Solutions for low volume from outer rows

[wes]

I've just refurbished a high quality lachenal and no matter my efforts, the outer key rows are significantly lower in volume output than the inside. Some time ago, I rebuilt another one that is exactly the same in appearance that is very balanced. These are the fine fretwork rosewood type, 20 button. I've swapped the valves out for lighter ones on those rows, but no real effect. The obvious is that the outer key rows lift the pads under the hands, and so dampen the sound, but this is not born out in other instruments I have that employ the radial reed pan design. Any ideas solutions welcome.

 

[Greg Jowaisas]

I would check to make sure the support blocks for the reed pan are secure and the right height.  If the chambered walls chamois is lower than the surrounding bellows pan chamois then air will escape and the reeds in this area will not get the benefit of full bellows pressure.

 

inspect the reed pan height and give each support block a good tug.  Sometimes the support block appears secure but is only glued tight to the chamois edge but not the frame.  You want all the blocks firmly glued to the frame so the reed pan is held rigid and the pad board can seal against the chamois.

 

You might also check that the reed pan edges are sealing against the bellows pan chamois in the area of the weak notes.  (A 20b rosewood Lachenal reed pan usually does not contact the two opposite sides of the bellows pan chamois with it its "long" sides but the chamois on its outermost chamber walls provide the seal in this area.)

 

Good luck,

 

Greg

[Dana Johnson]

I’d go with Greg’s thoughts on the support blocks, but for a different reason.  Even if the chamois is sealing, reed pans like firm contact with the action pan.  Reeds need to be mounted on a firm surface to sound well. If the reed pan can vibrate even slightly, it draws energy from the reed and keeps it from reaching full volume.  Even shimming corner blocks with cardboard (instead of resetting them or using wood shims to make up for shrinkage) provides a soft path that damps the vibration of the reeds.  Often it is easy to spot a loose corner block by the weak sound of the reeds that are close to it.

Dana

[d.elliott]

I dont see how Greg's suggestion would account for the the volume only on the outer rows. and by 'outer rows' it would imply  the outer row on each end of the instrument. Although I have no better option to offer. It sounds like a reedpan/ chambering design issue  on this specific instrument. Is it a particularly early model?

[wes]

First off, I want to say thanks so much for the great advice from the likes of you.

If any of you had the instrument in your hands for a moment, you would spot the problem, of that I am sure.

The advice on how essential the seal is did the trick. Upon opening the left side, I laid my straight edge over the partitions and found a slight raised area in the approximate center, more pronounced in the area of low volume reeds. (During the refurb, I had replaced the bellows skirt chamois, but not the partitions, as they seemed in good health). Then the straightedge on the action pan. Obviously warped. 

So now the disassembled action pans sit for a week or so clamped (after a bit of moistening), and then I'm faced with the very fiddly bit of another full adjustment of the action.

Here's the humorous part. The last concertina I refurbished was the same model, and had the same problem, and I did the same thing. Regulated the action after felting the buttons, mind you, and then having to do it all over again, when it dawned on me that the pans were warped!!!!!

(It's from the 1870s) 

Regarding Dana's input, I have never considered that bit about wood to wood, and usually go right for cardstock shim, but now I'll think on it. When I've worked on string instruments, connection areas seems to be critical for sound optimization.

Again, thank you all very much.

Wesley

 

 

[d.elliott]

Pleased to read that you have the issue resolved.