Phase plug for compression driver having improved assembly
This invention provides a phase plug for loudspeakers of the compression driver type having a body characterized by a plurality of channels, each channel constituting a wave passage for acoustic waves from an input surface (that receives acoustic waves) to an output surface (that transmits acoustic waves), the input surface being provided by an integral member. The positions and widths of the channel openings are determined in order to reduce acoustic resonances in the compression chamber. The acoustic channels are characterized by the fact that their openings towards the input surface depart in the axial direction. The width of the acoustic channels is computed in order to guaranteed that there will be no loss of acoustic intensity in the channels.
1. A phase plug having a body having a plurality of channels, each channel constituting a wave passage for acoustic waves from an input surface (that receives acoustic waves) to an output surface (that transmits acoustic waves), the input surface being provided by an integral member, in which the openings of the acoustic channels depart from the input surface following the axial direction and the width of the openings is greater by a factor 1/cos(Tn), wherein Tn is the angular position of the nth acoustic channel, than an opening corresponding to a channel oriented orthogonally to the phase plug input surface at the location of the opening whereby the acoustic intensity will be the same as if the channels were oriented locally orthogonal to the phase plug input surface.
2. A phase plug according to claim 1 , in which the input surface is convex.
3. A phase plug according to claim 1 , in which the input surface is concave.
4. In a phase plug design procedure, comprising determining suitable angular positions and widths of openings of acoustic channels in a phase plug input surface the improvement which comprises increasing
the width of said openings from the width determined as if the channel will depart orthogonally to the phase plug input surface at the location of the opening by a factor 1/cos(Tn), wherein Tn is the angular position of the channel opening such that the width adjustment ensures that, after realizing the acoustic channels in such a way that they depart axially from the input surface, the acoustic intensity will be the same as if the channel were oriented orthogonally to the phase plug input surface at the location of the opening.