Linn claims that the Keel is an application of its “close-tolerance aluminium machining”, first seen in the ingot casing of the Sondek CD12 CD player. The Keel, along with the Ekos SE tonearm and Trampolin Mk.2 were three Special Edition upgrades for the turntable’s 33⅓ birthday, 33⅓ being the standard rotational speed when playing LPs. Serial Number Of Unit Reviewed: 10587. Keel: One-piece subchassis, tonearm board, and tonearm mounting collar for Linn LP12 turntable. Serial Number Of Unit Reviewed: N/A. Trampolin: Accessory base for Linn LP12 turntable. Serial Number Of Unit Reviewed: N/A. Approximate Number of Dealers: 40. Linn then reset the Ittok’s serial number sequence to 0001. The Ittok remained in production until September 1993. In its latter years it approached the performance of Linn’s top Ekos arm, an all-black affair launched in 1988. The gap in price between the Ittok and Ekos models had also closed up, leading Linn to consolidate its line-up.

The LINN Sondek LP12 is one of the best and most iconic turntable designs in audio. Here is a description of the upgrades and a potted history of its development. We also provide a list of the best upgrades to do and the order in which it makes the most sense to do them.

Introduction

The Sondek LP12 turntable, introduced in 1972, utilises a suspended sub-chassis design and a patented tight-tolerance single-point bearing. The LP12 has evolved since its introduction, but its basic suspended sub-chassis design has remained. At its launch the design was similar to the Ariston RD11 and the Thorens TD150, both in turn based on the Acoustic Research XA turntable that was launched in 1961.

The thinking at the time was that the most important component of a high-end audio system is the loudspeakers. Linn presented an important challenge to that by claiming that the source (i.e. the turntable) was the most important part of the system.

Ivor Tiefenbrun has talked about how Sondek derives from the word Soundex as each hi-fi design always ends up having its own unique identifiable and recognisable sound.

Early versions were a platform for mounting third party tone-arms, had a basic power supply arrangements, and would only revolve at 33⅓ rpm. Those users requiring a 45 rpm option would have to purchase a special adaptor to increase the diameter of the motor pulley and platter speed accordingly.

Throughout the years, there have been many changes resulting from development efforts to improve this table.

Evolution

The Sondek has evolved quite dramatically since it’s introduction. Customers have often asked us to clarify what these upgrades are and which of the makes the biggest difference to the performance. Here is a brief history of the upgrades and modifications, the most critical being those in bold.

Changes thereto are elaborated below. related serial numbers in square brackets^[

• 1972, LP12 turntable introduced.
• 1974, Main bearing liner changed. Sub-chassis strengthened by addition of strap, spot welded in place. Motor control circuit changed from terminal strip to small PCB. Mains switch changed from two buttons to single with mains neon. [s/n 2,000]
• 1978, Top plate modified adding two holes for 6 x 0.5 self tappers into wood block. The idea was to make the metal stop plate more rigid and to reduce resonance [23,000]
• 1979, Lid prop removed, hinges changed to spring loading. [27,000]
• 1981, February. Nirvana mechanical components, including new springs and bolts. [32,826]
• 1982, May. Valhalla crystal-driven electronic power supply made standard. This offered a significant improvement in performance and pitch stability. [38,794]
• 1984, Enlarged plinth corner bracing to make the chassis more structurally sound. [53,000]
• 1984, June. Sub-chassis strengthening bar epoxy glued instead of spot welded. Again this strengthened and reduced resonance in the sub-chassis. [54,101]
• 1985, August. Cap head screws on bearing housing. [60,383]
• 1985, September. Diode modification to Valhalla board [61,090]
• 1985, December. Strengthening blocks on corners of plinth.
• 1986, May. New clear lid.
• 1986, Suspension springs improved.
• 1987, March. New bearing housing, New Formica and MDF armboard. [69,161]
• 1987, April. New springs. [69,591]
• 1987, Bearing improved with better lining (black) material and tighter tolerances. Change to black oil. Suspension springs ground to improved tolerance. Arm board composition improved. [70,000]
• 1989, Motor thrust pad changed. Valhalla surge guard modification. PCB mains lead (UK). [79,700]
• 1989, New MDF armboard, laminated top and bottom. [79,160]
• 1989, Harder suspension grommets fitted to increase stability and reduce “drift”. [81,000]
• 1990, External Lingo power supply available as add-on. Lingo improved pitch accuracy and also added 45 rpm.
• 1991, motor thrust pad cap added to Lingo models. [87,047]
• 1991, Valhalla board prototype with 45RPM (never went into production) [87,047]
• 1991, motor thrust pad cap added to Valhalla models. [87,206]
• 1991, Introduction of LP12 Basik, a stripped down version of the turntable [87,672]
• 1991, Solid base board replaces hardboard. [87,672]
• 1991, Trampolin base board with isolating feet available as an option [87,672].
• 1992, Improved top plate fixing. [88,950]
• 1993, Cirkus upgrade (larger and better machined inner platter and new bearing, new springs, armboard, belt) fitted as standard. [90,582]
• 1997, a limited edition commemorative LP12 was created to mark the 25th anniversary of the LP12. Amongst other features, it bears a plaque etched with the signature of Linn’s founder Ivor Tiefenbrun.
• 2000, 4th bolt added near motor on top plate, fitted as standard. Required extra cross beam on plinth.
• 2001, New motor used (first new motor since original 1972).
• 2006 Keel The Keel upgrade to the LP12 is a replacement subchassis, machined from solid aluminium. It builds on the Cirkus upgrade (now fitted as standard to new LP12s) but is not included as standard in ‘regular’ production LP12s. Linn claims that the Keel is an application of its “close-tolerance aluminium machining”, first seen in the ingot casing of the Sondek CD12 CD player. The Keel, along with the Ekos SE tonearm and Trampolin Mk.2 were three Special Edition upgrades for the turntable’s 33⅓ birthday, 33⅓ being the standard rotational speed when playing LPs.
• 2002, Maple plinth introduced adding to existing black, walnut, rosewood and afromosia options.
• 2013, Full-spec limited-edition (40 in all) 40th anniversary LP12, plinth made from oak casks from Highland Park distillery, priced at £25,000. This turntable also featured the Radikal Power supply and the Urika phono stage mounted inside the turntable.

Dating a turntable

Dating a Sondek isn’t as easy as you might think. The serial number on the back will tell you when the turntable was manufactured but won’t give you any indication of what has been fitted to the turntable in terms of upgrades since it was purchased. Knowing this is vital in terms of the value of the turntable and what you might have to spend to upgrade it. If you are in any doubt you’ll need a LINN retailer to do this. We can gladly oblige.

Upgrading a Sondek

The most important component in the turntable is the turntable itself. What I mean is that the actual turntable has greater importance than the tone-arm and the cartridge. We call this the motor unit. A cheaper motor unit with a higher end tone-arm and cartridge will always sound inferior to a better motor unit with a more basic tone-arm and cartridge. There are many reasons for this but the most important is pitch accuracy and isolation from vibration and feedback. The Sondek LP12 has a floating sub-chassis to completely isolate the playback surfaces from vibration and extraneous noise.

As a result of this the motor unit upgrades make the most sense to someone with an older Sondek. Simplest and best of these upgrades are as follows;

• New Springs and grommets £10
• New belt and oil £20

Both of these are inexpensive and should be done as part of a service. A service will cost about £70.

Linn Ekos Serial Numbers Doreen

• Cirkus Bearing Kit £490 fitted

  The Cirkus upgrade to the LP12 focuses on bearing performance and the connection of the bearing housing to the sub-chassis. The improved bearing and stronger sub-chassis connection provides the turntable with greater stability and ensures the bearing sits perfectly true to the chassis of the turntable. This in turn minimises the risk of turntable platter movement with respect to the sub-chassis and arm. Even the slightest movement will introduce audible degradation to the reproduced signal. Together the changes to the bearing and the sub-chassis make an enormous difference to the overall performance of the turntable. The specific changes are as follows:

  1. The thickness of the bearing housing mounting flange has been substantially increased and undercuts eliminated to make it many times more rigid. This also allows the use of larger mounting bolts.

  2. Increased distance between top and bottom liners in the bearing housing to make it as stable as possible eliminating even the smallest amount of rocking

  3. An increase in the height of the bearing housing from the top of its inner liner to increase oil capacity, ensuring proper lubrication of the top bearing at all times.

  4. Double thickness sub-chassis to improve rigidity, reducing flexing and improving control of the relationship between key components The attached kit of parts, which includes a new inner platter and spindle, is supplied to fit this upgrade. As always with Linn product improvements, new LP12 turntables will incorporate this upgrade as standard. The Cirkus kit also includes new springs and grommets, a new belt and a new arm-board.

• Kore or Keel

Kore £750

The Kore sub-chassis and arm-board is designed for extra rigidity, and removal of unwanted damping, making it a perfect performance upgrade for your Sondek LP12 turntable. It follows the design philosophies of the Keel, but is more affordable.

The Kore sub-chassis is very rigid being a multilayer box construction using 1.5mm thick aluminium. The Kore is comprised of three parts that are bonded together using a special Linn-specified adhesive. This forms an incredibly stiff structure to which the armboard, machined from solid aluminium using a similar process to Keel, is then bonded.

The armboard has strengthening ribs machined onto its underside, again providing excellent stiffness and rigidity, thus the sub-chassis and armboard exhibit the properties of a single unit. The arm has a direct connection to the main bearing, as the arm collar is effectively bolted directly to the sub-chassis. With its innovative design and very importantly a price that is less than that of the Keel, we feel the Kore is a very exciting and important new addition to Linn’s range of upgrades for the LP12.

The Kore is available in four versions: For Linn arms and also for the Naim Aro, plus Rega and SME type mountings.

Keel £2450

The Keel sub-chassis upgrade is an ultra high quality machined single piece aluminium unit that replaces both the steel Cirkus sub-chassis and the arm-board, taking rigidity between bearing and arm to new levels.

Consequently the lossy interface between the steel sub-chassis and the armboard formerly achieved with three self tapping screws is removed. This connection between the steel sub-chassis and the original main bearing was essential in the days before the Cirkus bearing, as it acted as a filter limiting transmission of unwanted vibration and noise passing from the main bearing into the arm and cartridge. This is why if unknowing enthusiasts replaced these small screws, and the job that they were doing with larger ones, or worse still with bolts through the sub-chassis and arm board making the connection more solid, the effect was to degrade sound quality. This is due to the increased transmission of the noise that was being produced in the original design.

So, you can see that use of the Keel sub-chassis is only possible because of the improvements that were made with the Cirkus bearing.

Every design aspect that the Keel uses affects its overall sound quality. Features such as the detail in the webbing on its underside, to the three raised areas beneath the main bearing (lands) so as to ensure a consistent contact area between it and the main bearing, all come together to create dramatic sonic improvements. This combined with the integrated arm collar, thus eliminating the need to bolt one onto the sub-chassis with the small but consequent loss of integrity, mean that the Keel is a leading piece of audiophile engineering and design. The Keel for Linn arms is a complete and very well thought solution, which allows so much more information retrieval from your record collection.

Once these things are done (or you proceed as far along this path as funds allow) we can look at the power supply to the LP12.

Power supplies

The power supply has to feed the motor with a pure and consistent voltage. The problem is the mains is variable and if you supply a variable feed into a motor it will fluctuate and the turntable will lose pitch accuracy. Also the motor will vibrate as it functions and the vibration can transmit back into the playback loop and be passed into the system as distortion or mechanical noise.

The Valhalla was discontinued in 2004. We can however maintain and service this fine product for £65. In fact we service all power supplies as they age and the capicitors leak. We return them like new and the difference is often massive. We would also suggest very old decks have a new motor fitted. These cost about £95 and return the Sondek to its former glory.

We work with CLASS A on servicing

The current range of LINN power supplies is 3 models.

Linn Ekos Serial Numbers List

The first of these is the Basik power supply and this comes with the Majik LP12 which costs £380. This is like an improved Valhalla but built into the metal strap that fits across the Sondek chassis.

The Lingo has been through 3 incarnations in its life. The current version is the Lingo 3 which costs £1215

Finally the reference Power supply is the Radikal. This is LINN’s finest power supply.

Linn, after much research on the subject of DC motors for the LP12, released the Radikal in 2009. Immediately, the Radikal received huge praise and acclaim, as quite simply any LP12 upgraded with the Radikal, had an absolutely massive lift in sound quality. This was an improvement much larger than other upgrades such as tonearm, cartridge or even the sub-chassis.

No matter how well engineered, a synchronous AC motor does produce some degree of electromagnetic noise, which can cause pickup effects on the cartridge. Although there were other DC motor solutions available for the LP12, in our opinion they never really worked musically, and it is really only with Linn’s own Radikal power supply and motor that we believe you really hear what the LP12 is capable of!

Just as many owners were coming to terms with just how good the Radikal was, Linn found a way of improving its performance still further. The Dynamik power supply upgrade to the Radikal’s own power supply within its box was immediately introduced into Radikal production. Linn’s care and attention to existing LP12 owners was again amply demonstrated, as the Dynamik power upgrade was made available to all existing Radikal owners, thus allowing them to upgrade to the latest specification if they wish giving another leap in performance.

The Radikal is the best power supply for your LP12. There are two casework versions, the Akurate and the Klimax which is shown above. Both of which, are available in either black or silver to blend in cosmetically with your existing system.

Free Serial Numbers

Linn Ekos 2 Serial Number

To conclude

We hope this information has provided a helpful insight into the history of the Sondek LP12. If you own one of these fine turntables we would be happy to maintain and service it for you or to date it and suggest how to improve it should you wish. Bear in mind that this has always been an extremely fine record player and even old versions can sound extremely capable. If you do decide to progress and want some helpful and practical advice we will be only to happy to help. We have all the tools and have been servicing Linn turntables for 27 years.

Happy listening!