Sub-chassis and Suspension
The sub-chassis is the backbone of the LP12. It is the frame on which the main bearing and tonearm are mounted and it in turn is sprung-mounted on the top-plate to form the famous LP12 suspension. The original sub-chassis was formed from a single piece of sheet steel in the shape of a kite. Over the decades it has evolved a couple of times from being braced with additional pieces of shaped steel and later on being machined from billets of alloy.
The sub-chassis will to a great degree determine the sound signature of the LP12. The three springs that the sub-chassis rests on will determine how well the turntable mechanism is isolated from the top-plate with the vibrating motor. Setup of the springs and the classic "Linn bounce" is vital, and must be carried out by an expert. A setup frame or jig is required for such a setup procedure.
A worhwhile upgrade
One of our LP12 fundis, Dewald Visser, studied his LP12 and realised that there was tremendous potential to improve on the sub-chassis of older turntables. The diamond-shaped sub-chassis of the older units is made of pressed sheet steel. We know that Linn has addressed this with their later models. The problem is that this is prohibitively expensive in South Africa, due to the exchange rate.
Startrail Sub Chassis
Two things are critical for a LP12 sub-chassis: rigidity and light mass. Dewaudio's Startrail offers both. Coupled with the Startrail armboard, also made of aluminium and devoid of any extra weight, you have a formiddable subchassis system.
Starmap Bottom Plate
This is not meant to be a hardware review, but the Dewaudio Starmap bottom plate has really made a big difference for me. Structurally it strengthens the plinth as it has quite a number of connection points around the plinth. It also allows easier access to the suspension springs and the tonearm cable. In addition, it offers more airflow and heat dissipation. Lastly the feet are height-adjustable. Sonically it has cleared up the slightly muddled sound older Sondeks are known for. There is an improved sense of space. It has been worth every cent.
The full kit
Dewald calls his upgrades the Dewaudio Starmap and Startrail. Without giving too many details, what I saw on his turntable was the following:
- A bottom plate in black with access to the three suspension springs and nuts, and the tonearm cable. This allows the suspension to be levelled without removing the base, and also to remove the tonearm's cable. In addition, it allows for better ventilation than the standard board. This is important for turntables with Valhalla power supplies which tend to generate a lot of heat. The bottom base plate also strengthens the plinth and improves the structural integrity.
- A new suspension, which includes the main sub-chassis as well as a new armboard to match.
- New springs, nuts, bolts, and grommets.
- A new top plate, available in black or silver.
I did not have enough time to spend with the turntable to assess the effect that the new components have. However, another LP12 owner has had all of these components installed and he claims a dramatically reduced noisefloor. Less noise is always a good thing.
You can have a look at the installation process here.
You can read TNT Audio's review as well as a review by the late Deon Schoeman of AVSA Magazine.