An apparatus for producing a corrugated product, comprising: a zero-contact roll having an outer circumferential surface; a pressure transducer; and a pair of corrugating rollers arranged downstream of the zero-contact roll along a web pathway for said medium material, wherein the corrugating rollers cooperate to define, at a nip therebetween, a corrugating labyrinth between respective and interlocking pluralities of corrugating teeth provided on said corrugating rollers, wherein said interlocking pluralities of corrugating teeth are effective to corrugate a web of medium material that is drawn through said nip during rotation of said corrugating rollers; wherein said web pathway follows a path around a portion of the outer circumferential surface of said zero-contact roll and through said corrugating labyrinth between said corrugating rollers; said zero-contact roll being operable to support said web of medium material at a variable height above its outer circumferential surface on a cushion of air that is emitted from that surface through openings provided through the outer circumferential surface of the zero-contact roll, said pressure transducer being adapted to detect a pressure of said cushion of air that supports said web above said outer circumferential surface; and said pressure transducer being operatively coupled to a feedback control loop adapted to regulate operation of a corrugating pre-tensioning mechanism to adjust a tension in said web of medium material based on the pressure of said cushion of air, to thereby dampen speed and/or tension oscillations in said web on entering said corrugating labyrinth that are induced as a result of the web being drawn therein between said interlocking pluralities of corrugating teeth. a zero-contact roll having an outer circumferential surface; a pressure transducer; and a pair of corrugating rollers arranged downstream of the zero-contact roll along a web pathway for said medium material, wherein the corrugating rollers cooperate to define, at a nip therebetween, a corrugating labyrinth between respective and interlocking pluralities of corrugating teeth provided on said corrugating rollers, wherein said interlocking pluralities of corrugating teeth are effective to corrugate a web of medium material that is drawn through said nip during rotation of said corrugating rollers; wherein said web pathway follows a path around a portion of the outer circumferential surface of said zero-contact roll and through said corrugating labyrinth between said corrugating rollers; said zero-contact roll being operable to support said web of medium material at a variable height above its outer circumferential surface on a cushion of air that is emitted from that surface through openings provided through the outer circumferential surface of the zero-contact roll, said pressure transducer being adapted to detect a pressure of said cushion of air that supports said web above said outer circumferential surface; and said pressure transducer being operatively coupled to a feedback control loop adapted to regulate operation of a corrugating pre-tensioning mechanism to adjust a tension in said web of medium material based on the pressure of said cushion of air, to thereby dampen speed and/or tension oscillations in said web on entering said corrugating labyrinth that are induced as a result of the web being drawn therein between said interlocking pluralities of corrugating teeth.