Linn Bedrok LP12 Plinth Upgrade

@lewm 

Don't you see the irony that you make that 149th comment as someone who doesn't even own an LP12.

The most precise manufacturing tolerance I ever encountered was the extremely tight shaft and bearing of my Thorens TD124.

You attach the shaft on the bottom of the 4.5kg (9.9lbs) cast iron platter, place it in the bearing, it takes several minutes for over 10lbs to fully lower, the air has to escape, push it, it is like an air spring, it bounces back. I will never forget the 1st time I put it back in and experienced that heavy platter floating on trapped air.

The many parts of it’s SME 3009 II Tonearm are such that required movement is easy yet impressively tight

I watched this video showing the assembly of Linn’s TT in a Bedrock Plinth, and I was quite surprised at the looseness of parts, at minute 5, the platter/shaft drops into the bearing, finishing with a clink or clunk, it happens twice and then, the tonearm post goes into the mount like a truck driving thru the Holland Tunnel at minute 6.

The Bedrock’s best feature seems to be captive threaded inserts to fasten the top and bottom metal plates, you can see it’s just an edge frame with corner blocks, not really a plinth in my thinking.

https://www.youtube.com/watch?v=SqP4eHBSlI4&t=2s

I was/am shocked to see the lack of precision, I always assumed fine manufacturing tolerances were part of Linn’s success.

That TD124/SME 3009 II combo combined with the V15VxMR microridge on beryllium produced the most impressive, tightest bass I ever experienced (tracking at only 1.0g). I’ve never forgotten or experienced it since having to part with it because it’s bearing was too succeptible to vertical movement from my springy wood floors.

I always felt quite certain it was due to ALL groove modulation being transferred to the cartridge, none escaping thru movement in the arm and TT. I have to believe that cannot be possible with the loose platter shaft and tonearm post seen in that video.

@elliottbnewcombjr The new Karousel bearing is reportedly machined to within 5 microns ( is that a lack of precision???). What do you believe your Thorens bearing is machined to?

BTW, you do realize that your SME example relies on a knife edge bearing and all that it brings?

newton-john. Of course I see the irony. Which is why I posted.  But the title of the thread indicates that the Bedrock is the subject, which, unless I missed something, you also do not own. We have that much in common. Anyway, I hope you know I bear no ill will toward the LP12 or the Bedrock. I originally commented in order to clarify for myself what the Bedrock is made of and how it is fashioned. Our of curiosity. My own preferences in TTs are pretty much the opposite of an LP12.

@lewm  I just took a look at your system. Nice. Have you had the opportunity of hearing what a new LP12 Akurate or Klimax model would be like in your system? 

I suspect you might be pleasantly surprised. 

@lewm

Since you mention the title of this thread, it is in full “Linn Bedrok LP12 Plinth Upgrade.”

It’s about a potential upgrade for a turntable that I own and you don’t.

Not much point in you considering the upgrade if you don’t have the turntable.

Incidentally, if you were to take up Davey’s suggestion, the Bedrok would be worthy of consideration.

The Majik LP12 with Bedrok could be an alternative to the Akurate, now Selekt LP12 or even the Klimax LP12. At least one dealer is offering a dem of all three configurations side by side.

I plumped for a second hand Klimax last year before the Bedrok became available. Maybe, I’d choose differently now.

watch the video

https://www.youtube.com/watch?v=SqP4eHBSlI4&t=2s

minute 5, the shaft simply drops into the bearing with no resistance

clunk

he removes it, adds a few drops of oil, it simply drops in again

clunk again.

There is no way in the world that that can be considered fine tolerances. and what makes the clunk noise? shouldn't it be zero contact floating on oil?

minute 6, drop the tonearm post in the mount indicates no close fit either.

I guess this thread should be a discussion only including LP12 owners, who also do not own the Bedrock. 

@lewm 

Not at all. Feel free to comment as much as you want. But expect what you say to be challenged occasionally. 

@elliottbnewcombjr  I have seen the video you posted and others that are more complete. The bearing is precise without having to be a tight fit! Remember, the bearing point is what the whole shaft rotates from. The bearing point is diamond hardened. Please do a little more research.

@elliottbnewcombjr

l have to agree totally with your deductions……l think the subject of tolerances in the shaft is critical for turntable stability.

l had a Thorens TD124 and experienced your claims for the very tight fit while ‘seating’ the shaft onto the bearing thrust pad.
My later table and my much loved classic period table of all time, the Logic DM101 Electronic is even closer in machined tolerance than the Thorens. After an oil change of ‘Gold Oil’ Mobil Velocite No.6, (l believe the Linn recommended oil) the time it takes the shaft to settle is about 10 minutes to displace the trapped air. I try to speed the seating process up with intermittent manual revolutions of the platter.

Vertical and horizontal tolerances in the bearing and shaft are just as critical as that found in a well designed tonearm.

l can’t believe there are suggestions made on this thread that the shaft tolerance is not important….that statement has to be plain nonsence! Without such a tight seat the platter shaft would slightly oscillate like a demented flag pole in the wind.

mylogic

Until you personally experience waiting SEVERAL MINUTES for a very heavy platter to drop into it’s bearing well, you cannot imagine how impressive it is. You mentioned 10 minutes, I am remembering around 6 minutes, just walk away, come back after a while.

I just jumped about learning a bit about the DM101 (I never saw or heard one), it seems it’s bearing, similar fine tolerances to the Thorens TD124 is the key to it’s following, I saw many comments about the springs, center spring, tweaking springs ..... but in all cases it’s the bearing that allows it’s superior bass performance.

I always assumed Linn had similar tight manufacturing tolerances, I remain shocked by what I saw in that video, and still wonder what made the clunk each time it was dropped into the bearing well?

It seems, from comments, the DM101 bottom thrust bearing was less susceptible to vertical movement than the TD124, or those vertical vibrations were curtailed by the softer spring suspension, as opposed to the firmer density rubber mushrooms Thorens used (I had installed new OEM mushrooms),

I built a skirt surround base like the Bedrock, with a continuous ledge (rather than Bedrock’s 4 corner blocks) with a continuous layer of foam supporting a top board cutout for the TD124, reduced but still didn’t solve the problem.

An old discussion here, just over 20 years ago

https://forum.audiogon.com/discussions/anyone-using-a-logic-turntable

simple search results 'dm101'

davey, Thank you for complimenting my system.  I presume you refer to the Sound Lab-based system.  As you may know, I also have a pair of fully functional Beveridge 2SW speakers in my second system, augmented below 80Hz by a pair of TL woofers I built myself.  I feel like a parent to both systems, and I love them both equally but for different strengths. 15-20 years ago, I got interested in vintage DD turntables, in part because the best ones are rare to find and collectible, and in part because I wanted to get away from belt drive turntables.  Along the way since then I also picked up a Lenco idler and modified it extensively. I am quite happy enough with what I have. My first real TT was an AR XA, back in the 70s.  Since then I have owned a Thorens TD125, a Transcriptors Reference (not super good but extremely fun to watch), a SOTA Star Sapphire Series III, and finally just brefore the DD conversion, a Hyperspace, which only became excellent after the addition of an outboard motor controller. My experience with the latter TT showed me that my Sapphire was not very good in several aspects, smearing piano decay and conveying vocalsl. Maybe there was something wrong with it. In any case, I have sworn off belt drives and especially spring-suspended belt drives. On the other hand, one of the finest TTs I have ever heard was my neighbor's Dohmann Helix. Go figure. So, while I am staying away from springs, I am quite impressed with the Minus K platform built into the Dohmann. Also, I heard an LP12 serving a system at the RMAF many years ago, and it seemed to be quite good. I got involved on this thread only because I was curious about the materials used to create the Bedrock and why it had to cost so much. I re-plinthed or heavily modified the original plinth for all of my DD TTs, except the Kenwood L07D.  So plinth materials is a subject that interests me.

@lewm I agree, plinth material is an interesting subject. I recently changed out my original Afro fluted plinth from the 80’s for a new Linn Oak plinth with the various mods like the corner bracing etc., the new plinth has two benefits for me: One is that it is much more aesthetically pleasing and two, it does sound slightly better. The Afro plinth was the last piece remaining from my original 80’s era LP12.

The new Bedrok plinth does not look as aesthetically pleasing to my eyes, but i can see why the extra rigidity would be beneficial. Only issue is the price asked, which I frankly think is way over the top. ( Due partly I believe to the fact that Linn are outsourcing this part).

Until you personally experience waiting SEVERAL MINUTES for a very heavy platter to drop into it’s bearing well, you cannot imagine how impressive it is. 

Its not that impressive to me.

My TT has a 26kg platter and it takes about 3-4 hours to seat, including constantly hand spiinning the platter when replacing the oil for that time - and it's an inverted bearing.

Check out the Vertere TT - you can turn the bearing upside down and the spindle will not come out.

@dover

You are talking about newer more refined engineering with your Vertere and years more thought in engineering so l would expect that too.

@elliottbnewcombjr was talking about a 50 year old Thorens TT that cost probably £150 or even less back then, so a comparison is not really a big deal here.

To Elliot…..

The unique six spring suspension (not compression), massive plinth and over engineered 8mm sub-chassis were always the reasons for the bass response in the Logic. No matter which MK model owned with or without the centre spring mod for heavier arms, the models were notably oblivious to footfall and vibrational feed back. The ‘secret’ is the configuration of the 6 spring suspension.

The bearing was also well engineered for its period and noted in reviews at the time. The three point six spring suspension as far as l know has never been used on any other TT. The DM101 beast is built like a tank.

dover

I’ve never seen any Vertere model, that kind of precision is beyond impressive, it’s downright scary.

The fit of the posts of the SME, Acos Lustre, JVC-Victor tonearms are all similar: snug, mated, properly aligned while making refined adjustments.

My 12.5" long tonearm from Russia, the post is not tightly fit, goes into it’s base plate very easily, like the Linn arm does in that video. They think it’s ok if it’s held in place by a set screw. I had them modify the base for 2 set screws (enhanced inconvenience, eh), and I added a layer of very thin tape around the post, a much finer fit, stays aligned while adjusting it’s height (with it’s built-in micrometer which is a nice feature).

@elliottbnewcombjr 

Just an after thought.

Logic had Syrinx manufacture their mounted tonearms originally but later developed their own Datum II and the highly regarded Datum IIS. I have known people who have bought a turntable just to lay their hands on a rare Datum IIS

mylogic

I found the Datum II and IIs silver wire version, it appears they changed the mount from a threaded post and nut below deck to a Jelco Type surface mounted 3 screw base plate, am I correct about that? I prefer removable headshells. They do not mention it, but I think I read that the Datum II and IIS includes azimuth adjustment at the end of the arm, I see what look like 2 screws

I just mounted my new to me Vintage JVC Victor UA-7082 11-1/8" long arm. It's counterweight section's rubber isolation sag was properly repaired. The anti-skate adjustment is the smoothest I ever encountered, like the Acos Lustre GST-801 it is easy to adjust while playing/listening, although I prefer setting it while lowered onto the smooth side of my alignment disc

. After releasing the JVC height locking ring, then you can place the stylus and adjust the height while playing, however final locking is a two handed job, not while playing.

My Acos Lustre GST-801 which I learned about here is my favorite arm, easy to release/adjust/lock everything while playing: height/tracking force/anti-skate. I use an AT headshell with azimuth adjustment. I wish they made a long version of it.

I just noticed, the Logic Datum II looks to have a very compact/short length counter-weight section, it might fit on the left side where my Mission/Jelco 774 is, I will need the measurement from pivot to the rear end, and I need to double check the overall height for clearance when the dust cover is on

This still shows the 12.5" blackbird arm, I removed it, spun the armboard around 180 degrees, and used the original hole that the 45 adapter is show in, where the original 7082 arm was.

Alignment LP, one side smooth for observing/setting anti-skate

@elliottbnewcombjr

Datum II & IIs

The Datum I was manufactured by Syrinx and up to that point had threaded posts and nuts to mount.

Logic aquired Syrinx and made in house the Datum II & IIs with the three point mounting collar. They mounted both Datum’s on their DM101 and Logic Tempo turntables.

Mounting hole 30.5mm

Effective length 228mm

Pivot to spindle 210.7mm

Overhang 17.3mm

Azimuth is adjustable by two bolts.

You are correct the counter balance is very up close to the pivot due to the tungston counter weight.

All of the Syrinx arms…LE1, up to the Datum I had the same measurements and these were carried over to the Logic produced Datum II & IIs

One thing to note is that when Logic folded the companies stock was bought by Manticore Systems Engineering. Their well liked Mantra turntable was a leading model in the UK. The later Datum IIs arms were modified to their new specs under the MSE logo which appears on the arm pivot. Superior bearings and improved external finishing also cured the anodising effect of UV in earlier models.

A Datum IIs with the silver wire was considered better than the Linn Ittok LV3 Mk2 and considerably less expensive. The Datum I, Syrinx PU2 and PU3 models were claimed by some to be ‘’Ittok Killers’’ within their individual timeframes.

Search the ‘’Vinyl Engine’’ archives further to confirm this information if you wish. l own a few Syrinx arms so l am sure l have given you the correct info.

watch the video

https://www.youtube.com/watch?v=SqP4eHBSlI4&t=2s

minute 5, the shaft simply drops into the bearing with no resistance

clunk

he removes it, adds a few drops of oil, it simply drops in again

clunk again.

There is no way in the world that that can be considered fine tolerances. and what makes the clunk noise? shouldn't it be zero contact floating on oil?

minute 6, drop the tonearm post in the mount indicates no close fit either.

This video is shocking. The guy has no idea of how to put a turntable together.

Not only is the bearing housing and shaft as loose as a goose,

 he puts no oil on the spindle before insertion.

In tight tolerance bearings you always smear oil around the spindle before insertion to avoid scouring when inserting.

Unbelievable - and the video reminds me of what a rube Goldberg contraption the Linn is along with the low tech bearing and motor the size of a weenie.

@dover

The guy is Gordon Inch at Linn. I found him to be very approachable.

He’ll no doubt be interested to hear your views on turntable set up.

https://www.facebook.com/share/1Bx1f5zKML/

Let me know how you get on.

@newton_john Tonight I asked a well respected mechanical engineer if the Linn bearing that Dover and others claims is not put together accurately, is in fact that. The gentleman told me that clearly the folks denigrating the Linn bearing design really do not understand how this particular Linn bearing functions.

Dover and the other naysayers clearly have a lot to discover...as you are pointing out.LOL.

@daveyf

Thank you.

In the days before social media, we used to think every village only had one idiot.

@daveyf 

It's basic engineering - you always put a smear of oil on both parts - housing and spindle to avoid scoring. If you rewatch the video when he first puts the spindle in the first time ( with no oil on the spindle ) he puts it in on an angle - scraping the top of the bearing housing.

I rewatched the video - few other items of concern

He drops the tonearm with delicate bearings straight onto the hard surface of the table - you can hear it clunk as he clumsily puts it down. I always place arms on soft pads to protect them.

Then he checks the vertical tracking force with the arm out of level. Most folk on this forum know that the tracking force will change when the vta is altered.

He should be checking the tracking force when the arm is level.

I also notice that when he checks the tracking force he manages to drop the lid and send it across the deck and almost wipes out the cantilever.

If this is the top Linn guy so be it.

Oh and he reckons the Linn should bounce evenly in a "pistonic" motion.

but of course it doesn't - watch the video - when he bounces the platter the side the tonearm sits on bounces much more ( the motion is higher and lower )than the other side - the whole thing is bouncing sideways, certainly not evenly let alone pistonic.

No If I spent $60k on a turntable I would not want that guy touching it.

YouTube video.

I felt l just had to watch this YouTube video after reading all this malarkey.

l will not get into a slanging match over what l observed, but it does appear to be a very lacklustre attempt to prove one thing or another that has obviously left more unanswered answers than it answers. As a tool for assembling this very expensive tonearm and deck it is very amateurish and unprofessional.

Recording and editing looks very rushed and calls into question why Linn signed this off. Quality control was thrown to the wind and appears quite comical. Everything looks like a ‘first take’ with no retakes.

Whoever oversaw the filming should maybe take note as the feedback just on this site alone can make them question if this YouTube link could be removed and recorded again. For this viewer it did not aspire much confidence in the senior engineer, and the production and can arguably damage the reputation of the brand.

@newton_john indeed, there are folks on this thread who assume a lot about the Linn table, you know what they say about folks who ‘assume’ things.

@dover My discussions with the mechanical engineer was in reference to the bearing, since you stated the shaft in the bearing would be “ as loose as a goose”.

This told me and was confirmed by the mechanical engineer that you really did not comprehend how the Karousel bearing functions.
As to the setup of the tonearm, I might agree with you, somewhat. The Ekos SE has very limited set up adjustments, one of the issues I see with that arm.

Where did you see the part where you say the lid is dropped? I did not see that in the video, nor did I see the part where you say he drops the tonearm carelessly onto the table..!!

On side one, or side two……

Everyone will be in one camp or another. I wonder if anyone’s opinion has changed? But harken…..l can see the light through yonder window glow to stop this discussion from turning very dark…..like the old foreboding ‘Darkest Africa’ expression in the 19th Century, l suggest a change to a lighter note.

Memories of, ‘’’Dr. Linninstone l presume?’’

Now how about an LP12 on a granite plinth……that would be less expensive. Anyone had the courage to try it?

l hear the sound…….of distant drums……far away……farrrr away. .Jim Reeves.

Since all you guys love Linn Products and the LP12 so much, I am sure you’ll want to wish Ivor Tiefenbrun a happy 79th birthday. Here is a little bit on him that I lifted from Facebook.

“Born on March 18, 1946, Tiefenbrun founded Linn in Glasgow, Scotland, in 1972. Linn’s first product was the iconic “Sondek” LP12 turntable which is still in production today. The LP12 challenged the prevailing belief that loudspeakers were the most critical component in an audio system. Tiefenbrun emphasized the importance of the source, asserting that a high-quality turntable was essential for accurate music playback.

Under his leadership, Linn Products expanded its product line to include a range of audio equipment, from loudspeakers to digital music systems. Tiefenbrun’s commitment to precision engineering and innovation has earned Linn Products a reputation for excellence and reliability. His dedication to pushing the boundaries of audio technology has garnered a loyal following among audiophiles worldwide.

In recognition of his contributions, Tiefenbrun was appointed a Member of the Order of the British Empire (MBE) in 1992. His legacy is one of relentless pursuit of perfection, a passion for music, and a commitment to delivering unparalleled listening experiences. His impact on the industry continues to inspire both seasoned audiophiles and newcomers alike.“

@newton_john   +1

davey, Can you relay what the engineer said as regards the apparent looseness of the Karosel bearing as seen in the video under discussion? Thanks.

A very happy birthday to Ivor.

Ivor

Ahhhh….Hero worship…l love it

@mylogic 

Hero worship? Don’t think so.

On the one hand, he did great work promoting the importance of the source in hifi. On the other, he’s a Conservative. So feet of clay for me.

https://www.bbc.co.uk/news/uk-scotland-glasgow-west-11484322

....he’s a Conservative????

What does politics have to do with Hi~Fi ?

@newton_john 

Feet of Clay

It just dawned on me….You are right, and l get the joke now.

There IS politics in Hi-Fi

@lewm After I showed the engineer the video, he remarked that the bearing is a single point oil bearing. If I remember correctly, he mentioned that the oil is what acts as a surface for the tension between the shaft and the walls. I believe he mentioned that the shaft should not be that tight to interfere with rotational ability.

I believe it was also mentioned it is somewhat like a cam shaft sitting in an oil bearing of a car. He noticed the fact that the point was diamond hardened, stating this was a necessity for longer wear and that the precision of a reported 5 microns was also good.

Buy a Linn CD12 and no need for a fettler!

@jasonbourne71

The CD12 was great back in its heyday.

If anyone still wants one, Peter Tyson are selling one for about £4,000.

I heard it a few months ago against a Klimax DSM/3 Hub and a Klimax LP12. Sadly, the CD12 was outclassed by the newer sources.

Still, anyone one wanting to play CDs could probably do worse.

What exactly does 'diamond hardened' mean in this context?  I am looking for a metallurgical explanation, please!

@richardbrand 

You might find what you’re looking for here.

https://docs.linn.co.uk/wiki/index.php/Karousel

https://en.wikipedia.org/wiki/Diamond-like_carbon

Hope that helps.

@newton_john 

Thanks - exactly what I was looking for.  I will read "diamond hardened" to mean a "Diamond-Like Carbon Coating" which is likely to be plasma sputtered onto a substrate such as tool steel in a vacuum under tightly controlled conditions,

I admit I have trouble visualising the 'normal' crystal structure of diamond despite animations such as this:  Diamond cubic - Wikipedia

@richardbrand

No wonder it’s expensive.

Yes, I remember struggling at university with text book representations of three dimensional structures. It’s probably easier now with YouTube, etc.

   Linn has a way of adopting certain outside improvements to their LP12.  Case in point, the Bedrock plinth: The British outfit, "houseoflinn", Europe's Leading Linn Specialists(their quote) came up with a laminated Bamboo plinth, The Booplinth, years ago that was machined out of a single block laminated bamboo.  

   In the  August 1984 Page 51, issue of Hifi News And Record Review(J Atkinson was still editor), an article titled,"Sacrilege" by Martin Colloms, had to do with the reason LP12s had this sort of fat bass(personally I liked it and most owners), and he demonstrated the reason for it and a fix for it, the issue centered around the platter bearing/well.  The Cirkus wasn't released until (1993?) to address this issue.  By the way, I did Martin's fix and it worked marvelously( machinist made the part for me).  If you're an LP12 owner, a worthwhile read.  I still have my copy.  $2.75 at Krochs and Brentanos back then.  I think they're fifteen bucks or more now but still my favorite audio journal and authority on audio subjects.

@newton_john

Yes, and I studied crystallography for three years in the Cambridge lab set up by the Bragg father and son pair who invented X-ray diffraction crystallography.  Well before computers and computer graphics, and before Crick and Watson deduced the structure of DNA!  I can't even remember the names of the 2-D diagrams that showed the 3-D orientation of crystal planes ...

From another thread I've just discovered that Australia makes Dohmann turntables which also use Diamond-like coating for the main bearing.

@richardbrand

Fascinating Richard. It’s almost like everything is connected in some weird way. I also had experience of X-ray crystallography in a small way in the lab when studying Physics in the seventies at what is now the University of Westminster. I also had a great uncle who’d been some sort of technician/instrument maker at Cambridge and had worked with some of the great men who’d done much of the Physics that I was learning about. It wasn’t until later that I realised I'd missed the chance to ask him about them.

Since the focus of this thread seems to be the retail price of the new Linn plinth, I thought it might be worthwhile to post this extract from Pro-Ject's literature on their most expensive Signature turntable, which has a retail price of 12,000 Euros (my emphasis)

We‘re thrilled to offer these turntables at an extremely attractive price, as the development cost is not counted, as we anyway had to do the research to move forward with Pro-Ject technology in general

Obviously, all the development costs have been amortized in the revenue stream from their mass market products!

Every manufacturer has to cover their costs and make some profit, or they will go out of business.  Most manufacturers have high set up costs which have to be funded before the first unit makes its way to market.  After that, there are the direct costs associated with each extra unit produced.  So in setting a retail price, the manufacturer has to guess how many units they will sell so that the line becomes profitable once it reaches the breakeven number sold.  If the price is too high, the number sold may not even reach breakeven.

If the manufacturer only produces high-end expensive gear, they may need very deep pockets.  Wilson Benesch have been very adept at getting university collaboration and research grants to offset some development cost, at the time-cost of dealing with government!

Extreme examples of very high set up costs and low production costs include books, semi-conductor chips and polycarbonate disks which all have a unit direct production cost of around a dollar or less.

The above assumes that pricing is set on a rational value-for-money basis, but those rules don't apply to luxury goods where the consumer seemingly forgets about value-for-money and chases status and ego-boosting items.  I don't think the Bedrok is flashy enough to fall into the luxury category!

@richardbrand That’s an interesting point. I tend to agree with you that the Bedrok is not flashy enough to appeal to the folks who shop primarily with their eyes..and not their ears. 
However, since there have been a few Bedrok sales so far, I guess folk seem to believe that the SQ boost is worth it. 
I suspect these very same folk would have little problem with the same looking Bedrok if it was priced at three times the current ask. Question is what price is it that elicits push back??

Thanks - exactly what I was looking for.  I will read "diamond hardened" to mean a "Diamond-Like Carbon Coating" which is likely to be plasma sputtered onto a substrate such as tool steel in a vacuum under tightly controlled conditions,

No diamond hardening refers to a heating and cooling process used to harden the steel, it is not a coating. The Dohmann uses maraging steel - which is really an alloy, likely including elements of copper and nickel that results in a harder steel than ferrous metals, more stable.