 The Clarinet BBoard
|
Author: FT
Date: 2001-12-21 15:25
the vintage R13 comes with both cylindrical and conical barrels. How are they different??/ what's the advantage of having both???
|
|
Reply To Message
|
|
Author: Ed
Date: 2001-12-21 16:38
The conical will generally give a more focussed sound and also slightly different tuning characteristics. Depending on taste or the mouthpiece you use, you may like one or the other.
|
|
Reply To Message
|
|
Author: ron b
Date: 2001-12-21 18:08
It seems that I either read or was told, or maybe both or maybe just a senior pipe dream; either way it must've been a long time ago, (catch breath...) that the inside bores of some barrels (the conical ones?) are configured like the choke of a shotgun. I'm guessing that the conical barrels (choked) would focus the airstream by squeezing a certain quantity of air (from mpc) through a restricted opening (top of barrel), increasing its speed. The airstream would then expand to upper joint (inside) diameter, decreasing speed while retaining its forward direction, its focus.
Can't miss. Bullseye every time :]
Looks to me like the same principle as a steam boiler feedwater injector (!) 
EXCEPT that:
This works fine, as I understand it, as long as the integrity of the tube is maintained (low E). Which raises the question to me that when a tone hole is opened, allowing the vibrating air stream to change direction, disrupting its flow, lowering resistance/pressure (safety valve effect) - what difference at that stage will any barrel have?
Focused or not, have a happy Holiday Season all !
|
|
Reply To Message
|
|
Author: David Spiegelthal
Date: 2001-12-21 20:08
The problem with thinking of a clarinet simplistically as a tube in which air flows from the player through the instrument and out the bell and/or toneholes, is that it ignores the fundamental purpose of a wind instrument, namely, to produce STANDING waves of a particular fundamental frequency and harmonic content. The standing waves basically remain within the instrument while vibrating back and forth (or up and down or however you want to think of it), but the point is the wave is a series of reflections of pressure waves between two "boundaries" inside the clarinet. The purpose of blowing air into the clarinet is to initiate the standing wave, and to keep it alive by feeding it energy ---- the musical sound, if you will, is actually a result of the standing wave more so than the linear flow of air from the player through the horn. So discussing barrels in terms of linear flow, using venturi analogies, etc., is not very illustrative nor accurate. I wish it were as simple as fluid flow through a pipe.....but then we wouldn't have nearly as much fun talking about it or experimenting with different pieces of equipment!
I apologize for my lousy explanation --- I'm not a physicist, and Arthur Benade explains it all so much better in his book----- but the bottom line is, it's not a simple physical system to describe or predict. If it were, clarinets would be a heck of a lot closer to perfection in terms of response and intonation.
|
|
Reply To Message
|
|
Author: Mark Charette
Date: 2001-12-21 20:36
In a system designed for flow - the pressure drops and the velocity increases when there's a constriction in the cross-section of the pipe. In the case of a clarinet, the flow is pretty slow to begin with; the pressure/velocity change across the barrel constriction would be measurable but minor ... but ...
In a system designed for pressure wave reflectance (standing waves) and not flow, things get considerably more complicated! Small changes in diameter can cause very large effects (as most people would note as back pressure). This can be easily demonstrated if you have two barrels of different internal tapers (different types such as conical, double conical and reverse would be best to play with). First put the barrels without the mouthpiece on your clarinet and blow through the clarinet. We're now in a flow condition and I double very much if you can tell the difference between the barrels no matter how hard you blow. Now put the mouthpiece back on and I'll wager your backpressure will be different and noticeable. We're producing waves now and things are much more complex.
David - when you blow a long E the bell of the clarinet just acts like a large tonehole; the physics behind the pressure nodes is exactly the same as a fingered note - including the problem of the compromise in tone hole size - the tone hole for the long E isn't exactly the right size tone hole for the long B ;^)
|
|
Reply To Message
|
|
Author: ron b
Date: 2001-12-21 21:31
Hi, Dave
I appreciate your explanation because I think I'm beginning to get a better, or at least a different, idea of what happens when a clarinet makes music - although I have a woeful lack of knowledge in physics. I do wholeheartedly agree that a feedwater injector is not much fun to watch, even less fun to listen to : Poor example. It just seems to me that air set in motion at the mouthpiece, whether brass, flute, double reed, single reed etc., that, after that - not much more can be done to alter it. I was thinking more in terms of linear air flow, pictured in my imagination like book illustrations of a vibrating string. Dividing the string, shortening/lengthening it, changes the pitch. In that simplistic context a barrel alone wouldn't have any significant influence on the standing wavelength of any instrument. Wind instrument bores are either a uniform(more or less) diameter lengthwise or conical(tapered either small to large or vice versa), and round or square. But... now I'm more confused than when I started and other ideas spring to mind, making it worse. If a Barrel's bore could be made to change from round to square to round again (it could be done easily on a CNC lathe), would the tonal characteristic be altered? Did earlier single reed mouthpieces (as, 'in the olden days' retain their initial square shape longer than the rather abrupt change of modern ones?
Why aren't mouthpieces designed 'rounded' beginning at the lay?
I'm sure this has been thought through and through and expounded on often long before now. I have no idea where to find reference info to it though.
|
|
Reply To Message
|
|
The Clarinet Pages
|
 |
.jpg){kind=small}
.jpg){kind=small}
.jpg){kind=small}
.jpg){kind=small}
.jpg){kind=small}
.jpg){kind=small}
