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Undercut Toneholes, Design and Customization

Author: Ken Shaw
Date: 2001-04-09 18:03

Darby asked about undercut toneholes, but the answer got bigger than that, so I'm posting it separately.

Until the early 1950s, French clarinets had a relatively large, cylindrical bore and cylindrical tone holes.

In the 1940s and early 1950s, the Buffet workman Robert Carre experimented with a bore that was smaller by several thousandths of an inch, which gave a more focused tone. He got further improvement when he made the bore gradually smaller by a few thousandths of an inch from the top of the upper joint to just below the left middle finger hole and then larger from there to the bottom of the upper joint. Rather than use tapered reamers, the design was made with a series of 3 cylindrical reamers. The smallest was run completely through, the next was run partly through from the top and bottom, and the largest was run a smaller distance from the top and the bottom. This produced the "polycylindrical" bore used in the Buffet R-13. The differences are tiny -- only a few thousandths of an inch -- and are blended into one another, so they're not visible to the naked eye.

The small, polycylindrical bore R-13 became the standard in the United States. It was not perfect. First, the tone quality of every clarinet varies from note to note -- some are resonant, some are dull. The more focused sound of the polycylindrical bore made this unevenness more noticeable. In particular, if the register key is the best size (small) and in the best spot (high) to produce the clarion register with the best intonation, the throat Bb became unusable. Thus the register vent on the R-13 was made larger and placed lower, which gave a relatively bad Bb, but one that was usable, at the expense of a clarion register that was sharp.

To even out the resonance of other notes and adjust clarion register intonation, it was necessary to undercut many of the toneholes. This is also called "fraising." It's used in most Buffet models, the Selmer Signature and 10G, the Leblanc Opus, Concerto and Infinite and many Yamaha models. Large bore models such as the older Selmers and Leblancs and the pre-R-13 Buffets do not need this, but it has to be "designed into" the smaller bore models to even out the resonance from one note to the next and bring the twelfths in tune.

The process is shown very well in the Yamaha link that Mark posted in response to Darby's query.

Clarinet customizers go much further, to make additional refinements in tone and intonation. First, they make non-cylindrical barrels, most of which are reverse-conical, getting smaller by a few thousandths of an inch from top to bottom. Both the Moennig and Chadash barrels supplied by Buffet have this reverse taper. Kalmen Opperman, who makes the best barrels I have ever played, puts a reverse cone about 2/3 of the way down the barrel and a regular cone on the bottom 1/3, creating a "wasp waist" bore. This procedure is extremely delicate and has to be done by hand in almost invisible increments, or it doesn't work at all.

Customizers also adjust the undercutting of toneholes. The undercut can be at different tapers and can be pointed "north" or "south" in the bore, which can adjust the intonation in one register without affecting the other register. Again, this is as much an art as a science and is custom work.

Finally, as Arthur Benade's experiments showed, tone quality is affected strongly by the sharpness of the rim of a tonehole where it meets the bore. Rounding this rim slightly makes a dramatic improvement in tone and response, but rounding it even a tiny bit too much can be disastrous. I think this, more than anything else, is the reason plastic clarinets (which naturally have a sharp rim) don't sound as good as wood clarinets. Both Charles Bay and Kalmen Opperman have customized plastic instruments (particularly bass and contrabass clarinets) to play at a professional level by doing this work.

The great repairman Hans Moennig did custom adjusting on many models of clarinet, including the large bore pre-R-13 instruments. A couple of years ago, Alvin Swiney, who was a Moennig apprentice, gave a great description of the incredible amount of work this takes. Read http://www.sneezy.org/Databases/Logs/1999/05/000596.txt. A clarinet put through this process is a completely different instrument from where it started. Anthony Gigliotti's Moennig-customized R-13 was the basis for the Selmer 10G model.

The Buffet RC and Festival models have a slightly different bore from the R-13. I have read that they use only 2 reamers instead of 3. Also, there are adjustments in the bore and tonehole placement, and particularly in the register vent size and placement, to even out the scale and improve intonation. Tom Ridenour's work on the Leblanc Infinite model produces similar results, and there are several variations on the same theory in the Yamaha line. Tom's work on the Leblanc Opus and Concerto is a more radical departure from the R-13, as is the design of the Selmer Signature. These instruments have a tone quality that is noticeably more even from note to note and are better in tune than the stock R-13. In my opinion, though, they sacrifice the tone quality of the R-13, particularly those that have been artist-tweaked to improve evenness and intonation. Many important players (Larry Combs, for example) disagree, but that Larry Combs doesn't play a "stock" Opus, either. No instrument without hand-customization work plays like the real thing.

Best regards.

Ken Shaw

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