Air-jet type spinning device comprising - a body at least partially hollow, which delimits a cylindrical spinning chamber , the body comprising at least one injection hole configured to inject a flow of compressed air into said spinning chamber , - a fibre feeding device , facing said spinning chamber so as to feed the fibres into the spinning chamber , - the fibre feeding device comprising a fibre feeding channel having a first straight section leading, at a shoulder , into a pre-chamber facing and communicating with said spinning chamber , - a spinning spindle at least partially inserted in the spinning chamber and fitted with a spinning channel for the transit of yarn obtained from said fibres, the spinning channel having a main axis which defines a spinning direction (X-X), and having a front inlet for the introduction of the yarn in said spinning channel , wherein the distance between the at least one injection hole and the front inlet , measured parallel to the spinning direction (X-X), is greater than or equal to 0.3 mm, the injection hole being arranged upstream of the front inlet , wherein the spinning chamber is delimited at least partially by an outer side wall , opposite the spinning spindle , wherein on said outer side wall at least one thread is made, wherein said at least one injection hole is oriented so as to direct the jet of compressed air towards the at least one thread so as to be guided and oriented by the latter, wherein the spinning device comprises at least two injection holes that direct compressed air at two separate emission points of the same helical thread , characterised in that a diameter of the spinning chamber , measured relative to a cross-section plane perpendicular to said main axis, is between 5.6 and 7.4 mm and in that said emission points are diametrically opposite to a each other and send jets of compressed air in opposite directions to each other. - a body at least partially hollow, which delimits a cylindrical spinning chamber , the body comprising at least one injection hole configured to inject a flow of compressed air into said spinning chamber , - a fibre feeding device , facing said spinning chamber so as to feed the fibres into the spinning chamber , - the fibre feeding device comprising a fibre feeding channel having a first straight section leading, at a shoulder , into a pre-chamber facing and communicating with said spinning chamber , - a spinning spindle at least partially inserted in the spinning chamber and fitted with a spinning channel for the transit of yarn obtained from said fibres, the spinning channel having a main axis which defines a spinning direction (X-X), and having a front inlet for the introduction of the yarn in said spinning channel , wherein the distance between the at least one injection hole and the front inlet , measured parallel to the spinning direction (X-X), is greater than or equal to 0.3 mm, the injection hole being arranged upstream of the front inlet , wherein the spinning chamber is delimited at least partially by an outer side wall , opposite the spinning spindle , wherein on said outer side wall at least one thread is made, wherein said at least one injection hole is oriented so as to direct the jet of compressed air towards the at least one thread so as to be guided and oriented by the latter, wherein the spinning device comprises at least two injection holes that direct compressed air at two separate emission points of the same helical thread , characterised in that a diameter of the spinning chamber , measured relative to a cross-section plane perpendicular to said main axis, is between 5.6 and 7.4 mm and in that said emission points are diametrically opposite to a each other and send jets of compressed air in opposite directions to each other. <EOS>