Apparatus for manufacturing pods for beverage extraction machines comprising: - movement means to advance a belt of material in a predetermined rectilinear direction, - a plurality of forming plates arranged below the belt and individually provided with at least one cavity facing the belt itself, - movement means to advance said forming plates in the same direction as and in a synchronized manner with the belt, and - a plurality of operational devices arranged in succession along the running direction of the belt, wherein said operational devices comprise at least: - one device for pressing down a portion of the belt into the cavity of the forming plate below, impressing the shape of a cap therein, - a device for releasing a dose of a powder substance inside the cap placed in the cavity of the forming plate, - a device for compacting the dose inside the cap placed in the cavity of the forming plate, obtaining a compacted tablet, - a second cap of waterproof material, - a device for applying the second cap of waterproof material on the compacted tablet inside the cap placed in the cavity of the forming plate, - a device for sealing the second cap to the belt obtaining a pod, and - a device for cutting the belt separating the pod characterised in that the belt of material is a belt of waterproof material, and the device for compacting the dose comprises a vibrating group adapted to transmit a mechanical vibration to the dose, wherein the vibrating group comprises: - an ultrasonic generator adapted to generate an electric wave having a frequency in the ultrasound range, - an electromechanical transducer adapted to transform the electric wave into a mechanical vibration, and - a sonotrode adapted to transfer the mechanical vibration generated by the electromechanical transducer to the dose, wherein the device for compacting the dose comprises means adapted to move the sonotrode between a raised position, in which the sonotrode is separated from the dose, to a lowered positioned, in which the sonotrode presses the dose against the cap placed in the cavity of the forming plate, wherein the sonotrode is slidably received inside a guiding jacket which is movable between a raised position, in which the guiding jacket is spaced apart from the belt, and a lowered position, in which the guiding jacket presses and locks the belt against the forming plate, laterally surrounding the cap and the dose of coffee placed in the cavity of the forming plate. - movement means to advance a belt of material in a predetermined rectilinear direction, - a plurality of forming plates arranged below the belt and individually provided with at least one cavity facing the belt itself, - movement means to advance said forming plates in the same direction as and in a synchronized manner with the belt, and - a plurality of operational devices arranged in succession along the running direction of the belt, - one device for pressing down a portion of the belt into the cavity of the forming plate below, impressing the shape of a cap therein, - a device for releasing a dose of a powder substance inside the cap placed in the cavity of the forming plate, - a device for compacting the dose inside the cap placed in the cavity of the forming plate, obtaining a compacted tablet, - a second cap of waterproof material, - a device for applying the second cap of waterproof material on the compacted tablet inside the cap placed in the cavity of the forming plate, - a device for sealing the second cap to the belt obtaining a pod, and - a device for cutting the belt separating the pod characterised in that the belt of material is a belt of waterproof material, and the device for compacting the dose comprises a vibrating group adapted to transmit a mechanical vibration to the dose, wherein the vibrating group comprises: - an ultrasonic generator adapted to generate an electric wave having a frequency in the ultrasound range, - an electromechanical transducer adapted to transform the electric wave into a mechanical vibration, and - a sonotrode adapted to transfer the mechanical vibration generated by the electromechanical transducer to the dose, wherein the device for compacting the dose comprises means adapted to move the sonotrode between a raised position, in which the sonotrode is separated from the dose, to a lowered positioned, in which the sonotrode presses the dose against the cap placed in the cavity of the forming plate, wherein the sonotrode is slidably received inside a guiding jacket which is movable between a raised position, in which the guiding jacket is spaced apart from the belt, and a lowered position, in which the guiding jacket presses and locks the belt against the forming plate, laterally surrounding the cap and the dose of coffee placed in the cavity of the forming plate. - an ultrasonic generator adapted to generate an electric wave having a frequency in the ultrasound range, - an electromechanical transducer adapted to transform the electric wave into a mechanical vibration, and - a sonotrode adapted to transfer the mechanical vibration generated by the electromechanical transducer to the dose,