Reed goes is flat with low pressure

[ErnieDB]

Hi All,

 

I have a Wheatstone English treble (#2877) with an E7 (lowest E) reed that changes from a 1/4 tone flat at low pressure then goes to the correct pitch with normal pressure. This was after a retuning to correct for a sudden flattening. I switched the reed with the other E7 and the problem follows the bad reed in either chamber, so valves are probably not the problem. The response time of the reed is good. It has not changed pitch at all (with normal pressure) for the past few hours of playing. The reeds are brass. Thanks.

[Chris Ghent]

The reed is touching the frame or the wood, or something is caught between the frame and tongue.

 

Hitting the wood is extremely unlikely, hitting the frame is possible since it has just been tuned. A reed touching near the root raises the pitch, so it would have to be touching nearer the tip. However touching near the tip makes noise which you would hear. The most likely scenario is something caught between the frame and the tongue.

 

I have heared many reeds touching but It occurs to me belatedly I have never heard a brass reed touching and perhaps the sound of brass on brass is more muted. Either way, a good inspection with magnification and backlight, holding the reed closed, should show something.

 

Regs

 

Chris

[ErnieDB]

Hi Chris,

 

Thanks for the help. The reed does not appear to have a touch, as I tested it with a 0.001 inch shim. Also, I could hear no scratchyness. It is quite a bit off center though. The screws are frightenly tight, so I was afraid to put enough force on them to change its position. But just from handling the reed went even flatter (almost to E flat), and does not seem to be tunable. Must be a crack?

 

Ernie

[Geoff Wooff]

Hi Chris,

 

Thanks for the help. The reed does not appear to have a touch, as I tested it with a 0.001 inch shim. Also, I could hear no scratchyness. It is quite a bit off center though. The screws are frightenly tight, so I was afraid to put enough force on them to change its position. But just from handling the reed went even flatter (almost to E flat), and does not seem to be tunable. Must be a crack?

 

Ernie

 

 

 

 

I does sound like a crack Ernie... and perhaps not that uncommon with an old brass reed.

[Chris Ghent]

I should have payed more attention to the word "sudden" in your original post! That certainly sounds terminal, sorry, I hope you have easy access to a new tongue or a replacement assembly. Your description of it playing low at low pressure intrigued me as it is counter to the usual.

 

You would not normally loosen the screws to shift a reed sideways, careful levering with a shim about 8 thou thick will do it. Testing clearances with a shim is difficult even with practice as the reed will deflect by thousandths of an inch. Magnification and backlight are the key to adjusting sideways clearances.

 

Cheers

 

Chris