1980s-era Dickinson Wheatstone 46-key Hayden. I noticed while playing today that one note sounds faintly when I play another note. A little investigation reveals that it happens both on the push and on the pull and that the two notes are adjacently placed around the rim of the action board. I suspected that either one pad was lifting the adjacent pad or air was somehow leaking from one chamber into the adjacent chamber.
I took the end off and opened the action box to have a look. The two pads, while adjacent, were not close enough to each other for physical contact. I could easily convince myself, now that I could see it, that there was no way the movement of one pad was influencing the other. That left an air leak.
I put the action box back together and turned my attention to the reed pan. I removed it from where it fits into the bellows and held it up against the smooth surface of the action board in the correct orientation. Each hole in the action board was nicely encapsulated in its own chamber, none near enough to a partition to consider that one might actually straddle a partition. The chamois gaskets on the tops of the partitions seemed to be intact and in contact with the action board along their whole lengths.
But then I noticed something odd: a bit of a wobble in the way the reed pan and the action board related to each other. Sure enough, when the partition between the notes I was looking at was snug up against the action board, the ones 180 degrees around were flapping in the breeze. When I held it so that those were in contact with the action board, the one I was looking at pulled away from it. I was able to rock the reed pan against the action board as if one of them had a bulge in the middle. At the extremes of travel, there was about a millimeter or two clearance at one end or the other. I then took a straight-edge ruler and held it against the action board and sure enough, it also rocked, demonstrating a bulge in the action board.
Then I got onto the internet and googled my way to a page in DoN Nichols' web site:http://www.d-and-d.c...nas/tuning.html that includes this paragraph (what I have been calling the "action board," he calls the "valve-board"):
Interesting, but not really my problem. My corner blocks are firmly glued in place (I took it apart again and checked, that's when I took the picture), and I don't think the cardboard trick (while ingenious) will solve my problem of fitting a flat reed pan to a bulging action board.
If you hear a second note join the first above a minimal pressure on the bellows, the problem is cross-partition leakage. You can frequently spot where this has been happening by a darkening of the leather seal on the partition top, where airborne dirt has been deposited. The probable cause here is one of the corner blocks from the bellows frame. If the glue holding it has weakened, it will no-longer support the corner of the reed-pan, allowing it to warp away from the valve-board. Finish breaking it away if it shows any movement, clean off all old glue, and re-glue it. Try to glue it in a position so it properly supports the reed pan level with the edge of the bellows frame. If you cannot be precise, here, err on the side of too little support. You may than add small thicknesses of cardboard (such as that from a Kleenex box) until the level is correct. The cardboard alone will do if the block is securely mounted, but not at a sufficient height.
I expect I could treat the symptom by thickening the chamois gasket over the offending partition, but does this solve the problem? Are my action boards warping? Will it get worse? Are they supposed to be that way? Is there something I can/should do about it?
Any help appreciated.