Help! Reeds gone flat.

[Coenraads]

A friend reported problems with his reed organ and I encountered a problem new to me.
Two of the bass reeds on the 8' foot Diapason have inexplicably gone a semitone flat. Both the reeds and the channels are clean and are correctly "gapped." The speech also appears compromised, the attack being slow and with less volume than the other reeds near it.

Am I looking at a flaw in the reed (weakened metal?) or is this likely to be a winding problem? What should I look for and what can I expect to find?
In the 16' Sub-bass, I found one broken reed and another reed that was a semitone flat. Holding the valve wide open, however, changed nothing.

Help would be appreciated,
John

[myorgan]

John,

I think you addressed this in your post, but is there debris on those reeds? Shine a flashlight to see if there's something in the cells when you pull the reeds out.

Michael

[nutmegct]

John - that's the symptom I suffered on my George Woods. Played perfectly until one day one reed was about a half tone low, with a "weak" sound and change of timbre.

Nelson Pease diagnosed the problem as a cracked reed. He showed me the crack under a magnifying glass. Fortunately he had a replacement reed for me.
Tom M.

[Coenraads]

Thanks Tom.
Metal fatigue was high on my list of possible culprits. I looked for cracks, but without a magnifier, did not see any.
It explains why F and G were affected, which get heavily used.
This forum is a wonderful resource with so many people willing to share their knowledge.
Again thanks,
John

[Organfella]

I would agree that when the tone goes flat it indicates a slower vibration which could only come from a weaker reed tongue. The effect is the same as lengthening of the tongue. Metal fatique is as mentioned the culprit here. If the tone went up, it could among other things indicate debris on the base of the tongue effectively "shortening" it to sound at a higher pitch. Logic tells my single brain cell that you should start looking for replacements - and check the other reeds that may sound suspect also.
Sad state of affairs but as a good friend of mine often would say: "anything made by man is guaranteed to fail some time".
Luck
Nico

[Sammiam]

I just restored a reed organ, and using an app on my android for tuning & following directions (google it) you can retune your reeds individually, it was surprisingly easy

[Coenraads]

I'd like to report success. My organ-builder friend lent me his box of reeds, but I had no idea reeds came in so many sizes and pitch levels. Eventually I picked two reeds that came close in size to the bottom G and C I wanted to replace. The G slid in smoothly but the C was too thick. I discovered, however, that with a fine file I could remove enough material so that it too slid in. But, both reeds were about three semitones too high. I know that sometimes pipe organ reeds have solder on the tips of the reed to adjust the pitch, so I decided to give it a try. After adding and removing solder on the tips, I was eventually able to tune them to the required pitch using Pitch Lab, my favourite tuning app.

I suspect that the extra mass must stress the root of the reed, but for now, they sing beautifully. Besides, this reed organ resides in a chapel associated with a local hospital and the reed organ sees use about once a year for a carol sing. It also boasts a small Casavant pipe organ so the chapel will never lack for organ music.
And thanks for all the advice.
John