LP12 upgrade and setup secrets revealed

Secret No. 1 – Use great parts

Not for nothing do Linn work through improvements on the LP12. Over the years pretty much everything has seen some attention to improve the sound quality – of course it has to be commercial too, so there will always be room for 3rd party mods.

We generally use genuine Linn components – however there are three exceptions:

• The Revolution PSU from Vinyl Passion, which we think is excellent value for money for the Majik LP12 at £395.
• Our own-build arm cables, which are particularly good for Moving magnet cartridges including the Adikt at £300
• Some alternative cartridges from Ortofon, Lyra and MySonic.

All the other Secrets : – Attention to detail

There are wealth of hidden gems that one picks up over the years of building and setting up LP12s  some of these are described below as we upgrade and setup this customers LP12

  LP12 as it arrived with us  requiring Karousel bearing, Kore Subchassis, New motor,  New arm cable, and Trampolin base.

1st task is to check the arm bearings – balance it for zero tracking force and zero bias – it should swing smoothly across its range, and move vertically with a tiny (~1cm x 1cm) piece of paper dropped onto it. Then take the arm off and give it and the plinth a good clean. With the Adikt cartridge, it’s easy to remove the stylus to ensure nothing untoward happens to it.

  The old Baseplate is removed exposing sub-chassis, Lingo 1 connections and motor etc.
The Wiring strap, sub-chassis and motor are removed, ready for cleaning and new components

Next task here is to make the plinth and top-plate ready for the new goodies. Alignment of the spring support bolts is checked and adjusted to ensure they are true using Linn’s T-Bar spirit level

Spring bolt alignment

Each bolt is checked to be precisely at 90 degrees to the plinth – if it isn’t, the bolt is gently pulled in the appropriate direction and trueness checked again, both fore-and-aft as well as side-to-side. The T-Bar level is a bit of a sloppy fit so a balance between left right, for and aft gets it right.

Pictured here are the Old Cirkus sub-chassis and arm board compared to the new Kore sub-chassis with built-in armboard.  

The Karousel bearing is fitted and torqued up to the correct value (3.5Nm). Overtightening it will damage it. There has been a tendency on the past to massively over-tighten components in the LP12 – some things can take this (e.g. spring bolts) and some things not (Karousel bearing, arm board screws, wiring strap bolts etc).

Karousel fitting

  With the Karousel bearing installed in the combined  sub-chassis and armboard, this can now be fitted into the plinth with the springs and rubbers. The new motor is installed (check the motor bolts are in the correct opposing ends of the mounting slots on the top-plate)

We measure each spring as we find that the modulus varies slightly – the strongest spring wants to go closest to the Arm, the next strongest towards the front of the board, and the weakest furthest from the arm – this matches the loads on them. We find also that the springs also vary slightly in eccentricity – which is a good thing, as it allows you to align the lateral tension the spring gives, so the sum of the lateral forces coincide with the centre of gravity of the moving sub-chassis and components – this is checked with the bounce test (see later on).

 With the Wiring Strap, and Lingo connections installed, the assembly can be turned the right way up and the Arm collar installed in the correct place. Linn handily have an alignment tool (called the Kinky) which does this with little effort. The inner platter is temporarily gently slid into place after a few drops of Linn’s oil have been added to the bearing, then the Kinky tool is placed over the central spindle and into the arm collar. With the Kinky held snugly on the inner platter and gently tightened into the arm collar, the mounting screws for the arm collar can be tightened up (just enough so the anti-slip star washer bites firmly).

Tonearm alignment

The Tonearm can be slid into place and the grub-screw finger tightened. – With the outer platter in place, the screws on the spring support bolts are now adjusted so the floating sub-chassis and arm are level with the plinth. This needs a little to-and-fro with twisting the spring and rubber assembly around underneath, so the arm board sits evenly in the gap between the top plate and the plinth. We usually check the motor and drive belt alignment at this point: The outer platter is placed on the inner platter upside down – this allows you to see the track of the belt – it should run quite happily clear of the belt guide on the centre of the pulley. The tracking is adjusted by using the two screws either side of the motor to tilt it towards or away from the centre of the platter. This in turn governs the ride height of the drive belt and the speed the platter turns at (for fixed speed power supplies). The platter can then be replaced the right way up.

  Cartridge alignment

The cartridge alignment can now be checked with Linn’s alignment protractor – we never install the cartridge into the arm with it in situ – as it can put excessive strain on the bearings, so this is frequently an iterative process to get the stylus tracking the precise arc on the protractor whilst the offset angle is checked – The offset angle is checked on the grid on Linn’s protractor – we usually use a straight rule on the vertical flat of the cartridge for this, though it depends on the cartridge.

VTF & VTA adjustment

The next check is for the tracking weight, then the VTA (Vertical Tracking Angle – adjusted by the arm height) The aim is to get the arm parallel to the record surface whilst the cartridge is tracking at the correct weight (in the case of the Adikt ~1.7g). We use a tiny spirit level with the tracking weight wound down to compensate for the spirit level’s weight (see photo) and this makes it easy to get spot-on. The Tonearm grub screw can then be tightened to hold the arm firmly. If the tonearm has a scale on the counterweight or VTF spring – this is usually used as a guide only – we’ve found that these can be a bit out, and digital VTF scales can be a help here.

If there is no further need to invert the LP12, the inner platter can be removed and the bearing oil topped up  (this usually take a total of around 25 drops of oil for the Karousel (~40 for the Cirkus). We check it by wrapping some absorbent tissue around the bearing before lowering the inner platter in place – any excess is caught by the tissue and prevented from making a mess. When the inner platter is pulled out again, the oil level should be seen as a ring about 0.5 – 1cm from the top of the inner platter spindle, ensuring that there is oil on all of the bearing surfaces.

Speed adjustment

The speed is checked via the strobe lines on the alignment protractor, and Linn’s speed strobe slid into the back left lid support bracket. The aim is for to get greater than 10 seconds for one strobe line to pass under the guide – this is a speed accurate to >99.97%. For fixed speed power supplies like the Valhalla & Lingo 1 etc. the speed is adjusted by tilting the angle of the motor so the drive belt rides on a slightly different diameter part of the drive pulley. This is an iterative process requiring removing the outer platter, adjusting the screws (loosen the outer, tighten the inner to increase speed), then replacing the platter, and running the strobe again. NB if both screws are tightened too much it will bend the motor lugs and the whole motor will run too low.

Dynamic balance (bounce test)

With the platter running at the correct speed, and the tonearm and cartridge aligned, we turn our attention to the balance of the whole of the moving part of the Sub-chassis, Platters and Tonearm assembly. The arm cable, and earthing wire are checked and dressed, so that they don’t pull the sub-chassis and are adjusted as necessary. Another round of adjusting the support springs and rubbers gets the armboard to a pleasing alignment with the plinth, and bounce test is conducted – the platter is gently tapped between the spindle and tonearm to make the whole assembly gently bob up and down – this checks for free and unrestricted  movement, but also the alignment of the lateral forces from the springs. The aim is for the platter and armboard etc to bounce vertically, with no “jiggly”  lateral movement going on. This is another iterative process involving twisting the springs and rubbers under the plinth. It’s important to make sure the springs and rubbers are seated snugly in their natural positions otherwise when the LP12 is packed and transported to it’s working home, you’ll find the balance has shifted in transit.

NB it is very important not to have any mains power on the PSU at this point, as it is easy to accidentally touch “live” parts – particularly on a PSU like the valhalla – there are lethal voltages present which are easy to get your fingers on with the base removed and groping around for springs! – Been there, done that – lived to tell the tale and won’t do it again!

With some practice it is possible to get a balance between the spatial alignment of the armboard with the plinth, and the dynamic lateral movement of the whole. This can be very difficult if the springs are too different, too misaligned or indeed to perfectly matched and aligned (so twisting them with the rubbers around makes no difference). This process typically takes some time (up to 1/2 hour) to get right, but is worth the effort.

With the balance sorted, it’s time to go back to the speed and check that one last time, before fitting the Trampolin base. Depending on the vintage of your deck, and the arm cable fitted, it may be necessary to remove the cover plate which goes under the Tonearm to clear the arm cable connector. It’s important the earthing wire is dressed so it doesn’t foul the front spring, and the damping felts are stuck down – we stick them to the base plate all around, leaving small gaps around the screw positions.  Screwing the trampolin in place is another area where you don’t want to over-tighten the screws – at best it’ll mash the damping felt into nothingness, and at worst it’ll strip the wood out of the screw hole.

Listening test

Final job is a listening test – we do this for all turntables serviced, repaired or upgraded. It’s a chance for a complete once-over to see everything is working as it should,  to have a listen to check the connections are all good, and the turntable works silently and plays records effectively. We usually do a final VTF & Bias tune at this point listening for the sweet spot in the VTF range. We find all cartridges vary somewhat in production – The Adikt has a recommended range of between 1.5 and 2.0g – we mostly find these to be happier at slightly over 1.8g, but it varies. The new Linn Koil entry level Moving Coil cartridge has a recommended range of between 1.8 and 2.2g

The post LP12 upgrade and setup secrets revealed appeared first on HiFi Cinema.

Secret No. 1 – Use great parts Not for nothing do Linn work through improvements on the LP12. Over the years pretty much everything has seen some attention to improve the sound quality – of course it has to be commercial too, so there will always be room for 3rd party mods. We generally use […]

The post LP12 upgrade and setup secrets revealed appeared first on HiFi Cinema.