anything is good for is to use in a situation where damage to a good brass horn is not only possible, it's likely. OR, perhaps just keeping it in the trunk for any spontaneous jams that might occur. Otherwise, they suck, IMO. Although Matt may be on to something with swapping out parts-is-parts. He'll let us know.

[Matt K]

Can someone with calipers measure the OD of the male tuning slide, bell side leg? And the ID of the bell tuning slide receiver? On the lookout on fleabay for one seeing if my donor horn will need me to acquire a new tuning slide leg. Fortunately I picked up a spare a few weeks ago.

[sf105]

Agreed on a proper mouthpiece. pBones also excellent for outside, especially when it's cold.

[whitbey]

Just like with different metal alloys (red brass, yellow brass, etc), much of the difference we hear with those is feedback related, rather than the actual sound out front.

Pbone sounds like trombone out front. Not exactly like a brass one, but not far off. Behind the bell it sounds pretty massively different due to that feedback difference.

The conversation is fun. But the question was not about the sound out front, but the sound behind the bell. The answer above was the confirmation I was looking for.

I use the PBone at open houses I do for real estate. It is used because some kid may pick it up..... Again.
And because it is in other houses, each room is different and sound different. It was confusing me about what I was hearing. However, I did hear things I never heard on my good horns. When I got home, I was able to listen for the same thing and make some improvements to my playing on the good horns.

[timothy42b]

The conversation is fun. But the question was not about the sound out front, but the sound behind the bell. The answer above was the confirmation I was looking for.

The pBone is not as much fun to play because it doesn't sound good behind the bell, even if you're making music out front. IMO of course.

But consider this. How much of your sound do you hear when gigging? That's something that isn't part of my life right now and at my age it isn't likely to be. But in many venues, it's loud enough you can't hear yourself, and you're wearing ear plugs to protect what little hearing you have left. Outside the practice room, do you hear your sound?

I considered whether I should add a smiley. Hee, hee.

[lupusargentus]

I've been cogitating on this thread for a few days and would like to throw this out there. Is the problem with Pbones and similar plastic horns the material itself, design, or build quality? Is this more of an issue of "student quality" horn with lower grade materials and looser quality control? Is it an issue of poor design e.g. bad lead pipe design, bell flare, etc? Could a plastic horn be designed and built to be a "pro" horn? Butler is making some top notch horns with carbon fiber. (Never played one, just going by what I've read and heard)
Is the real issue not so much the material the horn is made from but the actual build quality?

Full disclosure; I have a Pbone and am not impressed. To my ears the sound at the end of the bell is ok but the horn is so clunky and feels cheap. I would take it over the standard tank used for pep band or marching, just because it is so darn light weight.

[Matt K]

I thought the exact same thing. I currently have one en route! If I have a spare few hours next weekend I'll see if I can figure out a reasonable way to attach it to a brass neckpipe/slide that I have and report back. I suspect that the bell itself alone on an otherwise brass instrument won't be much different than any other bell I put on that horn. Maybe even better... student bells are often quite heavy and I tend to prefer lighter bells.

[whitbey]

I used my PBone at an open house yesterday. I am a real estate guy. A toddler went after it. fell on the floor.

Still sounds the same.