View previous topic :: View next topic |
Author |
Message |
Proteus Veteran Member
Joined: 23 Sep 2010 Posts: 130 Location: Ottawa, Canada
|
Posted: Sat May 08, 2021 5:58 am Post subject: Cup depth: what's really happening? |
|
|
I understand that changes in cup depth results in changes in the frequencies and amplitudes of overtones in the sound, and that's why changing cup depth changes the sound.
But can anyone tell me what it is specifically about cup depth that actually drives this change? Put another way: we know it does - but why does it?
Thx. _________________ Bach 239 C
Kanstul 700
Getzen Proteus 907S Bb
Bach Strad 37 Bb (70s)
ACB Doubler flugel
Getzen Capri cornet |
|
Back to top |
|
|
JayKosta Heavyweight Member
Joined: 24 Dec 2018 Posts: 3298 Location: Endwell NY USA
|
Posted: Sat May 08, 2021 6:18 am Post subject: |
|
|
I'll make a guess - just to get the conversation started.
Daryll might be able to describe the 'science' involved.
The volume (and shape) of the cup determines how it will respond as a 'shock absorber' to the various vibration/pulsation frequencies and their amplitude.
The pressure inside the cup is always exerting a force back onto the lips, and the cup rim size / shape / volume / etc. has an influence on the precise blend of forces on the lips. _________________ Most Important Note ? - the next one !
KNOW (see) what the next note is BEFORE you have to play it.
PLAY the next note 'on time' and 'in rhythm'.
Oh ya, watch the conductor - they set what is 'on time'. |
|
Back to top |
|
|
Proteus Veteran Member
Joined: 23 Sep 2010 Posts: 130 Location: Ottawa, Canada
|
Posted: Sat May 08, 2021 6:44 am Post subject: |
|
|
Thanks for the quick input, Jay. I can see that "loading the back pressure" (for lack of a better description) from the cup might be a factor...but once it's loaded, it would be in a steady state (continuously loaded) from then on while blowing. _________________ Bach 239 C
Kanstul 700
Getzen Proteus 907S Bb
Bach Strad 37 Bb (70s)
ACB Doubler flugel
Getzen Capri cornet |
|
Back to top |
|
|
Proteus Veteran Member
Joined: 23 Sep 2010 Posts: 130 Location: Ottawa, Canada
|
Posted: Sat May 08, 2021 6:52 am Post subject: |
|
|
The other thing I considered (then quickly discounted) was that the internal volume somehow affected the frequencies (balance of overtones) and thus the resulting tone. But are mid-to-high frequency wavelengths meaningful within the small dimension of a mouthpiece cup?
I wonder: if we took the same horn and played the same notes on a succession of deeper-to-shallower mouthpieces and ran the output through a spectrum analyzer, would it show the lower frequencies remaining pretty much the same but the upper-mid and higher frequencies changing more markedly?
Could this be the correlation between cup depth and tone? _________________ Bach 239 C
Kanstul 700
Getzen Proteus 907S Bb
Bach Strad 37 Bb (70s)
ACB Doubler flugel
Getzen Capri cornet |
|
Back to top |
|
|
JayKosta Heavyweight Member
Joined: 24 Dec 2018 Posts: 3298 Location: Endwell NY USA
|
Posted: Sat May 08, 2021 6:52 am Post subject: |
|
|
My thought is that the 'back pressure' is not a single static 'psi amount' - it contains all the various frequencies and their associated strength (psi at each individual frequency). How all those various back pressureS affect lip movement is what impacts the tone. _________________ Most Important Note ? - the next one !
KNOW (see) what the next note is BEFORE you have to play it.
PLAY the next note 'on time' and 'in rhythm'.
Oh ya, watch the conductor - they set what is 'on time'. |
|
Back to top |
|
|
JayKosta Heavyweight Member
Joined: 24 Dec 2018 Posts: 3298 Location: Endwell NY USA
|
Posted: Sat May 08, 2021 7:02 am Post subject: |
|
|
Proteus wrote: | ... But are mid-to-high frequency wavelengths meaningful within the small dimension of a mouthpiece cup? ... |
---------------------------------------------
The resonate harmonics of the trumpet's tubing will get 'forced back' into the cup - it isn't a matter of the cup itself having harmonics. The trumpet sort of dictates the composition (frequencies and amplitudes) of the back pressure in the cup.
When just 'buzzing the mouthpiece' there is very little (if any) back pressure resonance - that's why it is possible to do a smooth no-jumps gliss of pitches from low to high on just the mouthpiece. _________________ Most Important Note ? - the next one !
KNOW (see) what the next note is BEFORE you have to play it.
PLAY the next note 'on time' and 'in rhythm'.
Oh ya, watch the conductor - they set what is 'on time'. |
|
Back to top |
|
|
Vin DiBona Heavyweight Member
Joined: 24 Dec 2003 Posts: 1473 Location: OHare area
|
Posted: Sat May 08, 2021 7:26 am Post subject: |
|
|
This can only be truly answered by expert mouthpiece makers.
Maybe a manufacturer who posts here has the time to give you the straight scoop.
Everything effects everything. What if you have a modified C/V cup? What does the throat entrances do? How does the back bore effect the shape and depth of the cup?
Read this.
https://www.everythingtrumpet.com/schilke/Symphony_Series.html
R. Tomasek |
|
Back to top |
|
|
Proteus Veteran Member
Joined: 23 Sep 2010 Posts: 130 Location: Ottawa, Canada
|
Posted: Sat May 08, 2021 8:05 am Post subject: |
|
|
Thanks for the Schilke link, RT. As expected, it states that deeper cups give this sound and shallower ones that sound, but doesn't come anywhere near to explaining why. While it also mentions that a cup's bowl-vs-V shape (as well as backbore and throat) are critical to overall resistance, it says nothing about why & how cup depth influence the overtone series. Hmmm...
Jay, I appreciate that each horn's characteristic influences the final sound, but would like to understand more about how a horn's standing waves get "forced back into the cup". I understand the mouthpiece inputs energy into the system (horn) but had not read that there is a feedback loop all the way back into the mouthpiece.
I'm also thinking that we can even hear a difference in the buzz when the same player buzzes into a shallow vs a deeper cup. So given the identical parameters of rim, throat and backbore, I'm pretty sure something is happening well before the horn. _________________ Bach 239 C
Kanstul 700
Getzen Proteus 907S Bb
Bach Strad 37 Bb (70s)
ACB Doubler flugel
Getzen Capri cornet |
|
Back to top |
|
|
Tpt_Guy Heavyweight Member
Joined: 16 Jul 2004 Posts: 1101 Location: Sacramento, Ca
|
Posted: Sat May 08, 2021 8:10 am Post subject: Re: Cup depth: what's really happening? |
|
|
Proteus wrote: | I understand that changes in cup depth results in changes in the frequencies and amplitudes of overtones in the sound, and that's why changing cup depth changes the sound.
But can anyone tell me what it is specifically about cup depth that actually drives this change? Put another way: we know it does - but why does it?
Thx. |
Some light reading for you.
https://cderksen.home.xs4all.nl/images/Conns_Blue_Booklet.pdf
The Proper Selection of Cup Mouthpieces by Jody C. Hall. A good little book that has much information about each component of a mouthpiece and its effects.
Here's a bit more reading.
http://newt.phys.unsw.edu.au/jw/brassacoustics.html#mouthpiece _________________ -Tom Hall-
"A good teacher protects his pupils from his own influence."
-Bruce Lee |
|
Back to top |
|
|
JWG Veteran Member
Joined: 27 Jul 2011 Posts: 257
|
Posted: Sat May 08, 2021 8:14 am Post subject: |
|
|
I am not an expert mouthpiece maker, but I suspect that there exists a verily simple principle behind the effect of mouthpiece depth.
The depth of the mouthpiece determines the frequencies that naturally form and propagate from it. Analogize from the micro of the mouthpiece to the macro of something like a pipe organ. The shorter the pipe, the higher the pitch and overtones; the longer the pipe, the lower the pitch and overtones. The reason "why" appears clear, lower pitches and overtones require longer distances to resonate while higher pitches require shorter distances to propagate. This fundamental principle appears true in all families of instruments: winds, strings, percussion, etc.
So, a shallow cup mouthpiece promotes higher overtones to resonate within its short depth while a deeper cup mouthpiece will promote lower overtones to resonate within its longer depth. _________________ Flip Oakes Wild Thing Bb and C with 1.5 TCC, XT, C, C-O, O, & L mouthpieces
Bach 183S (undersprung valves & straight taper pipe) with 1.5 Flip Oakes XF |
|
Back to top |
|
|
Proteus Veteran Member
Joined: 23 Sep 2010 Posts: 130 Location: Ottawa, Canada
|
Posted: Sat May 08, 2021 8:57 am Post subject: |
|
|
Quote: | a shallow cup mouthpiece promotes higher overtones to resonate within its short depth while a deeper cup mouthpiece will promote lower overtones to resonate within its longer depth. |
Exactly what I was wondering, hence my question re frequency lengths given the dimensions of a trumpet mouthpiece...and whether - given their wavelengths - the lower frequencies would therefore be pretty much the same for most pieces? _________________ Bach 239 C
Kanstul 700
Getzen Proteus 907S Bb
Bach Strad 37 Bb (70s)
ACB Doubler flugel
Getzen Capri cornet |
|
Back to top |
|
|
JayKosta Heavyweight Member
Joined: 24 Dec 2018 Posts: 3298 Location: Endwell NY USA
|
Posted: Sat May 08, 2021 9:03 am Post subject: |
|
|
Proteus wrote: | ...
Jay, I appreciate that each horn's characteristic influences the final sound, but would like to understand more about how a horn's standing waves get "forced back into the cup". I understand the mouthpiece inputs energy into the system (horn) but had not read that there is a feedback loop all the way back into the mouthpiece. ... |
--------------------------------
The standing wave(s) in the trumpet tubing have a 'termination point' near the mouthpiece (I don't know the exact location, it might be at the lips, cup, mpc throat, backbore, leadpipe venturi, etc.) where they get reflected back towards the bell.
This 'point of wave reflection' is where the standing waves 'interact' with the pressure waves (pulses) being produced by the player
edit: I didn't mean to imply that there is a single specific point where the reflection occurs. Each individual resonant wave (harmonics included) is likely to have a slightly different location. My main point is that there are termination/reflection points, and they are where the pressure forces from the player interfaces with the internal pressure of the trumpet's standing waves.
My (another) guess is that there is a good corollary in electrical oscillator circuits. Where the overall circuit has its own resonant harmonics (similar to the trumpet tubing). _________________ Most Important Note ? - the next one !
KNOW (see) what the next note is BEFORE you have to play it.
PLAY the next note 'on time' and 'in rhythm'.
Oh ya, watch the conductor - they set what is 'on time'.
Last edited by JayKosta on Sat May 08, 2021 10:43 am; edited 1 time in total |
|
Back to top |
|
|
Proteus Veteran Member
Joined: 23 Sep 2010 Posts: 130 Location: Ottawa, Canada
|
Posted: Sat May 08, 2021 10:09 am Post subject: |
|
|
Riiight...of course there'd have to be a point like that. Thx.
Wonder if Brent or another trumpet maker on the forum could advise on where that point is. Mouthpiece throat (ie. venturi) maybe? _________________ Bach 239 C
Kanstul 700
Getzen Proteus 907S Bb
Bach Strad 37 Bb (70s)
ACB Doubler flugel
Getzen Capri cornet |
|
Back to top |
|
|
Divitt Trumpets Heavyweight Member
Joined: 11 Aug 2015 Posts: 520 Location: Toronto
|
|
Back to top |
|
|
Andy Cooper Heavyweight Member
Joined: 15 Nov 2001 Posts: 1825 Location: Terre Haute, IN USA
|
|
Back to top |
|
|
JayKosta Heavyweight Member
Joined: 24 Dec 2018 Posts: 3298 Location: Endwell NY USA
|
Posted: Tue May 11, 2021 8:22 am Post subject: |
|
|
I've been looking for more details that explain WHY the mouthpiece shape and size affects the produced sound.
What I have mainly found is research and opinion about 'what shapes' result in 'what results', but very little about the HOW (physics and acoustics) of why the changes happen.
The interior volume and tapers of a mouthpiece are quite complex, and there is a lot of change happening in a short distance (rim to end of shank). Most of the physics/acoustic knowledge/theory is based on straight cylindrical tubing, and long even tapers. The interior changes from rim to bell are not an easy fit into the standard formula and principles.
One article mentioned the affect of lip protrusion into the mouthpiece, and how it varies from player to player, pitch, and loudness. _________________ Most Important Note ? - the next one !
KNOW (see) what the next note is BEFORE you have to play it.
PLAY the next note 'on time' and 'in rhythm'.
Oh ya, watch the conductor - they set what is 'on time'. |
|
Back to top |
|
|
|