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Felt Hammer Connection

Description

Interaction of a felt hammer against an object. It is very convenient in order to soften the excessively brutal attacks inherent in the strike connection. It fully models the hysteresis (the lag time of the effect of the interaction in relation to its cause), just as real felt behaves, and is based on Stulov's model.

(make-connection 'felt ... )

Lisp Syntax and Default Values

The 'felt connection can be created using the following Lisp syntax:

(make-connection 'felt acc_ref1 init-pos1 acc_ref2 init-pos2 thickness F0 alpha epsilon tau weight)

Parameters

The 'adhere connection takes ten arguments:

  • acc_ref1: access on striking object.
  • init-pos1: initial position of the striking object's access. (numerical value, not a controller)
  • acc_ref2: access on object to be struck.
  • init-pos2: initial position of the struck object's access. (numerical value, not a controller)
  • thickness: controller representing the thickness of the felt, in meters.
  • F0: first parameter of Stulov's model. Corresponds approximately to the strength or hardness of the felt.
  • alpha: the exponent for the law relating the force to the depression.
  • epsilon: controls the level of the hysteresis, 0 will block it, 1 will enable it fully.
  • tau: time constant for the hysteresis.
  • weight: (optional) controller weighing the interaction.

The two access positions must be numerical values, not controllers.

The various parameters for this connection are all controllers. The thickness controller represents the thickness of the felt in meters.

The F0 controller, the first parameter of Stulov's model, corresponds approximately to the strength or hardness of the felt. Higher values will yield brighter sounds, as if struck by metal, whereas lower values will sound more muted, as if struck by rubber. Typical values range from 0 to 1e15.

The alpha controller defines the exponent for the law relating the force to the depression. Higher values makes the resulting sound more damp, as if being struck by a softer material. Typically above 2.

The epsilon controller controls the level of the hysteresis, 0 will block it, 1 will enable it fully. Typical values ranging from 0 to .9 (Aurally, from the user's point of view, this seems to relate somewhat to surface fuzziness of the felt.)

The tau controller provides the time constant for the hysteresis. Lower values will make the felt recover quicker. Typical values range from 1e-7 to 1e-5 sec. (Aurally, from the user's point of view, this seems to relate somewhat to the surface hardness of the felt.)

The weight controller is optional. If not provided, it defaults to 1.

Discussion

The felt connection is similar to the strike connection. (...but it sounds a lot better!)

Options

There are no special options for this connection.

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