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Buzzing Valve?


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Hi everybody,

 

guess I have a buzzing valve, there's an added sound just one octave below the tone of the reed ("b" above the second "g", only on the pull). Have tried to alter the valve, to nearly no effect at all.

 

Any recommendations appreciated!

 

Best wishes - Wolf

Edited by blue eyed sailor
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Hi Wolf,

I find that sort of valve noise comes from the adjacent ( in this case, the press side C reed's valve ). For the lower pitched left hand side notes, a valve with more mass can de couple the reed and adjacent valve frequencies. For higher notes, I find that if the adjacent valve ( next to the active reed ) is arched slightly so that it touches at the top but is raised in the center, the valve will pop up and down in the center, alternately allowing bypass air through the inactive reed and shutting it off at some fraction of the active reed frequency. This varies the airflow through the active reed at a second frequency lower than the fundamental ( sort of a beat frequency overlaid on the fundamental ). Sometimes this occurrs when increasing humidity causes differential expansion of the top grain of the leather compared to the split side. Drying usually causes curling away from the reed pan. I either replace the offending valve, or hold it down in the center while lifting up the tip enough to allow it to lay flat when released. "Rough notes" from low to high are often a result of this phenomenon. There may be other causes for what you hear. This type of noise tends to go away when the pressure is high enough on the valve to force it to stay flat even in the rarefaction half of the acoustic oscillation. For low notes below C4' the coupling between the valve and adjacent reed can be strong enough to continue even at high volume.

Dana

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Hi Dana,

 

since I'm not able to have another go with my instrument right now I can just thank you for the immediate and thorough explanation. I will report what I will have been able to make of your suggestions. Maybe it's the valve of the push "b" as it is located in the same chamber together with the active reed (and might even be touching a chamber wall)...

 

However, what I can say at the moment is that the noise is rather occurring than disappearing with increasing the preasure...

 

Best wishes - Wolf

 

 

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My apologies, I often forget there are other kinds of concertinas besides Anglos. If the adjacent reed is the same note, the coupling would be stronger, and may be initiated by the sympathetically vibration of the other reed. This often is what drives the phenomena on the low reeds.

You might want to check to see if it is just a loose reed shoe. If it was only slightly loose, it might only become apparent at higher volume. And not have developed into a full blown rattle yet. Properly made reed shoes have a slight waist in the middle and fit tightly at the heel and tip. This allows for some movement of the wood before it pinches the reed. A reed can be slightly loose at the tip and heel, but still not fall out. Most of the time when I am pulling a reed for tuning and put it back in the slot, it sort of snaps into place, as the slightly wider tip and heel press past the slightly narrower part of the slot to where they made room for themselves when the natural expansion and contraction of the wood crushed the fibers around the solid metal.

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I get this with the changing of the humidity with seasons. At this point, I just wait it out and attempt to regulate humidity within the case. It always works out for me. It is a seasonal phenomenon, and although frustrating at time, it always works out.

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Like Noel, several keys on my Edeophone also responds to changes in the humidity with a strange buzzing or gurgling sound. The fix for my instrument is to pull out the offending reed and reseat it a little less tightly.

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Hi Dana & everyone,

 

thanks a lot for the input and good advice, as I have managed to fix the problem by now! Apparently it had been the valve of the push reed of the same note, took it off for re-glueing, which had to be improved once because the push reed sounded a bit sharp firstly. Now it is in tune again, and the buzzing has gone completely. Happily played a couple of airs in Gmaj resp. Emin this morning...

 

Apart from my having fixed the instrument it's once again amazing to see how free reeds work, or are affected...

 

Best wishes - Wolf

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