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 What does the double resonance key on the bell do?
Author: Lux 
Date:   2017-02-27 14:08

First of all, I do not understand the purpose of a resonance key. I know there is the F reso key and I have seen some fancy oboes with double resonance keys on the bell. What do these do? And why would you up for a horn without an F reso key?

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 Re: What does the double resonance key on the bell do?
Author: Chris P 
Date:   2017-02-27 14:38

Without the low Bb vent, the low Bb will be too flat with the current 435Hz length bell.

Ok, so why not just shorten the bell to sharpen the low Bb?

That has been done on some older Lorees to sharpen it by 5Hz to 440Hz, but it caused problems with the E. So to stabilise that note, the old 435Hz bell was reinstated and the low Bb was flat, but players put up with it for so long and something had to be done to correct this. So to counteract the flatness of the low Bb but keep the E sweet, the closed bell vent was added which only opens when low Bb is played. Hooray! Problem solved.

Marigaux have for a long time had the bell vent on their 901 oboes open for low B as well as Bb and has found its way onto the other pro models since. The bell vent on their oboes is located much lower down the bell and as a result is much larger in diameter.

Other oboes have since followed suit with the Marigaux style double bell key, but it is a more difficult key to make and is at risk of a lot of damage if the bell isn't assembled or removed correctly. You have to make sure you hold both the bell key closed and the bell vent key open - this is made easy as the bell vent has a small stopper foot soldered to the key barrel which can be held down raising the linkage between the bell and the linkages on the lower joint.

The double bell key has the bell vent open much earlier than for just low Bb, so it will add some resonance to the low B as well. The only way you can check this for certain is to disengage the bell linkage and play low B. Then open the bell vent and see what difference it makes. Also it may have some influence on the altissimo notes and others where the low B key is used to add resonance, to help with the tuning or help the response of certain notes

Former oboe finisher
Howarth of London
1998 - 2010

The opinions I express are my own.

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 Re: What does the double resonance key on the bell do?
Author: Chris P 
Date:   2017-02-27 14:47

The forked F vent and F resonance keys are two different things.

Forked F vent - this compensates for the closure of RH3 when playing F with the forked fingering xxx|xox in both 8ves. Oboes without it will need the Eb key to be held open to clear up the stuffiness of the forked F fingering and bring it up to pitch as it can be flat with the forked fingering on oboes lacking a forked F vent.

Usually the most basic oboes don't have it fitted (eg. Bundy or some Yamaha 200 series) as it involves a lot of parts, but older student model oboes and even some pro models lack the forked F vent - some older Lorees lack it as the keyed or LH F key fingerings were favoured over the forked fingering for F.

On conservatoire system oboes the forked F vent is a closed standing vent key - it's closed when no RH fingers are held down and only opens for the forked Fs. So it only opens when RH finger 3 is closed and RH finger 2 is raised. It's closed again when both RH finger 2 and 3 are closed together so the notes from E downwards can be played, so the adjustment is critical and knowing how to set it up is absolutely vital. On most thumbplate systems, the forked F vent is a much simpler affair, is open standing and is only closed when RH finger 2 is held down.

Conservatoire system oboes need the forked F vent to be closed as it causes problems with Bb (xxo|xoo) if it's open. This is the problem conservatoire system B&H Imperial oboes have as they have the basic, open standing forked F vent as their thumbplate counterparts instead of the closed standing forked F vent they should have.

F resonance key - this is a small closed key with a small tonehole usually located on the opposite side of the lower joint to the forked F vent and opens only when the F key is held open by both RH3 or the LH F key.

It helps stabilise the upper register F when played with the keyed F fingering (xxx|xx/o) which can be unstable on some oboes and has the tendency to go sharp and blow up to an F# if pushed too hard, if the F key venting is too large or if the reed isn't compliant.

German and German spec oboes usually have this extra vent key fitted, but some makers fit it to other models if the keyed fingering is troublesome, commonly labelled as a 'flying F' - so some really do give a flying F!

Former oboe finisher
Howarth of London
1998 - 2010

The opinions I express are my own.

Post Edited (2017-02-27 15:02)

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