Diaphragms for lousdspeaker drive units

A method of manufacturing a diaphragm for a tweeter loudspeaker drive unit, wherein the method comprises the steps of:

• providing a first part in the shape of a truncated dome-shaped member
• providing a second, dome-shaped, part,
• bonding the first part to the second part so as to form a rigid dome-shaped member having a constrained layer damping system, the rigid dome-shaped member having a peripheral region of greater thickness than a central region, and wherein
• a change in thickness between the peripheral region and the central region is step-wise when viewed in cross-section across a center of the diaphragm, and is centered at a location which is in the first quarter of a distance measured from a periphery of the rigid dome-shaped member along an external surface of the rigid dome-shaped member to the center of the diaphragm, the location being inset from the periphery of the dome-shaped member,
• and the step-wise change is located on the rearward-facing surface of the dome-shaped member
• wherein the step-wise change in thickness, when viewed in cross-section across a center of the diaphragm, is centered at a location which is between 5% and 25% of a distance measured from the periphery of the dome-shaped member along an external surface of the dome-shaped member to the center of the diaphragm.

A diaphragm for a loudspeaker drive unit, wherein

• the loudspeaker drive unit is a tweeter drive unit,
• the diaphragm comprises a rigid dome-shaped member comprising a first, ring-shaped part and a second, dome-shaped part, the first and second parts being joined to each other by an adhesive layer which, together with the first and second parts, form a constrained layer damping system,
• there is a step-wise change in thickness of the dome-shaped member in the region of the innermost boundary of the first part such that the dome-shaped member has a thickness that varies from a first thickness at a first location at a periphery of the dome-shaped member located outwardly away from the step-wise change in thickness to a second thickness at a second location, which is located inwardly of the step-wise change in thickness and thus nearer to the center of the dome-shaped member than the first location,
• the first thickness is more than twice the second thickness, and
• the adhesive layer has a thickness of at least 10 μm
• wherein the position, in the radial direction from the center to the periphery of the diaphragm, of the step-wise change in thickness is inset from the periphery of the diaphragm.

A diaphragm for a loudspeaker drive unit, wherein

• the loudspeaker drive unit is a tweeter drive unit,
• the diaphragm comprises a dome-shaped member comprising a first part, in the form of a ring-shaped truncated dome and a second, dome-shaped, part, the first and second parts being joined to each other by a bonding layer which, together with the first and second parts, form a constrained layer damping system,
• there is a step-wise change in thickness of the dome-shaped member in the region of the innermost boundary of the first part such that the dome-shaped member has a thickness that varies from a first thickness at a first location of the dome-shaped member located outwardly away from the step-wise change in thickness to a second thickness at a second location, which is located inwardly of the step-wise change in thickness and thus nearer to the center of the dome-shaped member than the first location,
• the first thickness is more than twice the second thickness,
• the step-wise change in thickness, when viewed in cross-section across a center of the diaphragm, is centered at a location which is in the first quarter of a distance measured from a periphery of the dome-shaped member along an external surface of the dome-shaped member to the center of the diaphragm, the location being inset from the periphery of the dome-shaped member, and
• the step-wise change is located on the rearward-facing surface of the dome-shaped member
• wherein the step-wise change in thickness, when viewed in cross-section across the center of the diaphragm, is localized within a distance of 1% of the width of the diaphragm.

A diaphragm for a loudspeaker drive unit, wherein

• the loudspeaker drive unit is a tweeter drive unit,
• the diaphragm comprises a dome-shaped member comprising a first part, in the form of a ring-shaped truncated dome and a second, dome-shaped, part, the first and second parts being joined to each other by a bonding layer which, together with the first and second parts, form a constrained layer damping system,
• there is a step-wise change in thickness of the dome-shaped member in the region of the innermost boundary of the first part such that the dome-shaped member has a thickness that varies from a first thickness at a first location of the dome-shaped member located outwardly away from the step-wise change in thickness to a second thickness at a second location, which is located inwardly of the step-wise change in thickness and thus nearer to the center of the dome-shaped member than the first location,
• the first thickness is more than twice the second thickness,
• the step-wise change in thickness, when viewed in cross-section across a center of the diaphragm, is centered at a location which is in the first quarter of a distance measured from a periphery of the dome-shaped member along an external surface of the dome-shaped member to the center of the diaphragm, the location being inset from the periphery of the dome-shaped member, and
• the step-wise change is located on the rearward-facing surface of the dome-shaped member
• wherein the maximum thickness of the dome-shaped member is less than 0.1 mm and the minimum thickness of the dome-shaped member is less than 50 μm.