At the design of the wind-channel the recorder builder has different possibilities to put his ideas of sound and speaking into effect. The height and width, the lengthways and crossways profile and different bends influences the tone and the speaking from simple and unpretentious to cunning and critical. Unfortunately, high solutions demand a lot from the player. For normal use a average solution which is usable for a normal player must be found.
For the player only one sort of care is possible. Push the block out with a hammer stick (a cooking spoon is possible too) and clean block and wind- channel with finest steel wool. To this wind a long strip of steel wool round a strip of wood, introduce it into the wind-channel and softly clean and smooth the surfaces . All sides of the wind tunnel must be free of pollutions and roughness of every sort. After the cleaning the block is reinstated by slight strokes with the upholstered hammer.
Details on the design of the wind channel: the line b-c can be more or less concave in the ceiling and in the block. At the block such a form also is possible at c . By splitting the surface and by inserting a mall wedge it is possible to adjust the opening at c, which is extremely important for the sound and the speaking. The largest distance (at b) can be more or less transferred in direction of c. These curves make the special attraction of a handmade instruments, however, but they must be used with caution and taste. (extreme curves often cause astonishing sound alterations for single registers, however, but make other registers unplayable simultaneously (e.g.: depth sounds interesting but height mentions no longer well). In addition has to be wondered about strong changes of the measurements, that differ a lot from the historical instruments.
In the place of e, the cross-section can be a little further than at f. When playing this difference becomes smaller. The cross-cut at the end of the wind-channel becomes more close. The different cross-cuts of the wind-channel physically cause an acceleration of the stream of air. After the laws of streaming gasses the speed of the air is connected reciprocal to the diameter. In the place of B, the air is slower than at the leaving at C.
At a and c respectively phases should be attached, these give a better swirling of the air.