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 Bell Vents
Author: DAVE 
Date:   2004-05-05 05:17

Has anyone ever experimented with (gasps) drilling a hole in the side of your bell to make a vent? If one was to do it, where to put it and how big? Is it possible that such a thing could help the flatness of the low register?

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 Re: Bell Vents
Author: David Spiegelthal 2017
Date:   2004-05-05 14:18

I've got an old Boosey & Hawkes "Imperial" bell that had two holes drilled in it by a previous owner -- they are effective in raising the pitch of the otherwise flat low E, and I use that bell on my modified Series 8-10 instead of the original bell. The low F (and of course the notes above that) are not at all affected, as far as I can tell.
Over the weekend I drilled a hole myself in the 1960's-vintage Cabart oboe I just renovated, guessing at the size and location of the hole --- beginner's luck...worked perfectly in raising the pitch of the originally-flat low-Bb. It may lack elegance, but the classic 'vent hole in the bell' is a simple solution that does work.
If you'd like I can measure the locations and sizes of the holes in my B&H clarinet bell and e-mail you (or post here) the numbers.

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 Re: Bell Vents
Author: Don Poulsen 
Date:   2004-05-05 14:30

As the location of the hole affects the pitch of the instruments lowest note (or the lowest note of the upper register) I wouldn't recommend such an alteration unless you knew precisely what you were doing or had a throwaway bell you could experiment on.

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 Re: Bell Vents
Author: L. Omar Henderson 
Date:   2004-05-05 14:40

(Disclaimer - I am a maker of the Forte' clarinet with a resonance bell vent)
Bell vents are effective in raising the pitch of the low register notes but the positioning, size, and fraising have subtle effects on other notes so much care should be exercised before you ruin a bell. The most effective approach in determining the size and positioning (although you should have an extra bell around unless you do not mind a swiss cheese effect on your bell) is to drill a number of holes of increasing size and position in the bell. Fill all the holes except one with plumbers putty (later with Bondo if you keep the same bell) and do a tuning chart with a tuner. Follow with the same proceedure on succeeding holes until the desired effect is achieved. The fine tuning is done by undercutting and fraising the hole to the desired effect. Exact measurements are then transferred to the new bell and the proper hole position and size are applied with subsequent fraising to a final vent configuration. Not all horns are equally susceptible to the improved tuning offered by a bell vent and the ideal situation is to have an extra key and a bell vent such as on some German horns or the newer pro model horns.
The Doctor

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 Re: Bell Vents
Author: William 
Date:   2004-05-05 14:47

Just for your info, my (relatively) new Buffet Prestige (low C) bass clarinet has a bell vent--I am not certain "why?", but the instrument plays very well in tune down to low C3 as well as on B4 & C5. When I "get around to it", I think I will find a cork and experimnet with how it plays after plugging the hole.

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 Re: Bell Vents
Author: mw 
Date:   2004-05-05 15:49

Some excellent advice from Omar on modification. IF you are looking for a "ready made" solution you might want to look into trying one of Morrie Backun's Bells. Morrie has been attending many shows & symposiums & also will allow you to order several Barrels or Bells with the ability to return same if they don't work for you. Caveat: Cost of Bells are something along the line of $250 (that's what I was billed) & a new R-13 Bell is $195 list and a new Concerto or Opus Bell is $230 list (list price is seldom charged).

Following Omar's advice, you might want to find an exact Bell which has been cracked - repaired or unrepaired - and use that as your guinea pig.



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 Re: Bell Vents
Author: David Spiegelthal 2017
Date:   2004-05-05 16:48

The advice from Don and mw has a minor flaw --- it you take a cracked/junker bell, slap that on your clarinet, and drill a hole, once you've find the right size and spot for the hole to give the desired intonation correction, that size/location is only valid FOR THAT PARTICULAR BELL. Since every bell (especially between different brands of clarinet) has its own length and flare (curvature), the results you get on the 'junker' bell may not be exactly correct for the actual bell.
But, I concede, it should get you very close.

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 Re: Bell Vents
Author: mw 
Date:   2004-05-05 20:52

My statement was:
"you might want to find an EXACT Bell which has been cracked"
---------------------------
We have measured Bells from (a given) manufacturer & found little variance in dimensions or intonation. Recall above, I said EXACT MODEL - meaning an OEM Bell for a particular model of clarinet. With that in mind, if one is going to affect intonation in the intended manner - it will be affected on any (such) model's (OEM) Bell.

However, no one implied that a Bell Vent is a cure-all for the ills of intonation. It is not - there is a limit to what can be achieved. All the toneholes have been passed by the time you get to the Bell. Modifications to the Bell are not as significant as modifications to Toneholes & the barrel, etc.



Post Edited (2004-05-05 21:44)

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 Re: Bell Vents
Author: john gibson 
Date:   2004-05-06 01:42

What about holes in the head?
jg

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 Re: Bell Vents
Author: David Spiegelthal 2017
Date:   2004-05-06 14:53

I have holes in my head but still play out of tune sometimes.

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 Re: Bell Vents
Author: mw 
Date:   2004-05-06 18:59

I would say that you should have your local Music store look at those holes & see if FRAISING will help them. Of course your Holes could be too big & you may find that thin duct tape (please, only light blue in color) should be applied to the front side of your Holes. Don't try this on Lower Holes.



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 Re: Bell Vents
Author: David Spiegelthal 2017
Date:   2004-05-06 19:10

mw,
Thanks for the advice. I shall attempt to STRAWBERRY my head-holes, and will check if the local Clar-Mart store carries any cheap (Chinese-made) light blue duct tape in case the holes (and corresponding twelfths) are oversized.
Speaking of wrong-sized twelfths (per Benade and Gibson) I took a hard look at my Boosey & Hawkes 8-10, then took some careful measurements with a good set of vernier calipers, and darned if I could find anything wrong with the size of the twelfths.....did I do something wrong?

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 Re: Bell Vents
Author: mw 
Date:   2004-05-06 23:25

Vernier Calipers won't work ... you need to use special Name Brand Digital InteriorHole Calipers!

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