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 Throat G# on bass opening at pressure test
Author: Micke Isotalo ★2017
Date:   2026-09-26 13:01

Is it normal for the throat G# key on a bass clarinet to open at a pressure test (blowing into the bore of the top joint with the keys and bottom end closed)? In this case a moderate pressure, not blowing as hard as you can, opens the key.

On a well adjusted soprano clarinet none of the keys of the upper joint opens at a pressure test, no matter how hard you blow (the feeling is as blowing into a bottle) - but are bass clarinets different?



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 Re: Throat G# on bass opening at pressure test
Author: kilo 
Date:   2026-09-26 15:40

I'd guess that the spring is weak but as long as the instrument is playable it doesn't seem like anything to be concerned about.

I tested all three of my basses. The Royal Global Max remained tight as a drum no matter how hard I blew. The Selmer Model 30 leaked a bit under high pressure but the key itself didn't budge. The Backun Alpha would open with moderate pressure but this has never been a problem when playing.

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 Re: Throat G# on bass opening at pressure test
Author: Micke Isotalo ★2017
Date:   2026-09-26 15:51

I actually also have an Alpha. My problem is some sensitivity for squeaks in the right hand first register (from about B natural down to low G). This concerns primarily accentuated notes in forte, with a breath before. With a 1980's Leblanc I didn't have this problem (but instead with the middle clarion notes, which however are very good on the Alpha). I will try with blocking the throat G# key and see if it makes a difference, but have to wait until tomorrow (everything else seems airtight on the Alpha, including the register vents).



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 Re: Throat G# on bass opening at pressure test
Author: kilo 
Date:   2026-09-26 17:10

As I understand, the Alphas are set up with the lightest effective spring action. You could certainly bend the spring a little, carefully, to increase the strength. I don't think that the throat G# key, usually activated by the side of the hand instead of direct finger pressure, needs to be set for as light a touch as some of the other keys.

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 Re: Throat G# on bass opening at pressure test
Author: rmk54 
Date:   2026-09-26 17:30

Before you start bending springs (which could break if you are not careful) why not close off the pad with a rubber band to see if that alleviates the problem?

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 Re: Throat G# on bass opening at pressure test
Author: Chris P 
Date:   2026-09-26 18:28

While pressurising the bore isn't going to happen in a real world playing scenario, closed standing keys should always have stronger spring tension to ensure the pads remain closed under that spring tension alone. Given the weight of the throat G# key on basses (particularly ones with Buffet style keywork which is a bit of a hefty lump), the spring tension also has to be relative to counteract the dead weight of the key.

If you're finding this key sprung too lightly, then it won't do you any harm in beefing up the spring tension and even better still if the spring can be unhitched while the key is still in situ if there's enough clearance under the spring cradle. Depending on the quality of the needle springs, some cheap ones don't retain any spring tension no matter how much of a bend you put in them and some can be brittle as anything and snap clean off if you overdo it.

If the spring is maxing out and still not giving the required closing force or just losing all the tension you put in after hitching it back in place, then you're best replacing it for a better quality one of the same gauge or going up in gauge by 0.5mm diameter and will have to ream out the spring hole in the pillar to do that. Use the blunt end of the oversize needle spring as a broach by grinding a flat on it and holding it in a pin vice to ream out the spring hole. You'll either have to rotate the pillar or remove it completely to gain better access to do this.

Former oboe finisher
Howarth of London
1998 - 2010


Independent Woodwind Repairer
Single and Double Reed Specialist

Oboes, Clarinets and Saxes

NOT A MEMBER OF N.A.M.I.R.

The opinions I express are my own.

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