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Linn Sondek DIY mods that work
Linn Sondek DIY mods that work
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Old 8th April 2015, 10:09 PM   #11
sreten is offline sreten  United Kingdom
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Join Date: Nov 2003
Location: Brighton UK
Hi,

I've modded lots of subchassis turntables. Linn's upgrade path
dissuades lot of owners veering off the straight and narrow.

YMMV but a Valhalla is hardly worth "upgrading" to an external
PSU with the the LVX arm fitted, your priorities are very wrong.
Arguably any external supply in an exercise in pointlessness.

Radical mods are exactly that, its no longer original, but
they are possible, it just won't be a LP12 anymore.

rgds, sreten.
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Old 8th April 2015, 10:17 PM   #12
andyr is offline andyr  Australia
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Join Date: Nov 2003
Location: Melbourne (Oz, not Florida!)
Quote:
Originally Posted by el donkey View Post

I still find it surprising there are no 'winning' diy mods after all these years? Ive removed the base board as this appears the only recommend action.
Hehe - here's my unique 'mod' for an LP12 ... which has definitely improved the sound which I had! So I sold my LP12 and Graham 2.2 arm and am a very happy chappie.

My 'SkeletaLinn'; it uses the following LP12 parts:
* Cirkus bearing / inner & outer platters
* springs & grommets
* motor & belt.

But no plinth and no top-plate.

The heart of it is a triangular 'chassis' made from aluminium U-channel. This sits on top of the 3 springs and, because the bearing and the arms are bolted to the chassis, it avoids the lossy connection which the standard pressed-steel chassis and armboard has - so delivering better low-level detail retrieval (just as the Keel does).

The motor is off-board - on a heavy, 3" brass 'pod' which acts as a vibration sink. With the 12" 'Univector' UP arm (made here in Melbourne - BTW a 9" one has just been fitted to a 'Keel'), it produced a significant increase in SQ over my LP12/G2.2.


Regards,

Andy
Attached Images
File Type: jpg SkeletaLinn v2 04.jpg (642.6 KB, 448 views)
File Type: jpg SkeletaLinn 016.jpg (268.0 KB, 429 views)
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Old 8th April 2015, 10:31 PM   #13
el donkey is offline el donkey  United Kingdom
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Join Date: Oct 2014
Quote:
Originally Posted by sreten View Post
Hi,


YMMV but a Valhalla is hardly worth "upgrading" to an external
PSU with the the LVX arm fitted, your priorities are very wrong.
Arguably any external supply in an exercise in pointlessness.

Radical mods are exactly that, its no longer original, but
they are possible, it just won't be a LP12 anymore.

rgds, sreten.
The Mose PSU will also be added with a new arm , the project 9cc which is the arm Linn now use.

Without the possibility to test every combination of possible updates I cannot claim this is the best path. Opinions vary greatly. The arm has cost me much less than an old ittok would. The PSU gets good feedback but the whole subject is as clear as mud.
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Old 8th April 2015, 10:39 PM   #14
el donkey is offline el donkey  United Kingdom
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Quote:
Originally Posted by andyr View Post

My 'SkeletaLinn'; it uses the following LP12 parts:
* Cirkus bearing / inner & outer platters
* springs & grommets
* motor & belt.


Regards,

Andy
clearly that was not an afternoons work
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Old 8th April 2015, 11:59 PM   #15
rayma is offline rayma  United States
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Quote:
Originally Posted by andyr View Post
The heart of it is a triangular 'chassis' made from aluminium U-channel.
Nice, can you post a dimensioned drawing of the chassis? I have an extra Linn that I'd like to do something with.
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Old 9th April 2015, 12:49 AM   #16
andyr is offline andyr  Australia
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Quote:
Originally Posted by el donkey View Post
The Mose PSU will also be added with a new arm , the project 9cc which is the arm Linn now use.

Without the possibility to test every combination of possible updates I cannot claim this is the best path. Opinions vary greatly. The arm has cost me much less than an old ittok would. The PSU gets good feedback but the whole subject is as clear as mud.
El d, the Mose/Hercules PSU is a good-sounding unit. There is also the Falcon/RoadRunner from the US. There is also (but not quite ready for Production status, yet!) the PSU which I am using on my SkeletaLinn (I bought a prototype unit). This is much more sophisticated than the others (and the Lingo!) because you can individually adjust:

* Hz, for platter speed (to 3dp).

* phase (to minimise motor vibration - to 3dp).

* voltage fed to the motor. This is a controversial issue but one which Steve Tuckett, the designer, and I have proven to be desirable (it flies directly in the face of the Lingo philosophy, where motor voltage is initially 110v - to kick start the motor - but then drops to 80v, to achieve minimum motor vibration). The Lingo has to do this because it doesn't have the capability to optimise phase (the optimal phase between the 2 pairs of Premotec motor wires is not exactly 90 deg!); once you can minimise motor vibration, the way is clear to increase motor voltage ... which increases torque ... which makes the music sound better! Steve's "Number9" speed controller can also independently control 2 motors ... a feature I am about to take advantage of, with my SkeletaLinn.


Regards,

Andy
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Old 9th April 2015, 01:11 AM   #17
andyr is offline andyr  Australia
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Join Date: Nov 2003
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Quote:
Originally Posted by el donkey View Post
clearly that was not an afternoons work
Haha - indeed El d!

I listened to the 12" Univector arm just before Christmas 2012 (mounted on an SME20) - and fell in love with it. So I spent most of my 3-week Christmas break trying to figure out how I could fit one to my LP12. It soon became obvious that I'd have to butcher the LP12, to do this ... which I wasn't prepared to do.

So I started sketching out a triangular chassis, which I decided would be made from bolted-together pieces of aluminium U-channel, 40x25x3mm (knowing that Linn had chosen ally for their Keel!), as this should produce a very stiff, light structure.

I then ordered the LP12 parts from a dealer in the UK and by June 2013 had v1 working - that's when I realised that it was a worthwhile result, so I began the process of breaking up my LP12 and selling the parts, individually.

Now, as with most things, v1 had a minor flaw ... just as with the LP12, one spring was more heavily weighted than the others! In the LP12's case, this is the spring nearest the arm; in my case, it was the spring nearest the platter. The solution was obvious - move this spring further away from the bearing ... however, calculating the right distance proved difficult. I eventually got some good advice from the Tweaks/DIY Forum on Audio Asylum (from an engineer who knew his trigonometry! ) and when a mate of mine agreed to buy v1 off me, for the cost of the parts, I started to build v2.

This was completed last October - the result (taking into account the weight of the 2 arms I have mounted on the chassis, as well as the weight of the platters & bearing) is that the weight distribution is 36% : 33% : 33%. So almost perfect - and better than what an LP12 achieves. (The heaviest weight is still on the spring nearest the bearing - I should've moved it out another 1/2".)


Regards,

Andy
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Old 9th April 2015, 01:15 AM   #18
andyr is offline andyr  Australia
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Quote:
Originally Posted by rayma View Post
Nice, can you post a dimensioned drawing of the chassis? I have an extra Linn that I'd like to do something with.
Glad to, rayma - but I'll email you instead. Please PM me your email address (there's more to it than just sending you a diagram which you can follow - after all, this is a personal project not a production dwg!).

Andy
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Old 9th April 2015, 07:56 AM   #19
el donkey is offline el donkey  United Kingdom
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The PSU is an interesting development also. So if you can figure a way to mount a strain gauge to the platter you can adjust your parameters to minimise the vibration. Anyone know of a suitable gauge? In a placeable housing With no inherent damping. Quite how you would wire it to a revolving platter is another question. Often thought of playing with one for stands and the like. But then the question arises are you detecting 'trapped' vibration or useful 'disapating' vibrations.
So is there no ideas to put this TT design into production?
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Old 9th April 2015, 09:18 AM   #20
sq225917 is offline sq225917  United Kingdom
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Just hold the motor In your hand while trimming phase to feel the lowest vibration setting.

A fully adjustable psu is the trick, then you can thick silicon oil in the bearing, which adds huge amounts of viscous drag to the platter rotation, this forces the motor to drive torque, which compresses the magnetic field, eliminates motor clogging and gives the most remarkable speed stability. But you do need to be able to trim speed exactly to compensate for what would otherwise be slightly slow running.

Here's the link to various pics of mine. It's a 50/50 lp12 Kuzma Stabi S hybrid.

https://flic.kr/s/aHsjz6rmuv
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