Volvere Design


BACKGROUND

Using expertise gained from years of research developing the Acutus turntable the Volvere was launched at the Belfast HIFI Show in 1998.

Setting new standards of excellence and providing a stepping-stone to the performance level achieved by the Acutus.

The original Volvere was designed with consideration to suggestions made from the trade, such as detachable arm-boards. It was quickly learned that these suggestions limited the performance. Redesigned avoiding external suggestions, relying on existing research and with maximum performance being the goal, we re-launched the Volvere.



DESIGN

The design principles of the Volvere are identical to Acutus. To remove stylus borne vibration from the record, ultra-low mechanical noise, rigidity, isolation from structures and speed stability under load. Maximising performance, compromise has been restricted to elements that have little effect on sound quality. The stylus as it traces the groove will make the record vibrate and uncontrolled will cause loss of information and distortion. In common with Acutus the record is clamped to the main bearing, giving the vibration present an earth point. The bearing is the same design as Acutus and acts like an electrical diode, transmitting the vibration to the sub-chassis.

The platter, made from a single billet of aluminium, now weighs 6.7Kg and to prevent ringing modes a peripheral rubber ring and bonded mat are fitted. The record interface (mat) is made from NBR/Cork material, especially chosen to reflect vibration back into the record to be drained at the main bearing. NBR/Cork is slightly softer than vinyl offering damping in the vertical direction, however due to the structure of this material it acts more rigidly at an angle reflecting vibration back to the record. As their mechanical impedances are very different the reflected energy has a very wide bandwidth.

The act of clamping makes the record more rigid, aiding its energy transmission properties. Flattening the record to the mat also provides a stable groove to be traced. The clamp itself works very simply, with one knurled knob to turn, automatically clamping the record to the bearing and dishing down to the mat in one action. The result is a record free of resonant feedback allowing more information retrieval, lower noise floor, focused sound and pinpoint stage-sounding.

The energy created by the stylus enters the main bearing, designed to pass energy to the subchassis one-way, much like an electrical diode. As the energy produced is equal and opposite, vibration also enters the pick-up arm and is ideally transmitted to the subchassis mounting. The bearing is inverted for several reasons; crucially the point of contact is only 4mm from the record aiding rapid energy transfer. A high centre of gravity to give stability and reduced noise. The point contact made from a sapphire cup jewel and tungsten carbide ball rotates concentrically. Commonly used bearings running on flat plates allow lateral platter movement causing loss of information. The supporting shaft is 16mm diameter stainless steel, tapered to the top. This prevents standing waves and creates the diode effect and friction fitting to the subchassis also increasing rigidity.

One-piece complex aluminium casting forms the subchassis. Most designs emphasise rigidity and damping, a contradiction as the more rigid an object the less it will damp. Rigid objects with added damping will give a non-linear performance. Take a flat sheet of paper; not very rigid until itís folded, its strength increasing more than 10 times. Any movement of the pick-up arm relative to the platter results in lost information, hence the link between arm mounting and bearing has to be the most rigid. For this reason no arm boards are used, the mounting integral with the casting. Three folds in the casting provide massive strength in this crucial area. Assuming that infinite rigidity is impossible this design puts strength were itís required and uses weakness to dissipate energy rapidly. The next in importance, the suspension points, are located on the end of shallow folds, with no strength being added to the flat panels between. These flat sections are less rigid and dissipate energy rapidly without loss of information. The irregular grain size and pattern of the material dissipates energy more effectively than extruded or rolled material and the paint finish applied has been developed to assist energy release by controlling material skin tension. The platter/arm/ bearing loop is complete.

Isolation of the "loop" is essential, otherwise structural energy reaches the stylus leading to distortion. Using our unique frequency adjustable suspension developed for the Acutus, three extension springs giving low centres of gravity and stability and are equally adjusted regardless of load. When the "loop" is level to the supporting base all springs react equally giving perfect stable vertical movement. High platter mass allows for a low 3.2Hz suspension setting within compact dimensions. Especially designed spring termination prevents subchassis rotation. Achieving perfect vertical isolation however highlights other problems. Rocking modes as the "loop" tries to topple over, pulling of the drive belt and external movement. Lateral damping rings in line with the drive belt and stiffer than the vertical frequency provides a perfect solution. Rocking modes are rapidly damped and energy transferred to vertical motion, also damped by the rings lateral tension. Being parallel to the drive belt stops rocking and allows maximum delivery of motor torque.

Traditionally motors driving turntables have been low powered AC synchronous devices driving high mass platters. Motor noise transmitted to the "loop" and cogging have traditionally been problems to be solved. During playback the platter is subject to varying stylus drag which, despite the flywheel effect puts load on a weak motor, loosing synchronicity, massively increasing vibration. Contradicting current trends a single extremely powerful AC synchronous motor is used to drive the 6.7Kg platter. In contrast to other designs, the motor controls platter speed. The motor output of 60mN-six times the power of conventional units-is modified to reduce vibration and noise to exceptionally low levels. The motor itself is integral with the base giving constant alignment with the platter. This is important in lower suspended mass designs to maintain good speed stability as the drive belt has more influence than higher mass designs, such as the Acutus. Powered by a state-of-the-art, split-phase quartz-locked purposed designed power supply keeps motor speed precisely constant. Conveniently attached to the underside of the base, it offers electronic speed change between 33 & 45RPM. Using a round section belt without retaining groove ensures no speed variation, even with the suspension oscillating. The high mass of the platter in conjunction with belt compliance eliminates any cogging present.

With all our designs we look for improvements were it's possible. The lack of changes over the years, especially in comparison to other designs, clearly shows we spend the time to do it right first time. Time well spent here offers you time well spent listening.