- Category: Turntables
- Written by Jim Clements
- Published on 19 December 2011
Design of the Pro-Ject 6 PerspeX Turntable and Sumiko Blackbird MC Cartridge
Pro-Ject makes a surprising number of turntable models that are grouped into four lines. The entry line is called the Essential Line. The next step up is the Debut Line. The remaining two Pro-Ject lines are their top lines. They are the RPM Line and the Classic Line. The price ranges overlap significantly between these two lines and the models in this upper range are differentiated by style more than by price. The RPM tables embody a contemporary look and design while tables in the Classic Line are characterized by a retro-style but with underlying modern technologies and materials.
The 6-perspeX table is marketed through the Pro-Ject Classic Line. It is the lowest Pro-Ject model that comes complete with Pro-Ject's newest and most advanced tonearm, the 9cc Evolution.
This turntable has a number of unique features. Probably the most striking feature is the use of magnets to support the sub-chassis. Also, the sub-chassis is formed from Corian, a material manufactured by DuPont that is essentially inert to internal resonances. Pro-Ject developed these two advances through a series of rigorous listening tests. The Pro-Ject team was reportedly very pleased with the increase in fine dynamics and the decrease in distortion as a result of these two design choices.
The AC synchronous motor is decoupled from the sub chassis and comes fitted with a pulley that has two races - one for 33-1/3 rpm and the other for 45 rpm. The motor sits on a Sorbothane pad in its cutout in the plinth. An optional speed box is available that offers electronic speed control so you can fine-tune the speed and switch between 33-1/3 and 45 rpm without moving the belt. The 6-perspeX table is not compatible with 78 rpm. Pro-ject makes other tables that can accommodate 78 rpm. Please see their catalog if you need this capability for your record collection.
The 6 PerspeX table's plinth is acrylic. This material is known for its durability and impact resistance. Not coincidentally, Perspex is one of many trade names for acrylic plastic.
The inverted bearing uses a stainless steel spindle to hold the ceramic bearing. The bearing plate is also ceramic. Another ingenious use of a modern material involves the inclusion of Sorbothane in three key areas. First, the table's adjustable aluminum feet are Sorbothane-damped. Second, Sorbothane is used to dampen the tonearm counter weight. And the decoupled motor sits on a Sorbothane pad as mentioned earlier. The 4.4 lb (2kg) platter is made from MDF and topped with a 0.16" (4mm) layer of vinyl. The unit comes complete with a screw-down record clamp, a spirit level and a hinged dust cover.
The 9cc Evolution tonearm is Pro-Ject's newest and most advanced tonearm. It is available in three lengths 9", 10" and 12". The respective model numbers are the 9cc Evolution, the 10cc Evolution and the 12cc Evolution.
The 9cc Evolution tonearm here is said to direct unwanted resonances away from the headshell while allowing precise tracking of the record groove. It also facilitates fine adjustment of vertical and horizontal tracking angles.
The integrated headshell and armtube are made from a single piece of carbon fiber. This is a very good material choice for this application as it is lightweight and stiff. Plus, it looks very cool and modern. The armtube is conically shaped to avoid wave reflections. The bearings are ground to ABEC 7 tolerances and the large outside ring is open to avoid resonances. The counterweight shaft has been lowered to record level to reduce dynamic wow when playing warped records (this worked well in practice).
The arm shipped with two counterweights. All told, there are 4 available counterweights compatible with cartridges ranging from 5 – 14g. The effective arm mass is a mere 8g.
For this review, I fitted a Sumiko Blackbird Cartridge to the 9cc Evolution arm. This is a high output moving coil design in the Sumiko Reference Line of cartridges. The coils are hand-wound and each unit is hand calibrated through a rigorous and labor-intensive process. The Blackbird's rated output is 2.5mV into a standard 47k Ohm input. I found this cartridge sufficiently drove typical MM phono stages without a step up transformer. Sumiko's claim is that this provides the best possible signal to noise ratio for real-world systems.
The cantilever is made of a stiff long-grain Boron. This differs from the design choice of many others who feel that a ductile material is better for a cantilever. My intuition leads me to believe that a stiffer cantilever would better track the groove and transmit all the vibrations to the motor structure. The stylus is a very tiny elliptical diamond. The cantilever and stylus are not user-serviceable, but Sumiko offers a low cost re-tipping service in the event you need to replace the stylus due to wear or damage.
This cartridge does not have an external cartridge body. The omission of the external body eliminates one additional source of possible sympathetic vibrations in the mechanical structure of the cartridge. Be warned that this design choice leaves the stylus, cantilever and leads exposed to possible damage if you do not exercise the utmost caution in handling and installing this device.
Another design advantage with this cartridge is that it attaches to the headshell by way of tapped, threaded screw holes. This design choice means you don't need nuts to attach the cartridge. This reduces the effective mass even further. All told, this table, arm and cartridge system is designed as a suite of products that will work together to transmit unwanted vibrations through the arm and into the armboard with the least possible effects to the musical signal. Furthermore, the entire system also reduces wow & flutter, hum & rumble, lowers the noise floor and expands the effective frequency response.