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Intonation changed ?!?

Carl H.

Distinguished Member
Distinguished Member
Anybody have any thoughts as to why the chalumeau on my SML has gone sharp? I had it in for minor adjustments and since coming home, the chalumeau has gone even sharper than it was before I sent it in. No key heights were changed. Clarion and up are fine. I used to be able to control it but now it is seriously sharp - pull out 2mm to play in tune sharp. I can't be messing around with pulling and pushing while playing just to keep in tune.

Same old reeds and mouthpiece but it doesn't play the way it did before. Where would you look first if it was your instrument? (On the instrument, I mean.)
 
Key pad height would be my first suspect for a tuning change, assuming that there is not a piece of a swab stuck somewhere (which would tend to send you flat, anyway).

Is it the whole lower register, or only from a given note downward? Any adjustment to the bridge mechanism that ties the two joints together?
 
i had one customer .. very astute player .. complain the use of one of his trill keys went 5c sharp. a sliver of wood in the bore above the tonehole was up slightly probably from a swab. flattened/glued sliver (more like a splinter) .. instrument played in tune as before.

live and learn eh ?

so .. i would check inside and out.

maybe key heights were fine until the cork started to compress whilst playing and slightly raised the keywork (with alot of assumptions). But it should be negligible unlike your description.

I can't be messing around with pulling and pushing while playing just to keep in tune.
sounds like you have a slide trombone ... or someone kicked you really hard on your instruments

sorry .. 2:30am .. i'm losing it
 
The tenon between the upper and lower joints was re-corked/fitted and the Bb/Eb linkage had an adjuster screw added. Nothing changed that I could see leading to this problem, other than the weather here, but that had little effect last season.
 
it's really hard without actually seeing or playing it.

but let me throw out a couple items

maybe a leak with the octave tube or thumb ring. if these are removed during the overhaul process when they are reinserted the normal routine is to melt wax around them to properly seal them. If you are getting a leakage from here it could have some effect on the chalumeau .. but i've never really experimented with those type of effects from the register tube (though i have been experimenting and making register tubes but installing and sealing them properly).
 
it's really hard without actually seeing or playing it.

but let me throw out a couple items

maybe a leak with the octave tube or thumb ring. if these are removed during the overhaul process when they are reinserted the normal routine is to melt wax around them to properly seal them. If you are getting a leakage from here it could have some effect on the chalumeau .. but i've never really experimented with those type of effects from the register tube (though i have been experimenting and making register tubes but installing and sealing them properly).
Not this past time, but the one before it, the tube was re sealed. It speaks just fine and tone is good, it's just the darned pitch.

Maybe I'll put some new reeds in service and see what happens.
 
Perhaps you are blowing more "hot air" than before and raising the pitch. :)

Seriously, it may be possible that the repair tech cleaned the toneholes and the bore if your clarinet causing a very slight change in pitch. According to Nederveen in "The Acoustical Aspects of Woodwind Instruments" to effect a 10 cent change in the pitch of a note vented by a particular tonehole would require:

- a 1% change in the distance from the acoustical top of the instrument
- a 10% hole diameter change
- a 20 % hole length change (height of chimney)

As you can see, it would take quite a change to alter the pitch to the point of being perceptible. You may try comparing the tuning of the 12ths with the register key open, and by overblowing with it closed. This may help to reveal the role, if any, the register key vent might be contributing to the problem you describe.

I know some people like the idea of an adjusting screw on the "bridge" linking mechanism. I am not in favor of this because the contact area the size of the end of a small screw is never as stable as the original flat wide surface of the key itself. Learning to judiciously use a good set of flat nosed pliers to reset the adjustment when it goes out is a much better solution for the player IMO.
 
Well, that was odd. It must have been the particular reed I used last time. Tonight's intonation was back to its normal traits. I guess that reed needed to go!:geezer2:

The adjusting screw was by my tech's suggestion and was done very well. Yes, the reduced contact point may accelerate wear, but SML clarinets are very solidly built. I have a light touch and monitor my equipment so I don't see any downside to the mod, other than using a screwdriver to do precise adjustments instead of pliers.
 
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