A device for controlling a fuel-oxidizer mixture for a premix gas burner , comprising: - an intake duct , which defines a cross section (S) for the admission of a fluid into the duct and includes an inlet for receiving the oxidizer, a mixing zone for receiving the fuel and allowing it to be mixed with the oxidizer, and an outlet for delivering the mixture to the burner ; - an injection duct , connected to the intake duct in the mixing zone to supply the fuel; - a monitoring device , configured to generate a control signal representing a state of combustion in the burner ; - a gas regulating valve , located along the injection duct ; - a fan , rotating at a variable speed of rotation (v) and located in the intake duct to generate therein a workflow in a direction of inflow (V) oriented from the inlet to the delivery outlet ; - a control unit configured to control the speed of rotation of the fan; - a regulator coupled to the intake duct to vary its cross section (S) as a function of the speed of rotation of the fan , wherein the control unit is configured to receive the control signal and to generate a drive signal representing a fuel flow rate as a function of the control signal in order to drive the gas regulating valve in real time, wherein the regulator includes a housing and a shutter , movable between a first limit position, corresponding to a first limit cross section, and a second limit position, corresponding to a second limit cross section, characterized in that the first limit cross section is different from zero and the first limit cross section is less than the second cross section, wherein the shutter is disengaged from the housing and wherein the shutter is in contact with the housing only in the first limit position. - an intake duct , which defines a cross section (S) for the admission of a fluid into the duct and includes an inlet for receiving the oxidizer, a mixing zone for receiving the fuel and allowing it to be mixed with the oxidizer, and an outlet for delivering the mixture to the burner ; - an injection duct , connected to the intake duct in the mixing zone to supply the fuel; - a monitoring device , configured to generate a control signal representing a state of combustion in the burner ; - a gas regulating valve , located along the injection duct ; - a fan , rotating at a variable speed of rotation (v) and located in the intake duct to generate therein a workflow in a direction of inflow (V) oriented from the inlet to the delivery outlet ; - a control unit configured to control the speed of rotation of the fan; - a regulator coupled to the intake duct to vary its cross section (S) as a function of the speed of rotation of the fan , wherein the control unit is configured to receive the control signal and to generate a drive signal representing a fuel flow rate as a function of the control signal in order to drive the gas regulating valve in real time, characterized in that the first limit cross section is different from zero and the first limit cross section is less than the second cross section, wherein the shutter is disengaged from the housing and wherein the shutter is in contact with the housing only in the first limit position. <EOS>