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macfan

LP12 Radikal Problem - Redux

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This subject appears like it might be controversial so my apologies in advance.

I was reading an excellent thread on another forum on the LP12 Radikal problem. It is quite a rabbit hole and ThomasOK had many insightful entries along with lejonklou and many others. I see the ThomasOK posts here and was hoping to get some clarification on the findings. For those that have not read the thread, the short version is the height of the Radikal motor could rest on the lip of the left rear foot of a Trampolin which apparently can result in significant sonic degradation. 

Questions:

1. Does the problem exist on Trampolin 2 or just the Trampolin 2 with the Urika / Urika 2 phono stage?

2. Is it correct to say the problem is the Radikal motor assembly comming in contact with the lip of the left back foot - introducing the issue.

3. It appears that a plinth with a height of < 65mm could encounter the issue when a Radikal and Trampolin 2 are introduced. For example, ThomasOK cited a customer's cocobolo plinth from Chris Harban that measured 68mm and was out of range where the problem would be encountered. Is there a a plinth height where we know the problem will not occur? Reading the other thread it seems the value could be around 66mm or 67mm.  

4. If one has a solid flat surface to place the LP12 would you elect to use the solid base with fixed feet in lieu of the Trampolin?

5. Does anyone think the Radikal motor assembly could have variability in its height? 

6. Does adding the weight of a vinyl record deflect the suspension enough where the motor could come in contact with the lip only when a record is on the platter? 

I am in the process of getting a new LP12 and have chose a Radikal Akurate and was going to do the Trampolin then read the thread about potential issues. BTW, I am using a Harban plinth and reached out to Chris who told me I should not have any issue as the height has been compensated for. However, I thought this could be. worthwhile discussion.

If it is allowed I can post the link to the other forum but did not want to break any rules.

Thanks -

macfan

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Posted (edited)

I have LP12 with Urika II, Radikal & Trampolin 2. It was set up by Peter Swain of Cymbiosis who checked it all very carefully and none of these problems exist on my LP12 even with a standard Linn plinth. Since moving to Urika II I’m totally amazed at the sound quality, it was good before, but I now have no thoughts of changing anything on my deck. It sounds wonderful to me. I know several fellow music fans who have LP12s and none have experienced these issues. 

So unless you’re very unlucky then I don’t think you’ll have any problem at all. 

I have looked at Lejonklou forum, but won’t be revisiting it as I found it eccentric rather than useful. I like Linn & Chord Electronics kit because it is fuss free. Once your LP12 is set up in your home by your dealer then it should simply be a case of playing and enjoying your records. 

Edited by Nestor Turton

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AFAIK, it’s the Radikal motor housing (potentially) coming into contact with one of the screw heads and not the lip of the foot. If this occurs, then it is a simple operation for the dealer to grind off the head of the screw - the threaded shaft remains in place so the fixing isn’t comprised to any great extent. I understand that recent Trampolins have had the orientation of that foot changed to avoid the issue anyway.

’troll

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Posted (edited)

I have an LP12 with Radikal, and Urika II ( Trampolin before that). I have no problems with interference. I did measure my plinth after reading the thread on the old Linn forum to which you referred. All was good.

Addressing your item 4, the Trampolin is a worthwhile sonic upgrade. It will clean up the upper bass a bit. It's such a good value.

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Edited by akamatsu
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Hello,  Sorry it has taken me a while to reply to this but I was out with health problems for a week and a half and then spent the second half of last week displaying with Fredrik Lejonklou at Axpona Hi-Fi show in Chicago.

To start I'll answer the questions, then elaborate.

Questions:

1. Does the problem exist on Trampolin 2 or just the Trampolin 2 with the Urika / Urika 2 phono stage?

It occurs with any Trampolin, whether or not a Urika is attached.

2. Is it correct to say the problem is the Radikal motor assembly comming in contact with the lip of the left back foot - introducing the issue.

Yes it is.  It is true that early Trampolin 2s had a more severe problem with a screw sticking up there, which most dealers learned to deal with by grinding it down.  But Linn fixed that by rotating the placement of the screws 45° so they are no longer in the way.  But the problem with contact of the rim of the foot persists.

3. It appears that a plinth with a height of < 65mm could encounter the issue when a Radikal and Trampolin 2 are introduced. For example, ThomasOK cited a customer's cocobolo plinth from Chris Harban that measured 68mm and was out of range where the problem would be encountered. Is there a a plinth height where we know the problem will not occur? Reading the other thread it seems the value could be around 66mm or 67mm.  

I would say that anything 66mm or over you are safe.  Every 65mm or lower plinth (there are several 64.5mm units out there from Linn and some early Harban units) has had the problem except one.  65.5 is hard to say.  I would recommend testing any plinth under 66mm to be sure.  There are not only small variances in the height of plinths, including Linn - most of which are 65mm, but there are slight variances in how deeply the rebate is cut for the Trampolin to fit into.  This is why it is best to test if unsure.  The paper test detailed on the Lejonklou forum is a simple and effective way to find if there is a problem.

4. If one has a solid flat surface to place the LP12 would you elect to use the solid base with fixed feet in lieu of the Trampolin?

I have found the Trampolin 2 to have a musical benefit, mostly in terms of bass tunefulness but it is audible well up into the midrange, on virtually any surface with the likely exception of Mana supports.  I have not had much direct experience with Mana as they were not as popular on this side of the pond, but I have read so many Mana owners stating that the Trampolin 2 doesn't work for them that I accept this is the case.  But whether on a heavy piece furniture (which it was designed for) or on the best turntable stands and wall shelves I have always found the Trampolin 2 more musical.

5. Does anyone think the Radikal motor assembly could have variability in its height? 

That is highly unlikely because of the way it is made, being custom machined by Linn.  Unless Linn has made a running change to newer units that they haven't mentioned.  I have not installed a new Radikal recently so I don't know if it has changed in the recent past.

6. Does adding the weight of a vinyl record deflect the suspension enough where the motor could come in contact with the lip only when a record is on the platter? 

No, the weight of a a record or even a record weight (which I do not recommend) should not make a difference here as that weight will be absorbed by the suspension and could make nothing more than the most minuscule difference in the spacing of the motor attached to the top plate and the Trampolin.

 

As to whether this is a real concern, I can only state as I have here and on other forums,  that my experience so far is that slightly more than 50% of LP12s with a Radikal and Trampolin2/Urika have had the problem.  This ratio has been found by others who are checking for it.  Every person I have done this for has noticed a significant musical improvement.  One of the big problems is that a Radikal is such a big musical improvement itself that you are likely not to notice the problem unless you hear another virtually identical table that doesn't have it.  If you want to bury your head in the sand, be my guest.  But considering a simple test and relatively simple and very inexpensive fix (which I have been doing for all my customers for free) can give you a more natural sense of timing and musicality, particularly in the bass, I can't see the sense in not checking for it.  As long as your dealer is aware of the concern and does check for it you should be fine.

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ThomasOK: Thanks for the detailed reply. My Linn dealer and I reviewed all of this and will be paying attention during the build. We would not have known about the issue without the informative threads. Also, I spoke to Chris H. and he has assured me we will not run into the height issue during the build. The plan is to stick with the Trampolin 2 until we encounter the issue and can not correct it with all the offered solutions. 

 The build is esentially a Akurate with a Radikal Akurate motor and a custom Chris Harban plinth. 

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Yes, if it is a newer Woodsong plinth you shouldn't have a problem.  Chris recognized the problem of the tall Radikal motor early on and started making his plinths slightly taller to compensate.  Some of his earlier ones do need the mod, however.

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I'm having my Radikal fitted next week (1984 fluted plinth). Will check if my dealer is aware of this issue. I have a Trampolin 2 from January 2018. What are my options? I really wanna keep the Trampolin 2 because it  vastly improved musicality. What are dealers advised to do? Change to a new plinth?

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Changing to a new plinth will not necessarily help as even current Linn LP12 plinths may be short enough to cause this problem.  There is a relatively easy fix, and other possibilities have been mentioned too.  This thread on the Lejonklou forum covers it quite well:

https://www.lejonklou.com/forum/viewtopic.php?f=3&t=4147

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Posted (edited)

Just as an aside on this one.

In addition  to variations in plinth height & rebate dimensions , there is a further small variable that may in some cases make the vital difference between a motor fouling the Trampolin foot and  not.

That being the topography of the individual top plate .   Although consistency has improved over the years,  top plates do not sit 100% flat  in the same plane as the top of the plinth  [even near the motor corner ] , with some maintaining  more of  a slight arch or domed profile than others .

This itself can also be due to small variations in plinth  dimensions [in this case width and front to back depth  ] but is also dependent  on the pre-tensioning of the individual top plate prior to fitting .

I further suspect that on some occasions the cause or a factor may be  over tightening the motor corner top plate bolt , thus pulling the top plate lower in the vicinity of the motor .  [Too many folks still forget that this bolt is there only to ensure that the edge of the top plate sits in good rattle free  contact with the plinth in that vital motor corner area....and only needs nipping up accordingly ]

Edited by Smokestack
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I doubt over-tightening the rear bolt would have much effect.  If you do that it first pushes up the corner brace and then snaps the stud off if taken too far.  But the height of the wood strips that the top plate sits on can vary a bit from plinth to plinth.  This causes the top plate to sit lower or higher compared to the top of the plinth, which would certainly have a bearing on the problem.  As mentioned in the link, the paper test is the most effective way to know if there is something that needs to be addressed.

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Posted (edited)

You probably  see far more [and far newer] decks than I do these days Thomas ...but in my experience down the years, the "topography" of top plates certainly varies by enough to influence this issue if its a close call   . And we're only talking about the thickness of a couple of  sheets of  paper as the difference between having a problem or not.

I also suspect that over torqueing the top plate stud would  produce a deflection of a mm or so in the plate before any disturbance to the very secure & strong plywood corner brace or causing  the stud itself to break free.

May have to agree to differ on this one Thomas :D 

Edited by Smokestack
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This isn't a big problem like some make out.

A Swedish bloke on the green forum seems to have a agenda with this subject

posting again and again every chance he gets even said its the reason why Linn closed its forum.

Thats complete rubbish.

He also even used a RIP thread to mention it again which was really bad form.

I had one of the first Radikals fitted when it was released and never had a problem.

I know loads of people with Radikals and the only problem they've had is there records sounding to good.

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It's like any issue affecting a few people ..

..the amount of flak flying around  gives the impression  that its a far more common problem than it actually is.

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Posted (edited)

The guy obviously has an agenda obsession to rubbish one manufacturer against another.

it's not rocket science for a good fettler to check for fouling with without strips of paper or otherwise.

How many decks out there.?

Just think about the old wheeltappers they know how to check. 9_9

Edited by Mr Kandid
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