A fluid regulator, comprising: a regulator body defining a fluid inlet, a fluid outlet, and a fluid flow path connecting the fluid inlet to the fluid outlet; and a valve trim disposed inside the regulator body, the valve trim comprising a valve stem, and a control element operatively coupled to the valve stem and disposed in the fluid flow path, the control element arranged to shift between at least a first position and a second position to control flow of fluid through the fluid flow path from the fluid inlet to the fluid outlet; and an actuator comprising: a housing operatively connected to the regulator body, the housing forming a first chamber and a second chamber; a diaphragm separating the first chamber from the second chamber; a first spring seat operatively coupled to the housing; a first control spring operatively coupled to the diaphragm and the first spring seat, wherein the first control spring biases the diaphragm in a first direction; and a linkage (80,80') operatively connecting the control element to the diaphragm via the valve stem; wherein the diaphragm is in fluid communication with the fluid outlet and operatively arranged to move the control element in response to fluid pressure at the fluid outlet, characterised in that the actuator further comprises a second control spring operatively coupled to the diaphragm and the first spring seat, wherein the second control spring biases the diaphragm in the first direction in parallel with and independently of the first spring; wherein the first control spring has a first natural frequency, and the second control spring has a second natural frequency different than the first natural frequency, wherein the first spring seat is a single component operatively connected to the housing and includes separate spring seat surfaces (96, 98) for the first and second springs (46, 48) and one or more protrusions extending between the first control spring and the second control spring forming one or more spacers to prevent contact between the first and second control springs (46, 48); and wherein the diaphragm is in fluid communication with the fluid outlet via one or more passages formed in the valve trim. a regulator body defining a fluid inlet, a fluid outlet, and a fluid flow path connecting the fluid inlet to the fluid outlet; and a valve trim disposed inside the regulator body, the valve trim comprising a valve stem, and a control element operatively coupled to the valve stem and disposed in the fluid flow path, the control element arranged to shift between at least a first position and a second position to control flow of fluid through the fluid flow path from the fluid inlet to the fluid outlet; and an actuator comprising: a housing operatively connected to the regulator body, the housing forming a first chamber and a second chamber; a diaphragm separating the first chamber from the second chamber; a first spring seat operatively coupled to the housing; a first control spring operatively coupled to the diaphragm and the first spring seat, wherein the first control spring biases the diaphragm in a first direction; and a linkage (80,80') operatively connecting the control element to the diaphragm via the valve stem; a housing operatively connected to the regulator body, the housing forming a first chamber and a second chamber; a diaphragm separating the first chamber from the second chamber; a first spring seat operatively coupled to the housing; a first control spring operatively coupled to the diaphragm and the first spring seat, wherein the first control spring biases the diaphragm in a first direction; and a linkage (80,80') operatively connecting the control element to the diaphragm via the valve stem; wherein the diaphragm is in fluid communication with the fluid outlet and operatively arranged to move the control element in response to fluid pressure at the fluid outlet, characterised in that the actuator further comprises a second control spring operatively coupled to the diaphragm and the first spring seat, wherein the second control spring biases the diaphragm in the first direction in parallel with and independently of the first spring; wherein the first control spring has a first natural frequency, and the second control spring has a second natural frequency different than the first natural frequency, wherein the first spring seat is a single component operatively connected to the housing and includes separate spring seat surfaces (96, 98) for the first and second springs (46, 48) and one or more protrusions extending between the first control spring and the second control spring forming one or more spacers to prevent contact between the first and second control springs (46, 48); and wherein the diaphragm is in fluid communication with the fluid outlet via one or more passages formed in the valve trim.