A.C.T. 25 tonearm
a.c.t. 25 tonearm - carbon fibre tonearm

Launched to celebrate the company’s 25th Silver Jubilee, the A.C.T. 25 is a precision-engineered reference level tonearm. Constructed from carbon fibre composite, the A.C.T. 25 is one of the world’s lightest, stiffest and most highly optimised tonearms. Combined with the Circle 25 Turntable, the A.C.T. 25 tonearm becomes part of a highly optimised reference level analogue replay system.

a.c.t. 25 tonearm - carbon fibre tonearm

At the inception of the Wilson Benesch business plan, our strap line, “The Future is Carbon”, acknowledged the potential for carbon fibre to change the way in which high performance systems would be manufactured and in doing so change the world as we know it. More than 25 years on, examples of this change can be seen across the aerospace and automotive industry where ultimate performance is required. Despite many applications using carbon fibre predominantly for its strength to weight advantages, it is the unique stiffness and damping properties of carbon composites which are of primary concern for Wilson Benesch within audio engineering.


The A.C.T. 25 Tonearm geometry has been highly optimised through finite element analysis (FEA) to provide stiffness and damping across the helical, tapered form of the tonearm. The geometry also reduces material use and thus the mass of the assembled tonearm, reducing the mass requirement of the counterweight and subsequently the system overall.


The carbon fibre arm tube terminates into the aluminium eggshell, the geometry of which has been optimised to achieve a maximal stiffness to weight ratio. Residing beneath the egg is a the kinematic bearing, formed by a brass mount which terminates with a brass ball cap holding captive, three 1mm carbon-chrome ball bearings. This creates a high pressure, triangulated frame of reference ensuring that the centre point of the bearing can never change. It is a beautifully simple, yet highly precise and stable design.


Internally the tonearm is wired with silk covered litz wire, terminated with gold plated RCA Phono plugs. Other features include a solid carbon fibre arm board to support the tonearm when not in use.


As the leader in advanced carbon composite engineering in the high-end audio industry, Wilson Benesch provide two tonearm options, the A.C.T. 25 Tonearm and the Nanotube One Tonearm. Both can be fitted to the Circle 25 turntable, or used with a third party turntable.

a.c.t. 25 tonearm - technology











Helix of 0 / 90 woven carbon fibre moulded into headshell in one piece. Carbon fibre bias plate.



INTERNAL: Silk covered litz wire

EXTERNAL: Star quad 4 × 96 × 0.05 Resseun shield. Core to core 70pf.
Resistance 0.108 Ω Termination gold plated RCA phono plugs



Effective mass: 9g

Overhang: 18mm

Effective length: 235mm

Mounting distance: 217mm (spindle to pillar)

Weight: 340g

Cartridge range: 5-16g (assuming a max required tracking force of 2g)

Wilson Benesch Ltd | Falcon House  |  Limestone Cottage Lane | Sheffield  | United Kingdom  | T +44 (0)114 285 2656


Designed and Built by Wilson Benesch 2016  |  All rights reserved

a.c.t. 25 tonearm - technology

Wilson Benesch Ltd | Falcon House  |  Limestone Cottage Lane | Sheffield  | United Kingdom  | T +44 (0)114 285 2656


Designed and built by Wilson Benesch 2016  |  All rights reserved