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MMD > Archives > August 1996 > 1996.08.27 > 06Prev  Next

Duo-Art Measurements and Adjustments
By Craig Brougher

Pete, something else is also wrong besides the fact that your expression box is not set up properly. I noticed it when you said, "It's still playing too loudly" even though your top power is only 20.5 inches.

In the first place, your accordions are to be set according to the book, to start with. #1 = 1/16", #2 = 1/8", #3 = 1/4", #4 = 1/2", both sides. The Theme spring should be a heavier spring than the Accomp spring. You don't need measurements in the thousandths because that box would never recognize such hair-splitting accuracy, anyway; also, the accordion measurements are given as a starting point. You may end up "adjusting them a little."

You should plot a curve, using your stack as the "bleed." Your felt muffler will never work the way you have it, so do it right or you'll never get it adjusted. A 1/4" hole in a flat piece of felt is not the same as a 1/4" hole through a rolled up 1"-long piece of muffler felt stuffed into a hole. So the first thing you will have to do is change it. It is the "pivot" around which all the intensities from 0 to 10 revolve.

Your chart should be linear. With 5" as a #0 accomp. intensity, and your top intensity (#15, no crash) draw a straight line. The pressures are plotted on the Y axis and the intensity steps on the X axis. Forget the db meter. I suggest first setting up the piano intensities the way they were originally done, then using the db meter if you wish.

Your top pressure should be about 35" or a little more, with a reasonably tight system, for the Theme response line. First, adjust the #10 intensity. The way you do that is, remove the felt muffler and slap a "Post-It" note over the hole so that its own natural curve allows a little gap. It won't be smack-tight. Operate accordions #2 and #8 and adjust the foot on that (accompaniment) side to just close the spill. When you see the paper pop off the hole by its own curl, then you have it. Replace the wad of muffler felt. Chart the box by beginning with a straight line between end points. Then plot your actual response by using all 14 combinations in-between. Don't fudge it, and you will see exactly how linear the box really is.

Another thing I am suspecting is that your pump is not doing its job. It seems to leak at high pressure and can't make it. That can either be the fault of the pump or the stack valves, or a combination of both.

When your pump is able to plot 35" or more at crash, that does not mean that your piano will play even louder than before! That means that now your piano has full control and will play everything correctly, from very soft to very loud, but the boring quality will have vanished.

Craig B.

(Message sent Mon 26 Aug 1996, 01:03:04 GMT, from time zone GMT.)

Key Words in Subject:  Adjustments, Duo-Art, Measurements

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