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.
Dewald calls his upgrades the Dewaudio Starmap and Startrail. Without giving too many details, what I saw on his turntable was the following:
- A base 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.
- 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 or below.
You can read TNT Audio's review as well as a review by the late Deon Schoeman of AVSA Magazine.