closed wrap is back, baby

[jacobgarchik]

viva la bends

[Burgerbob]

He's been playing it for a couple months... Thought it was a new Bach model until he announced he was leaving bach!

[tbonesullivan]

I guess they really didn't want anything sticking out the back of the horn?

Also, did you happen to see the horns that The Brass Ark is having made by Stephens? FLAT WRAP and tuning in slide.

http://www.brassark.com/new.html

[Kdanielsen]

Double Helix Wrap (TM)

[elmsandr]

I guess they really didn't want anything sticking out the back of the horn?

Also, did you happen to see the horns that The Brass Ark is having made by Stephens? FLAT WRAP and tuning in slide.

http://www.brassark.com/new.html

Heck Yeah!

Loving the "new" wraps out there. Having stuff stick out behind the main bow is silly. Ruins balance and takes up unnecessary space in halls/pits/cases.

Also love the short F attachment tuning slides. If it isn't long enough for a good E pull, it shouldn't be longer than about 2".

The Stephens wrap is nearly identical to the '20's Conn wraps. Simple.

That new Shires wrap is a creative use of parts already available. Looks great. I'd love to play one and see if it makes any difference.

Cheers,
Andy

[Tbarh]

I guess they really didn't want anything sticking out the back of the horn?

Also, did you happen to see the horns that The Brass Ark is having made by Stephens? FLAT WRAP and tuning in slide.

http://www.brassark.com/new.html

Heck Yeah!

Loving the "new" wraps out there. Having stuff stick out behind the main bow is silly. Ruins balance and takes up unnecessary space in halls/pits/cases.

Also love the short F attachment tuning slides. If it isn't long enough for a good E pull, it shouldn't be longer than about 2".

The Stephens wrap is nearly identical to the '20's Conn wraps. Simple.

That new Shires wrap is a creative use of parts already available. Looks great. I'd love to play one and see if it makes any difference.

Cheers,
Andy

"Ruins balance"???

[elmsandr]

"Ruins balance"???

Yes.

Physical balance. Take a traditional wrap with mass closer to your hand compared to a Bach Open wrap that pushes a bunch of that tubing farther back away from your hand.

Bring that center of mass back towards the hand.

I also wonder if this is why the Stephens horn has the wrap on the head side of the horn as opposed to the outside.

Cheers,
Andy

[boneagain]

I'd have a hard time with Stephen's new layout. I already east through the finish on my "gooseneck."
Looks like a condensation catcher just before the F tuning slide.
If he'd moved that loop back out of the neck area, the tuning slide could have been there, AND it would have been in an easy spot to pull and dump if condensation DID pool there!

I have traumatic memories of up-ending my early 70's big bell bach to dump the F attachment after long rests, just in time for entries where a burble would have been quite unwelcome.

I suspect the neck-side placement IS a good effort to keep that tubing pulling the bell toward the player, instead of straining the wrist in the other direction.

I did some turn counting.

NASA did some studies for ducts in various crafts. They found that acoustic and fluidic impedance in ducts did not change much once the radius of the bend was over twice the duct cross section.

So, according to NASA, the gentler bends in the Shires should not have any less impedence than the sharper bends in Stephen's.

OTOH, stuff in Benade's writing leads me to believe that having MORE bends DOES affect acoustical impedence. And by my count the total angle of turns in the Shires is over 1,000 degrees. The total angle of turns in Stephen's is 720.

I'll be interested to see how this resurgence in designs that DON'T complicate playing in a pit do in the market. And I'll be interested in how the Stephen's does with long rests in cold halls

[slipmo]

FWIW, The Stephens Ark model is the only one with this old school style closed wrap... standard models are going to be dropping very soon.

You are right about the wrap on the top, that was done with intention.

I've been playing this prototype and haven't had any valve wrap gurgle issues yet.

[sirisobhakya]

"Ruins balance"???

Yes.

Physical balance. Take a traditional wrap with mass closer to your hand compared to a Bach Open wrap that pushes a bunch of that tubing farther back away from your hand.

Bring that center of mass back towards the hand.

Cheers,
Andy

For me it is better to have the mass further back than being front-heavy. Maybe because I mainly play bass.

[HermanGerman]

NASA did some studies for ducts in various crafts. They found that acoustic and fluidic impedance in ducts did not change much once the radius of the bend was over twice the duct cross section.

So, according to NASA, the gentler bends in the Shires should not have any less impedence than the sharper bends in Stephen's.

Conclusion: Don´t play that baby out in space...

[HermanGerman]

Who needs bends?

https://jestaedt-instrumente.de/verkauf ... chenmarkt/

[Tbarh]

"Ruins balance"???

Yes.

Physical balance. Take a traditional wrap with mass closer to your hand compared to a Bach Open wrap that pushes a bunch of that tubing farther back away from your hand.

Bring that center of mass back towards the hand.

I also wonder if this is why the Stephens horn has the wrap on the head side of the horn as opposed to the outside.

Cheers,
Andy

No, No, No... Bring the weight behind Your head.. I find the best balance in my E185 bass with plug in D valve... Back heavy, yes, but very smooth sailing in outer positions.. The bulk of the weight are carried by the spine, not the shoulder or arms.. IMHO, that is..

[timothy42b]

OTOH, stuff in Benade's writing leads me to believe that having MORE bends DOES affect acoustical impedence. And by my count the total angle of turns in the Shires is over 1,000 degrees. The total angle of turns in Stephen's is 720.

My understanding from Benade, and I think some others, is that acoustically (to the wave) a bend looks like an expansion of the bore. That many bends might have the effect of having the attachment tubing seem wider.

That wouldn't be the same as the flow resistance which I would think does increase. At least when we calculate pump size for an HVAC system we include the number of bends as well as valves, overall length, etc.

This website isn't bad, but it gives bends in equivalent feet. My memory from my engineering early days was that we used equivalent pipe diameters. An elbow might have the same resistance as (30 times the pipe diameter) of straight pipe. https://www.wpb-radon.com/Piping_pressure_drop.html

I and a couple of others here have a jHorn. It is a 9 foot Bb baritone crammed into about a foot long by running the bends continuously. Once it gets condensation past where you can empty it there is very little you can do.

[Posaunus]

Has anyone calculated the Reynolds number of airflow through a trombone at typical playing conditions?
This will have a significant effect on "flow resistance!"

[BGuttman]

It's going to be pretty low. Think about it. How long can you play on one breath. That breath is around 3 liters. The velocity of the air can be measured in cm/minute (not even cm/second) and thus v is pretty small even though the density is pretty low as well.

More important is the acoustic impedance since the sound waves travel relatively fast compared to the air.

[OneTon]

The Reynolds number is going to be really low. The flow will be laminar. The moving air column is likely riding in a doughnut shaped cushion of air and never touches the inner wall surfaces after the mouthpiece and leadpipe. A standing wave model would probably suffice for most analysis purposes.

The caveat for this is near the mouthpiece and leadpipe. The newer Schilke mouthpieces don’t seem to be as sharp. If my memory is correct, the old Schilke mouthpieces could be used as weapons. Even with this disturbance, the airflow will remain laminar or quickly return to laminar flow. The perturbance due to gaps and misfits will most affect the standing wave or impedance.

Valves are down the road from the mouthpiece and leadpipe. We see a variety of valve and wrap configurations including some fairly sharp 90 degree bends. Everything affects the result: Some people seem to prefer single malt over blended Scotch.

However, a non-scientific inspection of Shires artists and their horns would seem to show a preference for the Shires rotary valve with basic 45 degree entries and exits, similar to the Duo-Gravis and some other King f-attachments. I would speculate that this configuration tends to render the valve transparent in impedance. And this leaves the remainder of the “tuning” to people like Steve Shires, Doug Elliott, Mr. Schilke, May he Rest In Peace, and other talented folks

[boneagain]

I agree with your understanding of Benade's comments on curves and apparent bore size.

Benade also confirmed to McCracken that the fluidic behavior of a horn is a good, but not perfect, analog for the acoustic behavior.

I have taken this to be similar to much electrical AC behavior being a good, but not perfect, analog for DC behavior. The analogy gets tenous as AC frequency shifts around, especially when dealing with reactive components instead of pure linear resistance.

So, if I understand Benade correctly (BIG "if") the presence of the cumulative fluidic ("DC") resistance can present as a discontinuity in the system, leading to changes in the standing wave of the moment.

Somewhere on the old TTF a member was in a group that did some acoustic reflectometry. They were able to establish all kinds of things about bore changes, valves, and (I THINK... foggy memory here) ferrule gaps. I wonder if that could be applied to characterize these wrap designs? Or if the reflectometry would just come back showing "meh... it's an F extension... go on home... nothing to see here?"

OTOH, stuff in Benade's writing leads me to believe that having MORE bends DOES affect acoustical impedence. And by my count the total angle of turns in the Shires is over 1,000 degrees. The total angle of turns in Stephen's is 720.

My understanding from Benade, and I think some others, is that acoustically (to the wave) a bend looks like an expansion of the bore. That many bends might have the effect of having the attachment tubing seem wider.

That wouldn't be the same as the flow resistance which I would think does increase. At least when we calculate pump size for an HVAC system we include the number of bends as well as valves, overall length, etc.

This website isn't bad, but it gives bends in equivalent feet. My memory from my engineering early days was that we used equivalent pipe diameters. An elbow might have the same resistance as (30 times the pipe diameter) of straight pipe. https://www.wpb-radon.com/Piping_pressure_drop.html

I and a couple of others here have a jHorn. It is a 9 foot Bb baritone crammed into about a foot long by running the bends continuously. Once it gets condensation past where you can empty it there is very little you can do.

[harrisonreed]

All this talk is assuming that a certain level of resistance based on science is ideal or not if it can be categorized, or that it is researched thoroughly by the maker or not, rather than the artist saying "I want a compact F attachment that looks cool and plays evenly" and Shires just going "look at this cool wrap we thought up using spare parts for your artist model -- what do you think if how it plays?" and the artist going "Yeah, this resistance feels great, and it looks so cool"

That's probably what happened. Maybe with a few trials and suggested improves before the final version.

I doubt there were dudes in lab coats looking through data from NASA, dripping sweat on their slide rules, stressing about flow dynamics.

[timothy42b]

The Reynolds number is going to be really low. The flow will be laminar. The moving air column is likely riding in a doughnut shaped cushion of air and never touches the inner wall surfaces after the mouthpiece and leadpipe. A standing wave model would probably suffice for most analysis purposes.

I think that is probably correct but I wonder about really loud playing.

An interesting point about loudness in brass instruments. In acoustics, we are usually interested in cases in which the amplitude of the sound pressure wave is only a tiny fraction of atmospheric pressure. Consequently, the medium (air) behaves linearly for such waves, which simplifies the mathematics considerably. For example, a sound of 120 dB is painfully loud, but it corresponds to a sound pressure of only 20 Pa, or 0.0002 atmospheres. At the position where the viola player is complaining about the pain in her ears from the trumpets behind her, the sound level is probably still below 120 dB.

However, inside the narrow bore of the instrument, the sound pressure is much higher, for two reasons. First, it is concentrated in a small cross sectional area, instead of spread out over a much larger area outside the instrument. Second, most of the sound inside the instrument is reflected at the ends to provide the standing waves we have discussed above. So the pressure inside a brass instrument can be a substantial fraction of atmospheric pressure, and so the medium can behave in a non-linear way. This can produce a shock wave in the instrument, which results not only in the conversion of power from low frequency to high, but also in the production of frequencies that are not harmonic. This phenomenon was analysed formally by Mico Hirschberg and colleagues (1996, JASA, 99, 1754-58). It is stronger in instruments with long, narrow sections of bore (trumpets and trombones) than in others (flugelhorn or tuba). Some scientists associate the onset of the shock wave with what some brass players refer to as cuivré or the sizzle point. (Here is a video showing the emergence of the shock wave.)

Quote is from a website that has been linked here fairly often:

http://www.phys.unsw.edu.au/jw/brassacoustics.html

[boneagain]

My part in this discussion does not make that assumption. I DO assume that the makers are pretty aware of those factors, white lab coats or no.

As to white coats, NASA, and slide rules... I don't know about Shires or Shires, but I DO have firsthand accounts from George McCracken. He DID go through some pretty tedius work with one of the first TI scientific calculators when designing the Duo Gravis bass bone and the Eroica horn. And he does a lot of on-the-fly estimates of resonant points when he is placing valves and ferrules on his horn designs. I bet some of the 3D in-the-head design and calculations he does would make even the NASA guys sweat harder!

And the artist specification for the Duo Gravis was for it to play a certain way. I have that from BOTH McCracken and Alan Raph. Not even any mention of looking cool (although, biased as I am, I think it looks way cool.)

BOTH of the new wraps avoid bends less than two tubing diameters. Both use a valve with larger-than-classical air passage radii. I don't think either of those decisions are random or just throwing together spare parts.

Oh.. dudes in lab coats? I also doubt that But you might be surprised at the range of rather hairy scientific stuff these guys DO review and even digest

All this talk is assuming that a certain level of resistance based on science is ideal or not if it can be categorized, or that it is researched thoroughly by the maker or not, rather than the artist saying "I want a compact F attachment that looks cool and plays evenly" and Shires just going "look at this cool wrap we thought up using spare parts for your artist model -- what do you think if how it plays?" and the artist going "Yeah, this resistance feels great, and it looks so cool"

That's probably what happened. Maybe with a few trials and suggested improves before the final version.

I doubt there were dudes in lab coats looking through data from NASA, dripping sweat on their slide rules, stressing about flow dynamics.